Szilard, Leo (1898-1964)
Hungarian-born US physicist who, in 1934, was one of the first scientists to realize that nuclear fission, or atom splitting, could lead to a chain reaction releasing enormous amounts of instantaneous energy. He emigrated to the USA in 1938 and there influenced Albert Einstein to advise President Roosevelt to begin the nuclear-arms programme. After World War II he turned his attention to the newly emerging field of molecular biology.