Szilard, Leo (sĭ`lärd), 1898–1964, American nuclear physicist and biophysicist, born in Hungary. He was educated at the Budapest Institute of Technology and the Univ. of Berlin, receiving a doctorate from the latter in 1922. Working at the Univ. of Chicago with Enrico Fermi, he developed the first self-sustained nuclear reactor based on uranium fission. Szilard was one of the first to realize that nuclear chain reactions could be used in bombs and was instrumental in urging the U.S. government to prepare the first atomic bomb, but he later actively protested nuclear warfare and supported the use of nuclear energy for peaceful purposes.

Szilard, Leo

(born Feb. 11, 1898, Budapest, Hung., Austria-Hungary—died May 30, 1964, La Jolla, Calif., U.S.) Hungarian-born U.S. physicist. He taught at the University of Berlin (1922–33), then fled to England (1934–37) and the U.S., where he worked at the University of Chicago from 1942. In 1929 he established the relation between entropy and transfer of information, and in 1934 he helped develop the first method of separating isotopes of artificial radioactive elements. He helped Enrico Fermi conduct the first sustained nuclear chain reaction and construct the first nuclear reactor. In 1939 he was instrumental in establishing the Manhattan Project, in which he helped develop the atomic bomb. After the first use of the bomb, he promoted the peaceful uses of atomic energy and the control of nuclear weapons, founding the Council for a Livable World. In 1959 he received the Atoms for Peace Award.

Szilard, Leo (1898–1964) physicist; born in Budapest, Hungary. He fled from Nazi Germany to England (1933), and emigrated to the U.S.A. to work on nuclear physics at Columbia University (1938–52). Influenced by Enrico Fermi, he convinced Albert Einstein to write the famous 1939 letter to President Franklin Roosevelt urging military development of atomic physics. Szilard was sent to the University of Chicago (1942–64), where he became a central figure in the Manhattan Project. He became an active advocate of peaceful uses of atomic energy, and turned his research toward bacteriology and investigations of human memory and aging. He joined the Salk Institute of Biological Studies in 1964.