He investigated the way in which energy is generated in the cores of stars. He also developed a theory that planetary systems were formed as a natural by-product of stellar evolution, condensing from vortices of gas. Weizsacker was born in Kiel and studied at Leipzig. He was professor at Strasbourg 1942-44. During World War II, he was a member of the research team investigating the feasibility of constructing nuclear weapons and harnessing nuclear energy, although he did not want his team to develop a weapon for the Nazi government. In 1946 he became director of a department in the Max Planck Institute of Physics in Goettingen. He was professor of philosophy at Hamburg 1957-69, and in 1970 he became a director of the Max Planck Institute. In 1938, Weizsaecker and German-born physicist Hans Bethe independently proposed the same theory of stellar evolution, which accounted both for the very high temperatures in stellar cores and for the production of ionizing and particulate radiation by stars. They proposed that hydrogen atoms fused to form helium via a proton-proton chain reaction.
