Editing Gilbert N. Lewis (section)

=== Relativity and quantum physics ===

In 1908 he published the first of several papers on [[theory of relativity|relativity]], in which he derived the [[mass]]-[[energy]] relationship in a different way from [[Albert Einstein]]'s derivation.<ref name=":9">{{Cite journal|author=Lewis, G. N.|year=1908|title=A revision of the Fundamental Laws of Matter and Energy|journal=Philosophical Magazine|volume=16|issue=95|pages=705–717|doi=10.1080/14786441108636549|title-link=s:A revision of the Fundamental Laws of Matter and Energy}}</ref> In 1909, he and [[Richard C. Tolman]] combined his methods with [[principle of relativity|special relativity]].<ref>{{Cite journal|author=Lewis, G. N. & [[Richard C. Tolman]]|year=1909|title=The Principle of Relativity, and Non-Newtonian Mechanics|journal=Proceedings of the American Academy of Arts and Sciences|volume=44|issue=25|pages=709–26|doi=10.2307/20022495|jstor=20022495|title-link=s:The Principle of Relativity, and Non-Newtonian Mechanics}}</ref> In 1912 Lewis and [[Edwin Bidwell Wilson]] presented a major work in mathematical physics that not only applied [[synthetic geometry]] to the study of [[spacetime]], but also noted the identity of a spacetime [[squeeze mapping]] and a [[Lorentz transformation]].<ref>{{cite journal|last1=Wilson|first1=Edwin B.|last2=Lewis|first2=Gilbert N.|year=1912|title=The Space-time Manifold of Relativity. The Non-Euclidean Geometry of Mechanics and Electromagnetics|journal=Proceedings of the American Academy of Arts and Sciences|volume=48|issue=11|pages=387–507|doi=10.2307/20022840|jstor=20022840}}</ref><ref>[https://web.archive.org/web/20091027012400/http://ca.geocities.com/cocklebio/synsptm.html Synthetic Spacetime], a digest of the axioms used, and theorems proved, by Wilson and Lewis. Archived by [[WebCite]]</ref>

In 1926, he coined the term "[[photon]]" for the smallest unit of radiant energy (light). Actually, the outcome of his letter to ''[[Nature (journal)|Nature]]'' was not what he had intended.<ref>
{{cite journal|author=Lewis, G.N.|year=1926|title=The conservation of photons|url=https://www.nature.com/articles/118874a0|journal=[[Nature (journal)|Nature]]|volume=118|issue=2981|pages=874–875|bibcode=1926Natur.118..874L|doi=10.1038/118874a0|s2cid=4110026}}</ref> In the letter, he proposed a photon being a structural element, not [[energy]]. He insisted on the need for a new variable, ''the number of photons''. Although his theory differed from the [[photon|quantum theory of light]] introduced by [[Albert Einstein]] in 1905, his name was adopted for what Einstein had called a '''light quantum''' (Lichtquant in German).