Einstein, Albert

Einstein, Albert (1879–1955)German‐Swiss‐American theoretical physicist. His theories of relativity helped to shape 20th-century science and had profound implications for astronomy. The special theory of relativity (published in 1905) arose out of the failure to detect the ether, and built on the work of the Dutch physicist Hendrik Antoon Lorentz (1853–1928) and the Irish physicist George Francis Fitzgerald (1851–1901). It yields the relation E = mc² between mass and energy, which was the key to understanding energy generation in stars. The general theory of relativity (announced 1915, published in expanded form 1916), which encompasses gravitation, assumes great importance in very large-scale systems, and rapidly had an impact on cosmology. Astronomy has furnished observational evidence to support these theories. Einstein produced no subsequent work of great significance, searching unsuccessfully for a theory that would link relativity with electromagnetic forces (a so-called grand unified theory). His Nobel Prize in Physics in 1921 was awarded primarily for his work on the photoelectric effect.