German born theoretical physicist, Albert Einstein became a citizen of Switzerland in 1901, the year he began a temporary position 1 a mathematics teacher at the Technical High School in Winterthur．The 2 year he was hired as a technical expert at the patent office in Berne, a position he 3 until 1909．Einstein completed his doctorate from the University of Zurich in 1905．
Working in his spare time Einstein 4 three remarkable papers in the year 1905．Each was revolutionary．The first paper on the quantum nature of light(photoelectric effect)led to a Nobel prize sixteen years later．His second paper 5 special relativity made Einstein a household name throughout the world．His third paper provided an explanation for 6 had been known as Brownian motion, the random and hitherto unexplained rapid movements of very small particles suspended in fluids or in air．Einstein’s explanation provided convincing evidence 7 the physical existence of atom-sized molecules．
After 1905 Einstein 8 important contributions to quantum theory and sought to extend the special theory of relativity 9 non-inertial(i．e．accelerating)reference frames．In 1907 Einstein articulated the principle of equivalence．This idea holds that gravitational acceleration is indistinguishable from acceleration 10 by mechanical forces．
In 1909 Einstein became professor of physics at the University of Zurich．He was 11 a full professor 12 the Karl-Ferdinand University in Prague in 1911．About 1912, Einstein began a new period of his gravitational research by 13 his work in terms of the tensor calculus of Tullio Levi-Civita and Gregorio Ricci-Curbastro．Einstein 14 his new work the general theory of relativity．
Einstein received 15 Nobel Prize in 1921 for his 1905 work on the photoelectric effect．A visit 16 the United States in 1932 was followed by the 17 of a post at Princeton which he assumed in December 1932．The following month the Nazis 18 into power in Germany and Einstein was never to return there．At Princeton his work attempted to unify the laws of physics．One week before his death Einstein signed his 19 letter, a letter to Bertrand Russell in which he agreed that his name should go on a manifesto urging all nations to 20 nuclear weapons．
