Léon Brillouin

Léon Nicolas Brillouin (1889-1969) was a French physicist who contributed to quantum mechanics, radio wave propagation, solid-state physics and information theory. Born at Sévres near Paris into a family of physicists, he studied at the École Normale Supérieure and with Arnold Sommerfeld in Munich, and took his doctorate at the University of Paris in 1920 with a thesis on the quantum theory of solids. He proposed what became known as Brillouin scattering, introduced the Brillouin zone in 1930, and was one of three physicists who independently developed the WKB approximation. He worked at the Collège de France, led the state broadcasting agency Radiodiffusion Nationale in 1939, and spent his later career in the United States at Brown, Harvard, IBM and Columbia. He coined the term negentropy and applied information theory to Maxwell demon. He was elected to the US National Academy of Sciences in 1953.