Editing Albert Einstein (section)

==== Stimulated emission ====
In 1917, at the height of his work on relativity, Einstein published an article in ''Physikalische Zeitschrift'' that proposed the possibility of [[stimulated emission]], the physical process that makes possible the [[maser]] and the [[laser]].<ref>Einstein (1917b).</ref>
This article showed that the statistics of absorption and emission of light would only be consistent with Planck's distribution law if the emission of light into a mode with n photons would be enhanced statistically compared to the emission of light into an empty mode. This paper was enormously influential in the later development of quantum mechanics, because it was the first paper to show that the statistics of atomic transitions had simple laws.<ref>{{Cite book |last1=Duncan |first1=Anthony |url=https://www.worldcat.org/oclc/1119627546 |title=Constructing quantum mechanics. Volume 1, The scaffold : 1900–1923 |last2=Janssen |first2=Michel |date=2019 |publisher=[[Oxford University Press]] |isbn=978-0-19-258422-9 |edition=1st |location=Oxford |pages=133–142 |oclc=1119627546}}</ref>