A. Einstein

Albert Einstein ( /ˈælbərt ˈaɪnstaɪn/; German: [ˈalbɐt ˈaɪnʃtaɪn] ( listen); 14 March 1879 – 18 April 1955) was a German-born theoretical physicist who developed the general theory of relativity,effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics[2][3] and the most influential physicist of the 20th century. While best known for hismass–energy equivalence formula E = mc2 (which has been dubbed "the world's most famous equation"),[4] he received the 1921 Nobel Prize in Physics "for his services to theoretical physics, andespecially for his discovery of the law of the photoelectric effect".[5] The latter was pivotal in establishing quantum theory.
Near the beginning of his career, Einstein thought that Newtonian mechanicswas no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led to the development of his special theory of relativity. He realized, however, thatthe principle of relativity could also be extended to gravitational fields, and with his subsequent theory of gravitation in 1916, he published a paper on the general theory of relativity. Hecontinued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the thermal properties of lightwhich laid the foundation of the photon theory of light. In 1917, Einstein applied the general theory of relativity to model the structure of the universe as a whole.[6]
He was visiting the UnitedStates when Adolf Hitler came to power in 1933, and did not go back to Germany, where he had been a professor at the Berlin Academy of Sciences. He settled in the U.S., becoming a citizen in 1940.[7] Onthe eve of World War II, he helped alert President Franklin D. Roosevelt that Germany might be developing an atomic weapon, and recommended that the U.S. begin similar research; this eventually led...