Hungarian-born US theoretical physicist. Eugene Wigner was one of the main pioneers in the application of group theory to quantum mechanics. This included applications to the theory of atoms, molecules, solids, nuclei, and elementary particles, notably the concepts of parity and time reversal symmetry, Wigner’s rule, and the Wigner–Seitz cell. He was awarded a share of the 1963 Nobel Prize for Physics for his work on symmetry principles.