Hans Bethe (1906-2005), German-US physicist. Bethe was awarded the Nobel Prize in Physics in 1967 for his work on energy production in stars. He proposed the carbon cycle as a source of stellar energy. This is a series of nuclear reactions involving carbon, nitrogen and oxygen, which plays a major part in energy production in hot stars. With Alpher and Gamow, he proposed a theory of the formation of heavy elements in the early universe. He also worked on the atomic bomb project during World War II.