Georg Placzek (26.09.1905-11.10.1955) - a theoretical physicist. He was born in Brno. In 1928 he received the degree of Doctor of Philosophy at the University of Vienna. In 1932 — 38 (with interruptions) he worked at the Institute of Theoretical Physics in Copenhagen. In 1938 he moved to the USA. He worked at Cornell University (1939 — 42), the Montreal Laboratory (1943—44), Los Alamos (1945—46), and from 1948 at the Institute for Advanced Study in Princeton.
His work was in the fields of molecular and neutron physics. He gave a quantum treatment of the Raman scattering of light and developed new ideas about molecular symmetry. He studied nuclear reactions under the action of neutrons, neutron resonances, the scattering, slowing down and absorption of neutrons in matter, and neutron diffusion. He constructed the theory of the elastic and inelastic scattering of neutrons in crystals and liquids. Independently of others, he put forward the idea of using graphite as a neutron moderator.