Nobel foundation · Public domain

A Hungarian-American theoretical physicist who, with Hermann Weyl, brought group theory into physics and gave quantum mechanics one of its foundational results, Wigner's theorem. He won the 1963 Nobel Prize in Physics for work on nuclear and particle symmetry, but he's also remembered for a quieter act: joining Leo Szilard and Albert Einstein in 1939 to sign the letter that persuaded Roosevelt to investigate the feasibility of an atomic bomb.