In 1939, leading physicists, including Hungarian émigrés Leo Szilard and Eugene P. Wigner as well as Italian expatriate Enrico Fermi, concluded that Germany was working on an atomic bomb. Szilard approached Einstein with a letter for President Franklin D. Roosevelt, urging that the U.S. government begin an atomic bomb project of its own to deter Adolf Hitler (assuming German efforts succeeded).
Einstein was apotheosized as perhaps the world's greatest physicist since Isaac Newton, and his signature on this letter carried considerable weight and authority. Dated 2 August 1939, it warned that it was now likely that scientists would establish and sustain a chain reaction in uranium, which could lead to the construction of "extremely powerful bombs of a new type." Einstein urged the president to form a partnership among government officials, industry specialists, and scientists to conduct feasibility studies; he also recommended securing supplies of uranium ore.
Alexander Sachs, economist and presidential confidant, delivered the letter on 11 October 1939. Sufficiently alarmed by Sachs's précis of its contents, Roosevelt appointed the Uranium Committee to begin preliminary studies, which became the basis for the manhattan Project organized in 1942 to build atomic bombs.
Einstein's letter served as the catalyst for the manhattan Project, but Einstein himself was excluded from the project. His pacifism, Zionism, and a supposedly lackadaisical attitude regarding military secrecy made him suspect to army intelligence. After the war, he campaigned unsuccessfully for a "world government" consisting of the United States, Great Britain, and the Soviet Union that would restrict further development and construction of atomic weapons. Einstein died in Princeton, New Jersey, on 18 April 1955.
William J. Astore
Einstein, Albert. Ideas and Opinions. New York: Bonanza Books, 1954.; Fölsing, Albrecht. Albert Einstein: A Biography. Trans. Ewald Osers. New York: Viking, 1997.; Pais, Abraham. "Subtle Is the Lord . . .": The Science and the Life of Albert Einstein. Oxford: Oxford University Press, 1982.; Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon and Schuster, 1986.