---
title: "Isaac Newton"
chunk: 6/17
source: "https://en.wikipedia.org/wiki/Isaac_Newton"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:07:12.165802+00:00"
instance: "kb-cron"
---

Newton argued that light is composed of particles or corpuscles, which were refracted by accelerating into a denser medium. He verged on soundlike waves to explain the repeated pattern of reflection and transmission by thin films (Opticks Bk. II, Props. 12), but still retained his theory of 'fits' that disposed corpuscles to be reflected or transmitted (Props.13). Despite his known preference of a particle theory, Newton noted that light had both particle-like and wave-like properties in Opticks; he believed that corpuscles must interact with waves in a medium to explain interference patterns and the general phenomenon of diffraction. 
In his Hypothesis of Light of 1675, Newton posited the existence of the ether to transmit forces between particles. The contact with the Cambridge Platonist philosopher Henry More revived his interest in alchemy. He replaced the ether with occult forces based on Hermetic ideas of attraction and repulsion between particles. His contributions to science cannot be isolated from his interest in alchemy. This was at a time when there was no clear distinction between alchemy and science.
Newton contributed to the study of astigmatism by helping to erect its mathematical foundation through his discovery that when oblique pencils of light undergo refraction, two distinct image points are created. This would later stimulate the work of Thomas Young.
In 1704, Newton published Opticks, in which he expounded his corpuscular theory of light, and included a set of queries at the end, which were posed as unanswered questions and positive assertions. In line with his corpuscle theory, he thought that normal matter was made of grosser corpuscles and speculated that through a kind of alchemical transmutation, with query 30 stating "Are not gross Bodies and Light convertible into one another, and may not Bodies receive much of their Activity from the Particles of Light which enter their Composition?" Query 6 introduced the concept of a black body. Opticks has been referred to as one of the "earliest exemplars of experimental procedure".
In 1699, Newton presented an improved version of his reflecting quadrant, or octant, that he had previously designed to the Royal Society. His design was probably built as early as 1677. It is notable for being the first quadrant to use two mirrors, which greatly improved the accuracy of measurements since it provided a stable view of both the horizon and the celestial body at the same time. His quadrant was built but appears to have not survived to the present. John Hadley would later construct his own double-reflecting quadrant that was nearly identical to the one invented by Newton. However, Hadley likely did not know of Newton's original invention, causing confusion regarding originality.
In 1704, Newton constructed and presented a burning mirror to the Royal Society. It consisted of seven concave glass mirrors, each about one foot in diameter. It is estimated that it reached a maximum possible radiant energy of 460 W cm⁻², which has been described as "certainly brighter thermally than a thousand Suns (1,000 × 0.065 W cm⁻²)" based on estimating that the intensity of the Sun's radiation in London in May of 1704 was 0.065 W cm⁻². As a result of the maximum radiant intensity possibly achieved with his mirror he "may have produced the greatest intensity of radiation brought about by human agency before the arrival of nuclear weapons in 1945." David Gregory reported that it caused metals to smoke, boiled gold and brought about the vitrification of slate. William Derham thought it be to the most powerful burning mirror in Europe at the time.
Newton also made early studies into electricity, as he constructed a primitive form of a frictional electrostatic generator using a glass globe, the first to do so with glass instead of sulfur, which had previously been used by scientists such as Otto von Guericke to construct their globes. He detailed an experiment in 1675 that showed when one side of a glass sheet is rubbed to create an electric charge, it attracts "light bodies" to the opposite side. He interpreted this as evidence that electric forces could pass through glass. Newton also reported to the Royal Society that glass was effective for generating static electricity, classifying it as a "good electric" decades before this property was widely known. His idea in Opticks that optical reflection and refraction arise from interactions across the entire surface is seen as a precursor to the field theory of the electric force. He also recognised the crucial role of electricity in nature, believing it to be responsible for various phenomena, including the emission, reflection, refraction, inflection, and heating effects of light. He proposed that electricity was involved in the sensations experienced by the human body, affecting everything from muscle movement to brain function. His theory of nervous transmission had an immense influence on the work of Luigi Galvani, as Newton's theory focused on electricity as a possible mediator of nervous transmission, which went against the prevailing Cartesian hydraulic theory of the time. He was also the first to present a clear and balanced theory for how both electrical and chemical mechanisms could work together in the nervous system. Newton's mass-dispersion model, ancestral to the successful use of the least action principle, provided a credible framework for understanding refraction, particularly in its approach to refraction in terms of momentum.
In Opticks, Newton introduced prisms as beam expanders and multiple-prism arrays, prismatic configurations that nearly 278 years later were incorporated into tunable lasers, where multiple-prism beam expanders became central to the development of narrow-linewidth systems. The use of these prismatic beam expanders led to the multiple-prism dispersion theory.
Newton was the first to theorise the Goos–Hänchen effect, an optical phenomenon in which linearly polarised light undergoes a small lateral shift when totally internally reflected. He provided both experimental and theoretical explanations for it using a mechanical model.
Science came to realise the difference between perception of colour and mathematisable optics. The German poet and scientist Johann Wolfgang von Goethe could not shake the Newtonian foundation but "one hole Goethe did find in Newton's armour, ... Newton had committed himself to the doctrine that refraction without colour was impossible. He, therefore, thought that the object-glasses of telescopes must forever remain imperfect, achromatism and refraction being incompatible. This inference was proved by Dollond to be wrong."