---
title: "Thomas Young (scientist)"
chunk: 3/3
source: "https://en.wikipedia.org/wiki/Thomas_Young_(scientist)"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:07:28.656184+00:00"
instance: "kb-cron"
---

=== Young–Laplace equation ===
In 1804, Young developed the theory of capillary phenomena on the principle of surface tension. He also observed the constancy of the angle of contact of a liquid surface with a solid, and showed how to deduce from these two principles the phenomena of capillary action. In 1805, Pierre-Simon Laplace, the French philosopher, discovered the significance of meniscus radii with respect to capillary action.
In 1830, Carl Friedrich Gauss, the German mathematician, unified the work of these two scientists to derive the Young–Laplace equation, the formula that describes the capillary pressure difference sustained across the interface between two static fluids.
Young was the first to define the term "energy" in the modern sense. He also did work on the theory of tides, paralleling that of Laplace and anticipating more well-known work by Airy.

=== Young's equation and Young–Dupré equation ===

Young's equation describes the contact angle of a liquid drop on a plane solid surface as a function of the surface free energy, the interfacial free energy, and the surface tension of the liquid. Young's equation was developed further, some 60 years later, by Dupré to account for thermodynamic effects, and this is known as the Young–Dupré equation.

=== Medicine ===
In physiology, Young made an important contribution to haemodynamics in the Croonian lecture for 1808 on the "Functions of the Heart and Arteries," where he derived a formula for the wave speed of the pulse. His medical writings included An Introduction to Medical Literature, including a System of Practical Nosology (1813) and A Practical and Historical Treatise on Consumptive Diseases (1815).
Young devised a rule of thumb for determining a child's drug dosage. Young's Rule states that the child dosage is equal to the adult dosage multiplied by the child's age in years, divided by the sum of 12 plus the child's age.

=== Languages ===
In an appendix to his 1796 Göttingen dissertation De corporis humani viribus conservatricibus, there are four pages added proposing a universal phonetic alphabet (so as "not to leave these pages blank"; "Ne vacuae starent hae paginae, libuit e praelectione ante disputationem habenda tabellam literarum universalem raptim describere"). It includes 16 "pure" vowel symbols, nasal vowels, various consonants, and examples of these, drawn primarily from French and English.
In his Encyclopædia Britannica article "Languages", Young compared the grammar and vocabulary of 400 languages. In a separate work in 1813, he introduced the term Indo-European languages, 165 years after the Dutch linguist and scholar Marcus Zuerius van Boxhorn proposed the grouping to which this term refers in 1647.

=== Egyptian hieroglyphs ===

Young made significant contributions to the decipherment of ancient Egyptian writing systems. He started his Egyptology work rather late, in 1813, when the work was already in progress among other researchers. He began by using an Egyptian demotic alphabet of 29 letters built up by Johan David Åkerblad in 1802 (14 turned out to be incorrect). Åkerblad was correct in stressing the importance of the demotic text in trying to read the inscriptions, but he wrongly believed that demotic was entirely alphabetic.
By 1814, Young had completely translated the "enchorial" text of the Rosetta Stone (using a list with 86 demotic words), and then studied the hieroglyphic alphabet but initially failed to recognise that the demotic and hieroglyphic texts were paraphrases and not simple translations.
There was considerable rivalry between Young and Jean-François Champollion while both were working on hieroglyphic decipherment. At first, they briefly cooperated in their work, but later, from around 1815, a chill arose between them. For many years, they kept details of their work away from each other. When Champollion finally published a translation of the hieroglyphs and the key to the grammatical system in 1822, Young (and many others) praised his work. Nevertheless, a year later, Young published an Account of the Recent Discoveries in Hieroglyphic Literature and Egyptian Antiquities, with the aim of having his own work recognised as the basis for Champollion's system.
Some of Young's conclusions appeared in the famous article "Egypt" he wrote for the 1818 edition of the Encyclopædia Britannica.
Young had correctly found the sound value of six hieroglyphic signs, but had not deduced the grammar of the language. Young himself acknowledged that he was somewhat at a disadvantage because Champollion's knowledge of the relevant languages, such as Coptic, was much greater.
Several scholars have suggested that Young's true contribution to Egyptology was his decipherment of the demotic script. He made the first major advances in this area; he also correctly identified demotic as being composed of both ideographic and phonetic signs.
Subsequently, Young felt that Champollion was unwilling to share the credit for the decipherment. In the ensuing controversy, strongly motivated by the political tensions of that time, the British tended to champion Young, while the French mostly championed Champollion. Champollion did acknowledge some of Young's contribution, but rather sparingly. However, after 1826, when Champollion was a curator in the Louvre, he did offer Young access to demotic manuscripts.
In England, while Sir George Lewis still doubted Champollion's achievement as late as 1862, others were more accepting. For example, Reginald Poole, and Sir Peter Le Page Renouf both defended Champollion.

=== Music ===
Young developed Young temperament, a method of tuning musical instruments.

== Legacy ==
Later scholars and scientists have praised Young's work, although they may know him only through the achievements he made in their fields. His contemporary Sir John Herschel called him a "truly original genius". Albert Einstein praised him in the 1931 foreword to an edition of Isaac Newton's Opticks. Other admirers include physicist Lord Rayleigh and Nobel Physics laureate Philip Anderson.
Thomas Young's name has been adopted as the name of the London-based Thomas Young Centre, an alliance of academic research groups engaged in the theory and simulation of materials.
Young Sound in eastern Greenland was named in his honour by William Scoresby (1789–1857).

== Selected writings ==
A Course of Lectures on Natural Philosophy and the Mechanical Arts (1807, republished 2002 by Thoemmes Press).
Miscellaneous Works of the Late Thomas Young, M.D., F.R.S. (1855, 3 volumes, editor John Murray, republished 2003 by Thoemmes Press).

== See also ==
Coandă effect
Color space
History of energy
List of Egyptologists
Refractive index
Ultrahydrophobicity
Thomas Young painting

== References ==

Works cited
Adkins, Lesley; Adkins, Roy (2000). The Keys of Egypt: The Obsession to Decipher Egyptian Hieroglyphs. Harper Collins Publishers. ISBN 978-0-06-019439-0.
Thomasson, Fredrik (2013). The Life of J. D. Åkerblad: Egyptian Decipherment and Orientalism in Revolutionary Times. BRILL.

== Further reading ==

== External links ==
 Media related to Thomas Young (scientist) at Wikimedia Commons
 Quotations related to Thomas Young (scientist) at Wikiquote
Works by or about Thomas Young at Wikisource
Thomas Young, the founder of wave theory Archived 19 August 2022 at the Wayback Machine
Works by Thomas Young at the Biodiversity Heritage Library 
Works by Thomas Young at Open Library 
Works by or about Thomas Young at the Internet Archive