Hans Bethe

Hans Bethe (1906 to 2005) was a German-American physicist, born in Strasbourg, who spent most of his career as a professor at Cornell University. His 1939 paper established the carbon-nitrogen-oxygen cycle as the main energy source of heavier main sequence stars, work for which he received the 1967 Nobel Prize in Physics. During the Second World War he led the Theoretical Division at the Los Alamos laboratory, where he helped calculate the critical mass of the first atomic bombs. After the war he worked on the hydrogen bomb and then campaigned against nuclear testing and the arms race. In the 1980s and 1990s he argued for the peaceful use of nuclear energy and served on the expert committee that analysed the Chernobyl accident, which found a fundamentally faulty reactor design and significant human error.