Born in Germany 1906, Hans Bethe was the son of a university professor. He received a Ph.D. in physics from the University of Munich and lectured in physics throughout various German universities until 1933, when he moved to England because of the rise to power of Hitler and the Nazi party. (His mother was Jewish.) In 1935 Bethe immigrated to the United States to join the physics faculty at Cornell University. In 1938 Bethe determined the sequences of nuclear reactions that power the stars, a problem that had remained unsolved for 75 years since William Thomson Kelvin and Hermann Helmholtz first described it. For this research, Bethe received the Nobel Prize in 1967. In addition to these accomplishments, he researched a wide range of other problems, such as electron densities in crystals and operational conditions in nuclear reactors. He was the director of the Theoretical Physics Division of the Los Alamos Laboratory from 1943 to 1946, working on the Manhattan Project to develop the atomic bomb. Bethe has been active in science policy discussions for several decades. In 1958 he served as a delegate to the first International Test Ban Conference at Geneva, and was a leader in the nuclear disarmament movement. Bethe also played an active role in the national debate on the "Star Wars" defense proposal.