Claim: Albert Einstein is best known for his theory of relativity.

Albert Einstein -LRB- -LSB- ˈaɪnstaɪn -RSB- -LSB- ˈalbɛɐ̯t ˈaɪnʃtaɪn -RSB- ; 14 March 1879 -- 18 April 1955 -RRB- was a German-born theoretical physicist . He developed the theory of relativity , one of the two pillars of modern physics -LRB- alongside quantum mechanics -RRB- . Einstein 's work is also known for its influence on the philosophy of science . Einstein is best known by the general public for his mass -- energy equivalence formula -LRB- which has been dubbed `` the world 's most famous equation '' -RRB- . He received the 1921 Nobel Prize in Physics `` for his services to theoretical physics , and especially for his discovery of the law of the photoelectric effect '' , a pivotal step in the evolution of quantum theory .   Near the beginning of his career , Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field . This led him to develop his special theory of relativity during his time at the Swiss Patent Office in Bern -LRB- 1902 -- 1909 -RRB- , Switzerland . He realized , however , that the principle of relativity could also be extended to gravitational fields , and with his subsequent theory of gravitation in 1916 , he published a paper on general relativity . He continued 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 light which laid the foundation of the photon theory of light . In 1917 , Einstein applied the general theory of relativity to model the large-scale structure of the universe .   Between 1895 and 1914 he lived in Switzerland -LRB- except for one year in Prague , 1911 -- 12 -RRB- , where he received his academic diploma from the Swiss Federal Polytechnic in Zürich -LRB- later the Eidgenössische Technische Hochschule , ETH -RRB- in 1900 . He later taught there at the same institute as a professor of theoretical physics between 1912 and 1914 before he left for Berlin . In 1901 , after being stateless for more than five years , Einstein acquired Swiss citizenship , which he kept for the rest of his life . In 1905 , Einstein was awarded a PhD by the University of Zürich . The same year , his annus mirabilis -LRB- miracle year -RRB- , he published four groundbreaking papers , which were to bring him to the notice of the academic world , at the age of 26 .   He was visiting the United States when Adolf Hitler came to power in 1933 and , being Jewish , did not go back to Germany , where he had been a professor at the Berlin Academy of Sciences . He settled in the United States , becoming an American citizen in 1940 . On the eve of World War II , he endorsed a letter to President Franklin D. Roosevelt alerting him to the potential development of `` extremely powerful bombs of a new type '' and recommending that the U.S. begin similar research . This eventually led to what would become the Manhattan Project . Einstein supported defending the Allied forces , but generally denounced the idea of using the newly discovered nuclear fission as a weapon . Later , with the British philosopher Bertrand Russell , Einstein signed the Russell -- Einstein Manifesto , which highlighted the danger of nuclear weapons . Einstein was affiliated with the Institute for Advanced Study in Princeton , New Jersey , until his death in 1955 .   Einstein published more than 300 scientific papers along with over 150 non-scientific works . Einstein 's intellectual achievements and originality have made the word `` Einstein '' synonymous with `` genius '' .