Carl Friedrich von Weizsacker

Atomic physicist and philosopher

Carl Friedrich von Weizsäcker, physicist and philosopher: born Kiel, Germany 28 June 1912; married 1937 Gundalena Wille (three sons, one daughter); died Starnberg, Germany 28 April 2007.

Carl Friedrich von Weizsäcker was the last of the German team who researched atomic weapons for the Nazis. When the Americans captured his laboratory at Strasbourg in December 1944, from papers they found it appeared that the Germans had never come close to developing their nuclear weapon.

But, after being captured in July 1945, von Weizsäcker and his fellow scientists were briefly interned near Cambridge, where their conversations were secretly recorded. In one, von Weizsäcker remarked, on hearing that the United States had dropped atom bombs on Hiroshima and Nagasaki: "If they were able to finish it by summer '45, then with a bit of luck we could have been ready in winter '44-45."

The German economic historian Rainer Karlsch claimed in 2005 that new research in Soviet and also Western archives, along with measurements carried out at one of the test sites on the Baltic Sea island of Rugen and at a test site in Thüringia, both later in the Soviet Zone, in 1944 and 1945, provided evidence for the existence of a German "hybrid tactical nuclear weapon" much smaller than those dropped on Japan.

Carl Friedrich von Weizsäcker was born in Kiel in 1912. From 1929 to 1933 he studied Physics, Mathematics and Astronomy in Berlin, Göttingen and Leipzig with the famous Werner Heisenberg, Friedrich Hund and the Dane Niels Bohr. In 1936, he was appointed a scientific researcher at the prestigious Kaiser Wilhelm Institute of Physics in Berlin. His first book, Die Atomkerne ("The Atomic Nucleus"), was published in 1937.

Von Weizsäcker attended the crucial meeting at army headquarters in September 1939 which launched the German atomic weapons project headed by his mentor Heisenberg. Von Weizsäcker had already developed the theory of the plutonium bomb. In July 1940, he informed the army weapons' procurement office that a plutonium weapon could be built using a nuclear reactor, and he continued with this research.

After the war, in 1946 Weizsäcker was appointed head of a department at the Max Planck Institute for Physics in Göttingen. Increasingly, however, he dedicated his energies to philosophy, becoming professor at the University of Hamburg in 1957.

In 1957 he joined other leading German physicists to form the Göttinger Achtzehn (the Göttingen 18), who called for world-wide nuclear disarmament. In 1962 he took part in the Tübinger Memorandum protest against equipping the West German army with nuclear weapons.

Von Weizsäcker's publications included Kriegsfolgen und Kriegsverhütung ("The Consequences of War and the Avoidance of War", 1970) and Wege in der Gefahr: eine Studie über Wirtschaft, Gesellschaft und Kriegsverhütung ("Dangerous Roads: a study of the economy, society and the avoidance of war", 1976).

David Childs