Dimension : 18 x 13cm Good condition, traces and marks of wear, see photos for detail, stamp on the back. FILE - Dr. Albert Einstein writes out an equation for the density of the Milky Way on the blackboard at the Carnegie Institute, Mt. Wilson Observatory headquarters in Pasadena, Calif., Jan. 14, 1931 Albert Einstein (14 March 1879 – 18 April 1955) was a German-born theoretical physicist best known for developing the theory of relativity. Einstein also made important contributions to quantum theory. His mass–energy equivalence formula E = mc2, which arises from special relativity, has been called "the world's most famous equation". 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". He was elected an International Member of the American Philosophical Society in 1930. In December 1930, Einstein began another significant sojourn in the United States, drawn back to the US by the offer of a two month research fellowship at the California Institute of Technology. Einstein resigned from the Prussian Academy in March 1933. His accomplishments in Berlin had included the completion of the general theory of relativity, proving the Einstein–de Haas effect, contributing to the quantum theory of radiation, and the development of Bose–Einstein statistics. sends by La Poste