Main Entry: ein·stein

Pronunciation: \ˈīn-ˌstīn\

Function: noun

: the radiant energy of a given frequency required to effect the complete photochemical transformation of one mole of a photosensitive substance being equal to about 0.004 erg second times the frequency in question

Ein·stein \ˈīn-ˌstīn, -ˌshtīn\ , Albert (1879–1955), American (German-born) physicist. Einstein is generally regarded as one of the very greatest scientists in history. His ideas and speculations have brought about the most profound revolution in scientific thought since Copernicus. In 1905 he published four great discoveries in theoretical physics: the special theory of relativity, the equivalence of mass and energy, the theory of Brownian motion, and the foundation of the photon theory of light. His famous special theory of relativity merged the traditionally absolute concepts of space and time into a space of four dimensions. In 1916 he advanced his general theory of relativity, which was substantiated by other scientists in 1919. In 1950 he introduced a merger of quantum theory with the general theory of relativity, thereby establishing one set of determinate laws for subatomic phenomena and large-scale physical phenomena. In 1952 the element einsteinium was identified by researchers at Berkeley, California, and named in his honor. Einstein was awarded the Nobel Prize for Physics in 1921.