Editing Albert Einstein (section)

==== Photons and energy quanta ====
[[File:Photoelectric effect in a solid - diagram.svg|alt=|thumb|The photoelectric effect. Incoming photons on the left strike a metal plate (bottom), and eject electrons, depicted as flying off to the right.]]
In a 1905 paper,<ref name=1905a/> Einstein postulated that light itself consists of localized particles (''[[quantum|quanta]]''). Einstein's light quanta were nearly universally rejected by all physicists, including Max Planck and Niels Bohr. This idea only became universally accepted in 1919, with [[Robert Millikan]]'s detailed experiments on the photoelectric effect, and with the measurement of [[Compton scattering]].

Einstein concluded that each wave of frequency ''f'' is associated with a collection of photons with energy ''hf'' each, where ''h'' is the [[Planck constant]]. He did not say much more, because he was not sure how the particles were related to the wave. But he did suggest that this idea would explain certain experimental results, notably the [[photoelectric effect]].<ref name=1905a/> Light quanta were dubbed ''[[photons]]'' by [[Gilbert N. Lewis]] in 1926.{{sfnp|Isaacson|2007|p=576}}