Enrico Fermi

Enrico Fermi made his name in statistical mechanics in the 1920s, applying Pauli's exclusion principle to ideal gases in what became Fermi-Dirac statistics; particles obeying that principle are now called fermions. He developed a theory of beta decay incorporating a particle he named the neutrino, describing what's now known as weak interaction, one of the four fundamental forces. His neutron experiments led him to discover that slow neutrons were more easily captured by nuclei, work for which he won the 1938 Nobel Prize - though what he thought were new elements turned out to be fission products. He left Italy that year as racial laws threatened his Jewish wife, Laura Capon, and joined the Manhattan Project in the United States. On 2 December 1942, his team at Chicago achieved the first self-sustaining nuclear chain reaction in Chicago Pile-1; he was present at Oak Ridge and Hanford when reactors went critical there, headed a division at Los Alamos working on Teller's hydrogen bomb, and witnessed Trinity on 16 July 1945. After the war he opposed the hydrogen bomb on moral and technical grounds and testified for Oppenheimer at the 1954 security hearing. An eleme