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Physicist; born in Ulm, Germany. He was an undistinguished student in Germany, but flourished at a high school near Zurich, Switzerland. Herequested Swiss citizenship in 1901 and took a post with the Swiss patent office (1902--5). By the time he received his Ph.D. (1905), he had achieved world fame for his publications on Brownian movement of molecules, his photoelectric theory that light and other radiation can behave as both waves and particles, and for his revolutionary special theory of relativity, which related matter and energy in the famous equation, E=Mc\v2. He developed his general theory of relativity (1915), which displaced Newtonian mechanics as the cornerstone of physics and introduced the concept of space-time. In 1921 he received the Nobel Prize, specifically for his ideas on photons and the photoelectric effect. He taught at several European institutions (1909--33), but after Hitler came to power, Einstein, a Jewish pacifist, emigrated in 1933 to the U.S.A. and accepted a post at the newly created Institute for Advanced Studies at Princeton, N.J. He became a U.S. citizen in 1940, and remained in Princeton after his retirement in 1945. Fear of Nazi expansion caused him to sign a letter to President Franklin Roosevelt in 1939 urging America to develop an atomic bomb. Einstein himself took no part in the bomb's construction and spent the remainder of his life promoting peace and humanitarian causes. He continued his unfulfilled search for a unified theory to combine quantum mechanics and relativity into one all-encompassing equation. A shy and gentle man, he was an accomplished violinist, and he made the world smirk when he once made an error while helping a young student with math homework.