Born in the northern German port city of Kiel on June 28, 1912, into a nationally prominent family of jurists and theologians, the diplomat's son studied physics and mathematics in Leipzig, Berlin and Göttingen, and became a professor of physics. His brother Richard was president of West Germany from 1984 to 1990 and of the reunited Germany until 1994.

As a sub-atomic physicist, he was closely linked to Germany's nuclear program before and during World War II, although his precise role is a matter of dispute.

After the war, Weizsäcker became a philosophy professor who espoused pacifism at the University of Hamburg. He also remained a physicist, conducting research for Germany's renowned Max Planck Institute.

Weizsäcker was a prominent peace activist, and made prevention of war his main area of activity during the Cold War era. In 1957, he and 17 other leading German physicists formed the "Göttinger 18", which protested the idea of arming the West German army with nuclear weapons.

As cited in the online encyclopedia Wikipedia, his special interest as a young researcher was the binding energy of atomic nuclei, and the nuclear processes in stars. Together with Hans Bethe he discovered a formula for the nuclear processing in stars, called the Bethe-Weizsäcker formula, and uncovered the cyclic process of fusion in stars, published in 1937 as the Bethe-Weizsäcker process.