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+title: "Adamic language"
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+
+The Adamic language, according to Abraham Abulafia and some Christians, is the language spoken by Adam (and possibly Eve) in the Garden of Eden. It is variously interpreted as either the language used by God to address Adam (the divine language), or the language invented by Adam with which he named all things (including Eve), as in the second Genesis creation narrative (Genesis 2:19).
+In the Middle Ages, various Jewish commentators held that Adam spoke Hebrew, a view also addressed in various ways by the late medieval Italian poet Dante Alighieri. In the early modern period, some authors continued to discuss the possibility of an Adamic language, some continuing to hold to the idea that it was Hebrew, while others such as John Locke were more skeptical. According to Ethiopian and Eritrean traditions, the ancient Semitic language of Geʽez is the language of Adam, the first and original language. More recently, a variety of Mormon authors have expressed various opinions about the nature of the Adamic language.
+
+== Patristic period ==
+Augustine addresses the issue in The City of God. While not explicit, the implication of there being but one human language prior to the Tower of Babel's collapse is that the language, which was preserved by Heber and his son Peleg, and which is recognized as the language passed down to Abraham and his descendants, is the language that would have been used by Adam.
+
+== Middle Ages ==
+
+Traditional Jewish exegesis such as Midrash says that Adam spoke the Hebrew language because the names he gives Eve – Isha and Chava – only make sense in Hebrew. By contrast, Abraham Abulafia (1240-1291) assumed that the language spoken in Paradise had been different from Hebrew, and rejected the claim then-current also among Christian authors, that a child left unexposed to linguistic stimulus would automatically begin to speak in Hebrew. 
+Both Muslim and Christian Arabs, such as Sulayman al-Ghazzi, considered Syriac the language spoken by Adam and Eve.
+Umberto Eco (1993) notes that Genesis is ambiguous on whether the language of Adam was preserved by Adam's descendants until the confusion of tongues, or if it began to evolve naturally even before Babel.
+Dante Alighieri addresses the topic in his De vulgari eloquentia (1302–1305). He argues that the Adamic language is of divine origin and therefore unchangeable. He also notes that according to Genesis, the first speech act is due to Eve, addressing the serpent, and not to Adam. Paracelsus believed in an Adamic language, as did Johann Reuchlin.
+In his Divine Comedy (c. 1308–1320), however, Dante changes his view to another that treats the Adamic language as the product of Adam. This had the consequence that it could no longer be regarded as immutable, and hence Hebrew could not be regarded as identical with the language of Paradise. Dante concludes (Paradiso XXVI) that Hebrew is a derivative of the language of Adam. In particular, the chief Hebrew name for God in scholastic tradition, El, must be derived of a different Adamic name for God, which Dante gives as I.
+
+== Early modern period ==
+
+=== Proponents ===
+
+Elizabethan scholar John Dee makes references to a language he called "Angelical", which he recorded in his private journals and those of scryer Edward Kelley. Dee's journals did not describe the language as "Enochian", instead preferring "Angelical", the "Celestial Speech", the "Language of Angels", the "First Language of God-Christ", the "Holy Language", or "Adamical" because, according to Dee's Angels, it was used by Adam in Paradise to name all things. The language was later dubbed Enochian, due to Dee's assertion that the Biblical Patriarch Enoch had been the last human (before Dee and Kelley) to know the language.
+Dutch physician, linguist, and humanist Johannes Goropius Becanus (1519–1572) theorized in Origines Antwerpianae (1569) that Antwerpian Babrantic, spoken in the region between the Scheldt and Meuse Rivers, was the original language spoken in Paradise. Goropius believed that the most ancient language on Earth would be the simplest language, and that the simplest language would contain mostly short words. Since Brabantic has a higher number of short words than do Latin, Greek, and Hebrew, Goropius reasoned that it was the older language. His work influenced that of Simon Stevin (1548–1620), who espoused similar ideas in "Uytspraeck van de weerdicheyt der Duytse tael", a chapter in De Beghinselen Der Weeghconst (1586).
+By the 17th century, Adamic was the most popular theory of the nature of language.
+
+=== Opponents ===
+The existence and nature of the alleged Adamic language was commonly discussed amongst European Jewish and Christian mystics and primitive linguists. Robert Boyle (1627–1691) was skeptical that Hebrew was the language best capable of describing the nature of things, stating:
+
+I could never find, that the Hebrew names of animals, mentioned in the beginning of Genesis, argued a (much) clearer insight into their natures, than did the names of the same or some other animals in Greek, or other languages (1665:45).
+John Locke (1632–1704) expressed similar skepticism in his An Essay Concerning Human Understanding (1690).
+
+== Modern period ==

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+title: "Adamic language"
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+
+=== Latter Day Saint movement ===
+Joseph Smith, founder of the Latter Day Saint movement, in his revision of the Bible, declared the Adamic language to have been "pure and undefiled". Some Mormons believe it to be the language of God. Glossolalia, or speaking in tongues, was commonplace in the early years of the movement, and it was commonly believed that the incomprehensible language spoken during these incidents was the language of Adam. However, this belief seems to have never been formally or officially adopted.
+Some other early Latter Day Saint leaders, including Brigham Young, Orson Pratt, and Elizabeth Ann Whitney, claimed to have received several words in the Adamic language by revelation. Some Latter Day Saints believe that the Adamic language is the "pure language" spoken of by Zephaniah and that it will be restored as the universal language of humankind at the end of the world.
+Apostle Orson Pratt declared that "Ahman", part of the name of the settlement "Adam-ondi-Ahman" in Daviess County, Missouri, was the name of God in the Adamic language. An 1832 handwritten page from the Joseph Smith Papers, titled "A Sample of the Pure Language", and reportedly dictated by Smith to "Br. Johnson", asserts that the name of God is Awman.
+The Latter Day Saint endowment prayer circle once included use of the words "Pay Lay Ale". These untranslated words are no longer used in temple ordinances and have been replaced by an English version, "O God, hear the words of my mouth". Some believe that the "Pay Lay Ale" sentence is derived from the Hebrew phrase "pe le-El" (פה לאל), "mouth to God".  "Pay Lay Ale" was identified in the temple ceremony as words from the "pure Adamic language".
+Other words thought by some Latter Day Saints to derive from the Adamic language include deseret ("honey bee") and Ahman ("God").
+The Book of Moses refers to "a book of remembrance" written in the language of Adam.
+
+=== Goidelic languages ===
+Nicholas Wolf writes that 19th-century Irish language speakers and publications claim that Irish (or some Goidelic language) is a language of Biblical primacy comparable to Hebrew, with some claiming it was the language of Adam.
+
+== In popular culture ==
+In the videogame Indiana Jones and the Great Circle, the language Adamic is discovered by the protagonist as an early human language spoken by giants, which was adapted into Egyptian and Sumerian in ancient times. It is also represented on stone tablets, resembling logographic writing systems of the early Bronze Age.
+
+== See also ==
+History of linguistics
+Mythical origins of language
+Origin of language
+Proto-Human language
+Universal language
+Enochian
+Sacred language
+
+== References ==
+
+== Bibliography ==
+Allison P. Coudert (ed.), The Language of Adam = Die Sprache Adams, Wiesbaden: Harrassowitz, 1999.
+Angelo Mazzocco, Linguistic Theories in Dante and the Humanists, (chapter 9: "Dante's Reappraisal of the Adamic language", 159–181).
+Umberto Eco, The Search for the Perfect Language (1993).

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+title: "Ancient Near Eastern cosmology"
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+
+The cosmology of the ancient Near East refers to beliefs about where the universe came from, how it developed, and its physical layout, in the ancient Near East, an area that corresponds with the Middle East today (including Mesopotamia, Egypt, Persia, the Levant, Anatolia, and the Arabian Peninsula). The basic understanding of the world in this region from premodern times included a flat earth, a solid layer or barrier above the sky (the firmament), a cosmic ocean located above the firmament, a region above the cosmic ocean where the gods lived, and a netherworld located at the furthest region in the direction down. Creation myths explained where the universe came from, including which gods created it (and how), as well as how humanity was created. These beliefs are attested as early as the fourth millennium BC and dominated until the modern era, with the only major competing system being the Hellenistic cosmology that developed in Ancient Greece in the mid-1st millennium BC.
+Geographically, these views are known from the Mesopotamian cosmologies from Babylonia, Sumer, and Akkad; the Levantine or West Semitic cosmologies from Ugarit and ancient Israel and Judah (the biblical cosmology); the Egyptian cosmology from Ancient Egypt; and the Anatolian cosmologies from the Hittites. This system of cosmology went on to have a profound influence on views in early Greek cosmology, later Jewish cosmology, patristic cosmology, and Islamic cosmology (including Quranic cosmology).
+
+== Summary ==
+The cosmology of the ancient Near East can be divided into cosmography, the understanding of the physical structure and features of the cosmos, and cosmogony, the creation myths describing the origins of the cosmos. The cosmos and the gods were also related, as cosmic bodies like heaven, earth, the stars were believed to be and/or personified as gods, and the sizes of the gods were frequently described as being of cosmic proportions. 
+
+=== Cosmography (structure of the cosmos) ===
+The many civilizations of the ancient Near East shared most of their main views about the structure of the cosmos, a situation which held for thousands of years. Widely held beliefs about cosmography included: 
+
+a flat earth and a solid heaven (firmament), both of which are disk-shaped
+a primordial cosmic ocean. When the firmament is created, it separates the cosmic ocean into two bodies of water:
+the heavenly upper waters located on top of the firmament, which act as a source of rain
+the lower waters that the earth is above and that the earth rests on; they act as the source of rivers, springs, and other earthly bodies of water
+the region above the upper waters, namely the abode of the gods
+the netherworld, the furthest region in the direction downwards, below the lower waters
+Paul Keyser categorizes the cosmology of the ancient Near East into a larger, cross-cultural group of cosmologies that he calls a "cradle cosmology", and Keyser suggests an even larger number of shared features between them all.
+Some misconceptions are held about Near Eastern cosmography. One misconception is the idea that ziggurats were considered cosmic objects that reached all the way up to heaven. Another misconception is that the firmament was shaped like a dome or a vault, whereas in reality, it was believed to be flat.
+Another controversy concerns whether the ancients thought this cosmography was literal or observational (phenomenological). John Hilber argues that ancient Near Eastern cosmography was not phenomenological for many reasons, including: based on the descriptions provided by cosmological texts, that non-cosmological texts assume the reality of this cosmography (like in incantations), anthropological studies showing that there are primitive cosmologies still believed in today and that these are not phenomenological, and that there is a cognitive expectation that humans will construct models to explain the observations they make, and that the cosmography described in cosmological texts would have played this role.
+
+=== Cosmogony (creation of the cosmos) ===
+Many widely held beliefs permeated the creation myths of ancient Near Eastern cosmogony: 
+
+Creatio ex materia from a primordial state of chaos; that is, the organization of the world from pre-existing, unordered and unformed (hence chaotic) elements, represented by a primordial body of water
+the presence of a divine creator
+the Chaoskampf motif: a cosmic battle between the protagonist and a primordial sea monster
+the separation of undifferentiated elements (to create heaven and earth)
+the creation of mankind
+Lisman uses the broader category of "Beginnings" to encompass three separate though inter-related categories: the beginning of the cosmos (cosmogony), the beginning of the gods (theogony), and the beginning of humankind (anthropogeny).
+There is evidence that Mesopotamian creation myths reached as far as Pre-Islamic Arabia.
+
+== Cosmos ==
+
+=== Overview ===
+The Mesopotamian cosmos can be understood as multiple planes of existence, layered above one another. The highest plane of existence was heaven, which was the home of the sky god Anu. Below heaven was the atmosphere which ranged from the bottom of heaven (or the lowermost firmament) to the ground that humans walk on. This region between heaven and earth was inhabited by Enlil, the king of the gods in Sumerian mythology. Below the ground was the cosmic ocean, and this was believed to be the place of residence of the sibling deities Enki and Ninhursag. The lowest plane of existence was the underworld. Other deities inhabited these planes of existence even if they did not reign over them, such as the sun and moon gods. In later Babylonian accounts, the god Marduk alone ascends to the top rank of the pantheon and rules over all domains of the cosmos. The three-tiered cosmos (sky-earth-underworld) is found in Egyptian artwork on coffin lids and burial chambers.

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+
+==== Terminology ====
+There were many ways to speak about or refer to the totality of the world, equivalent to contemporary words like "cosmos" or "universe". This included phrases like "heaven and earth" or "heaven and underworld". Terms like "all" or "totality" similarly connoted the entire universe. These ideas are found in hymns and royal inscriptions found in temples. Temples symbolized cosmic structures that reached heaven at their height and the underworld at their depths/foundations. Surviving evidence does not specify the exact physical bounds of the cosmos or what lies beyond the region described in the texts.
+
+==== Unity ====
+Mythical bonds, akin to ropes or cables, played the role of cohesively holding the entire world and all its layers of heaven and Earth together. These are sometimes called the "bonds of heaven and earth". They can be referred to with terminology like durmāhu (typically referring to a strong rope made of reeds), markaṣu (referring to a rope or cable, of a boat, for example), or ṣerretu (lead-rope passed through an animals nose). A deity can hold these ropes as a symbol of their authority, such as the goddess Ishtar "who holds the connecting link of all heaven and earth (or netherworld)". This motif extended to descriptions of great cities like Babylon which was called the "bond of [all] the lands," or Nippur which was "bond of heaven and earth," and some temples as well.
+
+==== Center ====
+The idea of a center to the cosmos played a role in elevating the status of whichever place was chosen as the cosmic center and in reflecting beliefs of the finite and closed nature of the cosmos. Babylon was described as the center of the Babylonian cosmos. In parallel, Jerusalem became "the navel of the earth" (Ezekiel 38:12). The finite nature of the cosmos was also suggested to the ancients by the periodic and regular movements of the heavenly bodies in the visible vicinity of the Earth.
+
+=== Heaven and earth ===
+"Heaven and earth" was a common phrase to the refer to the entire cosmos, describing it by its two main parts. Sometimes, a third region was added to refer to the entire cosmos in addition to these two, usually the netherworld or the region between heaven and earth. Heaven was believed to be located in the direction up (the word "heavenward" was synonymous with "upward"). It was the dwelling place of the gods, whereas earth was the dwelling place for humans. "Earth" means the land and the sea, but sometimes, it only means land (the terrestrial regions inhabited by humans and where they grew vegetation). The word heaven could refer to the general plane upwards inaccessible to humans, but often, it specifically means the firmament (a solid celestial barrier believed to be located above the sky). Although the gods and humans live in the two different planes of the cosmos in the present, some creation mythologies held that gods and humans once co-existed in the primordial past. In some myths, gods could dwell at the extreme ends of the earth, still beyond human reach. Temples could function as a cosmic axis that united the heavenly and earthly planes.
+
+==== Three heavens and earths ====
+In Mesopotamian cosmology, heaven and earth both had a three-part (tripartite) structure: a Lower Heaven/Earth, a Middle Heaven/Earth, and an Upper Heaven/Earth. The Upper Earth was where humans existed. Middle Earth, corresponding to the Abzu (primeval underworldly ocean), was the residence of the god Enki. Lower Earth, the Mesopotamian underworld, was where the 600 Anunnaki gods lived, associated with the land of the dead ruled by Nergal. As for the heavens: the highest level was populated by 300 Igigi (great gods), the middle heaven belonged to the Igigi and also contained Marduk's throne, and the lower heaven was where the stars and constellations were inscribed into. The extent of the Babylonian universe therefore corresponded to a total of six layers spanning across heaven and Earth. Notions of the plurality of heaven and earth are no later than the 2nd millennium BC and may be elaborations of earlier and simpler cosmographies. One text (KAR 307) describes the cosmos in the following manner, with each of the three floors of heaven being made of a different type of stone:30 “The Upper Heavens are Luludānītu stone. They belong to Anu. He (i.e. Marduk) settled the 300 Igigū (gods) inside. 31 The Middle Heavens are Saggilmud stone. They belong to the Igīgū (gods). Bēl (i.e. Marduk) sat on the high throne within, 32 the lapis lazuli sanctuary. And made a lamp? of electrum shine inside (it). 33 The Lower Heavens are jasper. They belong to the stars. He drew the constellations of the gods on them. 34 In the ... .... of the Upper Earth, he lay down the spirits of mankind. 35 [In the ...] of the Middle earth, he settled Ea, his father. 36 [.....] . He did not let the rebellion be forgotten. 37 [In the ... of the Lowe]r earth, he shut inside 600 Anunnaki. 38 [.......] ... [.... in]side jasper. Another text (AO 8196) offers a slightly different arrangement, with the Igigi in the upper heaven instead of the middle heaven, and with Bel placed in the middle heaven. Both agree on the placement of the stars in the lower heaven. Exodus 24:9–10 identifies the floor of heaven as being like sapphire, which may correspond to the blue lapis lazuli floor in KAR 307, chosen potentially for its correspondence to the visible color of the sky. One hypothesis holds that the belief that the firmament is made of stone (or a metal, such as iron in Egyptian texts) arises from the observation that meteorites, which are composed of this substance, fall from the firmament.
+
+==== Seven heavens and earths ====

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+
+=== Survival ===
+Copies from the Sippar Library indicate the Enuma Elish was copied into Seleucid times. One Hellenistic-era Babylonian priest, Berossus, wrote a Greek text about Mesopotamian traditions called the Babyloniaca (History of Babylon). The text survives mainly in fragments, especially by quotations in Eusebius in the fourth-century. The first book contains an account of Babylonian cosmology and, though concise, contains a number of echoes of the Enuma Elish. The creation account of Berossus is attributed to the divine messenger Oannes in the period after the global flood and is derivative of the Enuma Elish but also has significant variants to it. Babylonian cosmology also received treatments by the lost works of Alexander Polyhistor and Abydenus. The last known evidence for reception of the Enuma Elish is in the writings of Damascius (462–538), who had a well-informed source. As such, some learned circles in late antiquity continued to know the Enuma Elish. Echoes of Mesopotamian cosmology continue into the 11th century.
+
+=== Early Greek cosmology ===
+
+Early Greek cosmology was closely related to the broader domain of ancient near eastern cosmology, reflected 8th century BC works like the Theogony of Hesiod and the works of Homer, and prior to the emergence of an independent and systematic Hellenistic system of cosmology that was represented by figures such as Aristotle and the astronomer Ptolemy, starting with the Ionian School of philosophy at the city of Miletus from the 6th to 4th centuries BC. In early Greek cosmology, the Earth was conceived of as being flat, encircled by a cosmic ocean known as Oceanus, and that heaven was a solid firmament held above the Earth by pillars. Many believe that a Hurro-Hittite work from the 13th century BC, the Song of Emergence (CTH 344), was directly used by Hesiod on the basis of extensive similarities between their accounts.
+The notion of heaven and earth originally being in unity followed by their separation continues to be attested in later Greek cosmological texts, such as in the descriptions of Orphic cosmology according to the Wise Melanippe of Euripides in the 5th century BC and the Argonautica by Apollonius of Rhodes in the 3rd century BC, as well as in other and still later Greek accounts, such as the writings of Diodorus Siculus in the 1st century BC.
+
+=== Zoroastrian cosmology ===
+
+The earliest Zoroastrian sources describe a tripartite sky, with an upper heaven where the sun exists, a middle heaven where the moon exists, and a lower heaven where the stars exist and are fixed. Significant work has been done on comparing this cosmography to ones present in Mesopotamian, Greek, and Indian parallels. In light of evidence which has emerged in recent decades, the present view is that this idea entered into Zoroastrian thought through Mesopotamian channels of influence. Another influence is that the name that one of the planets took on in Middle Persian literature, Kēwān (for Saturn), was derived from the Akkadian language.
+
+=== Jewish cosmology ===
+
+Mesopotamian cosmology, especially as it manifested in the biblical Genesis creation narrative, exerted continued substantial influence on Jewish cosmology, especially as it is described in the rabbinic literature. Not all influence appears to have been mediated through the Bible. The dome-shaped firmament was described in Hebrew as a kippah, which has been related to its Akkadian cognate kippatšamê, though the latter only refers to flat objects. The Jewish belief in seven heavens, as it is absent from the Hebrew Bible, has often been interpreted as being taken from early interactions with Mesopotamian cosmologies.
+
+=== Christian cosmology ===
+
+Christian texts were familiar with ancient near eastern cosmology insofar as it had shaped the Genesis creation narrative. A genre of literature emerged among Jews and Christians dedicated to the composition of texts commenting precisely on this narrative to understand the cosmos and its origins: these works are called Hexaemeron. The first extant example is the De opificio mundi ("On the Creation of the World") by the first-century Jewish philosopher Philo of Alexandria. Philo preferred an allegorical form of exegesis, in line with that of the School of Alexandria, and so was partial to a Hellenistic cosmology as opposed to an ancient near eastern one. In the late fourth century, the Hexaemeral genre was revived and popularized by the Hexaemeron of Basil of Caesarea, who composed his Hexaemeron in 378, which subsequently inspired numerous works including among Basil's own contemporaries. Basil was much more literal in his interpretation than Philo, closer instead to the exegesis of the School of Antioch. Christian authors would heavily dispute the correct degree of literal or allegorical exegesis in future writings. Among Syrian authors, Jacob of Serugh was the first to produce his own Hexaemeron in the early sixth century, and he was followed later by Jacob of Edessa's Hexaemeron in the first years of the eighth century. The most literal approach was that of the Christian Topography by Cosmas Indicopleustes, which presented a cosmography very similar to the traditional Mesopotamian one, but in turn, John Philoponus wrote a harsh rebuttal to Cosmas in his own De opificio mundi. Syrian Christian texts also shared topographical features like the cosmic ocean surrounding the earth.

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+title: "Ancient Near Eastern cosmology"
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+
+Cosmographies were described in works other than those of the Hexaemeral genre. For example, in the genre of novels, the Alexander Romance would portray a mythologized picture of the journeys and conquests of Alexander the Great, ultimately inspired by the Epic of Gilgamesh. The influence is evident in the texts cosmography, as Alexander reaches an outer ocean circumscribing the Earth which cannot be passed. Both in the Alexander Romance, and in later texts like the Syriac Alexander Legend (Neshana), Alexander journeys to the ends of the Earth which is surrounded by an ocean. Unlike in the story of Gilgamesh, however, this ocean is an unpassable boundary that marks the extent to which Alexander can go. The Neshana also aligns with a Mesopotamian cosmography in its description of the path of the sun: as the sun sets in the west, it passes through a gateway in the firmament, cycles to the other side of the earth, and rises in the east in its passage through another celestial gateway. Alexander, like Gilgamesh, follows the path of the sun during his journey. These elements of Alexander's journey are also described as part of the journey of Dhu al-Qarnayn in the Quran. Gilgamesh's journey takes him to a great cosmic mountain Mashu; likewise, Alexander reaches a cosmic mountain known as Musas. The cosmography depicted in this text greatly resembles that outlined by the Babylonian Map of the World.
+
+=== Quranic cosmology ===
+
+The Quran conceives of the primary elements of the ancient near eastern cosmography, such as the division of the cosmos into the heavens and the Earth, a solid firmament, upper waters, a flat Earth, and seven heavens. As with rabbinic cosmology, however, these elements were not directly transmitted from ancient near eastern civilization. Instead, work in the field of Quranic studies has identified the primary historical context for the reception of these ideas to have been in the Christian and Jewish cosmologies of late antiquity. This conception of the cosmos was carried on into the traditionalist cosmologies that were held in the caliphate, though with a few nuances that appear to have emerged.
+
+== See also ==
+Ancient Mesopotamian religion
+Creation of life from clay
+Hexaemeron
+Pre-Islamic Arabian inscriptions
+King of the Universe
+Mandaean cosmology
+Panbabylonism
+Quranic studies
+
+== References ==
+
+=== Notes ===
+
+=== Citations ===
+
+=== Sources ===
+
+== Further reading ==
+Assman, Jan. The Search for God in Ancient Egypt, Cornell University Press, 2001, pp. 53–82.
+Clifford, Richard. Creation Accounts in the Ancient Near East and in the Bible, Wipf and Stock Publishers, 1994.
+Dalley, Myths from Mesopotamia: Creation, the Flood, Gilgamesh, and Others, Oxford University Press, 1998.
+George, A. Babylonian Topographical Texts, Peeters, 1992.
+Hetherington, Norriss S (ed.). Encyclopedia of Cosmology, Routledge, 2014.
+Hunger, Hermann, and John Steele, The Babylonian Astronomical Compendium MUL.APIN, Routledge, 2018.
+Jacobsen, Thorkild. "The Cosmos as a State" in The Intellectual Adventure of Ancient Man: An Essay of Speculative Thought in the Ancient Near East, University of Chicago Press, 1977.
+Keel, Othmar & Silvia Shroer, Creation: Biblical Theologies in the Context of the Ancient Near East, Eisenbrauns, 2015.
+Lu, Rosanna (2024). The Transformation of Tĕhôm: From Deified Power to Demonized Abyss. Brill.
+Sjöberg, Å. "In the beginning" in Riches Hidden in Secret Places: Ancient Near Eastern Studies in Memory of Thorkild Jacobsen, Eisenbrauns, 2002, pp. 229–247.
+Wiggermann, F. "Mythological foundations of nature" in Natural Phenomena: Their Meaning, Depiction and Description in the Ancient Near East, 1992.
+Zago, Silvia. A Journey through the Beyond: The Development of the Concept of Duat and Related, Lockwood Press, 2022.
+
+== External links ==
+Mesopotamian Creation Myths (Metropolitan Museum of Art)

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+
+Some texts describe seven heavens and seven earths, but within the Mesopotamian context, this is likely to refer to a totality of the cosmos with some sort of magical or numerological significance, as opposed to a description of the structural number of heavens and Earth. Israelite texts do not mention the notion of seven heavens or earths.
+
+=== Firmament ===
+
+The firmament was believed to be a solid boundary above the Earth, separating it from the upper or celestial waters. In the Book of Genesis, it is called the raqia. In ancient Egyptian texts, and from texts across the Near East generally, the firmament was described as having special doors or gateways on the eastern and western horizons to allow for the passage of heavenly bodies during their daily journeys. These were known as the windows of heaven or the gates of heaven. Canaanite text describe Baal as exerting his control over the world by controlling the passage of rainwater through the heavenly windows in the firmament. In Egyptian texts particularly, these gates also served as conduits between the earthly and heavenly realms for which righteous people could ascend. The gateways could be blocked by gates to prevent entry by the deceased as well. As such, funerary texts included prayers enlisting the help of the gods to enable the safe ascent of the dead. Ascent to the celestial realm could also be done by a celestial ladder made by the gods. Multiple stories exist in Mesopotamian texts whereby certain figures ascend to the celestial realm and are given the secrets of the gods.
+Four different Egyptian models of the firmament and/or the heavenly realm are known. One model was that it was the shape of a bird: the firmament above represented the underside of a flying falcon, with the sun and moon representing its eyes, and its flapping causing the wind that humans experience. The second was a cow, as per the Book of the Heavenly Cow. The cosmos is a giant celestial cow represented by the goddess Nut or Hathor. The cow consumed the sun in the evening and rebirthed it in the next morning. The third is a celestial woman, also represented by Nut. The heavenly bodies would travel across her body from east to west. The midriff of Nut was supported by Shu (the air god) and Geb (the earth god) lay outstretched between the arms and feet of Nut. Nut consumes the celestial bodies from the west and gives birth to them again in the following morning. The stars are inscribed across the belly of Nut and one needs to identify with one of them, or a constellation, in order to join them after death. The fourth model was a flat (or slightly convex) celestial plane which, depending on the text, was thought to be supported in various ways: by pillars, staves, scepters, or mountains at the extreme ends of the Earth. The four supports give rise to the motif of the "four corners of the world".
+
+=== Earth ===
+
+The ancient Near Eastern earth was a single-continent disk resting on a body of water sometimes compared to a raft. An aerial view of the cosmography of the earth is pictorially elucidated by the Babylonian Map of the World. Here, the city Babylon is near the Earth's center and it is on the Euphrates river. Other kingdoms and cities surround it. The north is covered by an enormous mountain range, akin to a wall. This mountain range was traversed in some hero myths, such as the Epic of Gilgamesh where Gilgamesh travels past it to an area only accessible by gods and other great heroes. The furthest and most remote parts of the earth were believed to be inhabited by fantastic creatures. In the Babylonian Map, the world continent is surrounded by a bitter salt-water Ocean (called marratu, or "salt-sea") akin to Oceanus described by the poetry of Homer and Hesiod in early Greek cosmology, as well as the statement in the Bilingual Creation of the World by Marduk that Marduk created the first dry land surrounded by a cosmic sea. Egyptian cosmology appears to have also shared this view, as one of the words used for sea, shen-wer, means "great encircler". World-encircling oceans are also found in the Fara tablet VAT 12772 from the 3rd millennium BC and the Myth of Etana.
+
+==== Four corners of the earth ====
+Texts mention the four corners of the world, referring to the extremities of the world. A common title among powerful kings who ascribed to themselves that they ruled over this area was King of the Four Corners. For example, Hammurabi (ca. 1810–1750 BC) received the title of "King of Sumer and Akkad, King of the Four Quarters of the World". Monarchs of the Assyrian empire like Ashurbanipal also took on this title. (Although the title implies a square or rectangular shape, in this case it is taken to refer to the four quadrants of a circle which is joined at the world's center.) Likewise, the "four corners" motif would also appear in some biblical texts, such as Isaiah 11:12.
+In Greco-Roman and Jewish literature, the phrase "ends of the earth" referred to the outermost points of the earth that terminated at Oceanus, the outer ocean circling around the earth disc. The furthest point south was identified with Ethiopia and Sheba, and to the West, Spain, specifically the city of Gades.
+
+==== Cosmic mountain ====

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+According to iconographic and literary evidence, the cosmic mountain, known as Mashu in the Epic of Gilgamesh, was thought to be located at or extend to both the westernmost and easternmost points of the earth, where the sun could rise and set respectively. As such, the model may be called a bi-polar model of diurnal solar movement. The gates for the rising and setting of the sun were also located at Mashu. Some accounts have Mashu as a tree growing at the center of the earth with roots descending into the underworld and a peak reaching to heaven. The cosmic mountain is also found in Egyptian cosmology, as Pyramid Text 1040c says that the mountain ranges on the eastern and western sides of the Nile act as the "two supports of the sky." In the Baal Cycle, two cosmic mountains exist at the horizon acting as the point through which the sun rises from and sets into the underworld (Mot). The tradition of the twin cosmic mountains may also lie behind Zechariah 6:1.
+
+=== Heavenly bodies ===
+
+==== Sun ====
+The sun god (represented by the god Utu in Sumerian texts or Shamash in Akkadian texts) rises in the day and passes over the earth. Then, the sun god falls beneath the earth in the night and comes to a resting point. This resting point is sometimes localized to a designated structure, such as the chamber within a house in the Old Babylonian Prayer to the Gods of the Night. To complete the cycle, the sun comes out in the next morning. Likewise, the moon was thought to rest in the same facility when it was not visible. A similar system was maintained in Egyptian cosmology, where the sun travelled beneath the surface of the earth through the underworld (known among ancient Egyptians as Duat) to rise from the same eastern location each day. These images result from anthropomorphizing the sun and other astral bodies also conceived as gods. For the sun to exit beneath the earth, it had to cross the solid firmament: this was thought possible by the existence of opening ways or corridors in the firmament (variously illustrated as doors, windows or gates) that could temporarily open and close to allow astral bodies to pass across them. The firmament was conceived as a gateway, with the entry/exit point as the gates; other opening and closing mechanisms were also imagined in the firmament like bolts, bars, latches, and keys. During the sun's movement beneath the earth, into the netherworld, the sun would cease to flare. This enabled the netherworld to remain dark. But when it rose, it would flare up and again emit light. This model of the course of the sun had an inconsistency that later models evolved to address. The issue was to understand how, if the sun came to a resting point beneath the earth, could it also travel beneath the earth the same distance under it that it was observed to cross during the day above it such that it would rise periodically from the east. One solution that some texts arrived at was to reject the idea that the sun had a resting point. Instead, it remained unceasing in its course. 
+Overall, the sun god's activities in night according to Sumerian and Akkadian texts proceeds according to a regular and systematic series of events: (1) The western door of heaven opens (2) The sun passes through the door into the interior of heaven (3) Light falls below the western horizon (4) The sun engages in certain activities in the netherworld like judging the dead (5) The sun enters a house, called the White House (6) The sun god eats the evening meal (7) The sun god sleeps in the chamber agrun (8) The sun emerges from the chamber (9) The eastern door opens and the sun passes through as it rises. In many ancient near eastern cultures, the underworld had a prominent place in descriptions of the sun journey, where the sun would carry out various roles including judgement related to the dead. 
+
+In legend, many hero journeys followed the daily course of the sun god. These have been attributed to Gilgamesh, Odysseus, the Argonauts, Heracles and, in later periods, Alexander the Great. In the Epic of Gilgamesh, Gilgamesh reaches the cosmic mountain Mashu, which is either two mountains or a single twin-peaked mountain. Mashu acts as the sun-gate, from where the sun sets in its path to and out from the netherworld. In some texts, the mountain is called the mountain of sunrise and sunset. According to the Epic: 
+The name of the mountain was Mashu. When [he] arrived at Mount Mashu, which daily guards the rising [of the sun,] – their tops [abut] the fabric of the heavens, their bases reach down to Hades – there were scorpion-men guarding its gate, whose terror was dread and glance was death, whose radiance was terrifying, enveloping the uplands – at both sunrise and sunset they guard the sun... 
+Another texts describing the relationship between the sun and the cosmic mountain reads: 
+O Shamash, when you come forth from the great mountain, When you come forth from the great mountain, the mountain of the deep, When you come forth from the holy hill where destinies are ordained, When you [come forth] from the back of heaven to the junction point of heaven and earth...A number of additional texts share descriptions like these.

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+
+==== Moon ====
+Mesopotamians believed the moon to be a manifestation of the moon god, known as Nanna in Sumerian texts or Sîn in Akkadian texts, a high god of the pantheon, subject to cultic devotion, and father of the sun god Shamash and the Venus god Inanna. The path of the moon in the night sky and its lunar phases were also of interest. At first, Mesopotamia had no common calendar, but around 2000 BC, the semi-lunar calendar of the Sumerian center of Nippur became increasingly prevalent. Hence, the moon god was responsible for ordering perceivable time. The lunar calendar was divided into twelve months of thirty days each. New months were marked by the appearance of the moon after a phase of invisibility. The Enuma Elish creation myth describes Marduk as arranging the paths of the stars and then spends considerable space on Marduk's ordering of the moon:12 He made Nannaru (=the moon-god) appear (and) entrusted the night to him. 13 He assigned him as the jewel of the night to determine the days. 14 Month by month without cease, he marked (him) with a crown: 15 “At the beginning of the month, while rising over the land, 16 you shine with horns to reveal six days. 17 On the seventh day, (your) disc shall be halved. 18 On the fifteenth day, in the middle of each month, you shall stand in opposition. 19 As soon as Šamaš (= the sun-god) sees you on the horizon, 20 reach properly your full measure and form yourself back. 21 At the day of disappearance, approach the path of Šamaš. 22 [... 3]0. day you shall stand in conjunction. You shall be equal to Šamaš. The ideal course of the moon was thought to form one month every thirty days. However, the precise lunar month is 29.53 days, leading to variations that made the lunar month counted as 29 or 30 days in practice. The mismatch between the predictions and reality of the course of the moon gave rise to the idea that the moon could act according to its expected course as a good omen or deviate from it as a bad omen. In the 2nd millennium BC, Mesopotamian scholars composed the Enūma Anu Enlil, a collection of at least seventy tablets concerned with omens. The first fourteen (1–14) relate to the appearance of the moon, and the next eight (15–22) deal with lunar eclipses. 
+The moon was also assigned other functions, such as providing illumination during the night, and already in this period, had a known influence on the tides. During the day when the moon was not visible, it was thought that the moon descended beneath the flat disk of the earth and, like the sun, underwent a voyage through the underworld. The cosmic voyage and motion of the moon also allowed it to exert influence over the world; this belief naturally allowed for the practice of divination to arise.
+
+==== Stars and planets ====
+
+Mesopotamian cosmology would differ from the practice of astronomy in terms of terminology: for astronomers, the word "firmament" was not used but instead "sky" to describe the domain in which the heavenly affairs were visible. The stars were located on the firmament. The earliest texts attribute to Anu, Enlil, and Enki (Ea) the ordering of perceivable time by creating and ordering the courses of the stars. Later, according to the Enuma Elish, the stars were arranged by Marduk into constellations representing the images of the gods. The year was fixed by organizing the year into twelve months, and by assigning (the rising of) three stars to each of the twelve months. The moon and zenith were also created. Other phenomena introduced by Marduk included the lunar phases and lunar scheme, the precise paths that the stars would take as they rose and set, the stations of the planets, and more. Another account of the creation of the heavenly bodies is offered in the Babyloniaca of Berossus, where Bel (Marduk) creates stars, sun, moon, and the five (known) planets; the planets here do not help guide the calendar (a lack of concern for the planets also shared in the Book of the Courses of the Heavenly Luminaries, a subsection of 1 Enoch). Concern for the establishment of the calendar by the creation of heavenly bodies as visible signs is shared in at least seven other Mesopotamian texts. A Sumerian inscription of Kudur-Mabuk, for example, reads "The reliable god, who interchanges day and night, who establishes the month, and keeps the year intact." Another example is to be found in the Exaltation of Inanna.
+
+The word "star" (mul in Sumerian; kakkabu in Akkadian) was inclusive to all celestial bodies, stars, constellations, and planets. A more specific term for planets existed however (udu.idim in Sumerian; bibbu in Akkadian, literally "wild sheep") to distinguish them from other stars (of which they were a subcategory): unlike the stars thought to be fixed into their location, the planets were observed to move. By the 3rd millennium BC, the planet Venus was identified as the astral form of the goddess Inanna (or Ishtar), and motifs such as the morning and evening star were applied to her. Jupiter became Marduk (hence the name "Marduk Star", also called Nibiru), Mercury was the "jumping one" (in reference to its comparatively fast motion and low visibility) associated with the gods Ninurta and Nabu, and Mars was the god of pestilence Nergal and thought to portend evil and death. Saturn was also sinister. The most obvious characteristic of the stars were their luminosity and their study for the purposes of divination, solving calendrical calculations, and predictions of the appearances of planets, led to the discovery of their periodic motion. From 600 BC onwards, the relative periodicity between them began to be studied.
+
+=== Upper waters ===

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+Above the firmament was a large, cosmic body of water which may be referred to as the cosmic ocean or celestial waters. In the Tablet of Shamash, the throne of the sun god Shamash is depicted as resting above the cosmic ocean. The waters are above the solid firmament that covers the sky. In the Enuma Elish, the upper waters represented the waters of Tiamat, contained by Tiamat's stretched out skin. Canaanite mythology in the Baal Cycle describes the supreme god Baal as enthroned above the freshwater ocean. Egyptian texts depict the sun god sailing across these upper waters. Some also convey that this body of water is the heavenly equivalent of the Nile River.
+
+=== Lower waters ===
+
+Both Babylonian and Israelite texts describe one of the divisions of the cosmos as the underworldly ocean. In Babylonian texts, this is coincided with the region/god Abzu. In Sumerian mythology, this realm was created by Enki. It was also where Enki lived and ruled over. Due to the connection with Enki, the lower waters were associated with wisdom and incantational secret knowledge. In Egyptian mythology, the personification of this subterranean body of water was instead Nu. The notion of a cosmic body of water below the Earth was inferred from the realization that much water used for irrigation came from under the ground, from springs, and that springs were not limited to any one part of the world. Therefore, a cosmic body of water acting as a common source for the water coming out of all these springs was conceived.
+
+=== Underworld ===
+
+The Underworld/Netherworld (kur or erṣetu in Sumerian) is the lowest region in the direction downwards, below even Abzu (the primeval ocean/lower waters). It is geographically parallel with the plane of human existence, but was so low that both demons and gods could not descend to it. One of its names was "Earth of No Return". It was, however, inhabited by beings such as ghosts, demons, and local gods. The land was depicted as dark and distant: this is because it was the opposite of the human world and so did not have light, water, fields, and so forth. According to KAR 307, line 37, Bel cast 600 Annunaki into the underworld. They were locked away there, unable to escape, analogous to the enemies of Zeus who were confined to the underworld (Tartarus) after their rebellion during the Titanomachy. During and after the Kassite period, Annunaki were largely depicted as underworld deities; a hymn to Nergal praises him as the "Controller of the underworld, Supervisor of the 600".
+In Canaanite religion, the underworld was personified as the god Mot. In Egyptian mythology, the underworld was known as Duat and was ruled by Osiris, the god of the afterlife. It was also the region where the sun (manifested by the god Ra) made its journey from west (where it sets) to the east (from where it would rise again the next morning). 
+
+== Creation ==
+
+=== Creation of the cosmos ===
+The world was thought to be created ex materia. That is, out of pre-existing, and unformed, eternal matter. This is in contrast to the later notion of creation ex nihilo, which asserts that all the matter of the universe was created out of nothing. The primeval substance had always existed, was unformed, divine, and was envisioned as an immense, cosmic, chaotic mass of water or ocean (a representation that still existed in the time of Ovid). In the Mesopotamian theogonic process, the gods would be ultimately generated from this primeval matter, although a distinct process is found in the Hebrew Bible where God is initially distinct from the primeval matter. For the cosmos and the gods to ultimately emerge from this formless cosmic ocean, the idea emerged that it had to be separated into distinct parts and therefore be formed or organized. This event can be imagined of as the beginning of time. Furthermore, the process of the creation of the cosmos is coincident or equivalent to the beginning of the creation of new gods. In the 3rd millennium BC, the goddess Nammu was the one and singular representation of the original cosmic ocean in Mesopotamian cosmology. From the 2nd millennium BC onwards, this cosmic ocean came to be represented by two gods, Tiamat and Abzu who would be separated from each other to mark the cosmic beginning. The Ugaritic god Yam from the Baal Cycle may also represent the primeval ocean.
+Sumerian and Akkadian sources understand the matter of the primordial universe out of which the cosmos emerges in different ways. Sumerian thought distinguished between the inanimate matter that the cosmos was made of and the animate and living matter that permeated the gods and went on to be transmitted to humans. In Akkadian sources, the cosmos is originally alive and animate, but the deaths of Abzu (male deity of the fresh waters) and Tiamat (female sea goddess) give rise to inanimate matter, and all inanimate matter is derived from the dead remains of these deities.

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+
+=== Creation of the gods ===
+The core Mesopotamian myth to explain the gods' origins begins with the primeval ocean, personified by Nammu, containing Father Sky and Mother Earth within her. In the god-list TCL XV 10, Nammu is called 'the mother, who gave birth to heaven and earth'. The conception of Nammu as mother of Sky-Earth is first attested in the Ur III period (early 2nd millennium BC), though it may go back to an earlier Akkadian era. Earlier in the 3rd millennium BC, the starting point was not Nammu, but just Sky and Earth, with little apparent question about their own origins.
+The representation of Sky as male and Earth as female may come from the analogy between the generative power of the male sperm and the rain that comes from the sky, which respectively fertilize the female to give rise to newborn life or the Earth to give rise to vegetation. In the desert-dweller milieu, life depended on pastureland. Sky and Earth are in a union. Because they are the opposite sex, they inevitably reproduce. Every generation of their offspring includes a pair of gods, and altogether, this successive pairs or generations of gods is known as the Enki-Ninki deities. It has been named this way because in every version of the story, the first pair of offspring gods are Enki and Ninki ("Lord and Lady Earth"). The only other consistent feature between all versions of the story is that the last pair is made up of Enlil and Ninlil. In addition, in each pair, one member is male (indicated by the En- prefix) and the other is female (indicated by the Nin- prefix). The birth of Enlil results in the separation of heaven and earth as well as the division of the primordial ocean into the upper and lower waters. Sky, now known as Anu, can mate with other deities after being separated from Earth: he mates with his mother Nammu to give birth to Enki (different from the earlier Enki) who takes dominion over the lower waters. The siblings Enlil and Ninlil mate to give birth to Nanna (also known as Sin), the moon god, and Ninurta, the warrior god. Nanna fathers Utu (known as Shamash in Akkadian texts), the sun god, and Inanna (Venus). By this point, the main features of the cosmos had been created/born.
+A variation of this myth existed in Egyptian cosmology. Here, the primordial ocean is given by the god Nu. The creation act neither takes its materials from Nu, unlike in Mesopotamian cosmology, nor is Nu eliminated by the creation act.
+
+=== Separation of heaven and earth ===
+
+The cosmic union, or marriage, of heaven and earth is spoken of in ancient Near Eastern texts stretching back to the 3rd millennium BC. The first source that mentions their separation is from the late 3rd millennium BC, known as the Song of the hoe. During the 2nd millennium BC, these texts shift in their focus from the union to the separation of heaven and earth, as shown by Sumerian, Akkadian, Phoenician, Egyptian, and Greek mythologies.
+The cause of the separation involves either the agency of Enlil or takes place as a spontaneous act. One recovered Hittite text states that there was a time when they "severed the heaven from the earth with a cleaver", and an Egyptian text refers to "when the sky was separated from the earth" (Pyramid Text 1208c). OIP 99 113 ii and 136 iii says Enlil separated Earth from Sky and separated Sky from Earth. Enkig and Ninmah 1–2 also says Sky and Earth were separated in the beginning. The introduction of Gilgamesh, Enkidu, and the Netherworld says that heaven is carried off from the earth by the sky god Anu to become the possession of the wind god Enlil. Several other sources also present this idea.
+
+In the Akkadian Enuma Elish, written in the early 1st millennium BC, the god Marduk divides the corpse of the slain primordial goddess Tiamat into two parts, one stretched out to create heaven, the other to create the earth. As begins in lines 135–138:135 The Lord [Marduk] rested, examining her [Tiamat's] dead body, 136. To divide the abortion (and) to create ingenious things (therewith). 137. He split her open like a mussel (?) into two (parts); 138. Half of her he set in place and formed the sky (therewith) as a roof....The nature of the original mass is described in several ways. In older, Sumerian texts from the 3rd to early 2nd millennia BC, the original mass was a solid. In the younger Akkadian tradition, such as the Enuma Elish, the original mass was a water. In the Sumerian sources, heaven and earth are separated over the course of "long days and nights" (similar to the six-day timeline in the Genesis creation narrative), by two gods: Anu, the King of Heaven, and Enlil, the King of Earth.

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+title: "Ancient Near Eastern cosmology"
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+source: "https://en.wikipedia.org/wiki/Ancient_Near_Eastern_cosmology"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:43.951701+00:00"
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+---
+
+=== Stretching out the heavens ===
+The idiom of the heavens and earth being stretched out plays both a cultic and cosmic role in the Hebrew Bible where it appears repeatedly in the Book of Isaiah (40:22; 42:5; 44:24; 45:12; 48:13; 51:13, 16), with related expressions in the Book of Job (26:7) the Psalms (104:2), Jeremiah (10:12) and in Zechariah (12:1). One example reads "The one who stretched out the heavens like a curtain / And who spread them out like a tent to dwell in" (Is 40:22). The idiom is used in these texts to identify the creative element of Yahweh's activities and the expansion of the heavens signifies its vastness, acting as Yahweh's celestial shrine. In Psalmic tradition, the "stretching" of the heavens is analogous to the stretching out of a tent. The Hebrew verb for the "stretching" of the heavens is also the regular verb for "pitching" a tent. The heavens, in other words, may be depicted as a cosmic tent (a motif found in many ancient cultures). This finds architectural analogy in descriptions of the tabernacle, which is itself a heavenly archetype, over which a tent is supposed to have been spread. The phrase is frequently followed by an expression that God sits enthroned above and ruling the world, paralleling descriptions of God being seated in the Holy of Holies of the Tabernacle where he is stated to exercise rule over Israel. Biblical references to stretching the heavens typically occur in conjunction with statements that God made or laid the foundations of the earth.
+
+Similar expressions may be found elsewhere in the ancient world. A text from the 2nd millennium BC, the Ludlul Bēl Nēmeqi, says "Wherever the earth is laid, and the heavens are stretched out", though the text does not identify the creator of the cosmos. The Enuma Elish also describes the phenomena, in IV.137–140:137 He split her into two like a dried fish: 138 One half of her he set up and stretched out as the heavens. 139 He stretched the skin and appointed a watch. 140 With the instruction not to let her waters escape. In this text, Marduk takes the body of Tiamat, who he has killed, and stretches out Tiamat's skin to create the firmamental heavens which, in turn, comes to play the role of preventing the cosmic waters above the firmament from escaping and being unleashed onto the earth. Whereas the Masoretic Text of the Hebrew Bible states that Yahweh stretched heaven like a curtain in Psalm 104:2, the equivalent passage in the Septuagint instead uses the analogy of stretching out like "skin", which could represent a relic of Babylonian cosmology from the Enuma Elish. Nevertheless, the Hebrew Bible never identifies the material out of which the firmament was stretched. Numerous theories about what the firmament was made of sprung up across ancient cultures.
+
+=== Creation of humanity ===
+
+Many stories emerged to explain the creation of humanity and the birth of civilization. Earlier Sumerian language texts from the 3rd and 2nd millennia BC can be divided into two traditions depending on if they come from the city of Nippur or the city of Eridu. The Nippur tradition asserts that Heaven (An) and Earth (Ki) were coupled in a cosmic marriage. After they are separated by Enlil, Ki receives semen from An and gives rise to the gods, animals, and man. The Eridu tradition says that Enki, the offspring of An and Namma (in this tradition, the freshwater goddess) is the one who creates everything. Periodical relations between Enki and Ninhursaga (in this tradition, the personification of Earth) gives rise to vegetation. With the help of Namma, Enki creates man from clay. A famous work of the Eridu tradition is Eridu Genesis. A minority tradition in Sumerian texts, distinct from Nippur and Eridu traditions, is known from KAR 4, where the blood of a slaughtered deity is used to create humanity for the purpose of making them build temples for the gods. 
+Later Akkadian language tradition can be divided into various minor cosmogonies, cosmogonies of significant texts like Enuma Elish and Epic of Atrahasis, and finally the Dynasty of Dunnum placed in its own category. In the Atrahasis Epic, the Anunnaki gods force the Igigi gods to do their labor. However, the Igigi became fed up with this work and rebel. To solve the problem, Enlil and Mami create humanity by mixing the blood of gods with clay, who in the stead of the Igigi are assigned the gods' work. In the Enuma Elish, divine blood alone is used to make man.
+
+== Main texts ==
+
+=== Overview and limitations ===
+The Hebrew Bible, especially in the Genesis creation narrative, undergirds known beliefs about biblical cosmology in ancient Israel and Judah. From Mesopotamia, cosmological evidence has fragmentarily survived in cuneiform literature especially in the Sumerian and Akkadian languages, like the Enuma Elish. Cosmogonic information has been sourced from Enki-Ninki god lists. Cosmogonic prologues preface texts falling in the genre of the Sumerian and Akkadian disputation poems, as well as individual works like the Song of the hoe, Gilgamesh, Enkidu, and the Netherworld, and Lugalbanda I. Evidence is also available in Ugaritic (Ritual Theogony of the Gracious Gods) and Hittite (Song of Emergence) sources. Egyptian papyri and inscriptions, like the Memphite Theology, and later works such as the Babyloniaca of Berossus, offer additional evidence. A less abundant source are pictorial/iconographic representations, especially the Babylonian Map of the World. 
+Limitations of these types of texts (papyri, cuneiform, etc.) is that the majority are administrative and economic in their nature, saying little about cosmology. Detailed descriptions are unknown before the first millennium BC. As such, reconstructions from that time depend on gleaning information from surviving creation myths and etiologies.
+
+=== Enuma Elish ===

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+title: "Ancient Near Eastern cosmology"
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+
+The Enuma Elish is the most famous Mesopotamian creation story and was widely known in among learned circles across Mesopotamia, influencing both art and ritual. It is also the only complete cosmogony, whereas others must be reconstructed from disparate sources. The story was, in many ways, an original work, and as such is not a general representative of ancient Near Eastern or even Babylonian cosmology as a whole, and its survival as the most complete creation account appears to be a product of it having been composed in the milieu of Babylonian literature that happened to survive and get discovered in the present day. On the other hand, recent evidence suggests that after its composition, it played an important role in Babylonian scribal education. The story is preserved foremost in seven clay tablets discovered from the Library of Ashurbanipal in Nineveh. The creation myth seeks to describes how the god Marduk created the world from the body of the sea monster Tiamat after defeating her in battle, after which Marduk ascends to the top of the heavenly pantheon. The Enuma Elish is one of a broader set of Near Eastern traditions describing the cosmic battle between the storm and sea gods, but only Israelite cosmogonies share with it the act of creation that follows the storm gods victory.
+The following is a synopsis of the account. The primordial universe is alive and animate, made of Abzu, commonly identified as a male deity of the fresh waters, and Tiamat, the female sea goddess of salt waters. The waters mingle to create the next generations of deities. However, the younger gods are noisy and this noise eventually incenses Abzu so much that he tries to kill them. In trying to do so, however, he is killed by Ea (Akkadian equivalent of the Sumerian Enki). This eventually leads to a battle between Tiamat and the son of Ea, Marduk. Marduk kills Tiamat and fashions the cosmos, including the heavens and Earth, from Tiamat's corpse. Tiamat's breasts are used to make the mountains and Tiamat's eyes are used to open the sources of the Tigris and Euphrates rivers. Parts of the watery body were used to create parts of the world including its wind, rain, mist, and rivers. Marduk forms the heavenly bodies including the sun, moon, and stars to produce periodic astral activity that is the basis for the calendar, before finally setting up the cosmic capital at Babylon. Marduk attains universal kingship and the Tablet of Destinies. Tiamat's helper Kingu is also slain and his life force is used to animate the first human beings.
+The Enuma Elish is in continuity with other texts like the Myth of Anzû, the Labbu Myth, and KAR 6. In both the Enuma Elish and the Myth of Anzu, a dragon (Anzu or Tiamat) steals the Tablet of Destinies from Enlil, the chief god and in response, the chief god looks for someone to slay the dragon. Then, in both stories, a champion among the gods is chosen to fight the dragon (Ninurta or Marduk) after two or three others before them reject the offer to fight. The champion wins, after which he is acclaimed and given many names. The Enuma Elish may have also drawn from the myth of the Ninurta and the dragon Kur. The dragon is formerly responsible for holding up the primordial waters. Upon being killed, the waters begin to rise; this problem is solved by Ninurta heaping stones upon them until the waters are held back. One of the most significant differences between the Enuma Elish and earlier creation myths is in its exaltation of Marduk as the highest god. In prior myths, Ea was the chief god and creator of mankind.
+
+=== Genesis creation narrative ===
+
+The Genesis creation narrative, composed perhaps in the 7th or 6th century BC, spans Gen 1:1–2:3 and covers a one-week (seven-day) period. In each of the first three days there is an act of division: day one divides the darkness from light, day two the "waters above" from the "waters below", and day three the sea from the land. In each of the next three days these divisions are populated: day four populates the darkness and light with "greater light" (Sun), "lesser light" (Moon) and stars; day five populates seas and skies with fish and fowl; and finally land-based creatures and mankind populate the land. According to Victor Hamilton, most scholars agree that the choice of "greater light" and "lesser light", rather than the more explicit "Sun" and "Moon", is anti-mythological rhetoric intended to contradict widespread contemporary beliefs that the Sun and the Moon were deities themselves.
+In 1895, Hermann Gunkel related this narrative to the Enuma Elish via an etymological relationship between Tiamat and təhôm ("the deep" or "the abyss") and a sharing of the Chaoskampf motif. Today, another view rejects these connections and groups the Genesis creation narrative with other West Semitic cosmologies like those of Ugarit.

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+title: "Ancient Near Eastern cosmology"
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+
+=== Other biblical creation narratives ===
+Other prominent biblical cosmogonies include Psalm 74:12–17; Psalm 89:6–13; and Job 26:7–13, with a variety of additional briefer passages expounding on subsections of these lengthier passages (like Isaiah 51:9–10). Like traditions from Babylon, Egypt, Anatolia, and Canaan and the Levant, these cosmogonies describe a cosmic battle (on the part of Yahweh in the biblical versions) with a sea god (named Leviathan, Rahab) but only with Babylonian versions like the Enuma Elish is the victory against the sea god followed by an act of creation. The seemingly well-known cosmogony proceeded as follows: Yahweh fights and subdues the sea god while portrayed as holding a weapon and fighting with meteorological forces; the Sea that previously covered the earth is forced to make way for dry land and parts of it are confined behind the seashore, in the clouds, and into storehouses below the earth; Mount Zaphon is established and a temple for Yahweh is erected; finally, Yahweh is enthroned above all the gods.
+An alternative cosmogony appears in the doxologies of Amos (4:13; 5:8; 9:5–6). Instead of the earth being already covered by a primal sea, the earth is originally in a dry state and only later is the sea stretched over it. No cosmic battle takes place. The winds and mountains, which elsewhere primordially exist, in this account are both created. Like some passages in Deutero-Isaiah, these doxologies appear to present a view of creation ex-nihilo.
+These cosmogonies are relatively mythologized compared to the Genesis cosmogony. In addition, the Genesis cosmogony differs by describing the separation of the upper and lower waters by the creation of a firmament, whereas here, they are typically assembled into clouds. The closest cosmogony to Genesis is the one in Psalm 104.
+
+=== Babyloniaca of Berossus ===
+
+The first book of the Babyloniaca of the Babylonian priest Berossus, composed in the third century BC, offers a variant (or, perhaps, an interpretation) of the cosmogony of the Enuma Elish. This work is not extant but survives in later quotations and abridgements. Berossus' account begins with a primeval ocean. Unlike in the Enuma Elish, where sea monsters are generated for combat with other gods, in Berossus' account, they emerge by spontaneous generation and are described in a different manner to the 11 monsters of the Enuma Elish, as it expands beyond the purely mythical creatures of that account in a potential case of influence from Greek zoology. The fragments of Berossus by Syncellus and the Armenian of how he described his cosmogony are as follows:
+
+Syncellus: There was a time, he says, when everything was [darkness and] water and that in it fabulous beings with peculiar forms came to life. For men with two wings were born and some with four wings and two faces, having one body and two heads, male and female, and double genitalia, male and female ... [a list of monstrous beings follows]. Over all these a woman ruled named Omorka. This means in Chaldaean Thalatth, in Greek it is translated as ‘Sea’ (Thalassa) ... When everything was arranged in this way, Belos rose up and split the woman in two. Of one half of her he made earth, of the other half sky; and he destroyed all creatures in her ... For when everything was moist, and creatures had come into being in it, this god took off his own head and the other gods mixed the blood that flowed out with earth and formed men. For this reason they are intelligent and share in divine wisdom. Belos, whom they translate as Zeus, cut the darkness in half and separated earth and sky from each other and ordered the universe. The creatures could not endure the power of the light and were destroyed. When Belos saw the land empty and barren, he ordered one of the gods to cut off his own head and to mix the blood that flowed out with earth and to form men and wild animals that were capable of enduring the air. Belos also completed the stars and the sun and the moon and the five planets. Alexander Polyhistor says that Berossus asserts these things in his first book.
+Syncellus: They say that in the beginning all was water, which was called Sea (Thalassa). Bel made this one by assigning a place to each, and he surrounded Babylon with a wall. 
+
+Armenian: All, he said, was from the start water, which was called Sea. And Bel placed limits on them (the waters) and assigned a place to each, allocated their lands, and fortified Babylon with an enclosing wall.
+The conclusion of the account states that Belus then created the stars, sun, moon, and five planets. The account of Berossus agrees largely with the Enuma Elish, such as its reference to the splitting of the woman whose halves are used to create heaven and earth, but also contain a number of differences, such as the statement about allegorical exegesis, the self-decapitation of Belus in order to create humans, and the statement that it is the divine blood which has made humans intelligent. Some debate has ensued about which elements of these may or may not go back to the original account of Berossus. Some of the information Berossus got for his account of the creation myth may have come from the Enuma Elish and the Babylonian Dynastic Chronicle.
+
+=== Other ===
+Additional minor texts also present varying cosmogonical details. The Bilingual Creation of the World by Marduk describes the construction of Earth as a raft over the cosmic waters by Marduk. An Akkadian text called The Worm describes a series of creation events: first Heaven creates Earth, Earth creates the Rivers, and eventually, the worm is created at the end of the series and it goes to live in the root of the tooth that is removed during surgery.
+
+== Influence ==

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+title: "Animal magnetism"
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+source: "https://en.wikipedia.org/wiki/Animal_magnetism"
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+
+Animal magnetism, also known as mesmerism, is a pseudoscientific theory promoted by German physician Franz Mesmer in the 18th century. It posits the existence of an invisible natural force (Lebensmagnetismus) possessed by all living things, including humans, animals, and vegetables. He claimed that the force could have physical effects, including healing.
+The vitalist theory attracted numerous followers in Europe and the United States and was popular into the 19th century. Practitioners were often known as magnetizers rather than mesmerists. It had an important influence in medicine for about 75 years from its beginnings in 1779, and continued to have some influence for another 50 years. Hundreds of books were written on the subject between 1766 and 1925, but it is no longer practiced today except as a form of alternative medicine in some places. This theory also had a strong influence on the development of Kardecism.
+
+== Etymology and definitions ==
+
+=== Magnetizer ===
+The terms magnetizer and mesmerizer have been applied to people who study and practice animal magnetism. These terms have been distinguished from mesmerist and magnetist, which are regarded as denoting those who study animal magnetism without being practitioners; and from hypnotist, someone who practises hypnosis.
+The etymology of the word magnetizer comes from the French magnétiseur ('practicing the methods of mesmerism'), which in turn is derived from the French verb magnétiser. The term refers to an individual who has the power to manipulate the "magnetic fluid" with effects upon other people present that were regarded as analogous to magnetic effects. This sense of the term is found, for example, in the expression of Antoine Joseph Gorsas: "The magnetizer is the imam of vital energy".
+
+=== Mesmerism ===
+A tendency emerged amongst British magnetizers to call their clinical techniques "mesmerism"; they wanted to distance themselves from the theoretical orientation of animal magnetism that was based on the concept of "magnetic fluid".  At the time, some magnetizers attempted to channel what they thought was a magnetic "fluid", and sometimes they attempted this with a "laying on of hands". Reported effects included various feelings: intense heat, trembling, trances, and seizures.
+Many practitioners took a scientific approach, such as Joseph Philippe François Deleuze (1753–1835), a French physician, anatomist, gynecologist, and physicist.  One of his pupils was Théodore Léger (1799–1853), who wrote that the label "mesmerism" was "most improper".
+Noting that, by 1846, the term galvanism had been replaced by electricity, Léger wrote that year:
+
+Mesmerism, of all the names proposed [to replace the term animal magnetism], is decidedly the most improper; for, in the first place, no true science has ever been designated by the name of a man, whatever be the claims he could urge in his favor; and secondly, what are the claims of Mesmer for such an honor? He is not the inventor of the practical part of the science, since we can trace the practice of it through the most remote ages; and in that respect, the part which he introduced has been completely abandoned. He proposed for it a theory which is now [viz., 1846] exploded, and which, on account of his errors, has been fatal to our progress. He never spoke of the phenomena which have rehabilitated our cause among scientific men; and since nothing remains to be attributed to Mesmer, either in the practice and theory, or the discoveries that constitute our science, why should it be called mesmerism?
+
+== Royal commission ==
+
+In 1784 two French royal commissions appointed by Louis XVI studied Mesmer's magnetic fluid theory to try to establish it by scientific evidence. The commission of the Academy of Sciences included Majault, Benjamin Franklin, Jean Sylvain Bailly, Jean-Baptiste Le Roy, Sallin, Jean Darcet, de Borey, Joseph-Ignace Guillotin, and Antoine Lavoisier. The commission of the Royal Society of Medicine was composed of Poissonnier, Caille, Mauduyt de la Varenne, Andry, and Antoine Laurent de Jussieu.
+Whilst the commission agreed that the cures claimed by Mesmer were indeed cures, it also concluded there was no evidence of the existence of his "magnetic fluid", and that its effects derived from either the imaginations of its subjects or charlatanry.
+
+== Royal Academy investigation ==
+A generation later, another investigating committee, appointed by a majority vote in 1826 in The Royal Academy of Medicine in Paris, studied the effects and clinical potentials of the mesmeric procedure, without trying to establish the physical nature of any magnetic fluidum. The report says:
+
+what we have seen in the course of our experiments bears no sort of resemblance to what the Report of 1784 relates with regard to the magnetizers of that period. We neither admit nor reject the existence of the fluid, because we have not verified the fact; we do not speak of the baquet ... nor of the assemblage of a great number of people together, who were magnetized in the presence of a crowd of witnesses; because all our experiments were made in the most complete stillness ... and always upon a single person at a time. We do not speak of ... the crisis.
+Among the conclusions were:
+
+== Mesmerism and hypnotism ==
+
+=== Faria and "oriental hypnosis" ===
+Abbé Faria was one of the disciples of Franz Anton Mesmer who continued with Mesmer's work following the conclusions of the Royal Commission. In the early 19th century, Abbé Faria is said to have introduced oriental hypnosis to Paris and to have conducted experiments to prove that "no special force was necessary for the production of the mesmeric phenomena such as the trance, but that the determining cause lay within the subject himself"—in other words, that it worked purely by the power of suggestion.
+
+=== Braid and "hypnotism" ===
+Hypnotism, a designation coined by the Scottish surgeon, James Braid, originates in Braid's response to an 1841 exhibition of "animal magnetism", by Charles Lafontaine, in Manchester. Writing in 1851, Braid was adamant that, in the absence of the sorts of "higher phenomena" reportedly produced by the mesmerists,

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+title: "Animal magnetism"
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+category: "reference"
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+
+and in contra-distinction to the Transcendental [i.e., metaphysical] Mesmerism of the Mesmerists … [allegedly] induced through the transmission of an occult influence from [the body of the operator to that of the subject,] Hypnotism, [by which] I mean a peculiar condition of the nervous system, into which it can be thrown by artificial contrivance … [a theoretical position that is entirely] consistent with generally admitted principles in physiological and psychological science [would] therefore [be most aptly] designated Rational Mesmerism.
+
+=== "Mesmerism" and "hypnotism" ===
+While there is a great range of theories and practices collectively denoted mesmerism, research has clearly identified that there are substantial and significant differences between "mesmerism" and "hypnotism" however they may be defined.
+
+== Vital fluid and animal magnetism ==
+A 1791 London publication explains Mesmer's theory of the vital fluid:
+
+Modern philosophy has admitted a plenum or universal principle of fluid matter, which occupies all space; and that as all bodies moving in the world, abound with pores, this fluid matter introduces itself through the interstices and returns backwards and forwards, flowing through one body by the currents which issue therefrom to another, as in a magnet, which produces that phenomenon which we call Animal Magnetism. This fluid consists of fire, air and spirit, and like all other fluids tends to an equilibrium, therefore it is easy to conceive how the efforts which the bodies make towards each other produce animal electricity, which in fact is no more than the effect produced between two bodies, one of which has more motion than the other; a phenomenon serving to prove that the body which has most motion communicates it to the other, until the medium of motion becomes an equilibrium between the two bodies, and then this equality of motion produces animal electricity.
+According to an anonymous writer of a series of letters published by editor John Pearson in 1790, animal magnetism can cause a wide range of effects ranging from vomiting to what is termed the "crisis". The purpose of the treatment (inducing the "crisis") was to shock the body into convulsion in order to remove obstructions in the humoral system that were causing sicknesses. Furthermore, this anonymous supporter of the animal magnetism theory purported that the "crisis" created two effects: first, a state in which the "[individual who is] completely reduced under Magnetic influence, although he should seem to be possessed of his senses, yet he ceases to be an accountable creature", and a second "remarkable" state, which would be "conferred upon the [magnetized] subject … [namely] that of perfect and unobstructed vision … in other words, all opacity is removed, and every object becomes luminous and transparent". A patient under crisis was believed to be able to see through the body and find the cause of illness, either in themselves or in other patients.
+The Marquis of Puységur's miraculous healing of a young man named Victor in 1784 was attributed to, and used as evidence in support of, this "crisis" treatment. The Marquis was allegedly able to hypnotize Victor and, while hypnotized, Victor was said to have been able to speak articulately and diagnose his own sickness.
+Jacob Melo discusses in his books some mechanisms by which the perceived effects of animal magnetism have been claimed to operate.
+
+== Skepticism in the Romantic Era ==
+
+The study of animal magnetism spurred the creation of the Societies of Harmony in France, where members paid to join and learn the practice of magnetism. Doctor John Bell was a member of the Philosophical Harmonic Society of Paris, and was certified by the society to lecture and teach on animal magnetism in England. The existence of the societies transformed animal magnetism into a secretive art, where its practitioners and lecturers did not reveal the techniques of the practice based on the society members that have paid for instruction, veiling the idea that it was unfair to reveal the practice to others for free. Although the heightened secrecy of the practice contributed to the skepticism about it, many supporters and practitioners of animal magnetism touted the ease and possibility for everyone to acquire the skills to perform its techniques.
+Popularization of animal magnetism was denounced and ridiculed by newspaper journals and theatre during the Romantic Era. Many deemed animal magnetism to be nothing more than a theatrical falsity or quackery. In a 1790 publication, an editor presented a series of letters written by an avid supporter of animal magnetism and included his own thoughts in an appendix stating: 
+"No fanatics ever divulged notions more wild and extravagant; no impudent empiric ever retailed promises more preposterous, or histories of cures more devoid of reality, than the tribe of magnetisers".
+The novelist and playwright Elizabeth Inchbald wrote the farce Animal Magnetism in the late 1780s. The plot revolved around multiple love triangles and the absurdity of animal magnetism. The following passage mocks the medical prowess of those qualified only as mesmerists:

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+
+Doctor: They have refused to grant me a diploma—forbid me to practice as a physician, and all because I don't know a parcel of insignificant words; but exercise my profession according to the rules of reason and nature; Is it not natural to die, then if a dozen or two of my patients have died under my hands, is not that natural? ...
+Although the doctor's obsession with the use of animal magnetism, not merely to cure but to force his ward to fall in love with him, made for a humorous storyline, Inchbald's light-hearted play commented on what society perceived as threats posed by the practice.
+De Mainanduc brought animal magnetism to England in 1787 and promulgated it into the social arena. In 1785, he had published proposals to the ladies of Britain to establish a "hygean society" or society of health, by which they would pay to join and enjoy his treatments. As both popularity and skepticism increased, many became convinced that animal magnetism could lead to sexual exploitation of women. Not only did the practice involve close personal contact via the waving of hands over the body, but people were concerned that the animal magnetists could hypnotize women and direct them at will.
+
+Having removed all misconceptions, foretelling of the future, explicit or implicit invocation of the devil, the use of animal magnetism is indeed merely an act of making use of physical media that are otherwise licit and hence it is not morally forbidden, provided it does not tend toward an illicit end or toward anything depraved. (The Sacred Congregation of the Holy Office: 28 July 1847.)
+
+== Political influence ==
+The French Revolution catalyzed existing internal political friction in Britain in the 1790s; a few political radicals used animal magnetism as more than just a moral threat but also a political threat. Major politicians and people in power were accused by radicals of practising animal magnetism on the general population.
+In his article "Under the Influence: Mesmerism in England", Roy Porter notes that James Tilly Matthews suggested that the French were infiltrating England via animal magnetism. Matthews believed that "magnetic spies" would invade England and bring it under subjection by transmitting waves of animal magnetism to subdue the government and people. Such an invasion from foreign influences was perceived as a radical threat.
+
+== Mesmerism and spiritual healing practices ==
+During the Romantic period, mesmerism produced enthusiasm and inspired horror in the spiritual and religious context. Though discredited as a medical practice, mesmerism created a venue for spiritual healing. Some animal magnetists advertised their practices by stressing the "spiritual rather than physical benefits to be gained from animal magnetism" and were able to gather a good clientele from among the spiritually inspired population.
+Mesmerism has been used in parts of the world as an attempt to treat illness in humans, as well as disease in domestic, farm, circus, and zoo animals.
+Some authors including Johann Peter Lange and Allan Kardec claimed that the source of Jesus' miracles was animal magnetism. Others, like John Campbell Colquhoun and Mary Baker Eddy, denounced the comparison. Mary Baker Eddy went so far as to claim animal magnetism "lead[s] to moral and to physical death."
+
+== Professional magnetizers ==
+In the Classical era of animal magnetism, the late 17th century to the mid-19th century, there were professional magnetizers, whose techniques were described by authors of the time as particularly effective. Their method was to spend prolonged periods "magnetizing" their customers directly or through "mesmeric magnets". It was observed that in some conditions, certain mesmerizers were more likely to achieve the result than others, regardless of their degree of knowledge.
+
+== In literature ==
+Ursule Mirouët, an 1841 novel by Honoré de Balzac, features a character who converts to Christianity in part because of an experience with animal magnetism.
+Edgar Allan Poe's 1845 short story "The Facts in the Case of M. Valdemar" is based on the premise that a person could be mesmerised at the moment of death. Poe published the work without explicitly stating that it was fictional, leading some readers to believe it was a true account. In another Poe work, "Some Words with a Mummy", characters are stated to detail facts of phrenology and animal magnetism to an ancient mummy who was revitalized.
+Nathaniel Hawthorne's writings show his curiosity with mesmerism, particularly his 1851 novel The House of the Seven Gables, in which Alice and later Phoebe are apparently mesmerised by members of the Maule family.
+Aldous Huxley's 1962 novel "Island".  References Professor John Elliotson and animal magnetism as a way to perform painless surgery without anaesthesia.  Mesmerism/Magnestism/Hypnosis are themes running throughout the book. Used primarily as a tool to enhance independent thought within the population.
+Axel Munthe's 1929 book of memoirs "The Story of San Michele". A lightly embellished biography of Dr Axel Munthe and his history around owning Villa San Michele in Ana Capri; with a series of completely unsubstantiated fanciful references to Charcot and mesmerism in chapter XIX, "Hypnotism".
+William Faulkner's 1930 novel “As I Lay Dying” references animal magnetism in a brief chapter in which the character Cash explains his rationale for the design of the wooden coffin he built for his mother Addie.
+Robert Browning's poem "Mesmerism" was published in 1855. It describes the experience of violent passion for a woman. In after years, Ezra Pound wrote a poem of the same name, acknowledging his debt to Browning while gently mocking the poet's obscure style.
+Ambrose Parry’s crime novel (under the joint pen-name of authors Christopher Brookmyre and Marisa Haetzman), “Voices of the Dead” (2023) is concerned with Mesmerism in mid-19th century Edinburgh and its impact on the medical establishment of the time.

data/en.wikipedia.org/wiki/Animal_magnetism-3.md

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+---
+title: "Animal magnetism"
+chunk: 4/4
+source: "https://en.wikipedia.org/wiki/Animal_magnetism"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:45.147761+00:00"
+instance: "kb-cron"
+---
+
+== See also ==
+Biomagnetism – Magnetic fields produced by organisms
+Caloric theory – Obsolete scientific theory of heat flow
+James Esdaile – Scottish surgeon
+Charles Lafontaine – 19th-century French showman known for demonstrations of animal magnetism
+Magnetoception – Biological ability to perceive magnetic fieldsPages displaying short descriptions of redirect targets
+Odic force – Hypothetical vital energy or life force
+Royal Commission on Animal Magnetism – 1784 French scientific bodies' investigations involving systematic controlled trials
+The Zoist: A Journal of Cerebral Physiology & Mesmerism, and Their Applications to Human Welfare – Academic journal devoted to pseudoscientific concepts
+
+== References ==
+
+== Sources ==
+
+== Further reading ==
+Anton Mesmer, "Propositions Concerning Animal Magnetism" (1779), from: Binet, A. & Féré, C. Animal Magnetism, New York: Appleton and Co., 1888; web archive
+The Baron Dupotet de Sennevoy. An Introduction to the Study of Animal Magnetism. London: Saunders & Otley, 1838; full text
+William Gregory. Letters to a Candid Inquirer on Animal Magnetism. Philadelphia: Blanchard and Lea, 1851; full text
+Charles Poyen. Animal magnetism. Boston: Weeks, Jordan & co., 1837; full text
+
+== External links ==
+ The dictionary definition of animal magnetism at Wiktionary
+Ripley, George; Dana, Charles A., eds. (1879). "Animal Magnetism" . The American Cyclopædia.
+ Media related to Animal magnetism at Wikimedia Commons
+ Quotations related to Animal magnetism at Wikiquote

data/en.wikipedia.org/wiki/Annals_of_Philosophy-0.md

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+---
+title: "Annals of Philosophy"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Annals_of_Philosophy"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:52.713869+00:00"
+instance: "kb-cron"
+---
+
+Annals of Philosophy; or, Magazine of Chemistry, Mineralology, Mechanics, Natural History, Agriculture and the Arts was a learned journal founded in 1813 by the Scottish chemist Thomas Thomson. It shortly became a leader in its field of commercial scientific periodicals. Contributors included John George Children, Edward Daniel Clarke,  Philip Crampton, Alexander Crichton,  James Cumming, John Herapath,  William George Horner, Thomas Dick Lauder,  John Miers, Matthew Paul Moyle, Robert Porrett,  James Thomson, and Charles Wheatstone.
+Thomson edited it until 1821, when he was succeeded in 1821 by Richard Phillips. The journal was bought by Richard Taylor in 1827, and closed down for the benefit of the Philosophical Magazine.
+The Annals of Philosophy were issued monthly following a standard pattern. Often the first article was a biographical article (10 pages) on a living or recently deceased scientist. This was then followed by a series of extended pieces (5-10 pages) on particular topics, sometimes by eminent authors. Then there were shorter news items and correspondence. Summaries followed: first of the proceedings of learned bodies (Royal Society, Linnean, French Institute -if available: the Napoleonic Wars made communications with the continent difficult at first, etc.), then of patents, and finally of new books. The last section was a meteorological journal. Every six months a title page, index, and preface were issued which could be bound before the six monthly issues to make a half-yearly volume.  Including front matter, volumes were just under 500 pages each.
+
+
+== References ==
+
+
+=== Citations ===
+
+
+=== Bibliography ===

data/en.wikipedia.org/wiki/Anthropic_units-0.md

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 source: "https://en.wikipedia.org/wiki/Anthropic_units"
 category: "reference"
 tags: "science, encyclopedia"
-date_saved: "2026-05-05T07:14:17.794215+00:00"
+date_saved: "2026-05-05T09:31:59.511854+00:00"
 instance: "kb-cron"
 ---
 

data/en.wikipedia.org/wiki/Antiperistasis-0.md

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+---
+title: "Antiperistasis"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Antiperistasis"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:46.342176+00:00"
+instance: "kb-cron"
+---
+
+Antiperistasis, in philosophy, is a general term for various processes, real or contrived, in which one quality heightens the force of another, opposing, quality. 
+
+
+== Overview ==
+Historically, antiperistasis as a type of explanation was applied to numerous phenomena, from the interaction of quicklime with cold water, to the origin of thunder and lightning.
+In his Timaeus, Plato introduces the concept of periosis pushing around in order to explain various phenomena. Plato, for instance, appeals to it to explain how respiration functions in human beings. His 'theory' has been most famously adopted by Aristotle who made popular the term antiperistasis. In a nutshell it was "the doctrine that a moving object, which is no longer in touch with the mover, is moved by the medium through which it moves. Logically, it is connected to the  idea that void does not exist.
+It was using this explanation that academic philosophers claimed that cold, on many occasions, increases a body's temperature, and dryness increases its moisture. Thus, it was said, quicklime (CaO) was apparently set ablaze when doused with cold water (an effect later explained as an exothermic reaction). It was also the understood reason for why water, such as that in wells, appeared warmer in winter than in summer (later explained as an example of sensory adaptation). It was also suggested that thunder and lightning were the results of antiperistasis caused by the coldness of the sky.
+Peripatetic philosophers, who were followers of Aristotle, made extensive use of the principle of antiperistasis. According to such authors,
+
+'Tis necessary that Cold and Heat be both of them endued with a self-invigorating Power, which each may exert when surrounded by its contrary; and thereby prevent their mutual Destruction. Thus it is supposed that in Summer, the Cold expelled from the Earth and Water by the Sun's scorching Beams, retires to the middle Region of the Air, and there defends itself against the Heat of the superior and inferior. And thus, also, in Summer, when the Air is about us in sultry hot, we find that Cellars and Vaults have the opposite Quality: so in Winter, when the external Air freezes the Lakes and Rivers, the internal Air, in the same Vaults and Cellars, becomes the Sanctuary of Heat; and Water, fresh drawn out of deeper Wells and Springs, in a cold Season, not only feels warm, but manifestly smokes.
+Other examples used by the proponents of antiperistasis included the aphoristical saying of Hippocrates, "the viscera are hottest in the winter"; and the production of hail in the upper atmosphere, believed to occur only in the summer due to the increased heat of the sun.
+Robert Boyle examined the doctrine in his work, "New Experiments and Observations upon Cold."
+
+
+== See also ==
+Le Chatelier's principle
+Homeostasis
+
+
+== References ==
+
+ This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed. (1728). "Antiperistasis". Cyclopædia, or an Universal Dictionary of Arts and Sciences (1st ed.). James and John Knapton, et al.
+"Antiperistasis", Cyclopædia, Ephraim Chambers, 1728

data/en.wikipedia.org/wiki/Arc_measurement-0.md

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+---
+title: "Arc measurement"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Arc_measurement"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:05.357865+00:00"
+instance: "kb-cron"
+---
+
+Arc measurement, sometimes called degree measurement (German: Gradmessung), is the astrogeodetic technique of determining the radius of Earth and, by extension, its circumference. More specifically, it seeks to determine the local Earth radius of curvature of the figure of the Earth, by relating the latitude difference (sometimes also the longitude difference) and the geographic distance (arc length) surveyed between two locations on Earth's surface. The most common variant involves only astronomical latitudes and the meridian arc length and is called meridian arc measurement; other variants may involve only astronomical longitude (parallel arc measurement) or both geographic coordinates (oblique arc measurement).
+Arc measurement campaigns in Europe were the precursors to the International Association of Geodesy (IAG).
+Nowadays, the method is replaced by worldwide geodetic networks and by satellite geodesy.
+
+
+== History ==
+
+The first known arc measurement was performed by Eratosthenes (240 BC) between Alexandria and Syene in what is now Egypt, determining the radius of the Earth with remarkable correctness. 
+In the early 8th century, Yi Xing performed a similar survey.
+The French physician Jean Fernel measured the arc in 1528. The Dutch geodesist Snellius (~1620) repeated the experiment between Alkmaar and Bergen op Zoom using more modern geodetic instrumentation (Snellius' triangulation).
+Later arc measurements aimed at determining the flattening of the Earth ellipsoid by measuring at different geographic latitudes. The first of these was the French Geodesic Mission, commissioned by the French Academy of Sciences in 1735–1738, involving measurement expeditions to Lapland (Maupertuis et al.) and Peru (Pierre Bouguer et al.).
+Friedrich Struve measured a geodetic control network via triangulation between the Arctic Sea and the Black Sea, the Struve Geodetic Arc. 
+
+
+=== Chronological list ===
+This is a partial chronological list of arc measurements:
+
+230 B.C.: Eratosthenes' arc measurement
+100 B.C.: Posidonius' arc measurement
+724 AD: Yi Xing's arc measurement
+827 A.D.: Al-Ma'mun's arc measurement
+1528: Fernel's arc measurement
+1617: Snellius' survey
+1633-1635: Norwood's arc measurement
+1658: Riccioli and Grimaldi's arc measurement
+1669: Picard's arc measurement
+1684-1718: Dunkirk-Collioure arc measurement (Cassini, Cassini, and de La Hire)
+1736-1737: French Geodesic Mission to Lapland
+1735-1739: French Geodesic Mission to the Equator
+1740: Dunkirk-Collioure arc measurement (Cassini de Thury and de Lacaille)
+1750-1751: Maire and Boscovich's arc measurement
+1752: De Lacaille's arc measurement
+1791-1853: Principal Triangulation of Great Britain
+1792-1798: meridian arc of Delambre and Méchain
+1802–1841: Great Trigonometric Survey of India
+1806-1809: Arago and Biot's arc measurement
+1816-1855: Struve Geodetic Arc
+1821-1825: Gauss' geodetic survey
+1841-1848: Maclear's arc measurement
+1879: West Europe-Africa Meridian-arc
+1899-1902: Swedish–Russian Arc-of-Meridian Expedition
+1921: Hopfner's arc measurement
+
+
+== Determination ==
+Assume the astronomic latitudes of two endpoints, 
+  
+    
+      
+        
+          ϕ
+          
+            s
+          
+        
+      
+    
+    {\displaystyle \phi _{s}}
+  
+ (standpoint) and 
+  
+    
+      
+        
+          ϕ
+          
+            f
+          
+        
+      
+    
+    {\displaystyle \phi _{f}}
+  
+ (forepoint) are known; these can be determined by astrogeodesy, observing the zenith distances of sufficient numbers of stars (meridian altitude method). 
+Then, the empirical Earth's meridional radius of curvature at the midpoint of the meridian arc can then be determined inverting the great-circle distance (or circular arc length) formula:
+
+  
+    
+      
+        R
+        =
+        
+          
+            
+              
+                
+                  Δ
+                
+              
+              ′
+            
+            
+              |
+              
+                ϕ
+                
+                  s
+                
+              
+              −
+              
+                ϕ
+                
+                  f
+                
+              
+              |
+            
+          
+        
+      
+    
+    {\displaystyle R={\frac {{\mathit {\Delta }}'}{\vert \phi _{s}-\phi _{f}\vert }}}
+  
+
+where the latitudes are in radians and 
+  
+    
+      
+        
+          
+            
+              Δ
+            
+          
+          ′
+        
+      
+    
+    {\displaystyle {\mathit {\Delta }}'}
+  
+ is the arc length on mean sea level (MSL).
+Historically, the distance between two places has been determined at low precision by pacing or odometry.
+High precision land surveys can be used to determine the distance between two places at nearly the same longitude by measuring a baseline and a triangulation network linking fixed points. The meridian distance 
+  
+    
+      
+        
+          
+            Δ
+          
+        
+      
+    
+    {\displaystyle {\mathit {\Delta }}}
+  
+ from one end point to a fictitious point at the same latitude as the second end point is then calculated by trigonometry. The surface distance 
+  
+    
+      
+        
+          
+            Δ
+          
+        
+      
+    
+    {\displaystyle {\mathit {\Delta }}}
+  
+ is reduced to the corresponding distance at MSL, 
+  
+    
+      
+        
+          
+            
+              Δ
+            
+          
+          ′
+        
+      
+    
+    {\displaystyle {\mathit {\Delta }}'}
+  
+ (see: Geographical distance#Altitude correction).
+
+
+== Extensions ==
+
+Additional arc measurements, at different latitudinal bands (each delimited by a new pair of standpoint and forepoint), serve to determine Earth's flattening.
+Bessel compiled several meridian arcs, to compute the famous Bessel ellipsoid (1841).
+Clarke (1858) combined most of the arc measurements then available to define a new reference ellipsoid.
+
+
+== See also ==
+Astrogeodesy
+Central European Arc Measurement
+Earth ellipsoid
+Geodesy
+Gradian § Relation to the metre
+History of geodesy
+Spherical Earth § History
+Meridian arc § History
+Earth's circumference § History
+Meridian arc
+Paris Meridian
+
+
+== References ==

data/en.wikipedia.org/wiki/Arca_Noë-0.md

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+---
+title: "Arca Noë"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Arca_Noë"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:47.505668+00:00"
+instance: "kb-cron"
+---
+
+Arca Noë ("Noah's Ark") is a book published in 1675 by the Jesuit scholar Athanasius Kircher. It is a study of the biblical story of Noah's Ark, published by the cartographer and bookseller Johannes van Waesbergen in Amsterdam. Kircher's aim in Arca Noë was to reconcile recent discoveries in nature and geography with the text of the Bible. This demonstration of the underlying unity and truth between revelation and science was a fundamental task of Catholic scholarship at the time. Together with its sister volume Turris Babel ("The Tower of Babel"), Arca Noë presented a complete intellectual project to demonstrate how contemporary science supported the account of the Book of Genesis.
+
+== Structure ==
+
+The work is divided into three volumes: the first, De rebus quae ante Diluvium, dealt with the story of Noah before the Genesis flood narrative, the building of the Ark, the choice of animals to go on board and how they were accommodated. The second, De iis, quae ipso Diluvio e jusque duratione, concerned the flood itself and how the Ark was managed while the flood lasted, as well as providing a mystical and allegorical explanation of its meaning, as a vessel carrying the human soul. The third volume, De iis, quae post Diluvium a Noëmo gesta sunt, discussed the deeds of Noah after the flood, compared the lands of the world as they had been before it and after, and explained how both people and animals dispersed over the globe.
+
+== Ideas discussed ==
+
+By the middle of the seventeenth century, the abundance and diversity of life discovered in the New World was calling into question the previously unchallenged belief that all life on earth originated from a single point of dispersal - Mount Ararat, after the Flood. One of the uncertainties which Kircher addressed in Arca Noë was how animals had managed to colonise lands so distant across the seas. Another, to which he devoted particular attention, was how so many creatures could have fitted into the Ark at all.
+Kircher had first discussed the question of the size of the Ark in 1640 during a mathematical convention to celebrate the centenary of the Jesuit order. Here he delivered a technical paper on Noah's Ark, discussing the exact length of a Biblical cubit.
+In Arca Noë, taking the dimensions given in the Bible, Kircher explained how it was possible that all the animals in the contemporary world could originate from a vessel of such limited size. The Book of Genesis does not identify the animals taken into the Ark, describing them only as both "clean" and "unclean". Kircher therefore speculated about which animals were aboard, how they were accommodated, and used this as a basis for working out how it could have been designed and constructed. He also described details such as the exact year of the Flood (2396 BC), the time between the fall of the first raindrop and Noah setting foot on dry land (365 days), where the Ark landed, and how the creatures spread over the earth after the Flood abated.
+Kircher explained that while Noah had built the Ark, the design came directly from God himself, ensuring that its form was thus a concrete manifestation of divine intelligence. Its dimensions served to rule out another matter which the work discussed: the Book of Genesis records that there were giants on planet Earth in ancient history, and some held that Noah himself was one of them.  Kircher demonstrated that the size of the Ark made this impossible - there would not have been room for a family of giants on board alongside all the animals. This affirmation of Noah's humanity allowed Kircher to show that the Ark represented not only the human body, vehicle of the living soul, but also symbolised the Christian Church itself, just as Noah prefigured Jesus as a mediator between God and sinful mankind.
+
+== Classification of animals in the ark ==

data/en.wikipedia.org/wiki/Arca_Noë-1.md

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+---
+title: "Arca Noë"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Arca_Noë"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:47.505668+00:00"
+instance: "kb-cron"
+---
+
+Kircher sought to account for how different kinds of animal were accommodated in the Ark, and to do this, he classified them, focusing mainly on Old World species. Echoing Pliny, he ignored the taxonomies of his contemporary scholars and simply classified them by size, from the elephant downwards. He went on to explain how they would have been accommodated, with plant-eaters separated from meat-eaters, land-dwellers from amphibians and water creatures, and 'clean' from 'unclean'.
+The chart showing the floor plan for the Ark shows how the animals were housed. On the lower deck one side berthed beavers, otters, crocodiles, hippopotami, goat-stags, gazelles, elks, bison, goats, sheep, cattle, deer, reindeer, wild goats, chamois, fallow deer, dogs, aquatic hare-hounds, Molossian hounds, Maltese dogs, Indian dogs, seals, turtles, hedgehogs, porcupines, badgers, dormice, martens and weasels.  The other side housed small Indian pigs, rabbits, hares, squirrels, monkeys, apes, cats, asses, donkeys, horses, dromedaries, camels, elephants, rhinoceroses, lions, bears, tigers, panthers, leopards, unicorns, other horned animals from Africa, lynxes, gluttons, wolves, foxes, wild boars and domestic pigs.
+The middle deck carried food and supplies both for the voyage and for life after it. On one side were stored agricultural tools, clothes and household linens, metal goods, wool, mills, bread, ovens and a furnace, oil, salt, assorted materials for use after the flood, dried fish and fish preserved in salt water, candles, honey, a dovecote, a chicken coop, acorns, nuts, dried fruit, rice and pulses, casks of water, straw and hay. On the other side were rope and household goods, wood, spices, grains and berries, fruit, bread, smoked meat, a sheep-fold and a goat-fold for feeding the carnivorous animals, butter, cheese, wheat, barley and oats, water, tree-leaves and hay for winter feed, as well as cattle, horses and asses for use after the flood.
+The top deck housed the cabins for Noah and his family, and apart from this was given over to birds.  On one side were river swallows, kingbirds, tits, corncrakes, creepers, shrikes, gryphon-falcons, harpies, doves, pigeons, chickens and fowl, with an aviary for small songbirds, crows, jackdaws and woodpeckers, sparrows, hoopoes, peacocks, cuckoos, robins, swallows, quail and birds of paradise.  On the other side were pelicans, spoonbills, pheasants, grouse, partridge, kingfishers, magpies, parrots, peacocks, turkeys, hawks, vultures, eagles, falcons, ostriches, cranes, storks, herons, geese, ducks, kites, coots, fig-peckers, oyster-catchers, starlings, wagtails, owls and bustards.
+
+== Animals not carried in the ark ==
+
+Kircher believed - as did many others at his time - that certain animals did not reproduce sexually, but through spontaneous generation.  Such creatures did not need a place in the Ark since they could simply produce themselves from dung or mud. In Kircher's account this included small mammals such as mice and voles, as well as reptiles and insects. Kircher did say that snakes were taken on the Ark, partly because of their unique medicinal value, and partly as food for some of the birds on board.
+Kircher also excluded all animals which he regarded as 'hybrid', including the giraffe. These creatures he argued were descended from offspring of different animals carried on the ark which later interbred. He considered the armadillo to be a hybrid of the hedgehog and the turtle, and the alpine marmot to be a mixture of the badger and the squirrel.
+Kircher also explained that many of the creatures of the New World did not need to have a place in the Ark. The original creatures of God's creation came from the Garden of Eden and were adapted to its climate; as they spread out over the world after the flood, they adapted to different climates and conditions, evolving over time into the new forms seen today. Through these arguments, Kircher claimed that the Biblical dimensions of the Ark (198 metres long, 33 metres wide and 19.8 metres high) afforded sufficient space to allow the ancestors of all modern creatures in the world to be carried.
+
+== Illustrations ==
+
+Arca Noë was dedicated to the twelve year-old king Charles II of Spain. Its attractiveness to children has been remarked on, with its lavish illustrations and half-playful tone. The dedication compared Noah's Ark to Charles' empire, pointing out that "what Noah had in a small space, you, High King, possess scattered throughout your realm." 
+Arca Noë included many illustrations, detailing the design and construction of the ark and the animals preserved in it.
+The frontispiece depicted God directing putti bearing a flaming sword, alpha and omega, above the dove the Holy Spirit.  Beneath them, surrounded by lost souls struggling in the waves to reach it, the Ark is afloat on the Flood, representing the Church with Christ keeping watch in the crow's nest and the words "Extra quam non est salus" ("outside of which there is no salvation") on its sail. The foreground shows Noah and his family giving thanks for their salvation.
+The interior of the book contained over 100 woodcut illustrations, including maps, charts and folding diagrams.  Three of the finest illustrations were by Coenraet Decker - the portrait of Charles II, Noah and His Progeny, and the Submerged Mountains. Arca Noë also contains the largest illustration contained in any of Kircher's books. This was the cutaway diagram of the interior of the Ark, showing where the animals were housed. Measuring 39 x 17 ½ inches, it was made from three separate plates and folded out of the book. An entire section of the work was devoted to animals Kircher considered to be hybrid. As well as allowing Kircher to minimise the number of animals requiring space on the Ark, these hybrids also provided a good opportunity for including many exotic and fanciful illustrations to attract the interest of the book's young patron.
+
+== External links ==
+Digital copy of Arca Noë (Bibliothèque nationale de France)
+Digital copy of Arca Noë (Bamberg State Library)
+Digital copy of Arca Noë (Austrian National Library)
+Digital copy of Arca Noë (Austrian National Library)
+
+== Bibliography ==
+Don Cameron Allen, The Arca Noe of Athanasius Kircher in The Legend of Noah: Renaissance Rationalism in Art, Science and Letters, Urbana 1949
+Davis A. Young, The Biblical Flood: A Case Study of the Church's Response to Extrabiblical Evidence, Eerdmans 1995
+
+== References ==

data/en.wikipedia.org/wiki/Azoic_hypothesis-0.md

@@ -0,0 +1,23 @@
+---
+title: "Azoic hypothesis"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Azoic_hypothesis"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:48.682838+00:00"
+instance: "kb-cron"
+---
+
+The Azoic hypothesis (sometimes referred to as the Abyssus theory) is a superseded scientific theory proposed by Edward Forbes in 1843, stating that the abundance and variety of marine life decreased with increasing depth and, by extrapolation of his own measurements, Forbes calculated that marine life would cease to exist below 300 fathoms (1,800 ft; 550 m).
+
+
+== Overview ==
+The theory was based upon Forbes' findings aboard HMS Beacon (1832), a survey ship to which he had been appointed naturalist by the ship's commander Captain Thomas Graves. With Forbes aboard, HMS Beacon set sail around the Aegean Sea on 17 April 1841, from Malta. It was at this point that Forbes began to take dredging samples at various depths of the ocean, he observed that samples from greater depths displayed a narrower diversity of creatures which were generally smaller in size.
+Forbes reported his findings from the Aegean Sea in his 1843 report to the British Association entitled Report on the Mollusca and Radiata of the Aegean Sea. His findings were widely accepted by the scientific community and were bolstered by other scientific figures of the time. David Page (1814–1879), a respected geologist, reinforced the theory by stating that "according to experiment, water at the depth of 1000 feet is compressed 1⁄340th of its own bulk; and at this rate of compression we know that at great depths animal and vegetable life as known to us cannot possibly exist – the extreme depressions of seas being thus, like the extreme elevations of the land, barren and lifeless solitudes."
+
+The theory was not disproven until the late 1860s when biologist Michael Sars, Professor of Zoology at Christiania (now Oslo) University, discovered life at a depth greater than 300 fathoms. Sars listed 427 animal species which had been found along the Norwegian coast at a depth of 450 fathoms, and gave a description of a crinoid Rhizocrinus lofotensis which his son had recovered from a depth of 300 fathoms in Lofoten.
+In 1869, Charles Wyville Thomson dredged marine life from a depth of 2,345 fathoms (14,070 ft; 4,289 m), finally dispelling Forbes' azoic theory.
+In light of this evidence, the Azoic hypothesis would come to be seen as a false hypothesis and give way to vastly increased efforts in deep-sea exploration and associated marine life. Since being discredited, the theory has been referenced widely in popular culture and alluded to in documentaries that explore and showcase deep-sea marine life.
+
+
+== References ==

data/en.wikipedia.org/wiki/Balance_of_nature-0.md

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+---
+title: "Balance of nature"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Balance_of_nature"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:49.833645+00:00"
+instance: "kb-cron"
+---
+
+The balance of nature, also known as ecological balance, is a theory that proposes that ecological systems are usually in a stable equilibrium or homeostasis, which is to say that a small change (the size of a particular population, for example) will be corrected by some negative feedback that will bring the parameter back to its original "point of balance" with the rest of the system. The balance is sometimes depicted as easily disturbed and delicate, while other times it is inversely portrayed as powerful enough to correct any imbalances by itself. The concept has been described as "normative", as well as teleological, as it makes a claim about how nature should be: nature is balanced because "it is supposed to be balanced". The theory has been employed to describe how populations depend on each other, for example in predator-prey systems, or relationships between herbivores and their food source. It is also sometimes applied to the relationship between the Earth's ecosystem, the composition of the atmosphere, and weather.
+The theory has been discredited by scientists working in ecology, as it has been found that constant disturbances leading to chaotic and dynamic changes are the norm in nature. During the later half of the 20th century, it was superseded by catastrophe theory, chaos theory, and thermodynamics. Nevertheless, the idea maintains popularity amongst conservationists, environmentalists and the general public.
+
+== History of the theory ==
+
+The concept that nature maintains its condition is of ancient provenance. Herodotus asserted that predators never excessively consume prey populations and described this balance as "wonderful". Two of Plato's dialogues, the Timaeus and Protagoras myths, support the balance of nature concept. Cicero advanced the theory of "a balance of nature generated by different reproductive rates and traits among species, as well as interactions among species".
+The balance of nature concept once ruled ecological research and governed the management of natural resources. This led to a doctrine popular among some conservationists that nature was best left to its own devices, and that human intervention into it was by definition unacceptable.
+The theory was a central theme in the 1962 book Silent Spring by Rachel Carson, widely considered to be the most important environmental book of the 20th century. The controversial Gaia hypothesis was developed in the 1970s by James Lovelock and Lynn Margulis. It asserts that living beings interact with Earth to form a complex system which self-regulates to maintain the balance of nature.
+The validity of a balance of nature was already questioned in the early 1900s, but the general abandonment of the theory by scientists working in ecology only happened in the last quarter of that century, when studies showed that it did not match what could be observed among plant and animal populations.
+
+== Predator-prey interactions ==
+Predator-prey populations tend to show chaotic behavior within limits, where the sizes of populations change in a way that may appear random but is, in fact, obeying deterministic laws based only on the relationship between a population and its food source illustrated by the Lotka–Volterra equation. An experimental example of this was shown in an eight-year study on small Baltic Sea creatures such as plankton, which were isolated from the rest of the ocean. Each member of the food web was shown to take turns multiplying and declining, even though the scientists kept the outside conditions constant. An article in the journal Nature stated: "Advanced mathematical techniques proved the indisputable presence of chaos in this food web ... short-term prediction is possible, but long-term prediction is not."
+
+== Human intervention ==
+Although some conservationist organizations argue that human activity is incompatible with a balanced ecosystem, there are numerous examples in history showing that several modern-day habitats originate from human activity: some of Latin America's rain forests owe their existence to humans planting and transplanting them, while the abundance of grazing animals in the Serengeti plain of Africa is thought by some ecologists to be partly due to human-set fires that created savanna habitats.
+One frequently cited example of human influence on ecosystem processes is the Australian Aboriginal practice of fire-stick farming. This practice uses low-intensity fire, applied when humidity is high enough to limit its spread, to reduce the amount of ground-level combustible material and thereby reduce the intensity and extent of forest fires started by lightning at the end of the dry season. Several plant species are adapted to such fire regimes, and some even require high temperatures to trigger seed germination.
+
+== Continued popularity of the theory ==

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+---
+title: "Balance of nature"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Balance_of_nature"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:49.833645+00:00"
+instance: "kb-cron"
+---
+
+Despite being discredited among ecologists, the theory is widely held to be true by the general public, conservationists and environmentalists, with one author calling it an "enduring myth". Environmental and conservation organizations such as the WWF, Sierra Club and Canadian Wildlife Federation continue to promote the theory, as do animal rights organizations such as PETA.
+Kim Cuddington considers the balance of nature to be a "foundational metaphor in ecology", which is still in active use by ecologists. She argues that many ecologists see nature as a "beneficent force" and that they also view the universe as being innately predictable; Cuddington asserts that the balance of nature acts as a "shorthand for the paradigm expressing this worldview". Douglas Allchin and Alexander J. Werth assert that although "ecologists formally eschew the concept of balance of nature, it remains a widely adopted preconception and a feature of language that seems not to disappear entirely."
+At least in Midwestern America, the balance of nature idea was shown to be widely held by both science majors and the general student population. In a study at the University of Patras, educational sciences students were asked to reason about the future of ecosystems which suffered human-driven disturbances. Subjects agreed that it was very likely for the ecosystems to fully recover their initial state, referring to either a 'recovery process' which restores the initial 'balance', or specific 'recovery mechanisms' as an ecosystem's inherent characteristic. In a 2017 study, Ampatzidis and Ergazaki discuss the learning objectives and design criteria that a learning environment for non-biology major students should meet to support them challenge the balance of nature concept. In a 2018 study, the same authors report on the theoretical output of a design research study, which concerns the design of a learning environment for helping students challenge their beliefs regarding the balance of nature and reach an up-to-date understanding about ecosystems' contingency.
+
+== In popular culture ==
+In Ursula K. Le Guin's Earthsea fantasy series, using magic means to "respect and preserve the immanent metaphysical balance of nature."
+The balance of nature (referred to as "the circle of life") is a major theme of the 1994 film, The Lion King. In one scene, the character Mufasa describes to his son Simba how everything exists in a state of delicate balance.
+The character Agent Smith, in the 1999 film The Matrix, describes humanity as a virus, claiming that humans fail to reach an equilibrium with their surrounding environment; unlike other mammals.
+The disruption of the balance of nature is a common theme in Hayao Miyazaki's films: Nausicaä of the Valley of the Wind, released in 1984, is set in a post-apocalyptic world where humans have upset the balance of nature through war; the 1997 film Princess Mononoke, depicts irresponsible activities by humans as having damaged the balance of nature; in the 2008 film Ponyo, the titular character disturbs the balance of nature when she seeks to become human.
+The titular character of the 2014 film Godzilla fights other sea monsters known as "MUTOs" in a bid to restore the balance of nature.
+In the 2018 film Avengers: Infinity War, the villain Thanos seeks to restore the balance of nature by eliminating half of the beings in the universe.
+
+== See also ==
+
+Ecological footprint
+Social metabolism
+
+== References ==

data/en.wikipedia.org/wiki/Basque_Museum_of_the_History_of_Medicine_and_Science-0.md

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+---
+title: "Basque Museum of the History of Medicine and Science"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Basque_Museum_of_the_History_of_Medicine_and_Science"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:27.636207+00:00"
+instance: "kb-cron"
+---
+
+The Basque Museum of the History of Medicine (MHM, Basque: Medikuntza Historiaren Euskal Museoa, Spanish: Museo Vasco de Historia de la Medicina) was founded in 1982 to preserve and conserve the historic memory of medicine and scientific heritage of Basque Country. The Museum is located on the university campus of Leioa (University of the Basque Country) and is important in student training in the Faculty of Medicine and other faculties and schools. Its director is Anton Erkoreka. 
+Its permanent exhibition comprises approximately 6,000 medical objects of the 19th and 20th centuries, thematically arranged in 24 rooms devoted to different medical specialties: folk medicine, unconventional medicine, pharmacy,  weights and measures, asepsis and antisepsis, microscopes, laboratory material, X-rays, obstetrics and gynaecology, surgery, anesthesia, endoscope, odontology, cardiology, ophthalmology, electrotherapy, pathological anatomy and natural sciences.  It also holds virtual exhibitions. 
+Teaching and research constitute the two pillars of the Museum, complemented with publications, the organization of conferences, lectures, and other activities.
+
+
+== References ==
+
+
+== External links ==
+Basque Museum of the History of Medicine and Science
+The museum in the bulletin of the European Association of Museums of the History of Medical Sciences
+Virtual exhibition about electrotherapy
+Virtual exhibition about Stultifera navis. The ship of fools
+Obstetrics and gynecology through history

data/en.wikipedia.org/wiki/Bedford_Level_experiment-0.md

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+---
+title: "Bedford Level experiment"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Bedford_Level_experiment"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:01.898253+00:00"
+instance: "kb-cron"
+---
+
+The Bedford Level experiment was a series of observations carried out along a 6-mile (10 km) length of the Old Bedford River on the Bedford Level of the Cambridgeshire Fens in the United Kingdom. They were performed during the 19th and early 20th centuries to deny the curvature of the Earth through measurement.
+Samuel Birley Rowbotham, who conducted the first observations starting in 1838, claimed that he had proven the Earth to be flat. However, in 1870, after adjusting Rowbotham's method to allow for the effects of atmospheric refraction, Alfred Russel Wallace found a curvature consistent with a spherical Earth.
+
+== The Bedford Level ==
+At the point chosen for all the experiments, the river is a slow-flowing drainage canal running in an uninterrupted straight line for a 6-mile (10 km) stretch to the north-east of the village of Welney. This makes it an ideal location to directly measure the curvature of the Earth, as Rowbotham wrote in Zetetic Astronomy:
+
+If the earth is a globe, and is 25,000 English statute miles in circumference, the surface of all standing water must have a certain degree of convexity—every part must be an arc of a circle. From the summit of any such arc there will exist a curvature or declination of 8 inches in the first statute mile. In the second mile the fall will be 32 inches; in the third mile, 72 inches, or 6 feet, as shown in the following diagram:
+
+...[A]fter the first few miles the curvature would be so great that no difficulty could exist in detecting either its actual existence or its proportion... In the county of Cambridge there is an artificial river or canal, called the "Old Bedford". It is upwards of twenty miles in length, and ... passes in a straight line through that part of the Fens called the "Bedford Level". The water is nearly stationary—often completely so, and throughout its entire length has no interruption from locks or water-gates of any kind; so that it is, in every respect, well adapted for ascertaining whether any or what amount of convexity really exists.
+
+== Experiments ==
+
+The first experiment at this site was conducted by Rowbotham in the summer of 1838. He waded into the river and used a telescope held 8 inches (20 cm) above the water to watch a boat, with a flag on its mast 3 feet (0.9 m) above the water, row slowly away from him. He reported that the vessel remained constantly in his view for the full 6 miles (10 km) to Welney Bridge, whereas, had the water surface been curved with the accepted circumference of a spherical Earth, the top of the mast should have been about 11 feet (3.4 m) below his line of sight. He published this observation using the pseudonym Parallax in 1849 and subsequently expanded it into a book, Earth Not a Globe published in 1865.
+
+Rowbotham repeated his experiments several times over the years, but his claims received little attention until, in 1870, a supporter by the name of John Hampden offered a wager that he could show, by repeating Rowbotham's experiment, that the Earth was flat. The naturalist and qualified surveyor Alfred Russel Wallace accepted the wager. Wallace, by virtue of his surveyor's training and knowledge of physics, avoided the errors of the preceding experiments and won the bet.
+The crucial steps were:
+
+To set a sight line 13 feet (4.0 m) above the water, and thereby reduce the effects of atmospheric refraction.
+To add a pole in the middle of the length of the canal that could be used to see the "bump" caused by the curvature of the Earth between the two end points.
+Despite Hampden initially refusing to accept the demonstration, Wallace was awarded the bet by the referee, John Henry Walsh, editor of The Field sports magazine.
+Hampden subsequently published a pamphlet alleging that Wallace had cheated, and sued for his money. Several protracted court cases ensued, with the result that Hampden was imprisoned for threatening to kill Wallace and for libel.
+The same court ruled that the wager had been invalid because Hampden retracted the bet and required that Wallace return the money to Hampden.
+Wallace, who had been unaware of Rowbotham's earlier experiments, was criticized by his peers for "his 'injudicious' involvement in a bet to 'decide' the most fundamental and established of scientific facts".
+In 1901, Henry Yule Oldham, a reader in geography at King's College, Cambridge, reproduced Wallace's results using three poles fixed at equal height above water level. When viewed through a theodolite, the middle pole was found to be about 6 feet (1.8 m) higher than the poles at each end. This version of the experiment was taught in schools in England until photographs of the Earth from space became available, and it remains in the syllabus for the Indian Certificate of Secondary Education for 2023.

data/en.wikipedia.org/wiki/Bedford_Level_experiment-1.md

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+---
+title: "Bedford Level experiment"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Bedford_Level_experiment"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:01.898253+00:00"
+instance: "kb-cron"
+---
+
+On 11 May 1904 Lady Elizabeth Anne Blount, who was later influential in the formation of the Flat Earth Society, hired a commercial photographer to use a telephoto-lens camera to take a picture from Welney of a large white sheet she had placed, the bottom edge near the surface of the river, at Rowbotham's original position 6 miles (10 km) away. The photographer, Edgar Clifton from Dallmeyer's studio, mounted his camera 2 feet (0.6 m) above the water at Welney and was surprised to be able to obtain a picture of the target, which he believed should have been invisible to him, given the low mounting point of the camera. Lady Blount published the pictures far and wide.
+These controversies became a regular feature in the English Mechanic magazine in 1904–05, which published Blount's photo and reported two experiments in 1905 that showed the opposite results. One of these, by Clement Stretton conducted on the Ashby Canal, mounted a theodolite on the canal bank aligned with the cabin roof of a boat. When the boat had moved one mile distant, the instrument showed a dip from the sight-line of about eight inches.
+
+== Refraction ==
+Atmospheric refraction can produce the results noted by Rowbotham and Blount. Because the density of air in the Earth's atmosphere decreases with height above the Earth's surface, all light rays travelling nearly horizontally bend downward, so that the line of sight is a curve. This phenomenon is routinely accounted for in levelling and celestial navigation.
+
+If the measurement is close enough to the surface, this downward curve may match the mean curvature of the Earth's surface. In this case, the two effects of assumed curvature and refraction could cancel each other out, and the Earth will then appear flat in optical experiments.
+This would have been aided, on each occasion, by a temperature inversion in the atmosphere with temperature increasing with altitude above the canal, similar to the phenomenon of the superior image mirage. Temperature inversions like this are common. An increase in air temperature or lapse rate of 0.11 Celsius degrees per metre of altitude would create an illusion of a flat canal, and all optical measurements made near ground level would be consistent with a completely flat surface. If the lapse rate were higher than this (temperature increasing with height at a greater rate), all optical observations would be consistent with a concave surface, a "bowl-shaped Earth". Under average conditions, optical measurements are consistent with a spherical Earth approximately 15% less curved than in reality. Repetition of the atmospheric conditions required for each of the many observations is not unlikely, and warm days over still water can produce favourable conditions.
+
+== Similar experiments conducted elsewhere ==
+On 25 July 1896, Ulysses Grant Morrow, a newspaper editor, conducted a similar experiment on the Old Illinois Drainage Canal, Summit, Illinois. Unlike Rowbotham, he was seeking to demonstrate that the surface of the Earth was curved: when he too found that his target marker, 18 inches (46 cm) above water level and 5 miles (8 km) distant, was clearly visible, he concluded that the Earth's surface was concavely curved, in line with the expectations of his sponsors, the Koreshan Unity society. The findings were dismissed by critics as the result of atmospheric refraction.
+
+== See also ==
+History of geodesy
+The Final Experiment (expedition)
+
+== Notes ==
+
+== References ==
+Michell, John (1984). Eccentric Lives and Peculiar Notions. London: Thames and Hudson. ISBN 0-500-01331-4.

data/en.wikipedia.org/wiki/Biofact_(philosophy)-0.md

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+---
+title: "Biofact (philosophy)"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Biofact_(philosophy)"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:54.054666+00:00"
+instance: "kb-cron"
+---
+
+In philosophy and sociology, a biofact is a being that is both an artifact and living being, or both natural and artificial. This being has been created by purposive human action but exists by processes of growth. The word is a neologism coined from the combination of the words bios and artifact.
+There are sources who cite some creations of genetic engineering as examples of biofacts.
+
+
+== History ==
+Biofact was introduced as early as 2001 by the German philosopher Nicole C. Karafyllis although her book Biofakte published in 2003 is commonly used as reference for the introduction of the term. According to Karafyllis, the word biofact first appeared in a German article (entitled 'Biofakt und Artefakt') in 1943, written by the Austrian protozoologist Bruno M. Klein. Addressing both microscopy and philosophy, Klein named a biofact something that is a visible dead product emerging from a living being while this being is still alive (e.g. a shell). However, Klein's distinction operated with the difference biotic/abiotic and dead/alive, not with nature/technology and growth/man-made. For her part, Karafyllis described biofact as a hermeneutic concept that allows the comparison between nature and technology in the domain of the living.
+
+
+== Philosophy ==
+With the term biofact, Karafyllis wants to emphasize that living entities can be highly artificial due to methods deriving from agriculture, gardening (e.g. breeding) or biotechnology (e.g. genetic engineering, cloning).  Biofacts show signatures of culture and technique.
+Primarily, the concept aims to argue against the common philosophical tradition to summarize all kinds of living beings under the category nature. The concept biofact questions if the phenomenon of growth is and was a secure candidate for differentiating between nature and technology.
+For the philosophy of technology the questions arise if a) biotechnology and agriculture should not be an integral part of reflexion, thereby adding new insights to the common focus on the machine and the artifact, and if b) established concepts of technique and technology which stress artificiality should not be modified. Karafyllis regards the inclusion of biofacts into a theory of techniques as a chance, to reformulate classic concepts of design and construction for defining the making of artifacts. In her view, biofacts depend on the method of provocation.
+For the philosophy of nature, biofacts highlight a need to clarify if nature is self-explanatory in every case. Biophilosophy is challenged to newly reflect upon the categories organism and living being.
+In the philosophy of science, approaches are challenged which only focus on the category thing (or epistemic thing) without historizing the technicality, mediality and materiality of its emerging as a living object. For the sociology of science the biofact concept is fruitful to discuss the exclusiveness of scientific knowledge (the role of the expert) while making scientific objects which are released into the lifeworld or public sphere.  Particularly because the biofact concept deals with the phenomenon of growth and the establishing of a self, it is also influential in the philosophical disciplines phenomenology, anthropology and ontology. It was Jürgen Habermas who recently stressed the anthropological consequences if mankind gives up the differentiation of "coming into being" and "making".
+Artifacts are artificial, i.e. man-made objects. Contrary to biofacts, they cannot be found in nature. Therefore, biofacts demarcate an ontological intersection. They are partially man-made, but growing. Like artifacts, they have been made for a certain utility. Biofacts can be seen as biotic artifacts which show their character as hybrids in multifold perspectives.
+The term is also enabling philosophers to criticize some concepts in technoscience, where the union of scientific knowledge about nature and the technical creation of technonature is seen as progress in the political sense. The term has also been adopted in the new BioArt, not rarely without using its critical impacts.
+As Karafyllis complemented the growth and reproduction of organisms with technical entities, she established a typology of different kinds of organisms according to their uses and these are:
+
+Natural life form
+Unaltered biofacts
+Reshaped biofacts
+Genetically reproduced biofacts
+Genetically modified biofacts.
+
+
+== References ==
+
+
+== Literature ==
+Nicole C. Karafyllis (ed.): Biofakte - Versuch über den Menschen zwischen Artefakt und Lebewesen. Paderborn, Mentis 2003 (in German).
+Nicole C. Karafyllis: Biofakte - Grundlagen, Probleme, Perspektiven. Discussion Unit in the journal Deliberation Knowledge Ethics / Erwaegen Wissen Ethik, Vol. 17, Nr. 4 (2006). (in German with English abstracts)
+Nicole C. Karafyllis: Growth of Biofacts: the real thing or metaphor?. In: R. Heil, A. Kaminski, M. Stippack, A. Unger and M. Ziegler (Ed.): Tensions and Convergences. Technological and Aesthetic (Trans)Formations of Society. Bielefeld (2007). 141–152. (in English)
+Nicole C. Karafyllis: Endogenous Design of Biofacts. Tissues and Networks in Bio Art and Life Science. In: sk-interfaces. Exploding borders - creating membranes in art, technology and society. Ed. by Jens Hauser. Liverpool: University of Liverpool Press (European Ed.) (2008), 42–58. (in English)
+Nicole C. Karafyllis: Ethical and epistemological problems of hybridizing living beings: Biofacts and Body Shopping. In: Wenchao Li and Hans Poser (Ed.): Ethical Considerations on Today's Science and Technology. A German-Chinese Approach. Münster: LIT 2007, 185–198. (in English)
+Karafyllis, N.C.: Artefakt – Lebewesen – Biofakt. Philosophische Aspekte lebendiger Bauten. In: G. de Bruyn et al. (Eds.): Lebende Bauten – Trainierbare Tragwerke. Schriftenreihe Kultur und Technik, Vol. 16. Münster, New York. 2009: LIT, 97–111. (in German)
+Karafyllis, N.C. Biofakte als neue Kategorie der Informatik? In: Raimund Jakob, Lothar Phillips, Erich Schweighofer, Czaba Varga (Eds.): Auf dem Weg zur Idee der Gerechtigkeit. Gedenkschrift für Ilmar Tammelo. Münster u.a.: LIT. 249–262. (in German)
+Karafyllis, N. C.: Provokation als Methode der biotechnischen Evolution, in: Volker Gerhardt, Klaus Lucas and Günter Stock (Eds.): Evolution. Theorie, Formen und Konsequenzen eines Paradigmas in Natur, Technik und Kultur. Berlin: Akademie Verlag 2011
+
+
+== Secondary literature (in English) ==
+Suzanne Anker, "Technogenesis", in: B. Andrew Lustig, Baruch A. Brody, Gerald P. McKenny (Eds.): Altering nature: concepts of nature and the natural in biotechnology debates, Springer 2008, pp. 275–322.
+Torsten Meyer and Uta Hassler: "Construction History and the History of Science ", Proceedings of the Third International Concress of Concstruction History, Cottbus May 2009
+Orlan: A Hybrid Body of Artworks, ed. by S. Shepherd and Orlan, Taylor&Francis 2010.
+Ingeborg Reichle: Art in the Age of Technoscience. Genetic Engineering, Robotics, and Artificial Life in Contemporary Art. Vienna, New York: Springer 2010.
+→ See the German Wikipedia entry for further literature in German.
+
+
+== External links ==
+Biofakt.com

data/en.wikipedia.org/wiki/Brain_matures_at_25_myth-0.md

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+---
+title: "Brain matures at 25 myth"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Brain_matures_at_25_myth"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:50.993982+00:00"
+instance: "kb-cron"
+---
+
+The "brain matures at 25" myth or "twenty-five year old brain" myth is the claim that the human brain, particularly the prefrontal cortex, reaches an adult level maturity approximately around age 25. This myth occasionally has others numbers cited, but 25 is by far the most commonly occurring. Teen brain theory is the pseudoscientific theory based on this myth. The myth suggests that a person does not have full adult capacity or maturity until this age threshold is achieved. It has been attributed to various figures, notably Jay Giedd and Laurence Steinberg. 
+
+It has been shown that the prefrontal cortex does prune gray matter with age, but these changes are not conclusively linked with better cognitive function or a higher level of socioemotional maturity. It is widely quoted on social media outlets, usually in debates regarding legal age limits or youth behavior.
+
+
+== Origin and spread ==
+A common source for the myth is from the research of Jay Giedd. The study in particular was longitudinal, following a group of thirteen people from 1994 to 2004 with ages at the end of the study ranging from 4–21 years old. His team of researchers found that changes in the prefrontal cortex were found to continue up until the oldest age in the study. He estimated that this "age of maturity" would be around 25 years old. "When we started, we thought we'd follow kids until about 18 or 20. If we had to pick a number now, we'd probably go to age 25." There were also other very similar articles predating 2004 that often used the work of Giedd along with neuroscientists Frances Jensen and BJ Casey, usually using the development of the prefrontal cortex as a scientific explanation for "teenage behavior."
+The work of Laurence Steinberg is also purported to a significant amount of influence in the spreading of this myth. His research generally focuses around adolescent brain development and risk-development and is generally used to influence the juvenile justice system and provide lighter sentences for offending youth. He proposes the science of neuroplasticity should redefine how society treats "adolescents" and that a specific range of 10- to 25-year-olds have undeveloped brains. He would later say, in a 2022 article, that he was not sure where the "25" number came from in regards to the age of brain maturity.
+There is historical precedent for claiming the twenties to be part of "adolescence". Around 1900, psychologist G. Stanley Hall considered youth to be roughly ages 12–21 for females and 14–25 for males. He tied it to being a stage of "storm and stress"; he noted higher crime rates, sensation seeking, susceptibility to media, and sensitivity to peer relationships, but later psychologists consider other major points outdated, such as his views on Lamarckian evolution, sexual development, and religious conversion.
+
+
+== Analysis ==
+The development of the brain is a lifelong process. Maturity is assessed via structural MRI (gray/white matter volume, cortical thickness), functional MRI (activation patterns), and diffusion tensor imaging (myelination/connectivity). These processes do not peak or end at 25 and no executive function changes are found around this age.
+Empirical data on youth risk varies, but individual differences matter more than chronological age. Equating structural changes with behavioral "immaturity" risks oversimplification; adolescents often have adult-like performance on many tasks. A major study (2025) identifies distinct developmental epochs in brain network organization across the lifespan, showing that maturation unfolds in phases with a prolonged and dynamic period extending into the early 30s rather than ending in the mid-20s. They found an epoch of 9–32 years of age. A study from 2023 found that brain signal latencies decrease across the lifespan by 0.73 ms until the age of 10, while decreasing by 0.43 ms between the ages of 20 and 30, with latency decreases ending at around 35 years of age or older. 
+It is not supported that marijuana use impairs cognitive function of those 18–25 more than it does those older than 25.
+
+
+== In popular culture ==
+The "brain matures at 25" myth is often the source of memes where the "immature frontal lobe" is used to excuse personal mistakes and poor judgement. The myth is also used in age-gap relationship discourse regarding the morality of being with a younger person. It is also commonly used as a form of ridicule against Leonardo DiCaprio's relationship patterns where his partner is usually no older than 25 years old.
+
+
+== References ==

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+---
+title: "Cardiocentric hypothesis"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Cardiocentric_hypothesis"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:55.250568+00:00"
+instance: "kb-cron"
+---
+
+According to the cardiocentric hypothesis, the heart is the primary location of human emotions, cognition, and awareness. This notion may be traced back to ancient civilizations such as Egypt and Greece, where the heart was regarded not only as a physical organ but also as a repository of emotions and wisdom. Aristotle, a well-known Greek philosopher in this field, contributed to the notion by thinking the heart to be the centre of both emotions and intellect. He believed that the heart was the center of the psycho-physiological system and that it was responsible for controlling sensation, thought, and body movement. He also observed that the heart was the origin of the veins in the body and that the existence of pneuma in the heart was to function as a messenger, traveling through blood vessels to produce sensation. This point of view remained throughout history, spanning the Middle Ages and Renaissance, influencing medical and intellectual debate.
+An opposing theory called "cephalocentrism", which proposed that the brain played the dominant role in controlling the body, was first introduced by Pythagoras in 550 BC, who argued that the soul resides in the brain and is immortal. His statements were supported by Plato, Hippocrates, and Galen of Pergamon. Plato believed that the body is a "prison" of the mind and soul and that in death the mind and soul become separated from the body, meaning that neither one of them could die.
+
+== History ==
+
+=== Ancient Egypt ===
+
+In ancient Egypt, people believed that the heart is the seat of the soul and the origin of the channels to all other parts of the body, including arteries, veins, nerves, and tendons. The heart was also depicted as determining the fate of ancient Egyptians after they died. It was believed that Anubis, the god of mummification, would weigh the deceased person's heart against a feather. If the heart was too heavy, it would be considered guilty and consumed by the Ammit, a mythological creature. If it was lighter than the feather, the spirit of the deceased would be allowed to go to heaven. Therefore, the heart was kept in the mummy while other organs were generally removed.
+
+=== Ancient Near East ===
+In the ancient Near East, the heart (libbu) was considered the seat of consciousness, moral agency, cognition, wisdom, understanding, and of the emotions subject to the will (desire, love, friendship, etc). Emotional expressions in Mesopotamian texts link a positive relationship between the heart and the occurrence of feelings of pride, desire, love, and notions of sexual arousal and shame. Idioms like "his heart is awake" were used to describe an individual regaining their consciousness, and "as it pleases the heart" could be used to describe the sensation of pleasure that one experiences. The heart is the source of both the good and evil in a person, as well as the center of the human capacity of religiosity.
+
+=== Ancient Greece ===
+However, the ancient Greeks, Aristotle promoted the cardiocentric hypothesis based on his experience with animal dissection. He found that certain primitive animals could move and feel without the brain, and so deduced that the brain was not responsible for movement or feeling. Apart from that, he pointed out that the brain was at the top of the body, far from the centre of the body, and felt cold. He also performed anatomical examinations after strangling the specimen, which would cause vasoconstriction of the arterioles in the lungs. This likely had the effect of forcing blood to engorge the veins and make them more visible in the following dissection. Aristotle observed that the heart was the origin of the veins in the body, and concluded that the heart was the centre of the psycho-physiological system. He also stated that the existence of pneuma in the heart was to function as a messenger, traveling through blood vessels to produce sensation. Movement of body parts was thought to be controlled by the heart as well. From Aristotle's perspective, the heart was composed of sinews which allowed the body to move.
+In the fourth century BC, Diocles of Carystus reasserted that the heart was the physiological centre of sensation and thought. He also recognised that the heart had two cardiac ears. Although Diocles also proposed that the left brain was responsible for intelligence and the right one was for sensation, he believed that the heart was dominant over the brain for listening and understanding. Praxagoras of Cos was a follower of Aristotle's cardiocentric theory and was the first one to distinguish arteries and veins. He conjectured that arteries carry pneuma while transporting blood. He also proved that a pulse can be detected from the arteries and explained that the arteries' ends narrowed into nerves.
+Lucretius stated around 55 BCE, "The dominant force in the whole body is that guiding principle which we term mind or intellect. This is firmly lodged in the midregion of the breast. Here is the place where fear and alarm pulsate. Here is felt the caressing touch of joy. Here, then, is the seat of the intellect and the mind."
+
+=== Christian world ===
+According to the Mystic Treatises of Isaac the Syrian, "the heart is the central organ of the inward senses; this means the sense of senses, because it is the root. And if the root is holy, so also are all the branches."
+
+=== Islamic world ===
+Cardiocentrism is accepted in the Quran. 
+The Islamic philosopher and physician Avicenna followed Galen of Pergamon, believing that one's spirit was confined in three chambers of the brain and accepted that nerves originate from the brain and spinal cord, which control body movement and sensation. However, he maintained the earlier cardiocentric hypothesis. He stated that activation for voluntary movement began in the heart and was then transported to the brain. Similarly, messages were delivered from a peripheral environment to the brain and then via the vagus nerve to the heart.

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+---
+title: "Cardiocentric hypothesis"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Cardiocentric_hypothesis"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:55.250568+00:00"
+instance: "kb-cron"
+---
+
+=== Europe ===
+In the Middle Ages, the German Catholic friar Albertus Magnus made contributions to physiology and biology. His treatise was based on Galen's cephalocentric theory and was profoundly affected by Avicenna's preeminent Canon, which itself had been influenced by Aristotle. He combined these ideas in a new way which suggested that nerves branched off from the brain but that the origin was the heart. He concluded that philosophically, all matters originated from the heart, and in the corporeal explanation, all nerves started from the brain.
+
+William Harvey, an early modern English physiologist, also agreed with Aristotle's cardiocentric view. He was the first to describe the basic operation of the circulatory system, by which blood was pumped by the heart to the rest of the body, in detail. He explained that the heart was the centre of the body and the source of life in his treatise De Motu Cordis et Sanguinis in Animalibus.
+
+== Cephalocentric perspective ==
+
+Hippocrates of Kos was the first to suggest that the brain was the seat of the soul and intelligence. From his treatise De morbo sacro, he pointed out that the brain controls the rest of the body and is responsible for sensation and understanding. Apart from that, he believed that all feelings originated from the brain.
+Galen of Pergamon was a biologist and physician. His approach to the investigation of the brain was due to his rigorous anatomical methodology. He pointed out that only correct dissection will support the incontrovertible statement. He reached the conclusion that the brain was responsible for sensation and thought, and that nerves originated at the spinal cord and brain.
+
+== Brain in heart ==
+
+The "little brain in the heart" is an intricate system of nerve cells that control and regulate the heart's activity. It is also called the intrinsic cardiac nervous system (ICNS). It consists of about 40,000 neurons that form clusters or ganglia around the heart, especially near the top where the blood vessels enter and exit. These neurons communicate with each other and with the brain through chemical and electrical signals.
+The intrinsic cardiac nervous system has several functions, such as:
+
+Adjusting the heart rate and rhythm according to the body's needs and emotions.
+Sensing and responding to changes in blood pressure, oxygen levels, hormones, and inflammation.
+Protecting the heart from damage during a heart attack or other stress.
+Learning and remembering from past experiences and influencing the brain’s memory and emotions.
+
+== References ==
+
+== Further reading ==
+Loukas, Marios; Youssef, Pamela; Gielecki, Jerzy; Walocha, Jerzy; Natsis, Kostantinos; Tubbs, R. Shane (2016-03-11). "History of cardiac anatomy: A comprehensive review from the egyptians to today". Clinical Anatomy. 29 (3): 270–284. doi:10.1002/ca.22705. ISSN 0897-3806. PMID 26918296. S2CID 30362746.

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+---
+title: "Center of the universe"
+chunk: 1/3
+source: "https://en.wikipedia.org/wiki/Center_of_the_universe"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:52.208732+00:00"
+instance: "kb-cron"
+---
+
+The center of the universe is a concept in historical cosmological models prior to the 20th century. 
+Modern cosmological theories are based on the Copernican principle that all locations are equivalent and the universe has no spatial center.
+Historically, different people have suggested various locations as the center of the Universe. Many mythological cosmologies included an axis mundi, the central axis of a flat Earth that connects the Earth, heavens, and other realms together. In the 4th century BC Greece, philosophers developed the geocentric model, based on astronomical observation; this model proposed that the center of the Universe lies at the center of a spherical, stationary Earth, around which the Sun, Moon, planets, and stars rotate. With the development of the heliocentric model by Nicolaus Copernicus in the 16th century, the Sun was believed to be the center of the Universe, with the planets (including Earth) and stars orbiting it.
+In the early-20th century, the discovery of other galaxies and the development of the Big Bang theory led to the development of cosmological models of a homogeneous, isotropic Universe which has no distinct spatial central point because, given that space expands from a shared central point in time (the Big Bang), the center of the universe is everywhere.
+
+== Outside astronomy ==
+
+In religion and mythology, the axis mundi (also cosmic axis, world axis, world pillar, columna cerului, center of the world) is a point described as the center of the world, the connection between it and Heaven, or both.
+
+Mount Hermon was regarded as the axis mundi in Canaanite tradition, from where the sons of God are introduced descending in 1 Enoch (1En6:6). The ancient Greeks regarded several sites as places of earth's omphalos (navel) stone, notably the oracle at Delphi, while still maintaining a belief in a cosmic world tree and in Mount Olympus as the abode of the gods. Judaism has the Temple Mount and Mount Sinai, Christianity has the Mount of Olives and Calvary, Islam has Mecca, said to be the place on earth that was created first, and the Temple Mount (Dome of the Rock). In Shinto, the Ise Shrine is the omphalos. In addition to the Kun Lun Mountains, where it is believed the peach tree of immortality is located, the Chinese folk religion recognizes four other specific mountains as pillars of the world.
+
+Sacred places constitute world centers (omphalos) with the altar or place of prayer as the axis. Altars, incense sticks, candles and torches form the axis by sending a column of smoke, and prayer, toward heaven. The architecture of sacred places often reflects this role. "Every temple or palace--and by extension, every sacred city or royal residence--is a Sacred Mountain, thus becoming a Centre." The stupa of Hinduism, and later Buddhism, reflects Mount Meru. Cathedrals are laid out in the form of a cross, with the vertical bar representing the union of Earth and heaven as the horizontal bars represent union of people to one another, with the altar at the intersection. Pagoda structures in Asian temples take the form of a stairway linking Earth and heaven. A steeple in a church or a minaret in a mosque also serve as connections of Earth and heaven. Structures such as the maypole, derived from the Saxons' Irminsul, and the totem pole among indigenous peoples of the Americas also represent world axes. The calumet, or sacred pipe, represents a column of smoke (the soul) rising form a world center. A mandala creates a world center within the boundaries of its two-dimensional space analogous to that created in three-dimensional space by a shrine.
+In medieval times some Christians thought of Jerusalem as the center of the world (Latin: umbilicus mundi, Greek: Omphalos), and was so represented in the so-called T and O maps. Byzantine hymns speak of the Cross being "planted in the center of the earth."
+
+== Center of a flat Earth ==
+
+The Flat Earth model is a belief that the Earth's shape is a plane or disk covered by a firmament containing heavenly bodies. Most pre-scientific cultures have had conceptions of a Flat Earth, including Greece until the classical period, the Bronze Age and Iron Age civilizations of the Near East until the Hellenistic period, India until the Gupta period (early centuries AD) and China until the 17th century. It was also typically held in the aboriginal cultures of the Americas, and a flat Earth domed by the firmament in the shape of an inverted bowl is common in pre-scientific societies. There would also be a unique point at the center of a spherical firmament (or a firmament that was a half-sphere).
+
+== Earth as the center of the Universe ==
+
+The Flat Earth model gave way to an understanding of a Spherical Earth. Aristotle (384–322 BC) provided observational arguments supporting the idea of a spherical Earth, namely that different stars are visible in different locations, travelers going south see southern constellations rise higher above the horizon, and the shadow of Earth on the Moon during a lunar eclipse is round, and spheres cast circular shadows while discs generally do not.
+This understanding was accompanied by models of the Universe that depicted the Sun, Moon, stars, and naked eye planets circling the spherical Earth, including the noteworthy models of Aristotle (see Aristotelian physics) and Ptolemy. This geocentric model was the dominant model from the 4th century BC until the 17th century AD.
+
+== Sun as center of the Universe ==

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+---
+title: "Center of the universe"
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+source: "https://en.wikipedia.org/wiki/Center_of_the_universe"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:52.208732+00:00"
+instance: "kb-cron"
+---
+
+Heliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around a relatively stationary Sun at the center of the Solar System. The word comes from the Greek (ἥλιος helios "sun" and κέντρον kentron "center").
+The notion that the Earth revolves around the Sun had been proposed as early as the 3rd century BC by Aristarchus of Samos, but had received no support from most other ancient astronomers.
+Nicolaus Copernicus' major theory of a heliocentric model was published in De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), in 1543, the year of his death, though he had formulated the theory several decades earlier. Copernicus' ideas were not immediately accepted, but they did begin a paradigm shift away from the Ptolemaic geocentric model to a heliocentric model. The Copernican Revolution, as this paradigm shift would come to be called, would last until Isaac Newton’s work over a century later.
+Johannes Kepler published his first two laws about planetary motion in 1609, having found them by analyzing the astronomical observations of Tycho Brahe. Kepler's third law was published in 1619. The first law was "The orbit of every planet is an ellipse with the Sun at one of the two foci."
+On 7 January 1610 Galileo used his telescope, with optics superior to what had been available  before. He described "three fixed stars, totally invisible by their smallness", all close to Jupiter, and lying on a straight line through it. Observations on subsequent nights showed that the positions of these "stars" relative to Jupiter were changing in a way that would have been inexplicable if they had really been fixed stars. On 10 January Galileo noted that one of them had disappeared, an observation which he attributed to its being hidden behind Jupiter. Within a few days he concluded that they were orbiting Jupiter: Galileo stated that he had reached this conclusion on 11 January. He had discovered three of Jupiter's four largest satellites (moons). He discovered the fourth on 13 January.
+
+His observations of the satellites of Jupiter created a revolution in astronomy: a planet with smaller planets orbiting it did not conform to the principles of Aristotelian Cosmology, which held that all heavenly bodies should circle the Earth. Many astronomers and philosophers initially refused to believe that Galileo could have discovered such a thing; by showing that, like Earth, other planets could also have moons of their own that followed prescribed paths, and hence that orbital mechanics did not apply only to the Earth, planets, and Sun, what Galileo had essentially done was to show that other planets might be "like Earth".
+Newton made clear his heliocentric view of the Solar System – developed in a somewhat modern way, because already in the mid-1680s he recognised the "deviation of the Sun" from the centre of gravity of the Solar System. For Newton, it was not precisely the centre of the Sun or any other body that could be considered at rest, but rather "the common centre of gravity of the Earth, the Sun and all the Planets is to be esteem'd the Centre of the World", and this centre of gravity "either is at rest or moves uniformly forward in a right line" (Newton adopted the "at rest" alternative in view of common consent that the centre, wherever it was, was at rest).
+
+== Milky Way's Galactic Center as center of the Universe ==
+Before the 1920s, it was generally believed that there were no galaxies other than the Milky Way (see for example The Great Debate). Thus, to astronomers of previous centuries, there was no distinction between a hypothetical center of the galaxy and a hypothetical center of the universe.
+
+In 1750 Thomas Wright, in his work An Original Theory or New Hypothesis of the Universe, correctly speculated that the Milky Way might be a body of a huge number of stars held together by gravitational forces rotating about a Galactic Center, akin to the Solar System but on a much larger scale. The resulting disk of stars can be seen as a band on the sky from the Earth's perspective inside the disk. In a treatise in 1755, Immanuel Kant elaborated on Wright's idea about the structure of the Milky Way. In 1785, William Herschel proposed such a model based on observation and measurement, leading to scientific acceptance of galactocentrism, a form of heliocentrism with the Sun at the center of the Milky Way.
+The 19th century astronomer Johann Heinrich von Mädler proposed the Central Sun Hypothesis, according to which the stars of the universe revolved around a point in the Pleiades.

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+---
+title: "Center of the universe"
+chunk: 3/3
+source: "https://en.wikipedia.org/wiki/Center_of_the_universe"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:52.208732+00:00"
+instance: "kb-cron"
+---
+
+== The nonexistence of a center of the Universe ==
+In 1917, Heber Doust Curtis observed a nova within what then was called the "Andromeda Nebula". Searching the photographic record, 11 more novas were discovered. Curtis noticed that novas in Andromeda were drastically fainter than novas in the Milky Way. Based on this, Curtis was able to estimate that Andromeda was 500,000 light-years away. As a result, Curtis became a proponent of the so-called "island Universes" hypothesis, which held that objects previously believed to be spiral nebulae within the Milky Way were actually independent galaxies.
+In 1920, the Great Debate between Harlow Shapley and Curtis took place, concerning the nature of the Milky Way, spiral nebulae, and the dimensions of the Universe. To support his claim that the Great Andromeda Nebula (M31) was an external galaxy, Curtis also noted the appearance of dark lanes resembling the dust clouds in this galaxy, as well as the significant Doppler shift. In 1922 Ernst Öpik presented an elegant and simple astrophysical method to estimate the distance of M31. His result put the Andromeda Nebula far outside this galaxy at a distance of about 450,000 parsec, which is about 1,500,000 ly. Edwin Hubble settled the debate about whether other galaxies exist in 1925 when he identified extragalactic Cepheid variable stars for the first time on astronomical photos of M31. These were made using the 2.5 metre (100 in) Hooker telescope, and they enabled the distance of Great Andromeda Nebula to be determined. His measurement demonstrated conclusively that this feature was not a cluster of stars and gas within this galaxy, but an entirely separate galaxy located a significant distance from the Milky Way. This proved the existence of other galaxies.
+
+=== Expanding Universe ===
+Hubble also demonstrated that the redshift of other galaxies is approximately proportional to their distance from Earth (Hubble's law). This raised the appearance of this galaxy being in the center of an expanding Universe, however, Hubble rejected the findings philosophically:
+
+...if we see the nebulae all receding from our position in space, then every other observer, no matter where he may be located, will see the nebulae all receding from his position. However, the assumption is adopted. There must be no favoured location in the Universe, no centre, no boundary; all must see the Universe alike. And, in order to ensure this situation, the cosmologist postulates spatial isotropy and spatial homogeneity, which is his way of stating that the Universe must be pretty much alike everywhere and in all directions."
+The redshift observations of Hubble, in which galaxies appear to be moving away from us at a rate proportional to their distance from us, are now understood to be associated with the expansion of the universe. All observers anywhere in the Universe will observe the same effect.
+
+=== Copernican and cosmological principles ===
+The Copernican principle, named after Nicolaus Copernicus, states that the Earth is not in a central, specially favored position. Hermann Bondi named the principle after Copernicus in the mid-20th century, although the principle itself dates back to the 16th-17th century paradigm shift away from the geocentric Ptolemaic system.
+The cosmological principle is an extension of the Copernican principle which states that the Universe is homogeneous (the same observational evidence is available to observers at different locations in the Universe) and isotropic (the same observational evidence is available by looking in any direction in the Universe). A homogeneous, isotropic Universe does not have a center.
+
+== See also ==
+
+== Notes ==
+
+== References ==

data/en.wikipedia.org/wiki/Classical_element-0.md

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+---
+title: "Classical element"
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+source: "https://en.wikipedia.org/wiki/Classical_element"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:56.401003+00:00"
+instance: "kb-cron"
+---
+
+The classical elements typically refer to earth, water, fire, air, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Angola, Tibet, India, and Mali had similar lists which sometimes referred, in local languages, to "air" as "wind", and to "aether" as "space".
+
+These different cultures and even individual philosophers had widely varying explanations concerning their attributes and how they related to observable phenomena as well as cosmology. Sometimes these theories overlapped with mythology and were personified in deities. Some of these interpretations included atomism (the idea of very small, indivisible portions of matter), but other interpretations considered the elements to be divisible into infinitely small pieces without changing their nature.
+While the classification of the material world among the ancient Indians, Hellenistic Egyptians, and ancient Greeks into air, earth, fire, and water was more philosophical; scientists of the Middle Ages used practical, experimental observation to classify materials. In Europe, the ancient Greek concept, devised by Empedocles, evolved into the systematic classifications of Aristotle and Hippocrates. This evolved slightly into the medieval system, and eventually became the object of experimental verification in the 17th century, at the start of the Scientific Revolution.
+Modern science does not support the classical elements to classify types of substances. Atomic theory classifies atoms into more than a hundred chemical elements such as oxygen, iron, and mercury, which may form chemical compounds and mixtures. The modern categories roughly corresponding to the classical elements are the states of matter produced under different temperatures and pressures. Solid, liquid, gas, and plasma share many attributes with the corresponding classical elements of earth, water, air, and fire, but these states describe the similar behaviour of different types of atoms at similar energy levels, not the characteristic behaviour of certain atoms or substances.
+
+== Hellenistic philosophy ==
+
+The ancient Greek concept of four basic elements, these being earth (γῆ  gê), water (ὕδωρ hýdōr), air (ἀήρ aḗr), and fire (πῦρ pŷr), dates from pre-Socratic times and persisted throughout the Middle Ages and into the early modern period, deeply influencing European thought and culture.
+
+=== Pre-Socratic elements ===
+
+==== Primordial element ====
+The classical elements were first proposed independently by several early Pre-Socratic philosophers. Greek philosophers had debated which substance was the arche ("first principle"), or primordial element from which everything else was made. Thales (c. 626/623 – c. 548/545 BC) believed that water was this principle. Anaximander (c. 610 – c. 546 BC) argued that the primordial substance was not any of the known substances, but could be transformed into them, and they into each other. Anaximenes (c. 586 – c. 526 BC) favoured air, and Heraclitus (fl. c. 500 BC) championed fire.
+
+==== Fire, earth, air, and water ====
+
+The Greek philosopher Empedocles (c. 450 BC) was the first to propose the four classical elements as a set: fire, earth, air, and water. He called them the four "roots" (ῥιζώματα, rhizōmata). Empedocles also proved (at least to his own satisfaction) that air was a separate substance by observing that a bucket inverted in water did not become filled with water, a pocket of air remaining trapped inside.
+Fire, earth, air, and water have become the most popular set of classical elements in modern interpretations. One such version was provided by Robert Boyle in The Sceptical Chymist, which was published in 1661 in the form of a dialogue between five characters. Themistius, the Aristotelian of the party, says:
+
+If You but consider a piece of green-Wood burning in a Chimney, You will readily discern in the disbanded parts of it the four Elements, of which we teach It and other mixt bodies to be compos'd. The fire discovers it self in the flame ... the smoke by ascending to the top of the chimney, and there readily vanishing into air ... manifests to what Element it belongs and gladly returnes. The water ... boyling and hissing at the ends of the burning Wood betrayes it self ... and the ashes by their weight, their firiness, and their dryness, put it past doubt that they belong to the Element of Earth.
+
+=== Humorism (Hippocrates) ===
+
+According to Galen, these elements were used by Hippocrates (c. 460 – c. 370 BC) in describing the human body with an association with the four humours: yellow bile (fire), black bile (earth), blood (air), and phlegm (water). Medical care was primarily about helping the patient stay in or return to their own personal natural balanced state.
+
+=== Plato ===
+
+Plato (428/423 – 348/347 BC) seems to have been the first to use the term "element (στοιχεῖον, stoicheîon)" in reference to air, fire, earth, and water.  The ancient Greek word for element, stoicheion (from stoicheo, "to line up") meant "smallest division (of a sun-dial), a syllable", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed.
+
+=== Aristotle ===
+
+In On the Heavens (350 BC), Aristotle defines "element" in general:
+
+An element, we take it, is a body into which other bodies may be analysed, present in them potentially or in actuality (which of these, is still disputable), and not itself divisible into bodies different in form. That, or something like it, is what all men in every case mean by element.
+In his On Generation and Corruption, Aristotle related each of the four elements to two of the four sensible qualities:
+
+Fire is both hot and dry.
+Air is both hot and wet (for air is like vapour, ἀτμὶς).
+Water is both cold and wet.
+Earth is both cold and dry.
+A classic diagram has one square inscribed in the other, with the corners of one being the classical elements, and the corners of the other being the properties. The opposite corner is the opposite of these properties, "hot – cold" and "dry – wet".

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+title: "Classical element"
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+category: "reference"
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+date_saved: "2026-05-05T09:32:56.401003+00:00"
+instance: "kb-cron"
+---
+
+==== Aether ====
+Aristotle added a fifth element, aether (αἰθήρ aither), as the quintessence, reasoning that whereas fire, earth, air, and water were earthly and corruptible, since no changes had been perceived in the heavenly regions, the stars cannot be made out of any of the four elements but must be made of a different, unchangeable, heavenly substance. It had previously been believed by pre-Socratics such as Empedocles and Anaxagoras that aether, the name applied to the material of heavenly bodies, was a form of fire. Aristotle himself did not use the term aether for the fifth element, and strongly criticised the pre-Socratics for associating the term with fire. He preferred a number of other terms indicating eternal movement, thus emphasising the evidence for his discovery of a new element. These five elements have been associated since Plato's Timaeus with the five platonic solids. Earth was associated with the cube, air with the octahedron, water with the icosahedron, and fire with the tetrahedron. Of the fifth Platonic solid, the dodecahedron, Plato obscurely remarked, "...the god used [it] for arranging the constellations on the whole heaven". Aristotle added a fifth element, aither (aether in Latin, "ether" in English) and postulated that the heavens were made of this element, but he had no interest in matching it with Plato's fifth solid.
+
+=== Neo-Platonism ===
+The Neoplatonic philosopher Proclus rejected Aristotle's theory relating the elements to the sensible qualities hot, cold, wet, and dry. He maintained that each of the elements has three properties. Fire is sharp (ὀξυτητα), subtle (λεπτομερειαν), and mobile (εὐκινησιαν) while its opposite, earth, is blunt (αμβλυτητα), dense (παχυμερειαν), and immobile (ακινησιαν); they are joined by the intermediate elements, air and water, in the following fashion:
+
+=== Hermeticism ===
+
+A text written in Egypt in Hellenistic or Roman times called the Kore Kosmou ("Virgin of the World") ascribed to Hermes Trismegistus (associated with the Egyptian god Thoth), names the four elements fire, water, air, and earth. As described in this book:
+
+And Isis answer made: Of living things, my son, some are made friends with fire, and some with water, some with air, and some with earth, and some with two or three of these, and some with all. And, on the contrary, again some are made enemies of fire, and some of water, some of earth, and some of air, and some of two of them, and some of three, and some of all. For instance, son, the locust and all flies flee fire; the eagle and the hawk and all high-flying birds flee water; fish, air and earth; the snake avoids the open air. Whereas snakes and all creeping things love earth; all swimming things love water; winged things, air, of which they are the citizens; while those that fly still higher love the fire and have the habitat near it. Not that some of the animals as well do not love fire; for instance salamanders, for they even have their homes in it. It is because one or another of the elements doth form their bodies' outer envelope. Each soul, accordingly, while it is in its body is weighted and constricted by these four.
+
+=== Manichaeism ===
+The Five Elements (Amahraspandān) occupy a central place in Manichaean cosmogony. They are portrayed as the five sons of the “First Man” (Ohrmizdbag): Ether (Frāwahr), Wind (Wād), Light (Rōšn), Water (Āb), and Fire (Ādur).  These elements also constitute the armor of the First Man.
+
+== Ancient Indian philosophy ==
+
+=== Hinduism ===
+
+The system of five elements are found in Vedas, especially Ayurveda, the pancha mahabhuta, or "five great elements", of Hinduism are:
+
+bhūmi or pṛthvī (earth),
+āpas or jala (water),
+agní or tejas (fire),
+vāyu, vyāna, or vāta (air or wind)
+ākāśa, vyom, or śūnya (space or zero) or  (aether or void).
+They further suggest that all of creation, including the human body, is made of these five essential elements and that upon death, the human body dissolves into these five elements of nature, thereby balancing the cycle of nature.
+The five elements are associated with the five senses, and act as the gross medium for the experience of sensations. The basest element, earth, created using all the other elements, can be perceived by all five senses — (i) hearing, (ii) touch, (iii) sight, (iv) taste, and (v) smell. The next higher element, water, has no odour but can be heard, felt, seen and tasted. Next comes fire, which can be heard, felt and seen. Air can be heard and felt. "Akasha" (aether) is beyond the senses of smell, taste, sight, and touch; it being accessible to the sense of hearing alone.
+
+=== Buddhism ===
+
+Buddhism has had a variety of thought about the five elements and their existence and relevance, some of which continue to this day.
+In the Pali literature, the mahabhuta ("great elements") or catudhatu ("four elements") are earth, water, fire and air. In early Buddhism, the four elements are a basis for understanding suffering and for liberating oneself from suffering. The earliest Buddhist texts explain that the four primary material elements are solidity, fluidity, temperature, and mobility, characterised as earth, water, fire, and air, respectively.
+The Buddha's teaching regarding the four elements is to be understood as the base of all observation of real sensations rather than as a philosophy. The four properties are cohesion (water), solidity or inertia (earth), expansion or vibration (air) and heat or energy content (fire). He promulgated a categorisation of mind and matter as composed of eight types of "kalapas" of which the four elements are primary and a secondary group of four are colour, smell, taste, and nutriment which are derivative from the four primaries.
+Thanissaro Bhikkhu (1997) renders an extract of Shakyamuni Buddha's from Pali into English thus:

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+---
+title: "Classical element"
+chunk: 3/4
+source: "https://en.wikipedia.org/wiki/Classical_element"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:56.401003+00:00"
+instance: "kb-cron"
+---
+
+Just as a skilled butcher or his apprentice, having killed a cow, would sit at a crossroads cutting it up into pieces, the monk contemplates this very body — however it stands, however it is disposed — in terms of properties: 'In this body there is the earth property, the liquid property, the fire property, & the wind property.'
+Tibetan Buddhist medical literature speaks of the pañca mahābhūta (five elements) or "elemental properties": earth, water, fire, wind, and space. The concept was extensively used in traditional Tibetan medicine. Tibetan Buddhist theology, tantra traditions, and "astrological texts" also spoke of them making up the "environment, [human] bodies," and at the smallest or "subtlest" level of existence, parts of thought and the mind. Also at the subtlest level of existence, the elements exist as "pure natures represented by the five female buddhas", Ākāśadhātviśvarī, Buddhalocanā, Mamakī, Pāṇḍarāvasinī, and Samayatārā, and these pure natures "manifest as the physical properties of earth (solidity), water (fluidity), fire (heat and light), wind (movement and energy), and" the expanse of space. These natures exist as all "qualities" that are in the physical world and take forms in it.
+
+== Ancient African philosophy ==
+
+=== Central Africa ===
+
+In traditional Bakongo religion, the five elements are incorporated into the Kongo cosmogram. This sacred symbol also depicts the physical world (Nseke), the spiritual world of the ancestors (Mpémba), the Kalûnga line that runs between the two worlds, the circular void that originally formed the two worlds (mbûngi), and the path of the sun. Each element correlates to a period in the life cycle, which the Bakongo people also equate to the four cardinal directions. According to their cosmology, all living things go through this cycle.
+
+Aether represents mbûngi, the circular void that begot the universe.
+Air (South) represents musoni, the period of conception that takes place during spring.
+Fire (East) represent kala, the period of birth that takes place during summer.
+Earth (North) represents tukula, the period of maturity that takes place during fall.
+Water (West) represents luvemba, the period of death that takes place during winter
+
+=== West Africa ===
+In traditional Bambara spirituality, the Supreme God created four additional essences of himself during creation. Together, these five essences of the deity correlate with the five classical elements.
+
+Koni is the thought and void (aether).
+Bemba (also called Pemba) is the god of the sky and air.
+Nyale (also called Koroni Koundyé) is the goddess of fire.
+Faro is the androgynous god of water.
+Ndomadyiri is the god and master of the earth.
+
+== Post-classical history ==
+
+=== Alchemy ===
+
+The elemental system used in medieval alchemy was developed primarily by the anonymous authors of the Arabic works attributed to Pseudo Apollonius of Tyana. This system consisted of the four classical elements of air, earth, fire, and water, in addition to a new theory called the sulphur-mercury theory of metals, which was based on two elements: sulphur, characterising the principle of combustibility, "the stone which burns"; and mercury, characterising the principle of metallic properties. They were seen by early alchemists as idealised expressions of irreducible components of the universe and are of larger consideration within philosophical alchemy.
+The three metallic principles—sulphur to flammability or combustion, mercury to volatility and stability, and salt to solidity—became the tria prima of the Swiss alchemist Paracelsus. He reasoned that Aristotle's four element theory appeared in bodies as three principles. Paracelsus saw these principles as fundamental and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke described the volatility (the mercurial principle), the heat-giving flames described flammability (sulphur), and the remnant ash described solidity (salt).
+
+=== Chinese ===
+
+Chinese traditional concepts adopt a set of elements called the 五行 (wuxing, literally "five phases"). These five are Metal or Gold (金 Jīn), Wood (木 Mù), Water (水 Shuǐ), Fire (火 Huǒ), and Earth or Soil (土 Tǔ). These can be linked to Taiji, Yinyang, Four Symbols, Bagua, Hexagram and I Ching. 
+
+Gold (West) represents the young yin symbol, autumn, the white colour, and White Tiger mascot, Taotie creature (Earth).
+Wood (East) represents the young yang symbol, spring, the green colour, and Azure Dragon mascot, Feilian creature (Wind).
+Water (North) represents the old yin symbol, winter, the black colour, and Black Turtle-Snake mascot.
+Fire (South) represents the old yang symbol, summer, the red colour, and Vermilion Bird mascot.
+Soil (Center) represents the Qi symbol, intermediate season, the yellow colour, and Yellow Dragon mascot, Hundun creature (Void).
+
+=== Japanese ===
+
+Japanese traditions use a set of elements called the 五大 (godai, literally "five great"). These five are earth, water, fire, wind/air, and void. These came from Indian Vastu shastra philosophy and Buddhist beliefs; in addition, the classical Chinese elements (五行, wu xing) are also prominent in Japanese culture, especially to the influential Neo-Confucianists during the medieval Edo period.
+
+Earth (地 Chi) represented rocks and stability.
+Water (水 Sui) represented fluidity and adaptability.
+Fire (火 Ka) represented life and energy.
+Wind (風 Fuu) represented movement and expansion.
+Void (空 Kuu) or Sky/Heaven represented spirit and creative energy.
+
+=== Medieval Aristotelian philosophy ===
+The Islamic philosophers al-Kindi, Avicenna and Fakhr al-Din al-Razi followed Aristotle in connecting the four elements with the four natures heat and cold (the active force), and dryness and moisture (the recipients).
+
+=== Medicine Wheel ===
+The medicine wheel symbol is a modern invention attributed to Native American peoples dating to approximately 1972, with the following descriptions and associations being a later addition. The associations with the classical elements are not grounded in traditional Indigenous teachings and the symbol has not been adopted by all Indigenous American nations.

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+---
+title: "Classical element"
+chunk: 4/4
+source: "https://en.wikipedia.org/wiki/Classical_element"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:56.401003+00:00"
+instance: "kb-cron"
+---
+
+Earth (South) represents the youth cycle, summer, the Indigenous race, and cedar medicine.
+Fire (East) represents the birth cycle, spring, the Asian race, and tobacco medicine.
+Wind/Air (North) represents the elder cycle, winter, the European race, and sweetgrass medicine.
+Water (West) represents the adulthood cycle, autumn, the African race, and sage medicine.
+
+== Modern history ==
+
+=== Chemical element ===
+
+The Aristotelian tradition and medieval alchemy eventually gave rise to modern chemistry, scientific theories and new taxonomies. By the time of Antoine Lavoisier, for example, a list of elements would no longer refer to classical elements. Some modern scientists see a parallel between the classical elements and the four states of matter: solid, liquid, gas and weakly ionized plasma.
+Modern science recognises classes of elementary particles which have no substructure (or rather, particles that are not made of other particles) and composite particles having substructure (particles made of other particles).
+
+=== Western astrology ===
+
+Western astrology uses the four classical elements in connection with astrological charts and horoscopes. The twelve signs of the zodiac are divided into the four elements: Fire signs are Aries, Leo and Sagittarius, Earth signs are Taurus, Virgo and Capricorn, Air signs are Gemini, Libra and Aquarius, and Water signs are Cancer, Scorpio, and Pisces.
+
+=== Criticism ===
+The Dutch historian of science Eduard Jan Dijksterhuis writes that the theory of the classical elements "was bound to exercise a really harmful influence. As is now clear, Aristotle, by adopting this theory as the basis of his interpretation of nature and by never losing faith in it, took a course which promised few opportunities and many dangers for science." Bertrand Russell says that Aristotle's thinking became imbued with almost biblical authority in later centuries. So much so that "Ever since the beginning of the seventeenth century, almost every serious intellectual advance has had to begin with an attack on some Aristotelian doctrine".
+
+== See also ==
+
+Arche – Basic proposition or assumptionPages displaying short descriptions of redirect targets
+Bagua – Eight trigrams used in Taoist cosmology
+Elemental – Mythic entity personifying one of the classical elements
+Jabir ibn Hayyan § The sulfur–mercury theory of metals – Early Islamic alchemy
+Periodic table – Tabular arrangement of the chemical elements
+Phlogiston theory – Superseded theory of combustion
+Prima materia – First or prime matter
+Qi – Vital force in traditional Chinese philosophy
+States of matter – Forms which matter can takePages displaying short descriptions of redirect targets
+
+== Notes ==
+
+== References ==
+
+=== Bibliography ===
+
+== External links ==
+ Media related to Classical elements at Wikimedia Commons
+Section on 4 elements in Buddhism

data/en.wikipedia.org/wiki/Corpuscular_theory_of_light-0.md

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+---
+title: "Corpuscular theory of light"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Corpuscular_theory_of_light"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:57.557855+00:00"
+instance: "kb-cron"
+---
+
+In optics, the corpuscular theory of light states that light is made up of small discrete particles called "corpuscles" (little particles) which travel in a straight line with a finite velocity and possess impetus. This notion was based on an alternate description of atomism of the time period.
+Isaac Newton laid the foundations for this theory through his work in optics. This early conception of the particle theory of light was an early forerunner to the modern understanding of the photon. This theory came to dominate the conceptions of light in the eighteenth century, displacing the previously prominent vibration theories, where light was viewed as "pressure" of the medium between the source and the receiver, first championed by René Descartes, and later in a more refined form by Christiaan Huygens. In part correct, being able to successfully explain refraction, reflection, rectilinear propagation and to a lesser extent diffraction, the theory would fall out of favor in the early nineteenth century, as the wave theory of light amassed new experimental evidence. The modern understanding of light is the concept of wave-particle duality.
+
+== Corpuscular theory of matter ==
+
+=== Mechanical philosophy ===
+
+In the early 17th century, natural philosophers began to develop new ways to understand nature gradually replacing Aristotelianism, which had been for centuries the dominant scientific theory, during the process known as the Scientific Revolution. Various European philosophers adopted what came to be known as mechanical philosophy sometime between around 1610 to 1650, which described the universe and its contents as a kind of large-scale mechanism, a philosophy that explained the universe is made with matter and motion. This mechanical philosophy was based on Epicureanism, and the work of Leucippus and his pupil Democritus and their atomism, in which everything in the universe, including a person's body, mind, soul and even thoughts, was made of atoms; very small particles of moving matter. During the early part of the 17th century, the atomistic portion of mechanical philosophy was largely developed by Gassendi, René Descartes and other atomists.
+
+=== Pierre Gassendi's atomist matter theory ===
+The core of Pierre Gassendi's philosophy is his atomist matter theory. In his work, Syntagma Philosophicum, ("Philosophical Treatise"), published posthumously in 1658, Gassendi tried to explain aspects of matter and natural phenomena of the world in terms of atoms and the void. He took Epicurean atomism and modified it to be compatible with Christian theology, by suggesting God created a finite number of indivisible and moving atoms, and has a continuing divine relationship to creation (of matter).
+Gassendi thought that atoms move in an empty space, classically known as the void, which contradicts the Aristotelian view that the universe is fully made of matter. Gassendi also suggests that information gathered by the human senses has a material form, especially in the case of vision.
+Corpuscular theories, or corpuscularianism, are similar to the theories of atomism, except that in atomism the atoms were supposed to be indivisible, whereas corpuscles could in principle be divided. Corpuscles are single, infinitesimally small, particles that have shape, size, color, and other physical properties that alter their functions and effects in phenomena in the mechanical and biological sciences. This later led to the modern idea that compounds have secondary properties different from the elements of those compounds. Gassendi asserts that corpuscles are particles that carry other substances and are of different types. These corpuscles are also emissions from various sources such as solar entities, animals, or plants. Robert Boyle was a strong proponent of corpuscularianism and used the theory to exemplify the differences between a vacuum and a plenum, by which he aimed to further support his mechanical philosophy and overall atomist theory. About a half-century after Gassendi, Isaac Newton used existing corpuscular theories to develop his particle theory of the physics of light.
+
+== Newtonian theory of light ==

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+---
+title: "Corpuscular theory of light"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Corpuscular_theory_of_light"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:57.557855+00:00"
+instance: "kb-cron"
+---
+
+Isaac Newton worked on optics throughout his research career, conducting various experiments and developing hypotheses to explain his results.  He dismissed Descartes' theory of light because he rejected Descartes’ understanding of space, which derived from it. With the publication of Opticks in 1704, Newton for the first time took a clear position supporting a corpuscular interpretation, though it would fall on his followers to systemise the theory.
+In the 1718 edition of Opticks, Newton added several uncertain hypotheses about the nature of light, formulated as queries. In query (Qu.) 16, he wondered whether the way a quavering motion of a finger pressing against the bottom of the eye causes the sensation of circles of colour is similar to how light affects the retina, and whether the independent continuation of the induced sensation for about a second indicates a vibrating nature of the motions in the eye. In Qu. 17, Newton compared the vibrations to the waves propagating in concentric circles after a stone has been thrown in water, and to "the Vibrations or Tremors excited in the Air by percussion". He therefore proposed that light rays would similarly excite waves of vibrations in a reflecting or refracting medium, which in turn could overtake the rays of light and alternately accelerate and retard them. Newton then suggested in Qu. 18 and Qu. 19 that light propagates through vacuum via a very subtle "Aethereal Medium", just like heat was thought to spread. 
+Although the previous hypotheses describe wave-like aspects of light, Newton still believed in particle-like properties. In Qu. 28, he asked: "Are not all Hypotheses erroneous in which Light is supposed to consist in Pression or Motion propagated through a fluid Medium." He did not believe the arguments explained the proposed new modifications of rays, and stressed how pression and motion would not propagate through fluid in straight lines beyond obstacles as light rays do. In Qu. 29, he wondered: "Are not the Rays of Light very small Bodies emitted from shining Substances? For such Bodies will pass through uniform Mediums in right Lines without bending into the Shadow, which is the Nature of the Rays of Light. They will also be capable of several Properties, and be able to conserve their Properties unchanged in passing through several Mediums, which is another Condition of the Rays of Light." He connected these properties to several effects of the interaction of light rays with matter and vacuum. 
+Newton's corpuscular theory was an elaboration of his view of reality as interactions of material points through forces. Note Albert Einstein's description of Newton's conception of physical reality:
+
+[Newton's] physical reality is characterised by concepts of space, time, the material point and force (interaction between material points).  Physical events are to be thought of as movements according to the law of material points in space. The material point is the only representative of reality in so far as it is subject to change. The concept of the material point is obviously due to observable bodies; one conceived of the material point on the analogy of movable bodies by omitting characteristics of extension, form, spatial locality, and all their 'inner' qualities, retaining only inertia, translation, and the additional concept of force.
+
+== Polarization ==
+The fact that light could be polarized was for the first time qualitatively explained by Newton using the particle theory. Étienne-Louis Malus in 1810 created a mathematical particle theory of polarization. Jean-Baptiste Biot in 1812 showed that this theory explained all known phenomena of light polarization. At that time polarization was considered proof of the particle theory. Nowadays, polarisation is considered a property of waves and may only manifest in transverse waves. Longitudinal waves may not be polarised.
+
+== End of corpuscular theory ==
+The dominance of Newtonian natural philosophy in the eighteenth century was one of the decisive factors ensuring the prevalence of the corpuscular theory of light. Newtonians maintained that the corpuscles of light were projectiles that travelled from the source to the receiver with a finite speed. In this description, the propagation of light is transportation of matter. 
+However by the turn of the century, beginning with Thomas Young's double-slit experiment in 1801, more evidence in the form of novel experiments on diffraction, interference, and polarization showcased issues with the theory. A wave theory based on Young, Augustin-Jean Fresnel and François Arago's work would materialise in a novel wave theory of light.
+
+== Quantum mechanics ==
+The notions of light as a particle resurfaced in the 20th century with the photoelectric effect. In 1905, Albert Einstein explained this effect by introducing the concept of light quanta or photons. Quantum particles are considered to have wave–particle duality. 
+Some authors consider that Newtonian theory of light, where corpuscles interact with the luminiferous aether, established a predecessor to the pilot wave theory, which is one of the interpretations of quantum mechanics.
+In quantum field theory, photons are explained as excitations of the electromagnetic field using second quantization.
+
+== See also ==
+Corpuscularianism
+Speed of gravity
+Photon
+Philosophy of physics
+Opticks by Isaac Newton
+The Skeptical Chemist by Robert Boyle
+
+== References ==
+
+== External links ==
+Observing the quantum behavior of light in an undergraduate laboratory JJ Thorn et al.: Am. J. Phys. 72, 1210-1219 (2004)
+Opticks, or, a Treatise of the Reflections, Refractions, Inflections, and Colours of Light. Sir Isaack Newton. 1704. Project Gutenberg book released 23 August 2010.
+Pierre Gassendi. Fisher, Saul. 2009. Stanford Encyclopedia of Philosophy.
+Isaac Newton. Smith, George. 2007. Stanford Encyclopedia of Philosophy.
+Robert Boyle. MacIntosh, J.J. 2010. Stanford Encyclopedia of Philosophy.
+YouTube video. Physics - Newton's corpuscular theory of light - Science. elearnin. Uploaded 5 Jan 2013.
+Robert Hooke's Critique of Newton's Theory of Light and Colors (delivered 1672) Robert Hooke. Thomas Birch, The History of the Royal Society, vol. 3 (London: 1757), pp. 10–15. Newton Project, University of Sussex.
+Corpuscule or Wave. Arman Kashef. 2022. Xaporia: The Free and Independent Blog.

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+---
+title: "Cosmic age problem"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Cosmic_age_problem"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:53.430171+00:00"
+instance: "kb-cron"
+---
+
+The cosmic age problem was a historical problem in astronomy concerning the age of the universe. The problem was that at various times in the 20th century, the universe was estimated to be younger than the oldest observed stars. Estimates of the universe's age came from measurements of the current expansion rate of the universe, the Hubble constant 
+  
+    
+      
+        
+          H
+          
+            0
+          
+        
+      
+    
+    {\displaystyle H_{0}}
+  
+, as well as cosmological models relating 
+  
+    
+      
+        
+          H
+          
+            0
+          
+        
+      
+    
+    {\displaystyle H_{0}}
+  
+ to the universe's matter and energy contents (see the Friedmann equations). Issues with measuring 
+  
+    
+      
+        
+          H
+          
+            0
+          
+        
+      
+    
+    {\displaystyle H_{0}}
+  
+ as well as not knowing about the existence of dark energy led to spurious estimates of the age. Additionally, objects such as galaxies, stars, and planets could not have existed in the extreme temperatures and densities shortly after the Big Bang.
+Since around 1997–2003, the problem is believed to have been solved by most cosmologists: modern cosmological measurements lead to a precise estimate of the age of the universe (i.e. time since the Big Bang) of 13.8 billion years, and recent age estimates for the oldest objects are either younger than this, or consistent allowing for measurement uncertainties.
+
+== Historical development ==
+
+=== Early years ===
+Following theoretical developments of the Friedmann equations by Alexander Friedmann and Georges Lemaître in the 1920s, and the discovery of the expanding universe by Edwin Hubble in 1929, it was immediately clear that tracing this expansion backwards in time predicts that the universe had almost zero size at a finite time in the past. This concept, initially known as the "Primeval Atom" by Lemaitre, was later elaborated into the modern Big Bang theory. If the universe had expanded at a constant rate in the past, the age of the universe now (i.e. the time since the Big Bang) is simply proportional to the inverse of the Hubble constant, often known as the Hubble time. For Big Bang models with zero cosmological constant and positive matter density, the actual age must be somewhat younger than this Hubble time; typically the age would be between 66% and 90% of the Hubble time, depending on the density of matter.
+Hubble's early estimate of his constant was 550 (km/s)/Mpc, and the inverse of that is 1.8 billion years. It was believed by many geologists in the 1920s that the Earth was probably around 2 billion years old, but with large uncertainty. The possible discrepancy between the ages of the Earth and the universe was probably one motivation for the development of the Steady State theory in 1948 as an alternative to the Big Bang; in the (now obsolete) steady state theory, the universe is infinitely old and on average unchanging with time. The steady state theory postulated spontaneous creation of matter to keep the average density constant as the universe expands, and therefore most galaxies still have an age less than 1/H0. However, if H0 had been 550 (km/s)/Mpc, our Milky Way galaxy would be exceptionally large compared to most other galaxies, so it could well be much older than an average galaxy, therefore eliminating the age problem.
+
+=== 1950–1970 ===
+In the 1950s, two substantial errors were discovered in Hubble's extragalactic distance scale: first in 1952, Walter Baade discovered there were two classes of Cepheid variable star. Hubble's sample comprised different classes nearby and in other galaxies, and correcting this error made all other galaxies twice as distant as Hubble's values, thus doubling the Hubble time. A second error was discovered by Allan Sandage and coworkers: for galaxies beyond the Local Group, Cepheids were too faint to observe with Hubble's instruments, so Hubble used the brightest stars as distance indicators. Many of Hubble's "brightest stars" were actually HII regions or clusters containing many stars, which caused another underestimation of distances for these more distant galaxies. Thus, in 1958 Sandage  published the first reasonably accurate measurement of the Hubble constant, at 75 (km/s)/Mpc, which is close to modern estimates of 68–74 (km/s)/Mpc.
+The age of the Earth (actually the Solar System) was first accurately measured around 1955 by Clair Patterson at 4.55 billion years, essentially identical to the modern value. For H0 ~ 75 (km/s)/Mpc, the inverse of H0 is 13.0 billion years; so after 1958 the Big Bang model age was comfortably older than the Earth.
+However, in the 1960s and onwards, new developments in the theory of stellar evolution enabled age estimates for large star clusters called globular clusters: these generally gave age estimates of around 15 billion years, with substantial scatter.  Further revisions of the Hubble constant by Sandage and Gustav Tammann in the 1970s gave values around 50–60 (km/s)/Mpc, and an inverse of 16-20 billion years, consistent with globular cluster ages.
+
+=== 1975–1990 ===
+However, in the late 1970s to early 1990s, the age problem re-appeared: new estimates of the Hubble constant gave higher values, with Gerard de Vaucouleurs estimating values 90–100 (km/s)/Mpc, while Marc Aaronson and co-workers gave values around 80-90  (km/s)/Mpc. Sandage and Tammann continued to argue for values 50–60, leading to a period of controversy sometimes called the "Hubble wars". The higher values for H0 appeared to predict a universe younger than the globular cluster ages, and gave rise to some speculations during the 1980s that the Big Bang model was seriously incorrect.

data/en.wikipedia.org/wiki/Cosmic_age_problem-1.md

@@ -0,0 +1,278 @@
+---
+title: "Cosmic age problem"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Cosmic_age_problem"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:53.430171+00:00"
+instance: "kb-cron"
+---
+
+=== Late 1990s: probable solution ===
+The age problem was eventually thought to be resolved by several developments between 1995 and 2003: firstly, a large program with the Hubble Space Telescope measured the Hubble constant at 72 (km/s)/Mpc with 10 percent uncertainty. Secondly, measurements of parallax by the Hipparcos spacecraft in 1995 revised globular cluster distances upwards by 5-10 percent; this made their stars brighter than previously estimated and therefore younger, shifting their age estimates down to around 12-13 billion years. Finally, from 1998 to 2003 a number of new cosmological observations including supernovae, cosmic microwave background observations and large galaxy redshift surveys led to the acceptance of dark energy and the establishment of the Lambda-CDM model as the standard model of cosmology. The presence of dark energy implies that the universe was expanding more slowly at around half its present age than today, which makes the universe older for a given value of the Hubble constant.  The combination of the three results above essentially removed the discrepancy between estimated globular cluster ages and the age of the universe.
+More recent measurements from WMAP and the Planck spacecraft lead to an estimate of the age of the universe of 13.80 billion years  with only 0.3 percent uncertainty (based on the standard Lambda-CDM model), and modern age measurements for globular clusters  and other objects are currently smaller than this value (within the measurement uncertainties). A substantial majority of cosmologists therefore believe the age problem is now resolved.
+New research from teams, including one led by Nobel laureate Adam Riess of the Space Telescope Science Institute in Baltimore, has found the universe to be between 12.5 and 13 billion years old, disagreeing with the Planck findings. Whether this stems merely from errors in data gathering, or is related to the as yet unexplained aspects of physics, such as Dark Energy or Dark Matter, has yet to be confirmed.
+
+== Dynamical modeling of the universe ==
+In this section, we wish to explore the effect of the dynamical modeling of the universe on the estimate of the universe's age. We will assume the modern observed Hubble value 
+  
+    
+      
+        
+          H
+          
+            0
+          
+        
+        ≈
+        70
+      
+    
+    {\displaystyle H_{0}\approx 70}
+  
+ km/s/Mpc so that the discussion below focuses on the effect of the dynamical modeling and less on the effect of the historical accuracy of the Hubble constant.
+The 1932 Einstein-de Sitter model of the universe assumes that the universe is filled with only matter and has vanishing curvature. This model received some popularity in the 1980s and offers an explicit solution for the scale factor (see, e.g., D. Baumann 2022)
+
+  
+    
+      
+        a
+        (
+        t
+        )
+        =
+        
+          
+            (
+            
+              
+                t
+                
+                  t
+                  
+                    0
+                  
+                
+              
+            
+            )
+          
+          
+            2
+            
+              /
+            
+            3
+          
+        
+         
+        ,
+      
+    
+    {\displaystyle a(t)=\left({\frac {t}{t_{0}}}\right)^{2/3}~,}
+  
+
+where 
+  
+    
+      
+        
+          t
+          
+            0
+          
+        
+      
+    
+    {\displaystyle t_{0}}
+  
+ is the universe's current age. This then implies that the age of the universe is directly related to the Hubble constant
+
+  
+    
+      
+        
+          t
+          
+            0
+          
+        
+        =
+        
+          
+            2
+            3
+          
+        
+        
+          H
+          
+            0
+          
+          
+            −
+            1
+          
+        
+         
+        .
+      
+    
+    {\displaystyle t_{0}={\frac {2}{3}}H_{0}^{-1}~.}
+  
+
+Substituting in the Hubble constant, the universe has an age of 
+  
+    
+      
+        
+          t
+          
+            0
+          
+        
+        ≈
+        9
+      
+    
+    {\displaystyle t_{0}\approx 9}
+  
+ billion years, in disagreement with, e.g., the age of the oldest stars.
+If one then allows for dark energy in the form of a cosmological constant 
+  
+    
+      
+        Λ
+      
+    
+    {\displaystyle \Lambda }
+  
+ in addition to matter, this two-component model predicts the following relationship between age and the Hubble constant
+
+  
+    
+      
+        
+          t
+          
+            0
+          
+        
+        =
+        
+          
+            2
+            3
+          
+        
+        
+          H
+          
+            0
+          
+          
+            −
+            1
+          
+        
+        ⋅
+        
+          
+            1
+            
+              
+                Ω
+                
+                  Λ
+                
+              
+            
+          
+        
+        
+          sinh
+          
+            −
+            1
+          
+        
+        ⁡
+        
+          (
+          
+            
+              
+                
+                  Ω
+                  
+                    Λ
+                  
+                
+                
+                  Ω
+                  
+                    m
+                  
+                
+              
+            
+          
+          )
+        
+         
+        .
+      
+    
+    {\displaystyle t_{0}={\frac {2}{3}}H_{0}^{-1}\cdot {\frac {1}{\sqrt {\Omega _{\Lambda }}}}\sinh ^{-1}\left({\sqrt {\frac {\Omega _{\Lambda }}{\Omega _{m}}}}\right)~.}
+  
+
+Plugging in observed values of the density parameters 
+  
+    
+      
+        (
+        
+          Ω
+          
+            Λ
+          
+        
+        ≈
+        0.7
+        ,
+         
+        
+          Ω
+          
+            m
+          
+        
+        ≈
+        0.3
+        )
+      
+    
+    {\displaystyle (\Omega _{\Lambda }\approx 0.7,~\Omega _{m}\approx 0.3)}
+  
+ results in an age of the universe 
+  
+    
+      
+        
+          t
+          
+            0
+          
+        
+        ≈
+        14
+      
+    
+    {\displaystyle t_{0}\approx 14}
+  
+ billion years, now consistent with stellar age observations.
+
+== References ==
+
+== External links ==
+http://map.gsfc.nasa.gov/universe/uni_age.html

data/en.wikipedia.org/wiki/Cosmic_pluralism-0.md

@@ -0,0 +1,66 @@
+---
+title: "Cosmic pluralism"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Cosmic_pluralism"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:58.727360+00:00"
+instance: "kb-cron"
+---
+
+Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the belief in numerous "worlds" (planets, dwarf planets or natural satellites) in addition to Earth (possibly an infinite number), which may harbour extraterrestrial life.
+The debate over pluralism began as early as the time of Anaximander (c. 610 – c. 546 BC) as a metaphysical argument, long predating the scientific Copernican conception that the Earth is one of numerous planets. It has continued, in a variety of forms, until the modern era.
+
+
+== Ancient Greek debates ==
+In Greek times, the debate was largely philosophical and did not conform to present notions of cosmology. Cosmic pluralism was a corollary to notions of infinity, and the purported multitude of life-bearing worlds were more akin to parallel universes (either contemporaneously in space or infinitely recurring in time) than to different solar systems. After Anaximander opened the door to an infinite universe, infinite higher dimensions, and an infinite amount of universes and other classes of verses, a strong pluralist stance was adopted by the atomists, notably Leucippus, Democritus, Epicurus—whose Epistle to Herodotus clearly lays out the Doctrine of Innumerable Worlds—and Lucretius who elaborates this Doctrine in his work De rerum natura. Anaxarchus told Alexander the Great that there were an infinite number of worlds that each harbored an infinite variety of unknown natural phenomena and extraterrestrial life, leading Alexander to weep, for he had not yet conquered even one. While these were prominent thinkers, their opponents—Plato and Aristotle—had greater effect. They argued that the Earth is unique and that there can be no other systems of worlds. This stance neatly dovetailed with later Christian ideas, and pluralism was effectively suppressed for approximately a millennium.
+
+
+== Medieval Islamic thought ==
+Many medieval Muslim scholars endorsed the idea of cosmic pluralism. Imam Muhammad al-Baqir  (676–733) wrote "Maybe you see that God created only this single world and that God did not create humans besides you. Well, I swear by God that God created thousands and thousands of worlds and
+thousands and thousands of humankind."
+Fakhr al-Din al-Razi (1149–1209), in dealing with his conception of physics and the physical world in his Matalib, rejects the Aristotelian and Avicennian notion of the Earth's centrality within the universe. Instead, he argues that there are "a thousand thousand worlds (alfa alfi 'awalim) beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has." To support his theological argument, he cites the Qur'anic verse, "All praise belongs to God, Lord of the Worlds," in Surah al-Fatiha emphasizing the term "Worlds."
+Two Qur'anic verses support the idea of God being Lord of multiple worlds: 1:2 and 41:09. Qur'an 16:8 says "He has created other things of which ye have no knowledge." However, some scholars argued that the expression used in the verses simply means "The Lord of all people".
+Cosmic pluralism was depicted in fictional Arabic literature. "The Adventures of Bulukiya", a tale from the One Thousand and One Nights (Arabian Nights), depicted a cosmos consisting of different worlds, some larger than Earth and each with their own inhabitants.
+
+
+== Scholastic thinkers ==
+Eventually, the Ptolemaic-Aristotelian system was challenged and pluralism reasserted, first tentatively by scholastics and then more seriously by followers of Copernicus. The telescope appeared to prove that a multitude of life was reasonable and an expression of God's creative omnipotence; still powerful theological opponents, meanwhile, continued to insist that although the Earth may have been displaced from the center of the cosmos, it was still the unique focus of God's creation. Thinkers such as Johannes Kepler were willing to admit the possibility of pluralism without truly supporting it. Medieval philosophers like Nicholas of Cusa and Nicole Oresme wrote the possibility of the plurality of the worlds.
+Thomas Bradwardine, the Archbishop of Canterbury, was investigating this concept, but he died of the Black Plague in 1349 before he could come to a conclusion.
+
+
+== Renaissance ==
+Giordano Bruno (1548-1600) introduced in his works the idea of multiple worlds instantiating the infinite possibilities of a pristine, indivisible  One. Bruno (through the mouth of his character Philotheo) in his De l'infinito, universo et mondi (1584) claims that "innumerable celestial bodies, stars, globes, suns and earths may be sensibly perceived therein by us and an infinite number of them may be inferred by our own reason."
+Teaching this was among the charges the Inquisition made against Bruno
+prior to his sentencing and execution.
+
+
+== Enlightenment ==
+During the Scientific Revolution and the later Enlightenment, cosmic pluralism became a mainstream possibility. Bernard Le Bovier de Fontenelle's Entretiens sur la pluralité des mondes (Conversations on the Plurality of Worlds) of 1686 was an important work from this period, speculating on pluralism and describing the new Copernican cosmology. Pluralism was also championed by philosophers such as John Locke, astronomers such as William Herschel and even politicians, including John Adams and Benjamin Franklin. As greater scientific skepticism and rigour were applied to the question, it ceased to be simply a matter of philosophy and theology and was properly bounded by astronomy and biology.
+The French astronomer Camille Flammarion was one of the chief proponents of cosmic pluralism during the latter half of the nineteenth century. His first book, La pluralité des mondes habités (1862) was a great popular success, going through 33 editions in its first twenty years. Flammarion was one of the first people to put forward the idea that extraterrestrial beings were genuinely alien, and not simply variations of earthly creatures.
+
+
+== Modern thought ==
+In the late nineteenth and twentieth centuries, the term "cosmic pluralism" became largely archaic as knowledge diversified and the speculation on extraterrestrial life focused on particular bodies and observations. The historic debate continues to have modern parallels, however. Carl Sagan and Frank Drake, for instance, could well be considered "pluralists" while proponents of the Rare Earth hypothesis are modern skeptics.
+Modern Islamic scholars like Abdullah Yusuf Ali point to the Qur'an (42:29) to argue for life on other planets: "And among His Signs is the creation of the heavens and the earth, and the living creatures that He has scattered through them". The verses uses the word da’bbah, which denotes living creatures on the surface of a planet. Other scholars like Herbert Eisenstein argued however that the word also refer to animals in general.
+
+
+== See also ==
+
+Buddhist cosmology
+Extraterrestrial life
+Exoplanet
+Exotheology
+Extraterrestrial life in fiction
+Hindu cosmology
+Mediocrity principle
+Mormon cosmology
+Planetary habitability
+Quiet and loud aliens
+
+
+== References ==
+
+
+== Further reading ==
+Ernst Benz (1978). Kosmische Bruderschaft. Die Pluralität der Welten. Zur Ideengeschichte des Ufo-Glaubens. Aurum Verlag. ISBN 3-591-08061-6. (later titled "Außerirdische Welten. Von Kopernikus zu den Ufos")

data/en.wikipedia.org/wiki/Cosmogony-0.md

@@ -0,0 +1,48 @@
+---
+title: "Cosmogony"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Cosmogony"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:59.903365+00:00"
+instance: "kb-cron"
+---
+
+Cosmogony, also spelled as cosmogeny, or cosmogenesis, is any model concerning the origin of the cosmos or the universe.
+
+== Types ==
+While cosmogony generally refers to origin stories, the nature and subject of these stories varies with times and sources. Ancient Greece developed a cosmogony focused on the origin of matter, space, and time with a transition from Chaos to Cosmos. This was a form of "philosophical cosmogony" that is distinct from modern empirical science but which nevertheless dealt with many similar questions. Another type of cosmogony focuses on the formation and evolution of the Solar System. or sometimes the formation of galaxies. The standard cosmological model of the early development of the universe is the Big Bang theory, but it is based on a model known to fail at the very earliest times. Thus modern cosmogony is not generally a consequence of modern cosmology theories.
+
+== Scientific cosmogenesis ==
+A Big Bang model for the dynamics of the universe is widely agreed among cosmologists.  Like most physical models, Big Bang models describe changes of state. Few physical models are designed to determine initial conditions: initial states are given by experimental measurements or by hypothesis.
+In cosmology, the initial state would be the origin of the universe. It is considered a valid challenge to address but there are significant disagreements over even the form of acceptable answers.
+
+=== Initial singularity ===
+
+Since the Big Bang model describes an expanding and cooling universe, it must have been denser and hotter in the past. Conceptually the model can be extrapolated back to time zero. However, this process cannot be run all the way back to time zero: the standard model assumes a density low enough to avoid quantum effects. As the model is followed to smaller times the density exceeds the validity of general relativity. This point in time is called the Planck time.
+
+=== General relativity initial state ===
+One approach to the limitations of running Big Bang model back to time zero simply stops extrapolating when the limit of valid general relativity is reached. This model by itself fails in several ways. First, the observable universe is much more homogeneous than an extrapolated Big Bang can account for. This problem is called the horizon problem because events on opposite sides of the horizon could not have mixed in the early universe and thus should not be homogeneous now.  Second, the expansion of the universe reduces curvature or equivalently increases flatness. Since the universe now is observed to be close to flat, a universe extrapolated back in time would have to be extremely flat. This almost but not quite zero curvature seems unnatural, an issue called the flatness problem. Third, this extrapolation gives poor results when compared to measurements of large scale structure and of the cosmic microwave background (CMB).
+
+=== Initial state theories ===
+Several different theories have been proposed as alternative to simple extrapolation of general relativity. The most successful approach is called inflation. In this model the universe goes through a very short phase of intense expansion not predicted by general relativity. The expansion is so immense and fast that all pre-existing particles are diluted and replaced by particles emerging from the field that drove inflation in an process called reheating. An initially homogeneous universe, inflated by an enormous factor explains why we can see homogeneous features across distances which ordinary causality asserts are independent.
+When combined with the Big Bang and other concepts of cosmology, inflation becomes the 
+consensus or standard model of cosmology, a model which successfully predicts details of large scale structure and the CMB. While inflation has been successful in developing an initial state for Big Bang models, it does not by itself describe the origin of the universe. The rapid expansion erases evidence of physical processes occurring before inflation.
+
+=== Quantum cosmology ===
+Sean M. Carroll, who specializes in theoretical cosmology and field theory, explains two competing explanations for the origins of the singularity, which is the center of a space in which a characteristic is limitless (one example is the singularity of a black hole, where gravity is the characteristic that becomes limitless — infinite).
+When the universe started to expand, the Big Bang occurred, which evidently began the universe. The other explanation, the Hartle–Hawking state, held by proponents such as Stephen Hawking, asserts that time did not exist when it emerged along with the universe. This assertion implies that the universe does not have a beginning, as time did not exist "prior" to the universe. Hence, it is unclear whether properties such as space or time emerged with the singularity and the known universe.
+
+== Mythology ==
+
+In mythology, creation or cosmogonic myths are narratives describing the beginning of the universe or cosmos.
+Some methods of the creation of the universe in mythology include:
+
+the will or action of a supreme being or beings,
+the process of metamorphosis,
+the copulation of female and male deities,
+from chaos,
+or via a cosmic egg.
+Creation myths may be etiological, attempting to provide explanations for the origin of the universe. For instance, Eridu Genesis, the oldest known creation myth, contains an account of the creation of the world in which the universe was created out of a primeval sea (Abzu). Creation myths vary, but they may share similar deities or symbols. For instance, the ruler of the gods in Greek mythology, Zeus, is similar to the ruler of the gods in Roman mythology, Jupiter. Another example is the ruler of the gods in Tagalog mythology, Bathala, who is similar to various rulers of certain pantheons within Philippine mythology such as the Bisaya's Kaptan.
+
+Recurring patterns of creation narratives can be identified across various cultures and beliefs. Creation myths are found in most religions, and can be split into five different classifications, based on a system created by Mircea Eliade and his colleague Charles Long: 

data/en.wikipedia.org/wiki/Cosmogony-1.md

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+---
+title: "Cosmogony"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Cosmogony"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:59.903365+00:00"
+instance: "kb-cron"
+---
+
+Creation ex nihilo in which the creation is through the thought, word, dream or bodily secretions of a divine being from initial state of nothing.
+Earth diver creation in which a diver, usually a bird or amphibian sent by a creator, plunges to the seabed through a primordial ocean to bring up sand or mud which develops into a terrestrial world.
+Emergence myths in which progenitors pass through a series of worlds and metamorphoses until reaching the present world.
+Creation by the dismemberment of a primordial being, as in the Ymir motif, otherwise known as the world parent myth.
+Creation by the splitting or ordering of a primordial unity such as the cracking of a cosmic egg or a bringing order from chaos.
+
+== Compared with cosmology ==
+In the humanities, the distinction between cosmogony and cosmology is blurred. For example, in theology, the cosmological argument for the existence of God (pre-cosmic cosmogonic bearer of personhood) is an appeal to ideas concerning the origin of the universe and is thus cosmogonical. Some religious cosmogonies have an impersonal first cause (for example Taoism).
+However, in astronomy, cosmogony can be distinguished from cosmology, which studies the universe and its existence, but does not necessarily inquire into its origins. There is therefore a scientific distinction between cosmological and cosmogonical ideas. Physical cosmology is the science that attempts to explain all observations relevant to the development and characteristics of the universe on its largest scale. Some questions regarding the behaviour of the universe have been described by some physicists and cosmologists as being extra-scientific or metaphysical. Attempted solutions to such questions may include the extrapolation of scientific theories to untested regimes (such as the Planck epoch), or the inclusion of philosophical or religious ideas.
+
+== See also ==
+Anthropic principle – Hypothesis about sapient life and the universe
+Chronology of the universe – History and future of the universe
+Cosmography – Science of mapping the universe
+Ultimate fate of the universe – Theories about the end of the universe
+Why is there anything at all?
+
+== References ==
+
+== External links ==
+ Media related to Cosmogony at Wikimedia Commons

data/en.wikipedia.org/wiki/Council_of_Jamnia-0.md

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+---
+title: "Council of Jamnia"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Council_of_Jamnia"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:54.611504+00:00"
+instance: "kb-cron"
+---
+
+Scholars refer to the Council of Jamnia (presumably Yavneh in the Holy Land) as a late 1st-century AD gathering that some claim finalized the canon of the Hebrew Bible in response to Christianity. Heinrich Graetz first proposed this theory in 1871, and many scholars accepted it throughout much of the 20th century. Since the 1960s, scholars have increasingly challenged and largely discredited the theory, arguing instead that the Hebrew canon emerged earlier, possibly during the Hasmonean period. Rabbinic and Messianic Jewish scholars, however, highlight Jamnia's role in consolidating Jewish textual tradition and communal identity, emphasizing its importance for scriptural interpretation and religious authority rather than formal canonical closure.
+
+== Background ==
+The Talmud records that shortly before the destruction of the Second Temple in 70 AD, Rabbi Yohanan ben Zakkai negotiated with the Roman authorities to establish a center of Jewish learning in Yavneh (Jamnia). After the Romans besieged Jerusalem, Yohanan ben Zakkai obtained permission from the Roman general Vespasian to relocate and found a school dedicated to studying and developing halakha (Jewish religious law). This action ensured that Jewish scholarship and religious life could continue outside the Temple-centric system, which the Romans had destroyed.
+Yohanan ben Zakkai and other leading rabbis transformed Judaism by shifting the focus from Temple worship to Torah study, prayer, and legal interpretation. The Yavneh academy became a hub for religious debate and decision-making, attracting prominent scholars who guided the Jewish community through Roman rule and the challenges of post-Temple identity.
+Scholars recognize Yavneh as the birthplace of Rabbinic Judaism. There, the rabbis began systematically compiling oral traditions and formulating theological responses to early Christianity. Although some historical details remain debated, scholars widely agree that Yohanan ben Zakkai's leadership and Yavneh's academy played a crucial role in preserving Jewish religious tradition during a turbulent era.
+The academy flourished into the late 1st and 2nd centuries AD, shaping much of the Jewish legal and ethical thought recorded in the Mishnah and Talmud.
+
+== The theory ==
+
+The Mishnah, compiled at the end of the 2nd century, describes a debate over the status of some books of Ketuvim, and in particular over whether or not they render the hands "impure". (By Rabbinic decree, Canonical books will "impurify" hands that touch it, which in turn will "impurify" food that they touch, rendering it inedible. This was decreed to prevent people from storing food near the scrolls, which would attract rodents. See Handwashing in Judaism.) Yadaim 3:5 calls attention to a debate over Song of Songs and Ecclesiastes. The Megillat Taanit, in a discussion of days when fasting is prohibited but that are not noted in the Bible, mentions the holiday of Purim. Based on these, and a few similar references, Heinrich Graetz concluded in 1871 that there had been a Council of Jamnia (or Yavne in Hebrew) which had decided the Jewish canon sometime in the late 1st century (c. 70–90).
+
+== Refutation ==
+W. M. Christie was the first to dispute this popular theory in an article entitled "The Jamnia Period in Jewish History". Jack P. Lewis wrote a critique of the popular consensus entitled "What Do We Mean by Jabneh?". Sid Z. Leiman made an independent challenge for his University of Pennsylvania thesis, published later as a book in 1976. Raymond E. Brown largely supported Lewis in his review published in The Jerome Biblical Commentary (also appears in the New Jerome Biblical Commentary of 1990), as did Lewis' discussion of the topic in 1992's Anchor Bible Dictionary.
+Albert C. Sundberg Jr. summarized the crux of Lewis' argument as follows:
+
+Jewish sources contain echoes of debate about biblical books, but canonicity was not the issue, and debate was not connected with Jabneh... Moreover, specific canonical discussion at Jabneh is attested only for Chronicles and Song of Songs. Both circulated before Jabneh. There was vigorous debate between Beth Shammai and Beth Hillel over Chronicles and Song; Beth Hillel affirmed that both "defile the hands", the rabbinic principle (enunciated in Mishnah Yadayim 3:5) according to which the Holy Scripture is so holy that they impart uncleanness; writings that are not holy, do not impart uncleanness. One text does speak of official action at Jabneh. It gives a blanket statement that "all Holy Scripture defile the hands", and adds "on the day they made R. Eleazar b. Azariah head of the college, the Song of Songs and Koheleth (Ecclesiastes) both render the hands unclean" (M. Yadayim 3.5). Of the apocryphal books, only Ben Sira is mentioned by name in rabbinic sources, and it continued to be circulated, copied, and cited. No book is ever mentioned in the sources as being excluded from the canon at Jabneh.
+According to Lewis:
+
+The concept of the Council of Jamnia is a hypothesis to explain the canonization of the Writings (the third division of the Hebrew Bible) resulting in the closing of the Hebrew canon. ...These ongoing debates suggest the paucity of evidence on which the hypothesis of the Council of Jamnia rests and raise the question whether it has not served its usefulness and should be relegated to the limbo of unestablished hypotheses. It should not be allowed to be considered a consensus established by mere repetition of assertion.
+The 20th-century evangelical scholar F. F. Bruce thought that it was "probably unwise to talk as if there were a Council or Synod of Jamnia which laid down the limits of the Old Testament canon." Other scholars have since joined in, and today the theory is largely discredited. Some hold that the Hebrew canon was established  during the Hasmonean dynasty (140–40 BCE).

data/en.wikipedia.org/wiki/Council_of_Jamnia-1.md

@@ -0,0 +1,30 @@
+---
+title: "Council of Jamnia"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Council_of_Jamnia"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:54.611504+00:00"
+instance: "kb-cron"
+---
+
+== Rabbinic and Messianic Jewish perspectives on Jamnia ==
+Rabbinic and Messianic Jewish scholars emphasize how the gatherings at Yavneh (Jamnia) actively shaped Jewish identity and religious literature after the destruction of the Second Temple. Eli Lizorkin-Eyzenberg, a scholar of Jewish Studies and founder of the Israel Bible Center, explains that the sages at Yavneh deliberately worked to define and consolidate sacred texts within the Jewish community during this turbulent period. He highlights that the discussions at Yavneh focused on establishing religious authority and scriptural interpretation rather than formalizing a closed biblical canon. Lizorkin-Eyzenberg stresses that these efforts helped unify the Jewish people by reaffirming shared traditions and texts amid the upheaval caused by the Temple's destruction and the rise of competing religious groups.
+Jacob Neusner, a leading scholar of Rabbinic Judaism, acknowledges that the sages at Yavneh did not formally finalize the Hebrew Bible canon in a single council. Instead, he shows how they engaged in authoritative debates and interpretations that gradually established normative boundaries for Jewish sacred literature. Neusner argues that this discursive process at Yavneh served as a critical foundation for the later codification of Jewish scripture and law.
+Jonathan Sacks, former Chief Rabbi of the United Kingdom, highlights how Yavneh became a central hub for Rabbinic authority and Torah study. He points out that the rulings and teachings developed there shaped Jewish textual and spiritual life for generations. While Sacks does not explicitly claim that Yavneh closed the canon, he emphasizes the continuity and vitality of both oral and written traditions emanating from the Yavnean sages, which preserved and transmitted Jewish faith and practice throughout subsequent centuries.
+These Rabbinic and Messianic Jewish perspectives contrast with the dominant critical scholarly view, which regards the Hebrew Bible's canonization as a slow, evolving process extending into the third century CE and later. Nonetheless, these interpretations underscore how the gatherings at Jamnia functioned as a decisive moment when Jewish leaders actively reinforced communal identity, religious authority, and textual tradition in response to historical challenges.
+Together, these scholars demonstrate that the significance of Jamnia lies less in a formalized decree and more in its role as a dynamic center for theological reflection, debate, and consolidation during a pivotal period in Jewish history.
+
+== References ==
+
+== Sources ==
+Kantor, Mattis, The Jewish timeline encyclopaedia: a year-by-year history from Creation to the present day, Jason Aronson Inc., Northvale N.J., 1992
+
+== External links ==
+Robert C. Newman, 'The Council of Jamnia and the Old Testament Canon' (1983), an in-depth discussion of the subject on the site of the Interdisciplinary Biblical Research Institute.
+Bob Stanley, 'The Deuterocanonicals' (2002), an interpretation of "The Council of Jamnia" presented on the website of The Catholic Treasure Chest.
+Jamina or  ( Jabneh ) at JewishEncyclopedia.com
+Jewish Encyclopedia: Academy of Jabneh
+Jewish Encyclopedia: Birkat ha-Minim
+Jewish Encyclopedia: Min
+"The Old Testament of the Early Church" Revisited, Albert C. Sundberg, Jr., 1997

data/en.wikipedia.org/wiki/De_mirabilibus_sacrae_scripturae-0.md

@@ -0,0 +1,23 @@
+---
+title: "De mirabilibus sacrae scripturae"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/De_mirabilibus_sacrae_scripturae"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:01.055248+00:00"
+instance: "kb-cron"
+---
+
+De mirabilibus sacrae scripturae (English: On the Miraculous Things in Sacred Scripture) is a Latin treatise written around 655 by an anonymous Irish writer and philosopher known as Augustinus Hibernicus or the Irish Augustine.
+The author's nickname is in reference to the philosopher Augustine of Hippo. This pseudo-Augustine was born in Ireland sometime in the first half of the seventh century and is noted especially for his natural philosophy.
+Around the year 655 he wrote a treatise called De mirabilibus Sacrae Scripturae. It has long been regarded as an exceptional work, in that it demonstrates a strictly scientific approach in the matter of making direct observations of nature and subjecting them to a strictly logical interpretation.
+His treatise seeks to explain each miracle in the Scriptures as an extreme case of phenomena, yet still within the laws of nature. Augustine also gives a list of the terrestrial mammals of Ireland, and solves the problem of how they reached Ireland after the flood of Noah by proposing a solution – hundreds of years ahead of its time – that the island had been cut off from continental Europe by marine erosion.
+
+
+== Further reading ==
+Bracken, Damian (1998), "Rationalism and the Bible in seventh-century Ireland", Chronicon, 2
+Duddy, Thomas (2002), A History of Irish Thought, New York: Routledge
+Esposito, Mario (1919), "On the Pseudo-Augustinian treatise De mirabilibus sanctae scripturae written in Ireland in the year 655", Proceedings of the Royal Irish Academy, 35 C: 189–207
+MacGinty, Gerard (1987), "The Irish Augustine: De mirabilibus sacrae Scripturae", in Ní Chatháin, Próinséas; Richter, Michael (eds.), Irland und die Christenheit: Bibelstudien und Mission / Ireland and Christendom: the Bible and the Missions, Stuttgart: Klett-Cotta, pp. 70–83
+Ó Fiannachta, Pádraig (1990), "De mirabilibus sacrae Scripturae", Léachtaí Cholm Cille, 20: 119–139
+Reeves, William (1861), "On Augustin, an Irish Writer of the Seventh Century", Proceedings of the Royal Irish Academy, 7: 514–522

data/en.wikipedia.org/wiki/Diatribe_de_Progidiosis_Crucibus-0.md

@@ -0,0 +1,41 @@
+---
+title: "Diatribe de Progidiosis Crucibus"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Diatribe_de_Progidiosis_Crucibus"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:02.221791+00:00"
+instance: "kb-cron"
+---
+
+Diatribe de progidiosis crucibus is a 1661 work by the Jesuit scholar Athanasius Kircher. It was printed in Rome by Blasius Deversin and dedicated to Archduke Leopold Wilhelm of Austria. A second edition of the work was published in Rome in 1666 and a German translation appeared in Gaspar Schott's Joco-seriorum naturae et artis (Würzburg, 1666).
+Diatribe is Kircher's most succinct and explicit statement in favour of seeking rational causes for phenomena through an understanding of natural laws, derived from observation, rather than seeking miraculous explanations. This continued the theme he had taken up in Scrutinium Physico-Medicum (1658) and pursued in greater detail in Mundus Subterraneus (1665).
+During an 1660 eruption of Vesuvius, small cross-shaped objects fell from the sky. They were seen as a message from the patron saint Saint Gennaro by the superstitious population of Naples. Kircher visited the volcano to investigate the phenomenon, and concluded that fine ash and moisture had settled on cloth, taking a cruciform shape defined by the weave itself. Kircher noted that the crosses had been seen on linen cloth but not on garments of wool, and that they had appeared only under certain specific conditions of temperature and moisture, causing "guttulae nitrosae" (nitrous drops) to form on the surface. The book covers his conclusions. 
+
+
+== Background ==
+ 
+On 3 July 1660 an eruption of Vesuvius began. A plume of ejected material rose up to 4 km (2.5 mi) into the air and was carried off to the southeast by the wind.  As was normal for Vesuvius, the late stages of the eruption involved the ejection of white ash. Along with this ash, free twinned augite phenocrysts were ejected, causing small cross-shaped objects to fall from the sky. This phenomenon appeared on the day the Sun entered Leo (21 July).
+The population of Naples believed at first that these crosses were a sign from their patron saint, Saint Gennaro, that he would protect them from the volcano. However many people in Southern Italy soon grew fearful that the crosses were a token of God's anger.
+Kircher wanted to undertake an investigation of the phenomenon that would reassure people and help avoid panic.  He had an intense dislike of superstition and its simplistic view of the world, which led people to prefer the idea of the disruptive intervention of a miracle rather than seeking to understand the complex mechanisms by which the world and nature operated. He had a prior research interest in Vesusius, having had himself lowered into its crater for research purposes in 1638. Between August and October 1660, Kircher travelled to the hamlets of Somma and Ottaviano to look for primary evidence himself, and also read accounts from other witnesses in southern Italy. These reported various extraordinary discoveries, such as that the crosses had appeared on altar drapes, and on objects inside locked chests and shuttered rooms.
+
+
+== Discussion and conclusions ==
+The first two thirds of the work consists of a pars historica and a pars physica, setting out both a historic narrative of the phenomenon and a physical description. Three possible explanations for the mysterious crosses were considered. Firstly, they may have been miraculous and involved a direct intervention by God in the events of the world; secondly, angels or demons might have made use of natural forces in extraordinary ways; and thirdly, the laws of nature could provide a perfectly good explanation.
+In Kircher's view the ultimate cause of all things was divine will, but this was expressed, for the most part, through understandable natural laws; studying these laws therefore revealed the forces that lay beneath natural phenomena. The explanation for the cross-shaped marks, he concluded, was that fine ash and moisture had settled on cloth, taking  cruciform shape defined by the weave itself.
+Kircher noted that the crosses had been seen on linen cloth but not on garments of wool, and that they had appeared only under certain specific conditions of temperature and moisture, causing "guttulae nitrosae" (nitrous drops) to form on the surface. To support his conclusion Kircher noted two instances of similar phenomena; when a tomcat had sprayed linen in the laundry room at the Jesuit College in Rome, the effect produced was yellow crosses following the weave of the cloth; the same had also been observed in the bed-linen of an elderly Jesuit who had accidentally wet his bed.
+He maintained however that an explanation through the operation of natural laws did not mean that the phenomenon did not contain an important divine message:
+
+"[Portents are] like hieroglyphic symbols swathed in enigmatic and allegorical meanings which the Divine Wisdom records in Heaven, Earth, and the elements as if in a hook and sets it before mortals to read; when they withdraw from the paths of Divine Will they are terrified by the threats held out before them, and turn back toward better fruits.
+
+
+== Critical reception ==
+Like all of Kircher's work, Diatribe had to be submitted to the censors of the Jesuit order before it could be published.  They did not block it, but informed Kircher that this was not the quality of work the order was expecting its scholars to produce. They noted that crosses had been found on meat and fruit as well as linen.  Furthermore, crosses were still continuing to appear, after the eruption had stopped and after the Sun had moved out of Leo. If they waited until the autumn rains washed the remaining ash out of the air, they would be able to see whether the conclusions of Diatribe still seemed satisfactory or not.  They therefore recommended that publication should be delayed. Before publication in 1661, Kircher added a discussion about the appearance of crosses on fruit and meat, arguing that, like linen, these were fibrous materials capable of producing the same effect on their surfaces.
+The work was widely disparaged, and in 1677, Gioseffo Petrucci published Prodromo apologetico alli studi chircheriani which sought to defend Kircher against those who thought his explanation of the phenomenon was too credulous.
+
+
+== References ==
+
+
+== External links ==
+digital copy of Diatribe

data/en.wikipedia.org/wiki/Dirac_large_numbers_hypothesis-0.md

@@ -0,0 +1,560 @@
+---
+title: "Dirac large numbers hypothesis"
+chunk: 1/2
+source: "https://en.wikipedia.org/wiki/Dirac_large_numbers_hypothesis"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:55.823362+00:00"
+instance: "kb-cron"
+---
+
+The Dirac large numbers hypothesis (LNH) is an observation made by Paul Dirac in 1937 relating ratios of size scales in the Universe to that of force scales. The ratios constitute very large, dimensionless numbers: some 40 orders of magnitude in the present cosmological epoch. According to Dirac's hypothesis, the apparent similarity of these ratios might not be a mere coincidence but instead could imply a cosmology with these unusual features:
+
+The strength of gravity, as represented by the gravitational constant, is inversely proportional to the age of the universe: 
+  
+    
+      
+        G
+        ∝
+        1
+        
+          /
+        
+        t
+        
+      
+    
+    {\displaystyle G\propto 1/t\,}
+  
+
+The mass of the universe is proportional to the square of the universe's age: 
+  
+    
+      
+        M
+        ∝
+        
+          t
+          
+            2
+          
+        
+      
+    
+    {\displaystyle M\propto t^{2}}
+  
+.
+Physical constants are actually not constant. Their values depend on the age of the Universe.
+Stated in another way, the hypothesis states that all very large dimensionless quantities occurring in fundamental physics should be simply related to a single very large number, which Dirac chose to be the age of the universe.
+
+== Background ==
+LNH was Dirac's personal response to a set of large number "coincidences" that had intrigued other theorists of his time. The "coincidences" began with Hermann Weyl (1919), who speculated that the observed radius of the universe, RU, might also be the hypothetical radius of a particle whose rest energy is equal to the gravitational self-energy of the electron:
+
+  
+    
+      
+        
+          
+            
+              R
+              
+                U
+              
+            
+            
+              r
+              
+                e
+              
+            
+          
+        
+        ≈
+        
+          
+            
+              r
+              
+                H
+              
+            
+            
+              r
+              
+                e
+              
+            
+          
+        
+        ≈
+        4.1666763
+        ⋅
+        
+          10
+          
+            42
+          
+        
+        ≈
+        
+          10
+          
+            42.62
+            …
+          
+        
+        ,
+      
+    
+    {\displaystyle {\frac {R_{\text{U}}}{r_{\text{e}}}}\approx {\frac {r_{\text{H}}}{r_{\text{e}}}}\approx 4.1666763\cdot 10^{42}\approx 10^{42.62\ldots },}
+  
+
+where,
+
+  
+    
+      
+        
+          r
+          
+            e
+          
+        
+        =
+        
+          
+            
+              e
+              
+                2
+              
+            
+            
+              4
+              π
+              
+                ϵ
+                
+                  0
+                
+              
+               
+              
+                m
+                
+                  e
+                
+              
+              
+                c
+                
+                  2
+                
+              
+            
+          
+        
+        ≈
+        2.81794032
+        ⋅
+        
+          10
+          
+            −
+            15
+          
+        
+        
+          m
+        
+      
+    
+    {\displaystyle r_{\text{e}}={\frac {e^{2}}{4\pi \epsilon _{0}\ m_{\text{e}}c^{2}}}\approx 2.81794032\cdot 10^{-15}\mathrm {m} }
+  
+
+  
+    
+      
+        
+          r
+          
+            H
+          
+        
+        =
+        
+          
+            
+              e
+              
+                2
+              
+            
+            
+              4
+              π
+              
+                ϵ
+                
+                  0
+                
+              
+               
+              
+                m
+                
+                  H
+                
+              
+              
+                c
+                
+                  2
+                
+              
+            
+          
+        
+        ≈
+        1.1741445
+        ⋅
+        
+          10
+          
+            28
+          
+        
+        
+        
+          m
+        
+      
+    
+    {\displaystyle r_{\text{H}}={\frac {e^{2}}{4\pi \epsilon _{0}\ m_{\text{H}}c^{2}}}\approx 1.1741445\cdot 10^{28}\,\mathrm {m} }
+  
+ with 
+  
+    
+      
+        
+          m
+          
+            H
+          
+        
+        
+          c
+          
+            2
+          
+        
+        =
+        
+          
+            
+              G
+              
+                m
+                
+                  e
+                
+                
+                  2
+                
+              
+            
+            
+              r
+              
+                e
+              
+            
+          
+        
+      
+    
+    {\displaystyle m_{\text{H}}c^{2}={\frac {Gm_{\text{e}}^{2}}{r_{\text{e}}}}}
+  
+
+and re is the classical electron radius, me is the mass of the electron, mH denotes the mass of the hypothetical particle, and rH is its electrostatic radius.
+The coincidence was further developed by Arthur Eddington (1931) who related the above ratios to N, the estimated number of charged particles in the universe, with the following ratio:
+
+  
+    
+      
+        
+          
+            
+              e
+              
+                2
+              
+            
+            
+              4
+              π
+              
+                ϵ
+                
+                  0
+                
+              
+               
+              G
+              
+                m
+                
+                  e
+                
+                
+                  2
+                
+              
+            
+          
+        
+        ≈
+        4.1666763
+        ⋅
+        
+          10
+          
+            42
+          
+        
+        ≈
+        
+          
+            N
+          
+        
+      
+    
+    {\displaystyle {\frac {e^{2}}{4\pi \epsilon _{0}\ Gm_{\text{e}}^{2}}}\approx 4.1666763\cdot 10^{42}\approx {\sqrt {N}}}
+  
+.
+In addition to the examples of Weyl and Eddington, Dirac was also influenced by the primeval-atom hypothesis of Georges Lemaître, who lectured on the topic in Cambridge in 1933. The notion of a varying-G cosmology first appears in the work of Edward Arthur Milne a few years before Dirac formulated LNH. Milne was inspired not by large number coincidences but by a dislike of Einstein's general theory of relativity. For Milne, space was not a structured object but simply a system of reference in which relations such as this could accommodate Einstein's conclusions:
+
+  
+    
+      
+        G
+        =
+        
+          (
+          
+            
+            
+              
+                
+                  c
+                  
+                    3
+                  
+                
+                
+                  M
+                  
+                    U
+                  
+                
+              
+            
+            
+          
+          )
+        
+        t
+        ,
+      
+    
+    {\displaystyle G=\left(\!{\frac {c^{3}}{M_{\text{U}}}}\!\right)t,}
+  
+
+where MU is the mass of the universe and t is the age of the universe. According to this relation, G increases over time.
+
+== Dirac's interpretation of the large number coincidences ==
+The Weyl and Eddington ratios above can be rephrased in a variety of ways, as for instance in the context of time:
+
+  
+    
+      
+        
+          
+            
+              c
+              
+              t
+            
+            
+              r
+              
+                e
+              
+            
+          
+        
+        ≈
+        3.47
+        ⋅
+        
+          10
+          
+            41
+          
+        
+        ≈
+        
+          10
+          
+            42
+          
+        
+        ,
+      
+    
+    {\displaystyle {\frac {c\,t}{r_{\text{e}}}}\approx 3.47\cdot 10^{41}\approx 10^{42},}
+  
+
+where t is the age of the universe, 
+  
+    
+      
+        c
+      
+    
+    {\displaystyle c}
+  
+ is the speed of light and re is the classical electron radius. Hence, in units where c = 1 and re = 1, the age of the universe is about 1040 units of time. This is the same order of magnitude as the ratio of the electrical to the gravitational forces between a proton and an electron: 
+
+  
+    
+      
+        
+          
+            
+              e
+              
+                2
+              
+            
+            
+              4
+              π
+              
+                ϵ
+                
+                  0
+                
+              
+              G
+              
+                m
+                
+                  p
+                
+              
+              
+                m
+                
+                  e
+                
+              
+            
+          
+        
+        ≈
+        
+          10
+          
+            40
+          
+        
+        .
+      
+    
+    {\displaystyle {\frac {e^{2}}{4\pi \epsilon _{0}Gm_{\text{p}}m_{\text{e}}}}\approx 10^{40}.}
+  
+
+Hence, interpreting the charge 
+  
+    
+      
+        e
+      
+    
+    {\displaystyle e}
+  
+ of the electron, the masses 
+  
+    
+      
+        
+          m
+          
+            p
+          
+        
+      
+    
+    {\displaystyle m_{\text{p}}}
+  
+ and 
+  
+    
+      
+        
+          m
+          
+            e
+          
+        
+      
+    
+    {\displaystyle m_{\text{e}}}
+  
+ of the proton and electron, and the permittivity factor 
+  
+    
+      
+        4
+        π
+        
+          ϵ
+          
+            0
+          
+        
+      
+    
+    {\displaystyle 4\pi \epsilon _{0}}
+  
+ in atomic units (equal to 1), the value of the gravitational constant is approximately 10−40. Dirac interpreted this to mean that 
+  
+    
+      
+        G
+      
+    
+    {\displaystyle G}
+  
+ varies with time as 
+  
+    
+      
+        G
+        ≈
+        1
+        
+          /
+        
+        t
+      
+    
+    {\displaystyle G\approx 1/t}
+  
+. Although George Gamow noted that such a temporal variation does not necessarily follow from Dirac's assumptions, a corresponding change of G has not been found.
+According to general relativity, however, G is constant, otherwise the law of conserved energy is violated. Dirac met this difficulty by introducing into the Einstein field equations a gauge function β that describes the structure of spacetime in terms of a ratio of gravitational and electromagnetic units. He also provided alternative scenarios for the continuous creation of matter, one of the other significant issues in LNH:
+
+'additive' creation (new matter is created uniformly throughout space) and
+'multiplicative' creation (new matter is created where there are already concentrations of mass).

data/en.wikipedia.org/wiki/Dirac_large_numbers_hypothesis-1.md

@@ -0,0 +1,40 @@
+---
+title: "Dirac large numbers hypothesis"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Dirac_large_numbers_hypothesis"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:55.823362+00:00"
+instance: "kb-cron"
+---
+
+== Later developments and interpretations ==
+Dirac's theory has inspired and continues to inspire a significant body of scientific literature in a variety of disciplines, with it sparking off many speculations, arguments and new ideas in terms of applications. In the context of geophysics, for instance, Edward Teller seemed to raise a serious objection to LNH in 1948 when he argued that variations in the strength of gravity are not consistent with paleontological data. However, George Gamow demonstrated in 1962 how a simple revision of the parameters (in this case, the age of the Solar System) can invalidate Teller's conclusions. The debate is further complicated by the choice of LNH cosmologies: In 1978, G. Blake argued that paleontological data is consistent with the "multiplicative" scenario but not the "additive" scenario. Arguments both for and against LNH are also made from astrophysical considerations. For example, D. Falik argued that LNH is inconsistent with experimental results for microwave background radiation whereas Canuto and Hsieh argued that it is consistent. One argument that has created significant controversy was put forward by Robert Dicke in 1961. Known as the anthropic coincidence or fine-tuned universe, it simply states that the large numbers in LNH are a necessary coincidence for intelligent beings since they parametrize fusion of hydrogen in stars and hence carbon-based life would not arise otherwise.
+Various authors have introduced new sets of numbers into the original "coincidence" considered by Dirac and his contemporaries, thus broadening or even departing from Dirac's own conclusions. Jordan (1947) noted that the mass ratio for a typical star (specifically, a star of the Chandrasekhar mass, itself a constant of nature, approx. 1.44 solar masses) and an electron approximates to 1060, an interesting variation on the 1040 and 1080 that are typically associated with Dirac and Eddington respectively. (The physics defining the Chandrasekhar mass produces a ratio that is the −3/2 power of the gravitational fine-structure constant (analogous to the electromagnetic fine-structure constant), 10−40.)
+
+=== Modern studies ===
+Several authors have recently identified and pondered the significance of yet another large number, approximately 120 orders of magnitude. This is for example the ratio of the theoretical and observational estimates of the energy density of the vacuum, which Nottale (1993) and Matthews (1997) associated in an LNH context with a scaling law for the cosmological constant. Carl Friedrich von Weizsäcker identified 10120 with the ratio of the universe's volume to the volume of a typical nucleon bounded by its Compton wavelength, and he identified this ratio with the sum of elementary events or bits of information in the universe.
+Valev (2019) found an equation connecting cosmological parameters (for example density of the universe) and Planck units (for example Planck density). This ratio of densities, and other ratios (using four fundamental constants: speed of light in vacuum c, Newtonian constant of gravity G, reduced Planck constant ℏ, and Hubble constant H) computes to an exact number, 32.8·10120. This provides evidence of the Dirac large numbers hypothesis by connecting the macro-world and the micro-world.
+
+== See also ==
+
+Dimensionless physical constant – Physical constant with no units
+Hierarchy problem – Unsolved problem in physics
+Time-variation of fundamental constants – Hypothetical conflict with the laws of physics as currently known
+
+== References ==
+
+== Further reading ==
+P. A. M. Dirac (1938). "A New Basis for Cosmology". Proceedings of the Royal Society of London A. 165 (921): 199–208. Bibcode:1938RSPSA.165..199D. doi:10.1098/rspa.1938.0053.
+P. A. M. Dirac (1937). "The Cosmological Constants". Nature. 139 (3512): 323. Bibcode:1937Natur.139..323D. doi:10.1038/139323a0. S2CID 4106534.
+P. A. M. Dirac (1974). "Cosmological Models and the Large Numbers Hypothesis". Proceedings of the Royal Society of London A. 338 (1615): 439–446. Bibcode:1974RSPSA.338..439D. doi:10.1098/rspa.1974.0095. S2CID 122802355.
+G. A. Mena Marugan; S. Carneiro (2002). "Holography and the large number hypothesis". Physical Review D. 65 (8) 087303. arXiv:gr-qc/0111034. Bibcode:2002PhRvD..65h7303M. doi:10.1103/PhysRevD.65.087303. S2CID 119452710.
+C.-G. Shao; J. Shen; B. Wang; R.-K. Su (2006). "Dirac Cosmology and the Acceleration of the Contemporary Universe". Classical and Quantum Gravity. 23 (11): 3707–3720. arXiv:gr-qc/0508030. Bibcode:2006CQGra..23.3707S. doi:10.1088/0264-9381/23/11/003. S2CID 119339090.
+S. Ray; U. Mukhopadhyay; P. P. Ghosh (2007). "Large Number Hypothesis: A Review". arXiv:0705.1836 [gr-qc].
+A. Unzicker (2009). "A Look at the Abandoned Contributions to Cosmology of Dirac, Sciama and Dicke". Annalen der Physik. 18 (1): 57–70. arXiv:0708.3518. Bibcode:2009AnP...521...57U. doi:10.1002/andp.20095210108. S2CID 11248780.
+
+== External links ==
+Audio of Dirac talking about the large numbers hypothesis
+Full transcript of Dirac's speech.
+Robert Matthews: Dirac's coincidences sixty years on
+The Mysterious Eddington–Dirac Number

data/en.wikipedia.org/wiki/Domus_Galilaeana-0.md

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+---
+title: "Domus Galilaeana"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Domus_Galilaeana"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:29.933385+00:00"
+instance: "kb-cron"
+---
+
+The Domus Galilaeana is a cultural and scientific institute and library, dedicated to the history of science, located in via Santa Maria #26, in Pisa, region of Tuscany, Italy. Currently, the Domus Galilaeana houses a library with more than 40,000 books and important files relating to scientists of the 20th century.
+
+
+== History ==
+The idea of creating an institute dedicated to the Pisan scientist was born in 1938 in anticipation of the celebrations for the centenary of the First Meeting of Italian scientists held in Pisa in 1839. The institute’s formation was the initiative of Giovanni Gentile and sponsored by the Italian Society for the Progress of Sciences, and was established in Rome with a commission to identify goals and objectives of the new society, as well as the city and its location within the city.
+The choice fell on Pisa. The presentation was made in 1939 in the Aula Magna of the University of Pisa. The Domus Galilaeana received its legal status with the law of 1941.
+Since then, the establishment has collected all the ancient and modern publications on Galileo and coordinated studies in the history of science, thanks to a large archive and a major library. In 2002 this public institution turned into a foundation, becoming subject to private law.
+
+
+== Headquarters ==
+The Head of the Institute is located in Santa Maria street, in the old Palazzotto Specola, situated between the houses of Antonio Pacinotti and Gabba. It is not the birthplace of Galileo, which can be found near the tribunal court, but the building that once housed the university library and the observatory tower for astronomical observation. The tower was demolished in the early part of the 19th century because of its instability.
+
+
+== Museum ==
+The Domus Galilaeana can not be considered a real museum. Throughout its history it has retained various scientific instruments on behalf of other institutions. It housed the instruments of Enrico Fermi, now in Rome, and equipment belonging to Antonio Pacinotti, now in the Museo degli Strumenti per il Calcolo di Pisa, including the "Macchinetta", the first model of an electric motor generator. Domus has also saved from destruction the CEP, Pisana Electronic Calculator, which forms part of the Museo degli Strumenti per il Calcolo collection. The instrumentation currently present at the Domus is closely bound to the archives found here,  along with the "sources" for the experiments on induced radioactivity of Enrico Fermi, the photographic instrumentation of the astronomer Pius Emanuelle and various machines from the Institute of Technical Physics, University of Pisa. Regular courses dedicated to schools are held on the most important characters in the history of science, from Galileo Galilei to the physicists of the 20th century.
+
+
+== References ==

data/en.wikipedia.org/wiki/Edinburgh_Philosophical_Journal-0.md

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+---
+title: "Edinburgh Philosophical Journal"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Edinburgh_Philosophical_Journal"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:03.370986+00:00"
+instance: "kb-cron"
+---
+
+The Edinburgh Philosophical Journal was founded by its editors, Robert Jameson and David Brewster in 1819 as a scientific journal to publish articles on the latest science of the day. In 1826 the two editors fell out, and Jameson continued publication as the Edinburgh New Philosophical Journal. Jameson died in 1854, and his place as editor was then taken over by Thomas Anderson, Sir William Jardine, John Hutton Balfour and, for America, Henry Darwin Rogers. In 1864 it was merged into the Quarterly Journal of Science, London.
+The Edinburgh Philosophical Journal was published by Archibald Constable and Company, then in 1826 publication of the Edinburgh New Philosophical Journal was taken on by Adam Black, later A & C Black of Edinburgh. The journal covered emerging scientific developments in chemistry, optics, electricity, magnetism, and natural history, as well as related topics including practical mechanics, inventions, and scientific instruments. As well as articles by the editors, it published contributions by many of the leading scientists at the time, including Charles Babbage, John Herschel, Robert Stevenson, William Scoresby, Alexander Humboldt and Humphry Davy.
+It was one of the publishing options for the Royal Society of Edinburgh, and after 1839 it published proceedings of the Wernerian Natural History Society.
+
+
+== References ==

data/en.wikipedia.org/wiki/Firmament-0.md

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+---
+title: "Firmament"
+chunk: 1/3
+source: "https://en.wikipedia.org/wiki/Firmament"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:58.201988+00:00"
+instance: "kb-cron"
+---
+
+In Ancient Near Eastern cosmology, the firmament was a celestial barrier  that separated the Heavenly waters above from the Earth below. In Biblical cosmology, the firmament (Hebrew: רָקִ֫יעַ‎ rāqīaʿ) was the vast solid dome created by God during the Genesis creation narrative to separate the primal sea into upper and lower portions so that the dry land could appear.
+The concept was adopted into the subsequent Classical and Medieval models of heavenly spheres, but was dropped with advances in astronomy in the 16th and 17th centuries. Today the word is sometimes used as a synonym for the sky or for heaven.
+
+== Etymology ==
+
+=== Firmament ===
+In English, the word "firmament" is recorded as early as 1250, in the Middle English Story of Genesis and Exodus. It later appeared in the King James Bible. The same word is found in French and German Bible translations, all from the Latin firmamentum (a firm object), used in the Vulgate (4th century). This in turn is a calque of the Greek στερέωμᾰ (steréōma), also meaning a solid or firm structure (Greek στερεός = rigid), which appears in the Septuagint, the Greek translation made by Jewish scholars around 200 BC.
+
+=== Raqia ===
+These words all translate the Biblical Hebrew word rāqīaʿ (רָקִ֫יעַ‎), used for example in Genesis 1.6, where it is contrasted with shamayim (שָׁמַיִם‎), translated as "heaven(s)" in Genesis 1.1. Rāqīaʿ derives from the root rqʿ (רָקַע‎), meaning "to beat or spread out thinly". The Hebrew lexicographers Brown, Driver and Briggs gloss the noun with "extended surface, (solid) expanse (as if beaten out)" and distinguish two main uses: 1. "(flat) expanse (as if of ice), as base, support", and 2. "the vault of heaven, or 'firmament,' regarded by Hebrews as solid and supporting 'waters' above it." A related noun, riqquaʿ (רִקּוּעַ‎), found in Numbers 16.38 (Hebrew numbering 17.3), refers to the process of hammering metal into sheets.  Gerhard von Rad explains:
+
+Rāqīaʿ means that which is firmly hammered, stamped (a word of the same root in Phoenecian means "tin dish"!). The meaning of the verb rqʿ concerns the hammering of the vault of heaven into firmness (Isa. 42.5; Ps.136.6). The Vulgate translates rāqīaʿ with firmamentum, and that remains the best rendering.
+
+== History ==
+
+=== Ancient Near Eastern cosmology ===
+
+A firmament is created according to the Enūma Eliš Babylonian creation myth. In the Hebrew Bible, it is mentioned in the Genesis creation narrative, the Psalms, and the Book of Isaiah. Between these two main sources, there is a fundamental agreement in the cosmological models pronounced: this included a flat and likely disk-shaped world with a solid firmament.
+The two prominent representations of the firmament were that it was either flat and hovering over the Earth, or that it was a dome and entirely enclosed the Earth's surface. Beyond the firmament is the upper waters, above which further still is the divine abode. The gap between heaven and Earth was bridged by ziggurats and these supported stairways that allowed gods to descend into the Earth from the heavenly realm. A Babylonian clay tablet from the 6th century BC illustrates a world map.
+
+=== Egyptian cosmology ===
+
+In ancient Egyptian texts, and from texts across the near east generally, the firmament was described as having special doors or gateways on the eastern and western horizons to allow for the passage of heavenly bodies during their daily journeys. These were known as the windows of heaven or the gates of heaven. In Egyptian texts particularly, these gates also served as conduits between the earthly and heavenly realms for which righteous people could ascend. The gateways could be blocked by gates to prevent entry by the deceased as well. As such, funerary texts included prayers enlisting the help of the gods to enable the safe ascent of the dead. Ascent to the celestial realm could also be done by a celestial ladder made by the gods.
+Four different Egyptian models of the firmament and/or the heavenly realm are known. One model was that it was the shape of a bird: the firmament above represented the underside of a flying falcon, with the sun and moon representing its eyes, and its flapping causing the wind that humans experience. The second was a cow, as per the Book of the Heavenly Cow. The cosmos is a giant celestial cow represented by the goddess Nut or Hathor. The cow consumed the sun in the evening and rebirthed it in the next morning. The third is a celestial woman, also represented by Nut. The heavenly bodies would travel across her body from east to west. The midriff of Nut was supported by Shu (the air god) and Geb (the earth god) lay outstretched between the arms and feet of Nut. Nut consumes the celestial bodies from the west and gives birth to them again in the following morning. The stars are inscribed across the belly of Nut and one needs to identify with one of them, or a constellation, in order to join them after death. The fourth model was a flat (or slightly convex) celestial plane which, depending on the text, was thought to be supported in various ways: by pillars, staves, scepters, or mountains at the extreme ends of the Earth. The four supports give rise to the motif of the "four corners of the world".
+
+=== Early Greek cosmology ===

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+---
+title: "Firmament"
+chunk: 2/3
+source: "https://en.wikipedia.org/wiki/Firmament"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:58.201988+00:00"
+instance: "kb-cron"
+---
+
+Prior to the systematic study of the cosmos by the Ionian School in the city of Miletus in the 6th century BC, the early Greek conception of cosmology was closely related to that of near eastern cosmology and envisioned a flat Earth with a solid firmament above the Earth supported by pillars. However, the work of Anaximander, Anaximenes, and Thales, followed by classical Greek theoreticians like Aristotle and Ptolemy ushered in the notions of a spherical Earth and an Earth floating in the center of the cosmos as opposed to resting on a body of water. This picture was geocentric and represented the cosmos as a whole as spherical.
+
+=== Patristic cosmology ===
+
+One problem for Christian interpreters was in understanding the distinction between the heaven created on the first day and the firmament created in the second day. Origen followed the cosmological dualism of the Hellenistic Jewish scholar Philo of Alexandria, who proposed a distinction between the material and eternal creations but does not appear to have associated matter or materiality with evil. Under Origen's influence the waters above became associated with the spiritual plane of Christian contemplative exercise and the waters below with the demonic and infernal. The firmament is the boundary between the physical and spiritual worlds.
+Origen's model of two heavens was followed by later writers who kept the concept of a spiritual and immaterial heaven of the first day (caelum) and the corporeal/sidereal firmamentum.
+Various views on the materiality of the firmament emerged among the Church Fathers, including that it had been made out of air, out of the four elements, or out of a yet-distinct fifth element. In the Hexaemeron of Basil of Caesarea the firmament is depicted as spherical or domed with a flat underside that formed a pocket or membrane in which the waters were held. Not all of the Church fathers followed Origen. Manlio Simonetti noted Basil of Caesarea's "strong tone of criticism"  of Origen's teaching.
+Appealing to a Platonic division between base matter and heavenly or spiritual matter, Augustine of Hippo would distinguish between the waters below the firmament and the waters above the firmament. This involved the spiritual interpretation of the upper waters. In this, he was followed by John Scotus Eriugena. In De Genesi ad litteram (perhaps his least studied work) Augustine wrote: "only God knows how and why [the waters] are there, but we cannot deny the authority of Holy Scripture which is greater than our understanding".
+Ambrose struggled with understanding how the waters above the firmament could be held up given the spherical nature of the cosmos: the solution was to be sought in God's dominion over the cosmos, in the same way that God held up the Earth in the middle of the cosmos though it has no support. About this Ambrose wrote: "Wise men of the world say that water cannot be over the heavens".
+The debate about the waters being located above the heavens continued into the Middle Ages. It made no sense under the explanations of the natural world proposed by Aristotle, recalling the statement from Augustine's literal commentary on Genesis: "Our business now, after all, is to inquire how God's Scriptures say he established things according to their proper natures." Scholastic theologians engaged in the pursuit of applying natural science to illuminate the sacred included Alexander of Hales, William of Auxerre (who offered that the location of the waters as recorded by Moses could only be explained by a miracle), William of Auvergne, and Philip the Chancellor.
+Whether the firmament was hard/firm or soft/fluid was also up for debate: the notion of a soft or fluid firmament was held until it was challenged in the 13th century by the introduction of the Aristotelian-Ptolemaic cosmos, a trend that would only culminate in the 16th century. Bede reasoned that the waters might be held in place if they were frozen solid: the siderum caelum (heaven of the celestial bodies) was made firm (firmatum) in the midst of the waters so should be interpreted as having the firmness of crystalline stone (cristallini Iapidis).
+
+=== Jewish cosmology ===

data/en.wikipedia.org/wiki/Firmament-2.md

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+---
+title: "Firmament"
+chunk: 3/3
+source: "https://en.wikipedia.org/wiki/Firmament"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:58.201988+00:00"
+instance: "kb-cron"
+---
+
+A distinctive collection of ideas about the cosmos were drawn up and recorded in the rabbinic literature, though the conception is rooted deeply in the tradition of near eastern cosmology recorded in Hebrew, Akkadian, and Sumerian sources, combined with some additional influences in the newer Greek ideas about the structure of the cosmos and the heavens in particular. The rabbis viewed the heavens to be a solid object spread over the Earth, which was described with the biblical Hebrew word for the firmament, raki’a. Two images were used to describe it: either as a tent, or as a dome; the former inspired from biblical references, though the latter is without an evident precedent. As for its composition, just as in cuneiform literature the rabbinic texts describe that the firmament was made out of a solid form of water, not just the conventional liquid water known on the Earth. A different tradition makes an analogy between the creation of the firmament and the curdling of milk into cheese. Another tradition is that a combination of fire and water makes up the heavens. This is somewhat similar to a view attributed to Anaximander, whereby the firmament is made of a mixture of hot and cold (or fire and moisture). Yet another dispute concerned how thick the firmament was. A view attributed to R. Joshua b. R. Nehemiah was that it was extremely thin, no thicker than two or three fingers. Some rabbis compared it to a leaf. On the other hand, some rabbis viewed it as immensely thick. Estimates that it was as thick as a 50 year journey or a 500 year journey were made. Debates on the thickness of the firmament also impacted debates on the path of the sun in its journey as it passes through the firmament through passageways called the "doors" or "windows" of heaven. The number of heavens or firmaments was often given as mo than one: sometimes two, but much more commonly, seven. It is unclear whether the notion of the seven heavens is related to earlier near eastern cosmology or the Greek notion of the surrounding of the Earth by seven concentric spheres: one for the sun, one for the moon, and one for each of the five other (known) planets. A range of additional discussions in rabbinic texts surrounding the firmament included those on the upper waters, the movements of the heavenly bodies and the phenomena of precipitation, and more.
+The firmament also appears in non-rabbinic Jewish literature, such as in the cosmogonic views represented in the apocrypha. A prominent example is in the Book of Enoch composed around 300 BC. In this text, the sun rises from one of six gates from the east. It crosses the sky and sets into a window through the firmament in the west. The sun then travels behind the firmament back to the other end of the Earth, from whence it could rise again. In the Testament of Solomon, the heavens are conceived in a tripartite structure and demons are portrayed as being capable of flying up to and past the firmament in order to eavesdrop on the decisions of God. Another example of Jewish literature describing the firmament can be found in Samaritan poetry.
+
+=== Quranic cosmology ===
+
+The Quran describes a concrete firmament above the Earth, built by God and lifted up: the firmament is maintained not by any pillars but by God directly maintaining it, in a description resembling that of the Syriac theologian Jacob of Serugh in his Hexaemeron. Another commonality between the two is in describing the firmament as being decorated by stars. The heavens are analogized to a roof, structure, and edifice without crack or fissure. It is extremely broad and stretched, but it is also constantly broadening. Though there has been some dispute over the exact shape of the Quranic firmament (primarily over whether it is flat or domed), the most recent study by Tabatabaʾi and Mirsadri favors a flat firmament. In addition, there are seven heavens or firmaments and they were made from smoke during the creation week, resembling the view of Basil of Caesarea.
+
+=== Modern cosmology ===
+The model established by Aristotle became the dominant model in the Classical and Medieval world-view, and even when Copernicus placed the Sun at the center of the system he included an outer sphere that held the stars (and by having the earth rotate daily on its axis it allowed the firmament to be completely stationary). Tycho Brahe's studies of the nova of 1572 and the Comet of 1577 were the first major challenges to the idea that orbs existed as solid, incorruptible, material objects, and in 1584 Giordano Bruno proposed a cosmology without a firmament: an infinite universe in which the stars are actually suns with their own planetary systems. After Galileo began using a telescope to examine the sky it became harder to argue that the heavens were perfect, as Aristotelian philosophy suggested, and by 1630 the concept of solid orbs was no longer dominant.
+
+== See also ==
+Abzu – Primeval sea in Mesopotamian mythology
+Chinese theology – Chinese theological conception of Heaven
+Cosmic ocean – Mythological motif
+Flood geology – Pseudoscientific attempt to reconcile geology with the Genesis flood narrative
+Heaven in Judaism – Dwelling place of God and other heavenly beings
+Nu – Ancient Egyptian personification of the primordial watery abyssPages displaying short descriptions of redirect targets
+Primum Mobile – Outermost moving sphere in the geocentric model of the universe
+Sky deity – Deity associated with the sky
+Wuji – The primordial in Chinese philosophy
+
+== References ==
+
+=== Citations ===
+
+=== Sources ===
+
+== Further reading ==
+
+== External links ==
+
+The Vault of Heaven.

data/en.wikipedia.org/wiki/Force-0.md

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+---
+title: "Force"
+chunk: 1/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+In physics, a force is an action that can cause an object to change its velocity or its shape, or to resist other forces, or to cause changes of pressure in a fluid. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the magnitude and direction of a force are both important, force is a vector quantity (force vector). The SI unit of force is the newton (N), and force is often represented by the symbol F.
+Force plays an important role in classical mechanics. The concept of force is central to all three of Newton's laws of motion. Types of forces often encountered in classical mechanics include elastic, frictional, contact or "normal" forces, and gravitational. The rotational version of force is torque, which produces changes in the rotational speed of an object. In an extended body, each part applies forces on the adjacent parts; the distribution of such forces through the body is the internal mechanical stress. In the case of multiple forces, if the net force on an extended body is zero the body is in equilibrium.
+In modern physics, which includes relativity and quantum mechanics, the laws governing motion are revised to rely on fundamental interactions as the ultimate origin of force. However, the understanding of force provided by classical mechanics is useful for practical purposes.
+
+== Development of the concept ==
+Philosophers in antiquity used the concept of force in the study of stationary and moving objects and simple machines, but thinkers such as Aristotle and Archimedes retained fundamental errors in understanding force. In part, this was due to an incomplete understanding of the sometimes non-obvious force of friction and a consequently inadequate view of the nature of natural motion. A fundamental error was the belief that a force is required to maintain motion, even at a constant velocity. Most of the previous misunderstandings about motion and force were eventually corrected by Galileo Galilei and Sir Isaac Newton. With his mathematical insight, Newton formulated laws of motion that were not improved for over two hundred years.
+By the early 20th century, Einstein developed a theory of relativity that correctly predicted the action of forces on objects with increasing momenta near the speed of light and also provided insight into the forces produced by gravitation and inertia. With modern insights into quantum mechanics and technology that can accelerate particles close to the speed of light, particle physics has devised a Standard Model to describe forces between particles smaller than atoms. The Standard Model predicts that exchanged particles called gauge bosons are the fundamental means by which forces are emitted and absorbed. Only four main interactions are known: in order of decreasing strength, they are: strong, electromagnetic, weak, and gravitational. High-energy particle physics observations made during the 1970s and 1980s confirmed that the weak and electromagnetic forces are expressions of a more fundamental electroweak interaction.
+
+== Pre-Newtonian concepts ==
+
+Since antiquity the concept of force has been recognized as integral to the functioning of each of the simple machines. The mechanical advantage given by a simple machine allowed for less force to be used in exchange for that force acting over a greater distance for the same amount of work. Analysis of the characteristics of forces ultimately culminated in the work of Archimedes who was especially famous for formulating a treatment of buoyant forces inherent in fluids.
+Aristotle provided a philosophical discussion of the concept of a force as an integral part of Aristotelian cosmology. In Aristotle's view, the terrestrial sphere contained four elements that come to rest at different "natural places" therein. Aristotle believed that motionless objects on Earth, those composed mostly of the elements earth and water, were in their natural place when on the ground, and that they stay that way if left alone. He distinguished between the innate tendency of objects to find their "natural place" (e.g., for heavy bodies to fall), which led to "natural motion", and unnatural or forced motion, which required continued application of a force. This theory, based on the everyday experience of how objects move, such as the constant application of a force needed to keep a cart moving, had conceptual trouble accounting for the behavior of projectiles, such as the flight of arrows. An archer causes the arrow to move at the start of the flight, and it then sails through the air even though no discernible efficient cause acts upon it. Aristotle was aware of this problem and proposed that the air displaced through the projectile's path carries the projectile to its target. This explanation requires a continuous medium such as air to sustain the motion.
+Though Aristotelian physics was criticized as early as the 6th century, its shortcomings would not be corrected until the 17th century work of Galileo Galilei, who was influenced by the late medieval idea that objects in forced motion carried an innate force of impetus. Galileo constructed an experiment in which stones and cannonballs were both rolled down an incline to disprove the Aristotelian theory of motion. He showed that the bodies were accelerated by gravity to an extent that was independent of their mass and argued that objects retain their velocity unless acted on by a force, for example friction. Galileo's idea that force is needed to change motion rather than to sustain it, further improved upon by Isaac Beeckman, René Descartes, and Pierre Gassendi, became a key principle of Newtonian physics.
+In the early 17th century, before Newton's Principia, the term "force" (Latin: vis) was applied to many physical and non-physical phenomena, e.g., for an acceleration of a point. The product of a point mass and the square of its velocity was named vis viva (live force) by Leibniz. The modern concept of force corresponds to Newton's vis motrix (accelerating force).
+
+== Newtonian mechanics ==

data/en.wikipedia.org/wiki/Force-1.md

@@ -0,0 +1,457 @@
+---
+title: "Force"
+chunk: 2/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+Sir Isaac Newton described the motion of all objects using the concepts of inertia and force. In 1687, Newton published his magnum opus, Philosophiæ Naturalis Principia Mathematica. In this work Newton set out three laws of motion that have dominated the way forces are described in physics to this day. The precise ways in which Newton's laws are expressed have evolved in step with new mathematical approaches.
+
+=== First law ===
+
+Newton's first law of motion states that the natural behavior of an object at rest is to continue being at rest, and the natural behavior of an object moving at constant speed in a straight line is to continue moving at that constant speed along that straight line. The latter follows from the former because of the principle that the laws of physics are the same for all inertial observers, i.e., all observers who do not feel themselves to be in motion. An observer moving in tandem with an object will see it as being at rest. So, its natural behavior will be to remain at rest with respect to that observer, which means that an observer who sees it moving at constant speed in a straight line will see it continuing to do so.
+
+=== Second law ===
+
+According to the first law, motion at constant speed in a straight line does not need a cause. It is change in motion that requires a cause, and Newton's second law gives the quantitative relationship between force and change of motion.
+Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.
+A modern statement of Newton's second law is a vector equation:
+
+  
+    
+      
+        
+          F
+        
+        =
+        
+          
+            
+              
+                d
+              
+              
+                p
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} ={\frac {\mathrm {d} \mathbf {p} }{\mathrm {d} t}},}
+  
+
+where 
+  
+    
+      
+        
+          p
+        
+      
+    
+    {\displaystyle \mathbf {p} }
+  
+ is the momentum of the system, and 
+  
+    
+      
+        
+          F
+        
+      
+    
+    {\displaystyle \mathbf {F} }
+  
+ is the net (vector sum) force. If a body is in equilibrium, there is zero net force by definition (balanced forces may be present nevertheless). In contrast, the second law states that if there is an unbalanced force acting on an object it will result in the object's momentum changing over time.
+In common engineering applications the mass in a system remains constant allowing as simple algebraic form for the second law. By the definition of momentum,
+
+  
+    
+      
+        
+          F
+        
+        =
+        
+          
+            
+              
+                d
+              
+              
+                p
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        =
+        
+          
+            
+              
+                d
+              
+              
+                (
+                
+                  m
+                  
+                    v
+                  
+                
+                )
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} ={\frac {\mathrm {d} \mathbf {p} }{\mathrm {d} t}}={\frac {\mathrm {d} \left(m\mathbf {v} \right)}{\mathrm {d} t}},}
+  
+
+where m is the mass and 
+  
+    
+      
+        
+          v
+        
+      
+    
+    {\displaystyle \mathbf {v} }
+  
+ is the velocity. If Newton's second law is applied to a system of constant mass, m may be moved outside the derivative operator. The equation then becomes
+
+  
+    
+      
+        
+          F
+        
+        =
+        m
+        
+          
+            
+              
+                d
+              
+              
+                v
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        .
+      
+    
+    {\displaystyle \mathbf {F} =m{\frac {\mathrm {d} \mathbf {v} }{\mathrm {d} t}}.}
+  
+
+By substituting the definition of acceleration, the algebraic version of Newton's second law is derived:
+
+  
+    
+      
+        
+          F
+        
+        =
+        m
+        
+          a
+        
+        .
+      
+    
+    {\displaystyle \mathbf {F} =m\mathbf {a} .}
+  
+
+=== Third law ===
+
+Whenever one body exerts a force on another, the latter simultaneously exerts an equal and opposite force on the first. In vector form, if 
+  
+    
+      
+        
+          
+            F
+          
+          
+            1
+            ,
+            2
+          
+        
+      
+    
+    {\displaystyle \mathbf {F} _{1,2}}
+  
+ is the force of body 1 on body 2 and 
+  
+    
+      
+        
+          
+            F
+          
+          
+            2
+            ,
+            1
+          
+        
+      
+    
+    {\displaystyle \mathbf {F} _{2,1}}
+  
+ that of body 2 on body 1, then
+
+  
+    
+      
+        
+          
+            F
+          
+          
+            1
+            ,
+            2
+          
+        
+        =
+        −
+        
+          
+            F
+          
+          
+            2
+            ,
+            1
+          
+        
+        .
+      
+    
+    {\displaystyle \mathbf {F} _{1,2}=-\mathbf {F} _{2,1}.}
+  
+
+This law is sometimes referred to as the action-reaction law, with 
+  
+    
+      
+        
+          
+            F
+          
+          
+            1
+            ,
+            2
+          
+        
+      
+    
+    {\displaystyle \mathbf {F} _{1,2}}
+  
+ called the action and 
+  
+    
+      
+        −
+        
+          
+            F
+          
+          
+            2
+            ,
+            1
+          
+        
+      
+    
+    {\displaystyle -\mathbf {F} _{2,1}}
+  
+ the reaction.
+Newton's third law is a result of applying symmetry to situations where forces can be attributed to the presence of different objects. The third law means that all forces are interactions between different bodies. and thus that there is no such thing as a unidirectional force or a force that acts on only one body.
+In a system composed of object 1 and object 2, the net force on the system due to their mutual interactions is zero:
+
+  
+    
+      
+        
+          
+            F
+          
+          
+            1
+            ,
+            2
+          
+        
+        +
+        
+          
+            F
+          
+          
+            2
+            ,
+            1
+          
+        
+        =
+        0.
+      
+    
+    {\displaystyle \mathbf {F} _{1,2}+\mathbf {F} _{2,1}=0.}
+  
+
+More generally, in a closed system of particles, all internal forces are balanced. The particles may accelerate with respect to each other but the center of mass of the system will not accelerate. If an external force acts on the system, it will make the center of mass accelerate in proportion to the magnitude of the external force divided by the mass of the system.
+Combining Newton's second and third laws, it is possible to show that the linear momentum of a system is conserved in any closed system. In a system of two particles, if 
+  
+    
+      
+        
+          
+            p
+          
+          
+            1
+          
+        
+      
+    
+    {\displaystyle \mathbf {p} _{1}}
+  
+ is the momentum of object 1 and 
+  
+    
+      
+        
+          
+            p
+          
+          
+            2
+          
+        
+      
+    
+    {\displaystyle \mathbf {p} _{2}}
+  
+ the momentum of object 2, then
+
+  
+    
+      
+        
+          
+            
+              
+                d
+              
+              
+                
+                  p
+                
+                
+                  1
+                
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        +
+        
+          
+            
+              
+                d
+              
+              
+                
+                  p
+                
+                
+                  2
+                
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        =
+        
+          
+            F
+          
+          
+            1
+            ,
+            2
+          
+        
+        +
+        
+          
+            F
+          
+          
+            2
+            ,
+            1
+          
+        
+        =
+        0.
+      
+    
+    {\displaystyle {\frac {\mathrm {d} \mathbf {p} _{1}}{\mathrm {d} t}}+{\frac {\mathrm {d} \mathbf {p} _{2}}{\mathrm {d} t}}=\mathbf {F} _{1,2}+\mathbf {F} _{2,1}=0.}
+  
+
+Using similar arguments, this can be generalized to a system with an arbitrary number of particles. In general, as long as all forces are due to the interaction of objects with mass, it is possible to define a system such that net momentum is never lost nor gained.

data/en.wikipedia.org/wiki/Force-10.md

@@ -0,0 +1,38 @@
+---
+title: "Force"
+chunk: 11/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+=== Electromagnetic ===
+Maxwell's equations and the set of techniques built around them adequately describe a wide range of physics involving force in electricity and magnetism. This classical theory already includes relativity effects. Understanding quantized electromagnetic interactions between elementary particles requires quantum electrodynamics (QED). In QED, photons are fundamental exchange particles, describing all interactions relating to electromagnetism including the electromagnetic force.
+
+=== Strong nuclear ===
+
+There are two "nuclear forces", which today are usually described as interactions that take place in quantum theories of particle physics. The strong nuclear force is the force responsible for the structural integrity of atomic nuclei, and gains its name from its ability to overpower the electromagnetic repulsion between protons.
+The strong force is today understood to represent the interactions between quarks and gluons as detailed by the theory of quantum chromodynamics (QCD). The strong force is the fundamental force mediated by gluons, acting upon quarks, antiquarks, and the gluons themselves. The strong force only acts directly upon elementary particles. A residual is observed between hadrons (notably, the nucleons in atomic nuclei), known as the nuclear force. Here the strong force acts indirectly, transmitted as gluons that form part of the virtual pi and rho mesons, the classical transmitters of the nuclear force. The failure of many searches for free quarks has shown that the elementary particles affected are not directly observable. This phenomenon is called color confinement.
+
+=== Weak nuclear ===
+
+Unique among the fundamental interactions, the weak nuclear force creates no bound states. The weak force is due to the exchange of the heavy W and Z bosons. Since the weak force is mediated by two types of bosons, it can be divided into two types of interaction or "vertices" — charged current, involving the electrically charged W+ and W− bosons, and neutral current, involving electrically neutral Z0 bosons. The most familiar effect of weak interaction is beta decay (of neutrons in atomic nuclei) and the associated radioactivity. This is a type of charged-current interaction. The word "weak" derives from the fact that the field strength is some 1013 times less than that of the strong force. Still, it is stronger than gravity over short distances. A consistent electroweak theory has also been developed, which shows that electromagnetic forces and the weak force are indistinguishable at a temperatures in excess of approximately 1015 K. Such temperatures occurred in the plasma collisions in the early moments of the Big Bang.
+
+== See also ==
+
+Contact force – Force between two objects that are in physical contact
+Force control – Aspect of robotics
+Force gauge – Instrument for measuring force
+Orders of magnitude (force) – Comparison of a wide range of physical forces
+Parallel force system – Situation in mechanical engineering
+Rigid body – Physical object which does not deform when forces or moments are exerted on it
+Specific force – Concept in physics
+
+== References ==
+
+== External links ==
+
+"Classical Mechanics, Week 2: Newton's Laws". MIT OpenCourseWare. Retrieved 2023-08-09.
+"Fundamentals of Physics I, Lecture 3: Newton's Laws of Motion". Open Yale Courses. Retrieved 2023-08-09.

data/en.wikipedia.org/wiki/Force-2.md

@@ -0,0 +1,50 @@
+---
+title: "Force"
+chunk: 3/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+=== Defining "force" ===
+Some textbooks use Newton's second law as a definition of force. However, for the equation 
+  
+    
+      
+        
+          F
+        
+        =
+        m
+        
+          a
+        
+      
+    
+    {\displaystyle \mathbf {F} =m\mathbf {a} }
+  
+ for a constant mass 
+  
+    
+      
+        m
+      
+    
+    {\displaystyle m}
+  
+ to then have any predictive content, it must be combined with further information. Moreover, inferring that a force is present because a body is accelerating is only valid in an inertial frame of reference. The question of which aspects of Newton's laws to take as definitions and which to regard as holding physical content has been answered in various ways, which ultimately do not affect how the theory is used in practice. Notable physicists, philosophers and mathematicians who have sought a more explicit definition of the concept of force include Ernst Mach and Walter Noll.
+
+== Combining forces ==
+
+Forces act in a particular direction and have sizes dependent upon how strong the push or pull is. Because of these characteristics, forces are classified as "vector quantities". This means that forces follow a different set of mathematical rules than physical quantities that do not have direction (denoted scalar quantities). For example, when determining what happens when two forces act on the same object, it is necessary to know both the magnitude and the direction of both forces to calculate the result. If both of these pieces of information are not known for each force, the situation is ambiguous.
+Historically, forces were first quantitatively investigated in conditions of static equilibrium where several forces canceled each other out. Such experiments demonstrate the crucial properties that forces are additive vector quantities: they have magnitude and direction. When two forces act on a point particle, the resulting force, the resultant (also called the net force), can be determined by following the parallelogram rule of vector addition: the addition of two vectors represented by sides of a parallelogram, gives an equivalent resultant vector that is equal in magnitude and direction to the transversal of the parallelogram. The magnitude of the resultant varies from the difference of the magnitudes of the two forces to their sum, depending on the angle between their lines of action.
+
+Free-body diagrams can be used as a convenient way to keep track of forces acting on a system. Ideally, these diagrams are drawn with the angles and relative magnitudes of the force vectors preserved so that graphical vector addition can be done to determine the net force.
+As well as being added, forces can also be resolved into independent components at right angles to each other. A horizontal force pointing northeast can therefore be split into two forces, one pointing north, and one pointing east. Summing these component forces using vector addition yields the original force. Resolving force vectors into components of a set of basis vectors is often a more mathematically clean way to describe forces than using magnitudes and directions. This is because, for orthogonal components, the components of the vector sum are uniquely determined by the scalar addition of the components of the individual vectors. Orthogonal components are independent of each other because forces acting at ninety degrees to each other have no effect on the magnitude or direction of the other. Choosing a set of orthogonal basis vectors is often done by considering what set of basis vectors will make the mathematics most convenient. Choosing a basis vector that is in the same direction as one of the forces is desirable, since that force would then have only one non-zero component. Orthogonal force vectors can be three-dimensional with the third component being at right angles to the other two.
+
+=== Equilibrium ===
+When all the forces that act upon an object are balanced, then the object is said to be in a state of equilibrium. Hence, equilibrium occurs when the resultant force acting on a point particle is zero (that is, the vector sum of all forces is zero). When dealing with an extended body, it is also necessary that the net torque be zero. A body is in static equilibrium with respect to a frame of reference if it at rest and not accelerating, whereas a body in dynamic equilibrium is moving at a constant speed in a straight line, i.e., moving but not accelerating. What one observer sees as static equilibrium, another can see as dynamic equilibrium and vice versa.
+
+==== Static ====

data/en.wikipedia.org/wiki/Force-3.md

@@ -0,0 +1,63 @@
+---
+title: "Force"
+chunk: 4/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+Static equilibrium was understood well before the invention of classical mechanics. Objects that are not accelerating have zero net force acting on them.
+The simplest case of static equilibrium occurs when two forces are equal in magnitude but opposite in direction. For example, an object on a level surface is pulled (attracted) downward toward the center of the Earth by the force of gravity. At the same time, a force is applied by the surface that resists the downward force with equal upward force (called a normal force). The situation produces zero net force and hence no acceleration.
+Pushing against an object that rests on a frictional surface can result in a situation where the object does not move because the applied force is opposed by static friction, generated between the object and the table surface. For a situation with no movement, the static friction force exactly balances the applied force resulting in no acceleration. The static friction increases or decreases in response to the applied force up to an upper limit determined by the characteristics of the contact between the surface and the object.
+A static equilibrium between two forces is the most usual way of measuring forces, using simple devices such as weighing scales and spring balances. For example, an object suspended on a vertical spring scale experiences the force of gravity acting on the object balanced by a force applied by the "spring reaction force", which equals the object's weight. Using such tools, some quantitative force laws were discovered: that the force of gravity is proportional to volume for objects of constant density (widely exploited for millennia to define standard weights); Archimedes' principle for buoyancy; Archimedes' analysis of the lever; Boyle's law for gas pressure; and Hooke's law for springs. These were all formulated and experimentally verified before Isaac Newton expounded his three laws of motion.
+
+==== Dynamic ====
+
+Dynamic equilibrium was first described by Galileo who noticed that certain assumptions of Aristotelian physics were contradicted by observations and logic. Galileo realized that simple velocity addition demands that the concept of an "absolute rest frame" did not exist. Galileo concluded that motion in a constant velocity was completely equivalent to rest. This was contrary to Aristotle's notion of a "natural state" of rest that objects with mass naturally approached. Simple experiments showed that Galileo's understanding of the equivalence of constant velocity and rest were correct. For example, if a mariner dropped a cannonball from the crow's nest of a ship moving at a constant velocity, Aristotelian physics would have the cannonball fall straight down while the ship moved beneath it. Thus, in an Aristotelian universe, the falling cannonball would land behind the foot of the mast of a moving ship. When this experiment is actually conducted, the cannonball always falls at the foot of the mast, as if the cannonball knows to travel with the ship despite being separated from it. Since there is no forward horizontal force being applied on the cannonball as it falls, the only conclusion left is that the cannonball continues to move with the same velocity as the boat as it falls. Thus, no force is required to keep the cannonball moving at the constant forward velocity.
+Moreover, any object traveling at a constant velocity must be subject to zero net force (resultant force). This is the definition of dynamic equilibrium: when all the forces on an object balance but it still moves at a constant velocity. A simple case of dynamic equilibrium occurs in constant velocity motion across a surface with kinetic friction. In such a situation, a force is applied in the direction of motion while the kinetic friction force exactly opposes the applied force. This results in zero net force, but since the object started with a non-zero velocity, it continues to move with a non-zero velocity. Aristotle misinterpreted this motion as being caused by the applied force. When kinetic friction is taken into consideration it is clear that there is no net force causing constant velocity motion.
+
+== Examples of forces in classical mechanics ==
+Some forces are consequences of the fundamental ones. In such situations, idealized models can be used to gain physical insight. For example, each solid object is considered a rigid body.
+
+=== Gravitational force or Gravity ===
+
+What we now call gravity was not identified as a universal force until the work of Isaac Newton. Before Newton, the tendency for objects to fall towards the Earth was not understood to be related to the motions of celestial objects. Galileo was instrumental in describing the characteristics of falling objects by determining that the acceleration of every object in free-fall was constant and independent of the mass of the object. Today, this acceleration due to gravity towards the surface of the Earth is usually designated as 
+  
+    
+      
+        
+          g
+        
+      
+    
+    {\displaystyle \mathbf {g} }
+  
+ and has a magnitude of about 9.81 meters per second squared (this measurement is taken from sea level and may vary depending on location), and points toward the center of the Earth. This observation means that the force of gravity on an object at the Earth's surface is directly proportional to the object's mass. Thus an object that has a mass of 
+  
+    
+      
+        m
+      
+    
+    {\displaystyle m}
+  
+ will experience a force:
+
+  
+    
+      
+        
+          F
+        
+        =
+        m
+        
+          g
+        
+        .
+      
+    
+    {\displaystyle \mathbf {F} =m\mathbf {g} .}
+  

data/en.wikipedia.org/wiki/Force-4.md

@@ -0,0 +1,374 @@
+---
+title: "Force"
+chunk: 5/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+For an object in free-fall, this force is unopposed and the net force on the object is its weight. For objects not in free-fall, the force of gravity is opposed by the reaction forces applied by their supports. For example, a person standing on the ground experiences zero net force, since a normal force (a reaction force) is exerted by the ground upward on the person that counterbalances his weight that is directed downward.
+Newton's contribution to gravitational theory was to unify the motions of heavenly bodies, which Aristotle had assumed were in a natural state of constant motion, with falling motion observed on the Earth. He proposed a law of gravity that could account for the celestial motions that had been described earlier using Kepler's laws of planetary motion.
+Newton came to realize that the effects of gravity might be observed in different ways at larger distances. In particular, Newton determined that the acceleration of the Moon around the Earth could be ascribed to the same force of gravity if the acceleration due to gravity decreased as an inverse square law. Further, Newton realized that the acceleration of a body due to gravity is proportional to the mass of the other attracting body. Combining these ideas gives a formula that relates the mass (
+  
+    
+      
+        
+          m
+          
+            ⊕
+          
+        
+      
+    
+    {\displaystyle m_{\oplus }}
+  
+) and the radius (
+  
+    
+      
+        
+          R
+          
+            ⊕
+          
+        
+      
+    
+    {\displaystyle R_{\oplus }}
+  
+) of the Earth to the gravitational acceleration:
+
+  
+    
+      
+        
+          g
+        
+        =
+        −
+        
+          
+            
+              G
+              
+                m
+                
+                  ⊕
+                
+              
+            
+            
+              
+                
+                  R
+                  
+                    ⊕
+                  
+                
+              
+              
+                2
+              
+            
+          
+        
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {g} =-{\frac {Gm_{\oplus }}{{R_{\oplus }}^{2}}}{\hat {\mathbf {r} }},}
+  
+
+where the vector direction is given by 
+  
+    
+      
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+      
+    
+    {\displaystyle {\hat {\mathbf {r} }}}
+  
+, is the unit vector directed outward from the center of the Earth.
+In this equation, a dimensional constant 
+  
+    
+      
+        G
+      
+    
+    {\displaystyle G}
+  
+ is used to describe the relative strength of gravity. This constant has come to be known as the Newtonian constant of gravitation, though its value was unknown in Newton's lifetime. Not until 1798 was Henry Cavendish able to make the first measurement of 
+  
+    
+      
+        G
+      
+    
+    {\displaystyle G}
+  
+ using a torsion balance; this was widely reported in the press as a measurement of the mass of the Earth since knowing 
+  
+    
+      
+        G
+      
+    
+    {\displaystyle G}
+  
+ could allow one to solve for the Earth's mass given the above equation. Newton realized that since all celestial bodies followed the same laws of motion, his law of gravity had to be universal. Succinctly stated, Newton's law of gravitation states that the force on a spherical object of mass 
+  
+    
+      
+        
+          m
+          
+            1
+          
+        
+      
+    
+    {\displaystyle m_{1}}
+  
+ due to the gravitational pull of mass 
+  
+    
+      
+        
+          m
+          
+            2
+          
+        
+      
+    
+    {\displaystyle m_{2}}
+  
+ is
+
+  
+    
+      
+        
+          F
+        
+        =
+        −
+        
+          
+            
+              G
+              
+                m
+                
+                  1
+                
+              
+              
+                m
+                
+                  2
+                
+              
+            
+            
+              r
+              
+                2
+              
+            
+          
+        
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} =-{\frac {Gm_{1}m_{2}}{r^{2}}}{\hat {\mathbf {r} }},}
+  
+
+where 
+  
+    
+      
+        r
+      
+    
+    {\displaystyle r}
+  
+ is the distance between the two objects' centers of mass and 
+  
+    
+      
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+      
+    
+    {\displaystyle {\hat {\mathbf {r} }}}
+  
+ is the unit vector pointed in the direction away from the center of the first object toward the center of the second object.
+This formula was powerful enough to stand as the basis for all subsequent descriptions of motion within the Solar System until the 20th century. During that time, sophisticated methods of perturbation analysis were invented to calculate the deviations of orbits due to the influence of multiple bodies on a planet, moon, comet, or asteroid. The formalism was exact enough to allow mathematicians to predict the existence of the planet Neptune before it was observed.
+
+=== Electromagnetic ===
+
+The electrostatic force was first described in 1784 by Coulomb as a force that existed intrinsically between two charges. The properties of the electrostatic force were that it varied as an inverse square law directed in the radial direction, was both attractive and repulsive (there was intrinsic polarity), was independent of the mass of the charged objects, and followed the superposition principle. Coulomb's law unifies all these observations into one succinct statement.
+Subsequent mathematicians and physicists found the construct of the electric field to be useful for determining the electrostatic force on an electric charge at any point in space. The electric field was based on using a hypothetical "test charge" anywhere in space and then using Coulomb's law to determine the electrostatic force. Thus the electric field anywhere in space is defined as
+
+  
+    
+      
+        
+          E
+        
+        =
+        
+          
+            
+              F
+            
+            
+              q
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {E} ={\mathbf {F}  \over {q}},}
+  
+
+where 
+  
+    
+      
+        q
+      
+    
+    {\displaystyle q}
+  
+ is the magnitude of the hypothetical test charge. Similarly, the idea of the magnetic field was introduced to express how magnets can influence one another at a distance. The Lorentz force law gives the force upon a body with charge 
+  
+    
+      
+        q
+      
+    
+    {\displaystyle q}
+  
+ due to electric and magnetic fields:
+
+  
+    
+      
+        
+          F
+        
+        =
+        q
+        
+          (
+          
+            
+              E
+            
+            +
+            
+              v
+            
+            ×
+            
+              B
+            
+          
+          )
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} =q\left(\mathbf {E} +\mathbf {v} \times \mathbf {B} \right),}
+  
+
+where 
+  
+    
+      
+        
+          F
+        
+      
+    
+    {\displaystyle \mathbf {F} }
+  
+ is the electromagnetic force, 
+  
+    
+      
+        
+          E
+        
+      
+    
+    {\displaystyle \mathbf {E} }
+  
+ is the electric field at the body's location, 
+  
+    
+      
+        
+          B
+        
+      
+    
+    {\displaystyle \mathbf {B} }
+  
+ is the magnetic field, and 
+  
+    
+      
+        
+          v
+        
+      
+    
+    {\displaystyle \mathbf {v} }
+  
+ is the velocity of the particle. The magnetic contribution to the Lorentz force is the cross product of the velocity vector with the magnetic field.
+The origin of electric and magnetic fields would not be fully explained until 1864 when James Clerk Maxwell unified a number of earlier theories into a set of 20 scalar equations, which were later reformulated into 4 vector equations by Oliver Heaviside and Josiah Willard Gibbs. These "Maxwell's equations" fully described the sources of the fields as being stationary and moving charges, and the interactions of the fields themselves. This led Maxwell to discover that electric and magnetic fields could be "self-generating" through a wave that traveled at a speed that he calculated to be the speed of light. This insight united the nascent fields of electromagnetic theory with optics and led directly to a complete description of the electromagnetic spectrum.
+
+=== Normal ===

data/en.wikipedia.org/wiki/Force-5.md

@@ -0,0 +1,352 @@
+---
+title: "Force"
+chunk: 6/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+When objects are in contact, the force directly between them is called the normal force, the component of the total force in the system exerted normal to the interface between the objects. The normal force is closely related to Newton's third law. The normal force, for example, is responsible for the structural integrity of tables and floors as well as being the force that responds whenever an external force pushes on a solid object. An example of the normal force in action is the impact force on an object crashing into an immobile surface.
+
+=== Friction ===
+
+Friction is a force that opposes relative motion of two bodies. At the macroscopic scale, the frictional force is directly related to the normal force at the point of contact. There are two broad classifications of frictional forces: static friction and kinetic friction.
+The static friction force (
+  
+    
+      
+        
+          
+            F
+          
+          
+            
+              s
+              f
+            
+          
+        
+      
+    
+    {\displaystyle \mathbf {F} _{\mathrm {sf} }}
+  
+) will exactly oppose forces applied to an object parallel to a surface up to the limit specified by the coefficient of static friction (
+  
+    
+      
+        
+          μ
+          
+            
+              s
+              f
+            
+          
+        
+      
+    
+    {\displaystyle \mu _{\mathrm {sf} }}
+  
+) multiplied by the normal force (
+  
+    
+      
+        
+          
+            F
+          
+          
+            N
+          
+        
+      
+    
+    {\displaystyle \mathbf {F} _{\text{N}}}
+  
+). In other words, the magnitude of the static friction force satisfies the inequality:
+
+  
+    
+      
+        0
+        ≤
+        
+          
+            F
+          
+          
+            
+              s
+              f
+            
+          
+        
+        ≤
+        
+          μ
+          
+            
+              s
+              f
+            
+          
+        
+        
+          
+            F
+          
+          
+            
+              N
+            
+          
+        
+        .
+      
+    
+    {\displaystyle 0\leq \mathbf {F} _{\mathrm {sf} }\leq \mu _{\mathrm {sf} }\mathbf {F} _{\mathrm {N} }.}
+  
+
+The kinetic friction force (
+  
+    
+      
+        
+          F
+          
+            
+              k
+              f
+            
+          
+        
+      
+    
+    {\displaystyle F_{\mathrm {kf} }}
+  
+) is typically independent of both the forces applied and the movement of the object. Thus, the magnitude of the force equals:
+
+  
+    
+      
+        
+          
+            F
+          
+          
+            
+              k
+              f
+            
+          
+        
+        =
+        
+          μ
+          
+            
+              k
+              f
+            
+          
+        
+        
+          
+            F
+          
+          
+            
+              N
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} _{\mathrm {kf} }=\mu _{\mathrm {kf} }\mathbf {F} _{\mathrm {N} },}
+  
+
+where 
+  
+    
+      
+        
+          μ
+          
+            
+              k
+              f
+            
+          
+        
+      
+    
+    {\displaystyle \mu _{\mathrm {kf} }}
+  
+ is the coefficient of kinetic friction. The coefficient of kinetic friction is normally less than the coefficient of static friction.
+
+=== Tension ===
+
+Tension forces can be modeled using ideal strings that are massless, frictionless, unbreakable, and do not stretch. They can be combined with ideal pulleys, which allow ideal strings to switch physical direction. Ideal strings transmit tension forces instantaneously in action–reaction pairs so that if two objects are connected by an ideal string, any force directed along the string by the first object is accompanied by a force directed along the string in the opposite direction by the second object. By connecting the same string multiple times to the same object through the use of a configuration that uses movable pulleys, the tension force on a load can be multiplied. For every string that acts on a load, another factor of the tension force in the string acts on the load. Such machines allow a mechanical advantage for a corresponding increase in the length of displaced string needed to move the load. These tandem effects result ultimately in the conservation of mechanical energy since the work done on the load is the same no matter how complicated the machine.
+
+=== Spring ===
+
+A simple elastic force acts to return a spring to its natural length. An ideal spring is taken to be massless, frictionless, unbreakable, and infinitely stretchable. Such springs exert forces that push when contracted, or pull when extended, in proportion to the displacement of the spring from its equilibrium position. This linear relationship was described by Robert Hooke in 1676, for whom Hooke's law is named. If 
+  
+    
+      
+        Δ
+        x
+      
+    
+    {\displaystyle \Delta x}
+  
+ is the displacement, the force exerted by an ideal spring equals:
+
+  
+    
+      
+        
+          F
+        
+        =
+        −
+        k
+        Δ
+        
+          x
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} =-k\Delta \mathbf {x} ,}
+  
+
+where 
+  
+    
+      
+        k
+      
+    
+    {\displaystyle k}
+  
+ is the spring constant (or force constant), which is particular to the spring. The minus sign accounts for the tendency of the force to act in opposition to the applied load.
+
+=== Centripetal ===
+
+For an object in uniform circular motion, the net force acting on the object equals:
+
+  
+    
+      
+        
+          F
+        
+        =
+        −
+        
+          
+            
+              m
+              
+                v
+                
+                  2
+                
+              
+            
+            r
+          
+        
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} =-{\frac {mv^{2}}{r}}{\hat {\mathbf {r} }},}
+  
+
+where 
+  
+    
+      
+        m
+      
+    
+    {\displaystyle m}
+  
+ is the mass of the object, 
+  
+    
+      
+        v
+      
+    
+    {\displaystyle v}
+  
+ is the velocity of the object and 
+  
+    
+      
+        r
+      
+    
+    {\displaystyle r}
+  
+ is the distance to the center of the circular path and 
+  
+    
+      
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+      
+    
+    {\displaystyle {\hat {\mathbf {r} }}}
+  
+ is the unit vector pointing in the radial direction outwards from the center. This means that the net force felt by the object is always directed toward the center of the curving path. Such forces act perpendicular to the velocity vector associated with the motion of an object, and therefore do not change the speed of the object (magnitude of the velocity), but only the direction of the velocity vector. More generally, the net force that accelerates an object can be resolved into a component that is perpendicular to the path, and one that is tangential to the path. This yields both the tangential force, which accelerates the object by either slowing it down or speeding it up, and the radial (centripetal) force, which changes its direction.
+
+=== Continuum mechanics ===
+
+Newton's laws and Newtonian mechanics in general were first developed to describe how forces affect idealized point particles rather than three-dimensional objects. In real life, matter has extended structure and forces that act on one part of an object might affect other parts of an object. For situations where lattice holding together the atoms in an object is able to flow, contract, expand, or otherwise change shape, the theories of continuum mechanics describe the way forces affect the material. For example, in extended fluids, differences in pressure result in forces being directed along the pressure gradients as follows:
+
+  
+    
+      
+        
+          
+            
+              F
+            
+            V
+          
+        
+        =
+        −
+        
+          ∇
+        
+        P
+        ,
+      
+    
+    {\displaystyle {\frac {\mathbf {F} }{V}}=-\mathbf {\nabla } P,}
+  

data/en.wikipedia.org/wiki/Force-6.md

@@ -0,0 +1,522 @@
+---
+title: "Force"
+chunk: 7/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+where 
+  
+    
+      
+        V
+      
+    
+    {\displaystyle V}
+  
+ is the volume of the object in the fluid and 
+  
+    
+      
+        P
+      
+    
+    {\displaystyle P}
+  
+ is the scalar function that describes the pressure at all locations in space. Pressure gradients and differentials result in the buoyant force for fluids suspended in gravitational fields, winds in atmospheric science, and the lift associated with aerodynamics and flight.
+A specific instance of such a force that is associated with dynamic pressure is fluid resistance: a body force that resists the motion of an object through a fluid due to viscosity. For so-called "Stokes' drag" the force is approximately proportional to the velocity, but opposite in direction:
+
+  
+    
+      
+        
+          
+            F
+          
+          
+            
+              d
+            
+          
+        
+        =
+        −
+        b
+        
+          v
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} _{\mathrm {d} }=-b\mathbf {v} ,}
+  
+
+where:
+
+  
+    
+      
+        b
+      
+    
+    {\displaystyle b}
+  
+ is a constant that depends on the properties of the fluid and the dimensions of the object (usually the cross-sectional area), and
+
+  
+    
+      
+        
+          v
+        
+      
+    
+    {\displaystyle \mathbf {v} }
+  
+ is the velocity of the object.
+More formally, forces in continuum mechanics are fully described by a stress tensor with terms that are roughly defined as
+
+  
+    
+      
+        σ
+        =
+        
+          
+            F
+            A
+          
+        
+        ,
+      
+    
+    {\displaystyle \sigma ={\frac {F}{A}},}
+  
+
+where 
+  
+    
+      
+        A
+      
+    
+    {\displaystyle A}
+  
+ is the relevant cross-sectional area for the volume for which the stress tensor is being calculated. This formalism includes pressure terms associated with forces that act normal to the cross-sectional area (the matrix diagonals of the tensor) as well as shear terms associated with forces that act parallel to the cross-sectional area (the off-diagonal elements). The stress tensor accounts for forces that cause all strains (deformations) including also tensile stresses and compressions.
+
+=== Fictitious ===
+
+There are forces that are frame dependent, meaning that they appear due to the adoption of non-Newtonian (that is, non-inertial) reference frames. Such forces include the centrifugal force and the Coriolis force. These forces are considered fictitious because they do not exist in frames of reference that are not accelerating. Because these forces are not genuine they are also referred to as "pseudo forces".
+In general relativity, gravity becomes a fictitious force that arises in situations where spacetime deviates from a flat geometry.
+
+== Concepts derived from force ==
+
+=== Rotation and torque ===
+
+Forces that cause extended objects to rotate are associated with torques. Mathematically, the torque of a force 
+  
+    
+      
+        
+          F
+        
+      
+    
+    {\displaystyle \mathbf {F} }
+  
+ is defined relative to an arbitrary reference point as the cross product:
+
+  
+    
+      
+        
+          τ
+        
+        =
+        
+          r
+        
+        ×
+        
+          F
+        
+        ,
+      
+    
+    {\displaystyle {\boldsymbol {\tau }}=\mathbf {r} \times \mathbf {F} ,}
+  
+
+where 
+  
+    
+      
+        
+          r
+        
+      
+    
+    {\displaystyle \mathbf {r} }
+  
+ is the position vector of the force application point relative to the reference point.
+Torque is the rotation equivalent of force in the same way that angle is the rotational equivalent for position, angular velocity for velocity, and angular momentum for momentum. As a consequence of Newton's first law of motion, there exists rotational inertia that ensures that all bodies maintain their angular momentum unless acted upon by an unbalanced torque. Likewise, Newton's second law of motion can be used to derive an analogous equation for the instantaneous angular acceleration of the rigid body:
+
+  
+    
+      
+        
+          τ
+        
+        =
+        I
+        
+          α
+        
+        ,
+      
+    
+    {\displaystyle {\boldsymbol {\tau }}=I{\boldsymbol {\alpha }},}
+  
+
+where
+
+  
+    
+      
+        I
+      
+    
+    {\displaystyle I}
+  
+ is the moment of inertia of the body
+
+  
+    
+      
+        
+          α
+        
+      
+    
+    {\displaystyle {\boldsymbol {\alpha }}}
+  
+ is the angular acceleration of the body.
+This provides a definition for the moment of inertia, which is the rotational equivalent for mass. In more advanced treatments of mechanics, where the rotation over a time interval is described, the moment of inertia must be substituted by the tensor that, when properly analyzed, fully determines the characteristics of rotations including precession and nutation.
+Equivalently, the differential form of Newton's second law provides an alternative definition of torque:
+
+  
+    
+      
+        
+          τ
+        
+        =
+        
+          
+            
+              
+                d
+              
+              
+                L
+              
+            
+            
+              d
+              t
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle {\boldsymbol {\tau }}={\frac {\mathrm {d} \mathbf {L} }{\mathrm {dt} }},}
+  
+
+where 
+  
+    
+      
+        
+          L
+        
+      
+    
+    {\displaystyle \mathbf {L} }
+  
+ is the angular momentum of the particle.
+Newton's third law of motion requires that all objects exerting torques themselves experience equal and opposite torques, and therefore also directly implies the conservation of angular momentum for closed systems that experience rotations and revolutions through the action of internal torques.
+
+=== Yank ===
+The yank is defined as the rate of change of force
+
+  
+    
+      
+        
+          Y
+        
+        =
+        
+          
+            
+              
+                d
+              
+              
+                F
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+      
+    
+    {\displaystyle \mathbf {Y} ={\frac {\mathrm {d} \mathbf {F} }{\mathrm {d} t}}}
+  
+
+The term is used in biomechanical analysis, athletic assessment and robotic control. The second ("tug"), third ("snatch"), fourth ("shake"), and higher derivatives are rarely used.
+
+=== Kinematic integrals ===
+
+Forces can be used to define a number of physical concepts by integrating with respect to kinematic variables. For example, integrating with respect to time gives the definition of impulse:
+
+  
+    
+      
+        
+          J
+        
+        =
+        
+          ∫
+          
+            
+              t
+              
+                1
+              
+            
+          
+          
+            
+              t
+              
+                2
+              
+            
+          
+        
+        
+          
+            F
+          
+          
+          
+            d
+          
+          t
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {J} =\int _{t_{1}}^{t_{2}}{\mathbf {F} \,\mathrm {d} t},}
+  
+
+which by Newton's second law must be equivalent to the change in momentum (yielding the Impulse momentum theorem).
+Similarly, integrating with respect to position gives a definition for the work done by a force:
+
+  
+    
+      
+        W
+        =
+        
+          ∫
+          
+            
+              
+                x
+              
+              
+                1
+              
+            
+          
+          
+            
+              
+                x
+              
+              
+                2
+              
+            
+          
+        
+        
+          
+            F
+          
+          ⋅
+          
+            
+              d
+            
+            
+              x
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle W=\int _{\mathbf {x} _{1}}^{\mathbf {x} _{2}}{\mathbf {F} \cdot {\mathrm {d} \mathbf {x} }},}
+  
+
+which is equivalent to changes in kinetic energy (yielding the work energy theorem).
+Power P is the rate of change dW/dt of the work W, as the trajectory is extended by a position change 
+  
+    
+      
+        d
+        
+          x
+        
+      
+    
+    {\displaystyle d\mathbf {x} }
+  
+ in a time interval dt:
+
+  
+    
+      
+        
+          d
+        
+        W
+        =
+        
+          
+            
+              
+                d
+              
+              W
+            
+            
+              
+                d
+              
+              
+                x
+              
+            
+          
+        
+        ⋅
+        
+          d
+        
+        
+          x
+        
+        =
+        
+          F
+        
+        ⋅
+        
+          d
+        
+        
+          x
+        
+        ,
+      
+    
+    {\displaystyle \mathrm {d} W={\frac {\mathrm {d} W}{\mathrm {d} \mathbf {x} }}\cdot \mathrm {d} \mathbf {x} =\mathbf {F} \cdot \mathrm {d} \mathbf {x} ,}
+  
+
+so
+
+  
+    
+      
+        P
+        =
+        
+          
+            
+              
+                d
+              
+              W
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        =
+        
+          
+            
+              
+                d
+              
+              W
+            
+            
+              
+                d
+              
+              
+                x
+              
+            
+          
+        
+        ⋅
+        
+          
+            
+              
+                d
+              
+              
+                x
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        =
+        
+          F
+        
+        ⋅
+        
+          v
+        
+        ,
+      
+    
+    {\displaystyle P={\frac {\mathrm {d} W}{\mathrm {d} t}}={\frac {\mathrm {d} W}{\mathrm {d} \mathbf {x} }}\cdot {\frac {\mathrm {d} \mathbf {x} }{\mathrm {d} t}}=\mathbf {F} \cdot \mathbf {v} ,}
+  

data/en.wikipedia.org/wiki/Force-7.md

@@ -0,0 +1,353 @@
+---
+title: "Force"
+chunk: 8/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+with 
+  
+    
+      
+        
+          v
+        
+        =
+        
+          d
+        
+        
+          x
+        
+        
+          /
+        
+        
+          d
+        
+        t
+      
+    
+    {\displaystyle \mathbf {v} =\mathrm {d} \mathbf {x} /\mathrm {d} t}
+  
+ the velocity.
+
+=== Potential energy ===
+
+Instead of a force, often the mathematically related concept of a potential energy field is used. For instance, the gravitational force acting upon an object can be seen as the action of the gravitational field that is present at the object's location. Restating mathematically the definition of energy (via the definition of work), a potential scalar field 
+  
+    
+      
+        U
+        (
+        
+          r
+        
+        )
+      
+    
+    {\displaystyle U(\mathbf {r} )}
+  
+ is defined as that field whose gradient is equal and opposite to the force produced at every point:
+
+  
+    
+      
+        
+          F
+        
+        =
+        −
+        
+          ∇
+        
+        U
+        .
+      
+    
+    {\displaystyle \mathbf {F} =-\mathbf {\nabla } U.}
+  
+
+Forces can be classified as conservative or nonconservative. Conservative forces are equivalent to the gradient of a potential while nonconservative forces are not.
+
+=== Conservation ===
+
+A conservative force that acts on a closed system has an associated mechanical work that allows energy to convert only between kinetic or potential forms. This means that for a closed system, the net mechanical energy is conserved whenever a conservative force acts on the system. The force, therefore, is related directly to the difference in potential energy between two different locations in space, and can be considered to be an artifact of the potential field in the same way that the direction and amount of a flow of water can be considered to be an artifact of the contour map of the elevation of an area.
+Conservative forces include gravity, the electromagnetic force, and the spring force. Each of these forces has models that are dependent on a position often given as a radial vector 
+  
+    
+      
+        
+          r
+        
+      
+    
+    {\displaystyle \mathbf {r} }
+  
+ emanating from spherically symmetric potentials. Examples of this follow:
+For gravity:
+
+  
+    
+      
+        
+          
+            F
+          
+          
+            g
+          
+        
+        =
+        −
+        
+          
+            
+              G
+              
+                m
+                
+                  1
+                
+              
+              
+                m
+                
+                  2
+                
+              
+            
+            
+              r
+              
+                2
+              
+            
+          
+        
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} _{\text{g}}=-{\frac {Gm_{1}m_{2}}{r^{2}}}{\hat {\mathbf {r} }},}
+  
+
+where 
+  
+    
+      
+        G
+      
+    
+    {\displaystyle G}
+  
+ is the gravitational constant, and 
+  
+    
+      
+        
+          m
+          
+            n
+          
+        
+      
+    
+    {\displaystyle m_{n}}
+  
+ is the mass of object n.
+For electrostatic forces:
+
+  
+    
+      
+        
+          
+            F
+          
+          
+            e
+          
+        
+        =
+        
+          
+            
+              
+                q
+                
+                  1
+                
+              
+              
+                q
+                
+                  2
+                
+              
+            
+            
+              4
+              π
+              
+                ε
+                
+                  0
+                
+              
+              
+                r
+                
+                  2
+                
+              
+            
+          
+        
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} _{\text{e}}={\frac {q_{1}q_{2}}{4\pi \varepsilon _{0}r^{2}}}{\hat {\mathbf {r} }},}
+  
+
+where 
+  
+    
+      
+        
+          ε
+          
+            0
+          
+        
+      
+    
+    {\displaystyle \varepsilon _{0}}
+  
+ is electric permittivity of free space, and 
+  
+    
+      
+        
+          q
+          
+            n
+          
+        
+      
+    
+    {\displaystyle q_{n}}
+  
+ is the electric charge of object n.
+For spring forces:
+
+  
+    
+      
+        
+          
+            F
+          
+          
+            s
+          
+        
+        =
+        −
+        k
+        r
+        
+          
+            
+              
+                r
+              
+              ^
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} _{\text{s}}=-kr{\hat {\mathbf {r} }},}
+  
+
+where 
+  
+    
+      
+        k
+      
+    
+    {\displaystyle k}
+  
+ is the spring constant.
+For certain physical scenarios, it is impossible to model forces as being due to a simple gradient of potentials. This is often due a macroscopic statistical average of microstates. For example, static friction is caused by the gradients of numerous electrostatic potentials between the atoms, but manifests as a force model that is independent of any macroscale position vector. Nonconservative forces other than friction include other contact forces, tension, compression, and drag. For any sufficiently detailed description, all these forces are the results of conservative ones since each of these macroscopic forces are the net results of the gradients of microscopic potentials.
+The connection between macroscopic nonconservative forces and microscopic conservative forces is described by detailed treatment with statistical mechanics. In macroscopic closed systems, nonconservative forces act to change the internal energies of the system, and are often associated with the transfer of heat. According to the Second law of thermodynamics, nonconservative forces necessarily result in energy transformations within closed systems from ordered to more random conditions as entropy increases.
+
+== Units ==
+The SI unit of force is the newton (symbol N), which is the force required to accelerate a one kilogram mass at a rate of one meter per second squared, or kg·m·s−2.The corresponding CGS unit is the dyne, the force required to accelerate a one gram mass by one centimeter per second squared, or g·cm·s−2. A newton is thus equal to 100,000 dynes.
+The gravitational foot-pound-second English unit of force is the pound-force (lbf), defined as the force exerted by gravity on a pound-mass in the standard gravitational field of 9.80665 m·s−2. The pound-force provides an alternative unit of mass: one slug is the mass that will accelerate by one foot per second squared when acted on by one pound-force. An alternative unit of force in a different foot–pound–second system, the absolute fps system, is the poundal, defined as the force required to accelerate a one-pound mass at a rate of one foot per second squared.
+The pound-force has a metric counterpart, less commonly used than the newton: the kilogram-force (kgf) (sometimes kilopond), is the force exerted by standard gravity on one kilogram of mass. The kilogram-force leads to an alternate, but rarely used unit of mass: the metric slug (sometimes mug or hyl) is that mass that accelerates at 1 m·s−2 when subjected to a force of 1 kgf. The kilogram-force is not a part of the modern SI system, and is generally deprecated, sometimes used for expressing aircraft weight, jet thrust, bicycle spoke tension, torque wrench settings and engine output torque.
+
+See also Ton-force.
+
+== Revisions of the force concept ==
+At the beginning of the 20th century, new physical ideas emerged to explain experimental results in astronomical and submicroscopic realms. As discussed below, relativity alters the definition of momentum and quantum mechanics reuses the concept of "force" in microscopic contexts where Newton's laws do not apply directly.
+
+=== Special theory of relativity ===
+
+In the special theory of relativity, mass and energy are equivalent (as can be seen by calculating the work required to accelerate an object). When an object's velocity increases, so does its energy and hence its mass equivalent (inertia). It thus requires more force to accelerate it the same amount than it did at a lower velocity. Newton's second law,
+
+  
+    
+      
+        
+          F
+        
+        =
+        
+          
+            
+              
+                d
+              
+              
+                p
+              
+            
+            
+              
+                d
+              
+              t
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} ={\frac {\mathrm {d} \mathbf {p} }{\mathrm {d} t}},}
+  

data/en.wikipedia.org/wiki/Force-8.md

@@ -0,0 +1,334 @@
+---
+title: "Force"
+chunk: 9/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+remains valid because it is a mathematical definition. But for momentum to be conserved at relativistic relative velocity, 
+  
+    
+      
+        v
+      
+    
+    {\displaystyle v}
+  
+, momentum must be redefined as:
+
+  
+    
+      
+        
+          p
+        
+        =
+        
+          
+            
+              
+                m
+                
+                  0
+                
+              
+              
+                v
+              
+            
+            
+              1
+              −
+              
+                v
+                
+                  2
+                
+              
+              
+                /
+              
+              
+                c
+                
+                  2
+                
+              
+            
+          
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {p} ={\frac {m_{0}\mathbf {v} }{\sqrt {1-v^{2}/c^{2}}}},}
+  
+
+where 
+  
+    
+      
+        
+          m
+          
+            0
+          
+        
+      
+    
+    {\displaystyle m_{0}}
+  
+ is the rest mass and 
+  
+    
+      
+        c
+      
+    
+    {\displaystyle c}
+  
+ the speed of light.
+The expression relating force and acceleration for a particle with constant non-zero rest mass 
+  
+    
+      
+        m
+      
+    
+    {\displaystyle m}
+  
+ moving in the 
+  
+    
+      
+        x
+      
+    
+    {\displaystyle x}
+  
+ direction at velocity 
+  
+    
+      
+        v
+      
+    
+    {\displaystyle v}
+  
+ is:
+
+  
+    
+      
+        
+          F
+        
+        =
+        
+          (
+          
+            
+              γ
+              
+                3
+              
+            
+            m
+            
+              a
+              
+                x
+              
+            
+            ,
+            γ
+            m
+            
+              a
+              
+                y
+              
+            
+            ,
+            γ
+            m
+            
+              a
+              
+                z
+              
+            
+          
+          )
+        
+        ,
+      
+    
+    {\displaystyle \mathbf {F} =\left(\gamma ^{3}ma_{x},\gamma ma_{y},\gamma ma_{z}\right),}
+  
+
+where
+
+  
+    
+      
+        γ
+        =
+        
+          
+            1
+            
+              1
+              −
+              
+                v
+                
+                  2
+                
+              
+              
+                /
+              
+              
+                c
+                
+                  2
+                
+              
+            
+          
+        
+        .
+      
+    
+    {\displaystyle \gamma ={\frac {1}{\sqrt {1-v^{2}/c^{2}}}}.}
+  
+
+is called the Lorentz factor. The Lorentz factor increases steeply as the relative velocity approaches the speed of light. Consequently, the greater and greater force must be applied to produce the same acceleration at extreme velocity. The relative velocity cannot reach 
+  
+    
+      
+        c
+      
+    
+    {\displaystyle c}
+  
+.
+If 
+  
+    
+      
+        v
+      
+    
+    {\displaystyle v}
+  
+ is very small compared to 
+  
+    
+      
+        c
+      
+    
+    {\displaystyle c}
+  
+, then 
+  
+    
+      
+        γ
+      
+    
+    {\displaystyle \gamma }
+  
+ is very close to 1 and
+
+  
+    
+      
+        
+          F
+        
+        =
+        m
+        
+          a
+        
+      
+    
+    {\displaystyle \mathbf {F} =m\mathbf {a} }
+  
+
+is a close approximation. Even for use in relativity, one can restore the form of
+
+  
+    
+      
+        
+          F
+          
+            μ
+          
+        
+        =
+        m
+        
+          A
+          
+            μ
+          
+        
+      
+    
+    {\displaystyle F^{\mu }=mA^{\mu }}
+  
+
+through the use of four-vectors. This relation is correct in relativity when 
+  
+    
+      
+        
+          F
+          
+            μ
+          
+        
+      
+    
+    {\displaystyle F^{\mu }}
+  
+ is the four-force, 
+  
+    
+      
+        m
+      
+    
+    {\displaystyle m}
+  
+ is the invariant mass, and 
+  
+    
+      
+        
+          A
+          
+            μ
+          
+        
+      
+    
+    {\displaystyle A^{\mu }}
+  
+ is the four-acceleration.
+The general theory of relativity incorporates a more radical departure from the Newtonian way of thinking about force, specifically gravitational force. This reimagining of the nature of gravity is described more fully below.
+
+=== Quantum mechanics ===
+
+Quantum mechanics is a theory of physics originally developed in order to understand microscopic phenomena: behavior at the scale of molecules, atoms or subatomic particles. Generally and loosely speaking, the smaller a system is, the more an adequate mathematical model will require understanding quantum effects. The conceptual underpinning of quantum physics is different from that of classical physics. Instead of thinking about quantities like position, momentum, and energy as properties that an object has, one considers what result might appear when a measurement of a chosen type is performed. Quantum mechanics allows the physicist to calculate the probability that a chosen measurement will elicit a particular result. The expectation value for a measurement is the average of the possible results it might yield, weighted by their probabilities of occurrence.
+In quantum mechanics, interactions are typically described in terms of energy rather than force. The Ehrenfest theorem provides a connection between quantum expectation values and the classical concept of force, a connection that is necessarily inexact, as quantum physics is fundamentally different from classical. In quantum physics, the Born rule is used to calculate the expectation values of a position measurement or a momentum measurement. These expectation values will generally change over time; that is, depending on the time at which (for example) a position measurement is performed, the probabilities for its different possible outcomes will vary. The Ehrenfest theorem says, roughly speaking, that the equations describing how these expectation values change over time have a form reminiscent of Newton's second law, with a force defined as the negative derivative of the potential energy. However, the more pronounced quantum effects are in a given situation, the more difficult it is to derive meaningful conclusions from this resemblance.
+Quantum mechanics also introduces two new constraints that interact with forces at the submicroscopic scale and which are especially important for atoms. Despite the strong attraction of the nucleus, the uncertainty principle limits the minimum extent of an electron probability distribution and the Pauli exclusion principle prevents electrons from sharing the same probability distribution. This gives rise to an emergent pressure known as degeneracy pressure. The dynamic equilibrium between the degeneracy pressure and the attractive electromagnetic force give atoms, molecules, liquids, and solids stability.
+
+=== Quantum field theory ===

data/en.wikipedia.org/wiki/Force-9.md

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+---
+title: "Force"
+chunk: 10/11
+source: "https://en.wikipedia.org/wiki/Force"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:04.607426+00:00"
+instance: "kb-cron"
+---
+
+In modern particle physics, forces and the acceleration of particles are explained as a mathematical by-product of exchange of momentum-carrying gauge bosons. With the development of quantum field theory and general relativity, it was realized that force is a redundant concept arising from conservation of momentum (4-momentum in relativity and momentum of virtual particles in quantum electrodynamics). The conservation of momentum can be directly derived from the homogeneity or symmetry of space and so is usually considered more fundamental than the concept of a force. Thus the currently known fundamental forces are considered more accurately to be "fundamental interactions".
+While sophisticated mathematical descriptions are needed to predict, in full detail, the result of such interactions, there is a conceptually simple way to describe them through the use of Feynman diagrams. In a Feynman diagram, each matter particle is represented as a straight line (see world line) traveling through time, which normally increases up or to the right in the diagram. Matter and anti-matter particles are identical except for their direction of propagation through the Feynman diagram. World lines of particles intersect at interaction vertices, and the Feynman diagram represents any force arising from an interaction as occurring at the vertex with an associated instantaneous change in the direction of the particle world lines. Gauge bosons are emitted away from the vertex as wavy lines and, in the case of virtual particle exchange, are absorbed at an adjacent vertex. The utility of Feynman diagrams is that other types of physical phenomena that are part of the general picture of fundamental interactions but are conceptually separate from forces can also be described using the same rules. For example, a Feynman diagram can describe in succinct detail how a neutron decays into an electron, proton, and antineutrino, an interaction mediated by the same gauge boson that is responsible for the weak nuclear force.
+
+== Fundamental interactions ==
+
+All of the known forces of the universe are classified into four fundamental interactions. The strong and the weak forces act only at very short distances, and are responsible for the interactions between subatomic particles, including nucleons and compound nuclei. The electromagnetic force acts between electric charges, and the gravitational force acts between masses. All other forces in nature derive from these four fundamental interactions operating within quantum mechanics, including the constraints introduced by the Schrödinger equation and the Pauli exclusion principle. For example, friction is a manifestation of the electromagnetic force acting between atoms of two surfaces. The forces in springs, modeled by Hooke's law, are also the result of electromagnetic forces. Centrifugal forces are acceleration forces that arise simply from the acceleration of rotating frames of reference.
+The fundamental theories for forces developed from the unification of different ideas. For example, Newton's universal theory of gravitation showed that the force responsible for objects falling near the surface of the Earth is also the force responsible for the falling of celestial bodies about the Earth (the Moon) and around the Sun (the planets). Michael Faraday and James Clerk Maxwell demonstrated that electric and magnetic forces were unified through a theory of electromagnetism. In the 20th century, the development of quantum mechanics led to a modern understanding that the first three fundamental forces (all except gravity) are manifestations of matter (fermions) interacting by exchanging virtual particles called gauge bosons. This Standard Model of particle physics assumes a similarity between the forces and led scientists to predict the unification of the weak and electromagnetic forces in electroweak theory, which was subsequently confirmed by observation.
+
+=== Gravitational ===
+
+Newton's law of gravitation is an example of action at a distance: one body, like the Sun, exerts an influence upon any other body, like the Earth, no matter how far apart they are. Moreover, this action at a distance is instantaneous. According to Newton's theory, the one body shifting position changes the gravitational pulls felt by all other bodies, all at the same instant of time. Albert Einstein recognized that this was inconsistent with special relativity and its prediction that influences cannot travel faster than the speed of light. So, he sought a new theory of gravitation that would be relativistically consistent. Mercury's orbit did not match that predicted by Newton's law of gravitation. Some astrophysicists predicted the existence of an undiscovered planet (Vulcan) that could explain the discrepancies. When Einstein formulated his theory of general relativity (GR) he focused on Mercury's problematic orbit and found that his theory added a correction, which could account for the discrepancy. This was the first time that Newton's theory of gravity had been shown to be inexact.
+Since then, general relativity has been acknowledged as the theory that best explains gravity. In GR, gravitation is not viewed as a force, but rather, objects moving freely in gravitational fields travel under their own inertia in straight lines through curved spacetime – defined as the shortest spacetime path between two spacetime events. From the perspective of the object, all motion occurs as if there were no gravitation whatsoever. It is only when observing the motion in a global sense that the curvature of spacetime can be observed and the force is inferred from the object's curved path. Thus, the straight line path in spacetime is seen as a curved line in space, and it is called the ballistic trajectory of the object. For example, a basketball thrown from the ground moves in a parabola, as it is in a uniform gravitational field. Its spacetime trajectory is almost a straight line, slightly curved (with the radius of curvature of the order of few light-years). The time derivative of the changing momentum of the object is what we label as "gravitational force".

data/en.wikipedia.org/wiki/Francien_language-0.md

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+---
+title: "Francien language"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Francien_language"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:59.387734+00:00"
+instance: "kb-cron"
+---
+
+Francien (French pronunciation: [fʁɑ̃sjɛ̃]), also anglicized as Francian (), is a 19th-century term in linguistics that was applied to the French dialect that was spoken during the Middle Ages in the regions of Île-de-France (with Paris at its centre), Orléanais, as well as Touraine, Berry, and Bourbonnais before the establishment of the French language as a standard language.
+According to one theory of the development of French, Francien was chosen out of all the competing oïl languages as an official language (Norman and Picard being the main competitors in the medieval period). The theory currently prevailing, however, is that Francien was one of the dialects in the dialect continuum on top of which an administrative language, untrammeled by perceived regionalisms, was imposed as a compromise means of communication and record to replace Latin.
+The existence and definition of Francien were put forward in the 19th century, partly to support the idea of the French language as enjoying a direct and pure lineage from Latin and to minimize the contributions of the various Romance languages of France. Nowadays, the question of Francien is a controversial topic in discussions of language policy in France.
+
+
+== See also ==
+Old French
+Ordinance of Villers-Cotterêts
+Jordain de Blaivies, a chanson de geste in this dialect
+
+
+== Notes ==

data/en.wikipedia.org/wiki/Geohumoral_theory-0.md

@@ -0,0 +1,15 @@
+---
+title: "Geohumoral theory"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Geohumoral_theory"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:34:00.516614+00:00"
+instance: "kb-cron"
+---
+
+Geohumoral theory or Geohumoralism was a racialist concept propounded in Renaissance Europe. Briefly, it "held that variations in topography and climate produced variations in national characteristics" (Wilson 133).
+This embodied the early modern "...common way of understanding human nature...through analyzing how European bodies altered as a result of being in one climate rather than another – some Europeans, notably those in cold northern climes, such as the English and Scots, and those in southern climes, such as those close to the shores of tropical Africa, had their bodies altered sufficiently by environmental factors so as to be morally defective and physically decrepit" (Abulafia qtd. in Burnard par. 7). Geohumoralism was, in part, a philosophical justification for the European imperial encroachment upon the New World.
+
+
+== References ==

data/en.wikipedia.org/wiki/Global_cooling-0.md

@@ -0,0 +1,26 @@
+---
+title: "Global cooling"
+chunk: 1/6
+source: "https://en.wikipedia.org/wiki/Global_cooling"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:34:02.304703+00:00"
+instance: "kb-cron"
+---
+
+Global cooling was a conjecture, especially during the 1970s, of imminent cooling of the Earth culminating in a period of extensive glaciation, due to the cooling effects of aerosols or orbital forcing. 
+Some press reports in the 1970s speculated about continued cooling; these did not accurately reflect the scientific literature of the time, which was generally more concerned with warming from an enhanced greenhouse effect.
+An overall warming trend from the late Industrial Revolution did slow and reverse slightly from the 1940s to the 1970s, but then continued sharply upward into the 2020s.
+
+== Introduction: general awareness and concern ==
+By the 1970s, scientists were becoming increasingly aware that estimates of global temperatures showed cooling since 1945, as well as the possibility of large scale warming due to emissions of greenhouse gases. In the scientific papers which considered climate trends of the 21st century, fewer than 10% were inclined towards future cooling, while most papers predicted future warming. The general public had little awareness of carbon dioxide's effects on climate, but Science News in May 1959 forecast a 25% increase in atmospheric carbon dioxide in the 150 years from 1850 to 2000, with a consequent warming trend. The actual increase in this period was 29%. Paul R. Ehrlich mentioned global warming from greenhouse gases as a counterforce to the cooling effect of aerosols in 1968. By the time the idea of global cooling reached the public press in the mid-1970s temperatures had stopped falling, and there was concern in the climatological community about carbon dioxide's warming effects. In response to such reports, the World Meteorological Organization issued a warning in June 1976 that "a very significant warming of global climate" was probable.
+Currently, there are some concerns about the possible regional cooling effects of a slowdown or shutdown of thermohaline circulation, which might be provoked by an increase of fresh water mixing into the North Atlantic due to glacial melting. The probability of this occurring is generally considered to be very low, and the IPCC notes, "even in models where the THC weakens, there is still warming over Europe. For example, in all AOGCM integrations where the radiative forcing is increasing, the sign of the temperature change over north-west Europe is positive."
+
+== Physical mechanisms ==
+The cooling period is reproduced by current (1999 on) global climate models that include the physical effects of sulfate aerosols, and there is now general agreement that aerosol effects were the dominant cause of the mid-20th century cooling. At the time there were two physical mechanisms that were most frequently advanced to cause cooling: aerosols and orbital forcing.
+
+=== Aerosols ===
+
+Human activity — mostly as a by-product of fossil fuel combustion, partly by land use changes — increases the number of tiny particles (aerosols) in the atmosphere. These have a direct effect: they effectively increase the planetary albedo, thus cooling the planet by reducing the solar radiation reaching the surface; and an indirect effect: they affect the properties of clouds by acting as cloud condensation nuclei. In the early 1970s some speculated that this cooling effect might dominate over the warming effect of the CO2 release: see discussion of Rasool and Schneider (1971), below. As a result of observations and a switch to cleaner fuel burning, this no longer seems likely; current scientific work indicates that global warming is far more likely. Although the temperature drops foreseen by this mechanism have now been discarded in light of better theory and the observed warming, aerosols are thought to have contributed a cooling tendency (outweighed by increases in greenhouse gases) and also have contributed to global dimming.
+
+=== Orbital forcing ===

data/en.wikipedia.org/wiki/Global_cooling-1.md

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+---
+title: "Global cooling"
+chunk: 2/6
+source: "https://en.wikipedia.org/wiki/Global_cooling"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:34:02.304703+00:00"
+instance: "kb-cron"
+---
+
+Orbital forcing refers to the slow, cyclical changes in the tilt of Earth's axis and shape of its orbit. These cycles alter the total amount of sunlight reaching the Earth by a small amount and affect the timing and intensity of the seasons. This mechanism is thought to be responsible for the timing of the ice age cycles, and understanding of the mechanism was increasing rapidly in the mid-1970s.
+The paper of Hays, Imbrie, and Shackleton "Variations in the Earth's Orbit: Pacemaker of the Ice Ages" qualified its predictions with the remark that "forecasts must be qualified in two ways. First, they apply only to the natural component of future climatic trends - and not to anthropogenic effects such as those due to the burning of fossil fuels. Second, they describe only the long-term trends, because they are linked to orbital variations with periods of 20,000 years and longer. Climatic oscillations at higher frequencies are not predicted ... the results indicate that the long-term trend over the next 20,000 years is towards extensive Northern Hemisphere glaciation and cooler climate".
+The idea that ice age cycles were predictable appears to have become conflated with the idea that another one was due "soon" - perhaps because much of this study was done by geologists, who are accustomed to dealing with very long time scales and use "soon" to refer to periods of thousands of years. A strict application of the Milankovitch theory does not allow the prediction of a "rapid" ice age onset (i.e., less than a century or two) since the fastest orbital period is about 20,000 years. Some creative ways around this were found, notably one championed by Nigel Calder under the name of "snowblitz", but these ideas did not gain wide acceptance.
+The length of the current interglacial temperature peak is similar to the length of the preceding interglacial peak (Sangamon/Eem), and so it could be concluded that we might be nearing the end of this warm period. This conclusion would be mistaken. Firstly, because the lengths of previous interglacials were not particularly regular; see figure. Petit et al. note that "interglacials 5.5 and 9.3 are different from the Holocene, but similar to each other in duration, shape and amplitude. During each of these two events, there is a warm period of 4 kyr followed by a relatively rapid cooling". Secondly, future orbital variations will not closely resemble those of the past.
+
+== Concern pre-1970s ==
+In 1923, there was concern about a new ice age and Captain Donald Baxter MacMillan sailed toward the Arctic sponsored by the National Geographical Society to look for evidence of advancing glaciers.
+In 1926, a Berlin astronomer was predicting global cooling but that it was "ages away".
+Concerns that a new ice age was approaching was revived in the 1950s. During the Cold War, there were concerns by Harry Wexler that setting off atom bombs could be hastening a new ice age from a nuclear winter scenario.
+J. Murray Mitchell showed as early as 1963 a multidecadal cooling since about 1940. At a conference on climate change held in Boulder, Colorado in 1965, evidence supporting Milankovitch cycles triggered speculation on how the calculated small changes in sunlight might somehow trigger ice ages. In 1966, Cesare Emiliani predicted that "a new glaciation will begin within a few thousand years." In his 1968 book The Population Bomb, Paul R. Ehrlich wrote "The greenhouse effect is being enhanced now by the greatly increased level of carbon dioxide ... [this] is being countered by low-level clouds generated by contrails, dust, and other contaminants ... At the moment we cannot predict what the overall climatic results will be of our using the atmosphere as a garbage dump."
+
+== Concern in the 1970s ==
+
+=== 1970s awareness ===
+
+Concern peaked in the early 1970s, though "the possibility of anthropogenic warming dominated the peer-reviewed literature even then"  (a cooling period began in 1945, and two decades of a cooling trend suggested a trough had been reached after several decades of warming). This peaking concern is partially attributable to the fact much less was then known about world climate and causes of ice ages. Climate scientists were aware that predictions based on this trend were not possible - because the trend was poorly studied and not understood. Despite that, in the popular press the possibility of cooling was reported generally without the caveats present in the scientific reports, and "unusually severe winters in Asia and parts of North America in 1972 and 1973 ... pushed the issue into the public consciousness".
+In the 1970s, the compilation of records to produce hemispheric, or global, temperature records had just begun.
+Spencer R. Weart's history of The Discovery of Global Warming says that: "While neither scientists nor the public could be sure in the 1970s whether the world was warming or cooling, people were increasingly inclined to believe that global climate was on the move, and in no small way" [emphasis added].
+On January 11, 1970, The Washington Post reported that "Colder Winters Held Dawn of New Ice Age".
+In 1972, Emiliani warned "Man's activity may either precipitate this new ice age or lead to substantial or even total melting of the ice caps".
+Also in 1972, a group of glacial-epoch experts at a conference agreed that "the natural end of our warm epoch is undoubtedly near"; but the volume of Quaternary Research reporting on the meeting said that "the basic conclusion to be drawn from the discussions in this section is that the knowledge necessary for understanding the mechanism of climate change is still lamentably inadequate". George Kukla and Robert Matthews, in a Science write-up of a conference, asked when and how the current interglacial would end; concluding that, unless there were impacts from future human activity, "Global cooling and related rapid changes of environment, substantially exceeding the fluctuations experienced by man in historical times, must be expected within the next few millennia or even centuries", but many other scientists doubted these conclusions.

data/en.wikipedia.org/wiki/Global_cooling-2.md

@@ -0,0 +1,28 @@
+---
+title: "Global cooling"
+chunk: 3/6
+source: "https://en.wikipedia.org/wiki/Global_cooling"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:34:02.304703+00:00"
+instance: "kb-cron"
+---
+
+=== 1970 SCEP report ===
+The 1970 Study of Critical Environmental Problems reported the possibility of warming from increased carbon dioxide, but no concerns about cooling, setting a lower bound on the beginning of interest in "global cooling".
+
+=== 1971 to 1975: papers on warming and cooling factors ===
+By 1971, studies indicated that human caused air pollution was spreading, but there was uncertainty as to whether aerosols would cause warming or cooling, and whether or not they were more significant than rising CO2 levels. J. Murray Mitchell still viewed humans as "innocent bystanders" in the cooling from the 1940s to 1970, but in 1971 his calculations suggested that rising emissions could cause significant cooling after 2000, though he also argued that emissions could cause warming depending on circumstances. Calculations were too basic at this time to be trusted to give reliable results.
+An early numerical computation of climate effects was published in the journal Science in July 1971 as a paper by S. Ichtiaque Rasool and Stephen H. Schneider, titled "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate".
+The paper used rudimentary data and equations to compute the possible future effects of large increases in the densities in the atmosphere of two types of human environmental emissions:
+
+greenhouse gases such as carbon dioxide;
+particulate pollution such as smog, some of which remains suspended in the atmosphere in aerosol form for years.
+The paper suggested that the global warming due to greenhouse gases would tend to have less effect with greater densities, and while aerosol pollution could cause warming, it was likely that it would tend to have a cooling effect which increased with density. They concluded that "An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5 ° K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age."
+Both their equations and their data were badly flawed, as was soon pointed out by other scientists and confirmed by Schneider himself. In January 1972, Robert Jay Charlson et al. pointed out that with other reasonable assumptions, the model produced the opposite conclusion. The model made no allowance for changes in clouds or convection, and erroneously indicated that eight times as much CO2 would only cause 2 °C of warming. In a paper published in 1975, Schneider corrected the overestimate of aerosol cooling by checking data on the effects of dust produced by volcanoes. When the model included estimated changes in solar intensity, it gave a reasonable match to temperatures over the previous thousand years and its prediction was that "CO2 warming dominates the surface temperature patterns soon after 1980."
+
+=== 1972 and 1974 National Science Board ===
+The National Science Board's Patterns and Perspectives in Environmental Science report of 1972 discussed the cyclical behavior of climate, and the understanding at the time that the planet was entering a phase of cooling after a warm period. "Judging from the record of the past interglacial ages, the present time of high temperatures should be drawing to an end, to be followed by a long period of considerably colder temperatures leading into the next glacial age some 20,000 years from now." But it also continued; "However, it is possible, or even likely, that human interference has already altered the environment so much that the climatic pattern of the near future will follow a different path."
+The board's report of 1974, Science And The Challenges Ahead, continued on this theme. "During the last 20-30 years, world temperature has fallen, irregularly at first but more sharply over the last decade." Discussion of cyclic glacial periods does not feature in this report. Instead it is the role of humans that is central to the report's analysis.
+"The cause of the cooling trend is not known with certainty. But there is increasing concern that man himself may be implicated, not only in the recent cooling trend but also in the warming temperatures over the last century". The report did not conclude whether carbon dioxide in warming, or agricultural and industrial pollution in cooling, are factors in the recent climatic changes, noting;
+"Before such questions as these can be resolved, major advances must be made in understanding the chemistry and physics of the atmosphere and oceans, and in measuring and tracing particulates through the system."

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+title: "Global cooling"
+chunk: 4/6
+source: "https://en.wikipedia.org/wiki/Global_cooling"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:34:02.304703+00:00"
+instance: "kb-cron"
+---
+
+=== 1975 National Academy of Sciences report ===
+There also was a Report by the U.S. National Academy of Sciences (NAS) entitled, "Understanding Climate Change: A Program for Action".
+The report stated (p. 36) that, "The average surface air temperature in the northern hemisphere increased from the 1880s until about 1940 and has been decreasing thereafter."
+It also stated (p. 44) that, "If both the CO2 and particulate inputs to the atmosphere grow at equal rates in the future, the widely differing atmospheric residence times of the two pollutants means that the particulate effect will grow in importance relative to that of CO2."
+The report did not predict whether the 25-year cooling trend would continue. It stated (Forward, p. v) that, "we do not have a good quantitative understanding of our climate machine and what determines its course [so] it does not seem possible to predict climate", and (p. 2) "The climates of the earth have always been changing, and they will doubtless continue to do so in the future. How large these future changes will be, and where and how rapidly they will occur, we do not know."
+The Report's "program for action" was a call for creation of a new National Climatic Research Program. It stated (p. 62), "If we are to react rationally to the inevitable climatic changes of the future, and if we are ever to predict their future course, whether they are natural or man-induced, a far greater understanding of these changes is required than we now possess. It is, moreover, important that this knowledge be acquired as soon as possible." For that reason, it stated, "the time has now come to initiate a broad and coordinated attack on the problem of climate and climatic change."
+
+=== 1974 Time magazine article ===
+While these discussions were ongoing in scientific circles, other accounts appeared in the popular media. In their June 24, 1974, issue, Time presented an article titled "Another Ice Age?" that noted "the atmosphere has been growing gradually cooler for the past three decades" but noted that "Some scientists ... think that the cooling trend may be only temporary."
+
+=== 1975 Newsweek article ===
+An April 28, 1975, article in Newsweek magazine was titled "The Cooling World", it pointed to "ominous signs that the Earth's weather patterns have begun to change" and pointed to "a drop of half a degree [Fahrenheit] in average ground temperatures in the Northern Hemisphere between 1945 and 1968." The article stated "The evidence in support of these predictions [of global cooling] has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it." The Newsweek article did not state the cause of cooling; it stated that "what causes the onset of major and minor ice ages remains a mystery" and cited the NAS conclusion that "not only are the basic scientific questions largely unanswered, but in many cases we do not yet know enough to pose the key questions."
+The article mentioned the alternative solutions of "melting the Arctic ice cap by covering it with black soot or diverting Arctic rivers" but conceded these were not feasible. The Newsweek article concluded by criticizing government leaders: "But the scientists see few signs that government leaders anywhere are even prepared to take the simple measures of stockpiling food or of introducing the variables of climatic uncertainty into economic projections of future food supplies ... The longer the planners (politicians) delay, the more difficult will they find it to cope with climatic change once the results become grim reality." The article emphasized sensational and largely unsourced consequences - "resulting famines could be catastrophic", "drought and desolation", "the most devastating outbreak of tornadoes ever recorded", "droughts, floods, extended dry spells, long freezes, delayed monsoons", "impossible for starving peoples to migrate", "the present decline has taken the planet about a sixth of the way toward the Ice Age."
+On October 23, 2006, Newsweek issued a correction, over 31 years after the original article, stating that it had been "so spectacularly wrong about the near-term future" (though editor Jerry Adler stated that "the story wasn't 'wrong' in the journalistic sense of 'inaccurate.'")
+
+=== Other 1970s sources ===
+Academic analysis of the peer-reviewed studies published at that time shows that most papers examining aspects of climate during the 1970s were either neutral or showed a warming trend.
+In 1977, a popular book on the topic was published, called The Weather Conspiracy: The Coming of the New Ice Age.
+
+=== 1979 WMO conference ===
+Later in the decade, at a WMO conference in 1979, F. Kenneth Hare reported:
+
+Fig 8 shows ... 1938 the warmest year. They [temperatures] have since fallen by about 0.4 °C. At the end there is a suggestion that the fall ceased in about 1964, and may even have reversed.
+Figure 9 challenges the view that the fall of temperature has ceased ... the weight of evidence clearly favours cooling to the present date ... The striking point, however, is that interannual variability of world temperatures is much larger than the trend ... it is difficult to detect a genuine trend
+It is questionable, moreover, whether the trend is truly global. Calculated variations in the 5-year mean air temperature over the southern hemisphere chiefly with respect to land areas show that temperatures generally rose between 1943 and 1975. Since the 1960-64 period this rise has been strong ... the scattered SH data fail to support a hypothesis of continued global cooling since 1938. [p 65]
+
+== Late-20th-century cooling predictions ==
+
+=== 1980s ===
+Concerns about nuclear winter arose in the early 1980s from several reports. Similar speculations have appeared over effects due to catastrophes such as asteroid impacts and massive volcanic eruptions.

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+title: "Global cooling"
+chunk: 5/6
+source: "https://en.wikipedia.org/wiki/Global_cooling"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:34:02.304703+00:00"
+instance: "kb-cron"
+---
+
+=== 1990s ===
+In 1991, a prediction by Carl Sagan and other scientists who had worked on the famous TTAPS study on nuclear winter that massive oil well fires in Kuwait would cause significant effects on climate was incorrect.
+In January 1999, contrarian Patrick Michaels wrote a commentary offering to "take even money that the 10 years ending on December 31, 2007, will show a statistically significant global cooling trend in temperatures measured by satellite", on the basis of his view that record temperatures in 1998 had been a blip. Indeed, over that period, satellite-measured temperatures never again approached their 1998 peak. Due to a sharp but temporary dip in temperatures in 1999–2000, a least-squares linear regression fit to the satellite temperature record showed little overall trend. The RSS satellite temperature record showed a slight cooling trend, but the UAH satellite temperature record showed a slight warming trend.
+
+== Twenty-first century ==
+In 2003, the Office of Net Assessment at the United States Department of Defense was commissioned to produce a study on the likely and potential effects of abrupt modern climate change should a shutdown of thermohaline circulation occur. The study, conducted under ONA head Andrew Marshall, modelled its prospective climate change on the 8.2 kiloyear event, precisely because it was the middle alternative between the Younger Dryas and the Little Ice Age. Scientists said that "abrupt climate change initiated by Greenland ice sheet melting is not a realistic scenario for the 21st century".
+
+== Present level of knowledge ==
+
+The concern that cooler temperatures would continue, and perhaps at a faster rate, has been observed to be incorrect, as was assessed in the IPCC Third Assessment Report of 2001. More has to be learned about climate. However, the growing records have shown that short term cooling concerns have not been borne out.
+As for the prospects of the end of the current interglacial, while the four most recent interglacials lasted about 10,000 years, the interglacial before that lasted around 28,000 years. Milankovitch-type calculations indicate that the present interglacial would probably continue for tens of thousands of years naturally in the absence of human perturbations. Other estimates (Loutre and Berger, based on orbital calculations) put the unperturbed length of the present interglacial at 50,000 years. A. Berger expressed the opinion in 2005 (EGU presentation) that the present CO2 perturbation will last long enough to suppress the next glacial cycle entirely. This is consistent with the prediction of David Archer and colleagues who argued in 2005 that the present level of CO2 will suspend the next glacial period for the next 500,000 years and will be the longest duration and intensity of the projected interglacial period and are longer than have been seen in the last 2.6 million years.
+A 2015 report by the Past Global Changes Project, including Berger, says simulations show that a new glaciation is unlikely to happen within the next approximately 50,000 years, before the next strong drop in Northern Hemisphere summer insolation occurs "if either atmospheric CO2 concentration
+remains above 300 ppm or cumulative carbon emissions exceed 1000 Pg C" (i.e. 1000 gigatonnes carbon). "Only for an atmospheric CO2 content below the preindustrial level may a glaciation occur within the next 10 ka. ... Given the continued anthropogenic CO2 emissions, glacial inception is very unlikely to occur in the next 50 ka, because the timescale for CO2 and temperature reduction toward unperturbed values in the absence of active removal is very long [IPCC, 2013], and only weak precessional forcing occurs in the next two precessional cycles." (A precessional cycle is around 21,000 years, the time it takes for the perihelion to move all the way around the tropical year.)
+As the NAS report indicates, scientific knowledge regarding climate change was more uncertain than it is today. At the time that Rasool and Schneider wrote their 1971 paper, climatologists had not yet recognized the significance of greenhouse gases other than water vapor and carbon dioxide, such as methane, nitrous oxide, and chlorofluorocarbons. Early in that decade, carbon dioxide was the only widely studied human-influenced greenhouse gas. The attention drawn to atmospheric gases in the 1970s stimulated many discoveries in subsequent decades. As the temperature pattern changed, global cooling was of waning interest by 1979.
+
+== The ice age fallacy ==
+A common argument used to dismiss the significance of human-caused climate change is to allege that scientists showed concerns about global cooling which did not materialise, and there is therefore no need to heed current scientific concerns about global warming. In a 1998 article promoting the Oregon Petition, Fred Singer argued that expert concerns about global warming should be dismissed on the basis that what he called "the same hysterical fears" had supposedly been expressed earlier about global cooling.
+Bryan Walsh of Time magazine (2013) calls this argument "the Ice Age Fallacy". Illustrating the argument, for several years an image had been circulated of a Time cover, supposedly dated 1977, showing a penguin above a cover story title "How to Survive the Coming Ice Age". In March 2013, The Mail on Sunday published an article by David Rose, showing this same cover image, to support his claim that there was as much concern in the 1970s about a "looming 'ice age'" as there was now about global warming. After researching the authenticity of the magazine cover image, in July 2013, Walsh confirmed that the image was a hoax, modified from a 2007 cover story image for "The Global Warming Survival Guide".
+
+== See also ==
+
+== References ==

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+title: "Global cooling"
+chunk: 6/6
+source: "https://en.wikipedia.org/wiki/Global_cooling"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:34:02.304703+00:00"
+instance: "kb-cron"
+---
+
+== Further reading ==
+Carslaw, K. S. "The Climate Record: The Last Several Centuries and Last Several Decades. Is the Climate Stable?". ENVI2150 Climate Change: Scientific Issues. Archived from the original on February 20, 2007. Retrieved November 17, 2005.
+unknown. "History of Continental Drift - Before Wegener". Archived from the original on November 23, 2005. Retrieved November 17, 2005.
+http://tvnews.vanderbilt.edu/program.pl?ID=52903 Vanderbilt Television News Archive
+Johnson, Scott K. (June 7, 2016). "That '70s myth—did climate science really call for a "coming ice age?"". Ars Technica. Retrieved June 8, 2019.
+
+== External links ==
+What were climate scientists predicting in the 1970s?, summaries for laypeople of research and conspiracy theories by Skeptical Science, described by the marine biologist Ove Hoegh-Guldberg "the most prominent knowledge-based website dealing with climate change in the world".
+Discussion and quotes from various papers about the "1970s prediction of an imminent ice age", by Wm Connolley
+SCOPE 13 - The Global Carbon Cycle, SCOPE, 1976.
+SCOPE 27 - Climate Impact Assessment, 1984.
+"Another Ice Age?". Time. June 24, 1974. Archived from the original on March 12, 2007.
+Chambers FM, Brain SA (2002). "Paradigm shifts in late-Holocene climatology?". The Holocene. 12 (2): 239–249. Bibcode:2002Holoc..12..239C. doi:10.1191/0959683602hl540fa. S2CID 128774561.
+Past Climate Change Beliefs - some newspaper scans
+A Study of Climatological Research as it Pertains to Intelligence Problems - CIA report from 1974
+Geohydrological implications of climate change on water resource development, C. W. Stockton and W. R. Boggess, Contract Report DACW 72-78-C-0031, for U. S. Army Coastal Engineering Res. Center, Fort Belvoir, Virginia, C. W. Stockton & associates, Tucson, May 15, 1979. (See p. 159)

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+title: "Great chain of being"
+chunk: 1/2
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+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:33:05.837285+00:00"
+instance: "kb-cron"
+---
+
+The great chain of being (from Latin  scala naturae 'ladder of being') is a hierarchical structure of all matter and life, thought by the medieval Islamic world and medieval Christianity to have been decreed by God. The chain begins with God and descends through angels, humans, animals and plants to minerals.
+The great chain of being is a concept derived from Plato, Aristotle (in his Historia Animalium), Plotinus and Proclus. Further developed during the Middle Ages, it reached full expression in early modern Neoplatonism.
+
+== Divisions ==
+The chain of being hierarchy consists of God at the top, above angels, which like him are entirely spirit, without material bodies, and hence unchangeable. Beneath them are humans, consisting both of spirit and matter; they change and die, and are thus essentially impermanent. Lower are animals and plants. At the bottom are the mineral materials of the earth itself; they consist only of matter. Thus, the higher the being is in the chain, the more attributes it has, including all the attributes of the beings below it. The minerals are, in the medieval mind, a possible exception to the immutability of the material beings in the chain, as alchemy promised to turn lower elements like lead into those higher up the chain, like silver or gold.
+
+== The Great Chain ==
+The Great Chain of being links God, angels, humans, animals, plants, and minerals. The links of the chain are:
+
+=== God ===
+Religions such as Judaism and Christianity hold that God created the entire universe and everything in it. He has spiritual attributes found in angels and humans. God has unique attributes of omnipotence, omnipresence, and omniscience. He is the model of perfection in all of creation.
+
+=== Angelic beings ===
+
+In the New Testament, the Epistle to the Colossians sets out a partial list: "everything visible and everything invisible, Thrones, Dominations, Sovereignties, Powers – all things were created through him and for him." The Epistle to the Ephesians also lists several entities: "Far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come".
+In the 5th and 6th centuries, Pseudo-Dionysius the Areopagite set out a more elaborate hierarchy, consisting of three lists, each of three types:
+
+Angels of presence, praising God
+Seraphim – spirits of love
+Cherubim – spirits of harmony
+Thrones – record keepers of universal laws
+Angels of government, spreading light
+Dominions – spirits of wisdom and knowledge
+Virtues – angels of movement and free will
+Powers – angels of form and space
+Angels of revelation, able to communicate with humans
+Principalities – angels of time and personality
+Archangels – powerful angels superior to ordinary angels
+Angels – governors of spirits of nature
+
+=== Humanity ===
+Humans uniquely share spiritual attributes with God and the angels above them, love and language, and physical attributes with the animals below them, like having material bodies that experienced emotions and sensations such as lust and pain, as well as physical needs such as hunger and thirst.
+
+=== Animals ===
+Animals have senses, are able to move, and have physical appetites. Apex predators like the lion could move vigorously, and has powerful senses like keen eyesight and the ability to smell their prey from a distance, while a lower order of animals might wiggle or crawl, or like oysters were sessile, attached to the sea-bed. All, however, share the senses of touch and taste.
+
+=== Plants ===
+Plants lack sense organs and the ability to move, but can grow and reproduce. The highest plants have important healing attributes within their leaves, buds, and flowers. 
+Lower plants include fungi and mosses.
+
+=== Minerals ===
+At the bottom of the chain, minerals were unable to move, sense, grow, or reproduce. Their attributes were being solid and strong, while the gemstones possessed magic. The king of gems was the diamond.
+
+== Natural science ==
+
+=== From Aristotle to Linnaeus ===
+
+The basic idea of a ranking of the world's organisms goes back to Aristotle's biology. In his History of Animals, where he ranked animals over plants based on their ability to move and sense, and graded the animals by their reproductive mode, live birth being "higher" than laying cold eggs, and possession of blood, warm-blooded mammals and birds again being "higher" than "bloodless" invertebrates.
+Aristotle's non-religious concept of higher and lower organisms was taken up by natural philosophers during the Scholastic period to form the basis of the Scala Naturae. The scala allowed for an ordering of beings, thus forming a basis for classification where each kind of mineral, plant and animal could be slotted into place. In medieval times, the great chain was seen as a God-given and unchangeable ordering. In the Northern Renaissance, the scientific focus shifted to biology; the threefold division of the chain below humans formed the basis for Carl Linnaeus's Systema Naturæ from 1737, where he divided the physical components of the world into the three familiar kingdoms of minerals, plants and animals.
+
+=== In alchemy ===
+Alchemy used the great chain as the basis for its cosmology. Since all beings were linked into a chain, so that there was a fundamental unity of all matter, the transformation from one place in the chain to the next might, according to alchemical reasoning, be possible. In turn, the unit of the matter enabled alchemy to make another key assumption, the philosopher's stone, which somehow gathered and concentrated the universal spirit found in all matter along the chain, and which ex hypothesi might enable the alchemical transformation of one substance to another, such as the base metal lead to the noble metal gold.
+
+=== In evolution ===

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+title: "Great chain of being"
+chunk: 2/2
+source: "https://en.wikipedia.org/wiki/Great_chain_of_being"
+category: "reference"
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+date_saved: "2026-05-05T09:33:05.837285+00:00"
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+---
+
+The set nature of species, and thus the absoluteness of creatures' places in the great chain, came into question during the 18th century. The dual nature of the chain, divided yet united, had always allowed for seeing creation as essentially one continuous whole, with the potential for overlap between the links. Radical thinkers like Jean-Baptiste Lamarck saw a progression of life forms from the simplest creatures striving towards complexity and perfection, a schema accepted by zoologists like Henri de Blainville. The very idea of an ordering of organisms, even if supposedly fixed, laid the basis for the idea of transmutation of species, whether progressive goal-directed orthogenesis or Charles Darwin's undirected theory of evolution.
+The chain of being continued to be part of metaphysics in 19th-century education, and the concept was well known. The geologist Charles Lyell used it as a metaphor in his 1851 Elements of Geology description of the geological column, where he used the term "missing links" about missing parts of the continuum. The term "missing link" later came to signify transitional fossils, particularly those bridging the gulf between man and beasts.
+
+The idea of the great chain, as well as the derived "missing link", was abandoned in early 20th-century science, as the notion that embryonic development recapitulates "lower" forms was abandoned in biology, to be replaced by an evolutionary tree supplemented by horizontal gene transfer, as well as more complex web structures. The idea of a certain sequence from lower to higher complexity and fitness is still popular, as is the idea of progress in biology.
+
+== Political implications ==
+Allenby and Garreau propose that the Catholic Church's narrative of the great chain of being kept the peace in Europe for centuries. The very concept of rebellion simply lay outside the reality within which most people lived, for to defy the King was to defy God. King James I himself wrote, "The state of monarchy is the most supreme thing upon earth: for kings are not only God's Lieutenants upon earth, and sit upon God's throne, but even by God himself they are called Gods."
+
+== Adaptations and similar concepts ==
+The American philosopher Ken Wilber described a "Great Nest of Being" which he claims to belong to a culture-independent "perennial philosophy" traceable across 3000 years of mystical and esoteric writings. Wilber's system corresponds with other concepts of transpersonal psychology. In his 1977 book A Guide for the Perplexed, the economist E. F. Schumacher described a hierarchy of beings, with humans at the top able mindfully to perceive the "eternal now".
+
+== See also ==
+
+== References ==
+
+=== Works cited ===
+
+== Further reading ==
+
+== External links ==
+"Chain of Being" in the Dictionary of the History of Ideas
+The Great Chain of Being reflected in the work of Descartes, Spinoza & Leibniz. Archived 2008-08-28 at the Wayback Machine. Peter Suber, Earlham College, Indiana

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+title: "Gromatici"
+chunk: 1/2
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+category: "reference"
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+date_saved: "2026-05-05T09:32:06.495473+00:00"
+instance: "kb-cron"
+---
+
+Gromatici (from Latin groma or gruma, a surveyor's pole) or agrimensores was the name for land surveyors amongst the ancient Romans.  The "gromatic writers" were technical writers who codified their techniques of surveying, most of whose preserved writings are found in the Corpus Agrimensorum Romanorum.
+
+== History ==
+
+=== Roman Republic ===
+At the foundation of a colony and the assignation of lands the auspices were taken, for which purpose the presence of the augur was necessary.  But the business of the augur did not extend beyond the religious part of the ceremony: the division and measurement of the land were made by professional measurers.  These were the finitores mentioned by the early writers, who in the later periods were called mensores and agrimensores.  The business of a finitor could only be done by a free man, and the honourable nature of his office is indicated by the rule that there was no bargain for his services, but he received his pay in the form of a gift.  These finitores appear also to have acted as judices, under the name of arbitri (single arbiter), in those disputes about boundaries which were purely of a technical, not a legal, character.  The first professional surveyor mentioned is Lucius Decidius Saxa, who was employed by Mark Antony in the measurement of camps.
+
+=== Roman Empire ===
+Under the empire the observance of the auspices in the fixing of camps and the establishment of military colonies was less regarded, and the practice of the agrimensores was greatly increased.  The distribution of land amongst the veterans, the increase in the number of military colonies, the settlement of Italian peasants in the provinces, the general survey of the empire under Augustus, the separation of private and state domains, led to the establishment of a recognized professional corporation of surveyors.  The practice was also codified as a system by technical writers such as Julius Frontinus, Hyginus, Siculus Flaccus, and other Gromatic writers, as they are sometimes termed.  The teachers of geometry in the large cities of the empire used to give practical instruction on the system of gromatics.  This practical geometry was one of the liberalia studia; but the professors of geometry and the teachers of law were not exempted from the obligation of being tutores, and from other such burdens, a fact which shows the subordinate rank which the teachers of elementary science then held.
+The agrimensor could mark out the limits of the centuriae, and restore the boundaries where they were confused, but he could not assign without a commission from the emperor.  Military persons of various classes are also sometimes mentioned as practising surveying, and settling disputes about boundaries.  The lower rank of the professional agrimensor, as contrasted with the finitor of earlier periods, is shown by the fact that in the imperial period there might be a contract with an agrimensor for paying him for his services.
+
+=== Late empire ===
+The agrimensor of the later period was merely employed in disputes as to the boundaries of properties.  The foundation of colonies and the assignation of lands were now less common, though we read of colonies being established to a late period of the empire, and the boundaries of the lands must have been set out in due form.  Those who marked out the ground in camps for the soldiers' tents are also called mensores, but they were military men.  The functions of the agrimensor are shown by a passage of Hyginus, in all questions as to determining boundaries by means of the marks (signa), the area of surfaces, and explaining maps and plans, the services of the agrimensor were required: in all questions that concerned property, right of road, enjoyment of water, and other easements (servitutes) they were not required, for these were purely legal questions. Generally, therefore, they were either employed by the parties themselves to settle boundaries, or they received their instructions for that purpose from a judex.  In this capacity they were advocati.  But they also acted as judices, and could give a final decision in that class of smaller questions which concerned the quinque pedes of the Lex Mamilia (the law setting which boundary spaces were not subject to usucapio), as appears from Frontinus.
+Under the Christian emperors the name mensores was changed into agrimensores to distinguish them from another class of mensores, who are mentioned in the codes of Theodosius I and Justinian I.  By a rescript of Constantine I and Constans (344 AD) the teachers and learners of geometry received immunity from civil burdens.  According to a constitution of Theodosius II and Valentinian III (440 AD), they received jurisdiction in questions of alluvio; but some writers disagree that this crucial passage is genuine. According to another constitution of the same emperors, the agrimensor was to receive an aureus from each of any three bordering proprietors whose boundaries he settled, and if he set a limes right between proprietors, he received an aureus for each twelfth part of the property through which fee restored the limes.  Further, by another constitution of the same emperors, the young agrimensores were to be called "clarissimi" while they were students, and when they began to practise their profession, "spectabiles".
+
+== Writers and works ==

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+source: "https://en.wikipedia.org/wiki/Gromatici"
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+instance: "kb-cron"
+---
+
+The earliest of the gromatic writers was Frontinus, whose De agrorum qualitate, dealing with the legal aspect of the art, was the subject of a commentary by Aggenus Urbicus, a Christian schoolmaster. Under Trajan a certain Balbus, who had accompanied the emperor on his Dacian campaign, wrote a still extant manual of geometry for land surveyors (Expositio et ratio omnium formarum or mensurarum, probably after a Greek original by Hero), dedicated to a certain Celsus who had invented an improvement in a gromatic instrument (perhaps the dioptra, resembling the modern theodolite); for the treatises of Hyginus see that name.
+Somewhat later than Trajan was Siculus Flaccus (De condicionibus agrorum, extant), while the most curious treatise on the subject, written in barbarous Latin and entitled Casae litterarum (long a school textbook) is the work of a certain Innocentius (4th-5th century). It is doubtful whether Boetius is the author of the treatises attributed to him. The Gromatici veteres also contains extracts from official registers (probably belonging to the 5th century) of colonial and other land surveys, lists and descriptions of boundary stones, and extracts from the Theodosian Codex.
+According to Mommsen, the collection had its origin during the 5th century in the office of a vicarius (diocesan governor) of Rome, who had a number of surveyors under him. The surveyors were known by various names: decempedator (with reference to the instrument used); finitor, metator or mensor castrorum in republican times; togati Augustorum as imperial civil officials; professor, auctor as professional instructors.
+The best edition of the Gromatici is by Karl Lachmann and others (1848) with supplementary volume, Die Schriften der römischen Feldmesser (1852). The 1913 edition of Carl Olof Thulin contains only a few works. The 2000 edition of Brian Campbell is much broader and also contains an English translation.
+
+== See also ==
+Bematist
+Triangulation (surveying)#History
+
+== References ==
+
+ This article incorporates text from a publication now in the public domain: Smith, William, ed. (1870). "Groma". Dictionary of Greek and Roman Antiquities. London: John Murray.
+
+== Further reading ==
+
+Campbell, Brian. 1996. "Shaping the Rural Environment: Surveyors in Ancient Rome." Journal of Roman Studies 86:74–99.
+Campbell, J. B. 2000. The Writings of the Roman Land Surveyors: Introduction, Text, Translation and Commentary. London: Society for the Promotion of Roman Studies.
+Classen, C. Joachim. 1994. "On the Training of the Agrimensores in Republican Rome and Related Problems: Some Preliminary Observations." Illinois Classical Studies 19:161-170.
+Cuomo, Serafina. 2000. "Divide and Rule: Frontinus and Roman Land-Surveying." Studies in the History and Philosophy of Science 31A:189–202.
+Dilke, Oswald Ashton Wentworth. 1967. "Illustrations from Roman Surveyors’ Manuals." Imago Mundi 21:9–29.
+Dilke, Oswald Ashton Wentworth. 1971. The Roman Land Surveyors: An Introduction to the Agrimensores. Newton Abbot, UK: David and Charles.
+Duncan-Jones, R. P. 1976. "Some Configurations of Landholding in the Roman Empire." In Studies in Roman Property. Edited by M. I. Finley, 7–24. Cambridge, UK, and New York: Cambridge Univ. Press.
+Gargola, Daniel J. 1995. Lands, Laws and Gods: Magistrates and Ceremony in the Regulation of Public Lands in Republican Rome. Chapel Hill: Univ. of North Carolina Press.
+Lewis, Michael Jonathan Taunton. 2001. Surveying Instruments of Greece and Rome. Cambridge, UK, and New York: Cambridge Univ. Press.
+Nicolet, Claude. 1991. "Control of the Fiscal Sphere: The Cadastres." In Space, Geography, and Politics in the Early Roman Empire. By Claude Nicolet, 149–169. Ann Arbor: Univ. of Michigan Press.

data/en.wikipedia.org/wiki/Historical_metrology-0.md

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+---
+title: "Historical metrology"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/Historical_metrology"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:31:58.287463+00:00"
+instance: "kb-cron"
+---
+
+Historical metrology is the science and study of the different units of measurement and measurement systems (including monetary units) which have been used by various countries and places throughout history.
+
+
+== Published reports ==
+For some countries, principal divisions of executive governments have published reports that compile formerly used weights and measures. For example, this has been done for Bolivia, Great Britain, Costa Rica, Mexico, Portugal, Spain, Tanzania and the United States. In 1954, 1955, and 1966, the United Nations compiled reports aimed at giving an overview of the non-metric units then in use in different parts of the world. In 2018, the first of three volumes of the book "Encyclopaedia of Historical Metrology, Weights, and Measures" was published. The book addresses the myriad units of measurement that have arisen through the ages, from weights used by ancient cultures to the scientific units of the modern world.
+
+
+== See also ==
+
+Dimensional metrology
+Forensic metrology
+Smart Metrology
+Time metrology
+Quantum metrology
+
+
+== References ==

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+---
+title: "History of Science Museum, Oxford"
+chunk: 1/1
+source: "https://en.wikipedia.org/wiki/History_of_Science_Museum,_Oxford"
+category: "reference"
+tags: "science, encyclopedia"
+date_saved: "2026-05-05T09:32:33.426666+00:00"
+instance: "kb-cron"
+---
+
+The History of Science Museum in Broad Street, Oxford, England, holds a leading collection of scientific instruments from Middle Ages to the 19th century. The museum building is also known as the Old Ashmolean Building to distinguish it from the newer Ashmolean Museum building completed in 1894. The museum was built in 1683, and it is the world's oldest surviving purpose-built museum.
+
+
+== History ==
+Built in 1683 to house Elias Ashmole's collection, the building was the world's first purpose-built museum building and was also open to the public. The original concept of the museum was to institutionalize the new learning about nature that appeared in the 17th century and experiments concerning natural philosophy were undertaken in a chemical laboratory in the basement, while lectures and demonstration took place in the School of Natural History, on the middle floor. Ashmole's collection was expanded to include a broad range of activities associated with the history of natural knowledge. In 1924, Lewis Evans donated his collection of historic scientific instruments, creating the Lewis Evans Collection. In 1935, with more donations, the museum's name was changed to the Museum of the History of Science. In 2018, the museum was renamed the History of Science Museum.
+
+
+== Historic building listings ==
+The History of Science Museum is a Grade I listed building, the highest grade reserved for "buildings of exceptional interest". The screen fronting the building, with busts of Roman Emperors in a continuance of the north screen of the Sheldonian Theatre, has a separate Grade I listing.
+
+
+== Collections and exhibitions ==
+
+The collection and the building itself now occupies a special position in the study of the history of science and in the development of western culture and collecting.
+One of the most iconic objects in the collection is Einstein's Blackboard that Albert Einstein used on 16 May 1931 in his lectures while visiting the University of Oxford, rescued by dons including E. J. Bowen and Gavin de Beer.
+The current collection contains around 18,000 objects from antiquity to the early 20th century, representing almost all aspects of the history of science and is used for both academic study and enjoyment by the visiting public.
+The museum contains a wide range of scientific instruments, such as quadrants, astrolabes (the most complete collection in the world with c.170 instruments), sundials, early mathematical instruments (used for calculating, astronomy, navigation, surveying and drawing), optical instruments (microscopes, telescopes and cameras), equipment associated with chemistry, natural philosophy and medicine, and a reference library regarding the history of scientific instruments that includes manuscripts, incunabula, prints and printed ephemera, and early photographic items.
+The museum shows the development of mechanical clocks. Lantern clocks and longcase clocks are exhibited in the Beeson Room, named after the antiquarian horologist Cyril Beeson (1889–1975) who gave his collection to the museum. Early turret clocks are exhibited above the stairs from the basement to the raised ground floor. The museum hold a collection of turned ivory and other objects made by Lady Gertrude Crawford.
+From October 2009 until February 2010, the Museum hosted the first major exhibition of Steampunk art objects, curated by Art Donovan and presented by Dr Jim Bennett, then the museum director.
+The museum is also home to the Rochester Avionic Archive, which includes a collection of avionics that originated with the Elliot Brothers, but also includes pieces from Marconi and BAE Systems.
+
+
+== Multaka network ==
+In 2019, the museum joined six similar museums in Germany, Italy, Greece and Switzerland, creating the international Multaka network. This intercultural museum project organizes guided tours for refugees and migrants designed and offered for free by specially trained Arabic-speaking Multaka guides. The visitor-centered discussions with migrants are focused on the historical origins and history of acquisition of cultural objects, including the visitors' own understanding of their country's cultural heritage.
+
+
+== Curators ==
+
+The following have been Curator or Secretary to the Committee or Director at the museum:
+
+R. T. Gunther (1924–40)
+F. Sherwood Taylor (1940–45, temporary; 1945–50)
+C. H. Josten (1950–64; 1964–94, emeritus)
+F. R. Maddison (1964–94)
+J. A. Bennett (1994–2012)
+Stephen Johnston (acting director, 2012–14)
+Silke Ackermann (2014 onwards)
+
+
+== See also ==
+Dr Jim Bennett, the museum's former Keeper/Director (retired in 2012)
+Dr Silke Ackermann, the museum's Director (from 2014)
+Oxford University Scientific Society
+Museum of Oxford
+Whipple Museum of the History of Science, the equivalent institution at the University of Cambridge
+
+
+== References ==
+
+
+== External links ==
+
+History of Science Museum website

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