Szilard, Leo

SUBJECT AREA: Weapons and armour

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b. 11 February 1898 Budapest, Hungary

d. 30 May 1964 La Jolla, California, USA

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Hungarian (naturalized American in 1943) nuclear-and biophysicist.

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The son of an engineer, Szilard, after service in the Austro-Hungarian army during the First World War, studied electrical engineering at the University of Berlin. Obtaining his doctorate there in 1922, he joined the faculty and concentrated his studies on thermodynamics. He later began to develop an interest in nuclear physics, and in 1933, shortly after Hitler came to power, Szilard emigrated to Britain because of his Jewish heritage.

In 1934 he conceived the idea of a nuclear chain reaction through the breakdown of beryllium into helium and took out a British patent on it, but later realized that this process would not work. In 1937 he moved to the USA and continued his research at the University of Columbia, and the following year Hahn and Meitner discovered nuclear fission with uranium; this gave Szilard the breakthrough he needed. In 1939 he realized that a nuclear chain reaction could be produced through nuclear fission and that a weapon with many times the destructive power of the conventional high-explosive bomb could be produced. Only too aware of the progress being made by German nuclear scientists, he believed that it was essential that the USA should create an atomic bomb before Hitler. Consequently he drafted a letter to President Roosevelt that summer and, with two fellow Hungarian émigrés, persuaded Albert Einstein to sign it. The result was the setting up of the Uranium Committee.

It was not, however, until December 1941 that active steps began to be taken to produce such a weapon and it was a further nine months before the project was properly co-ordinated under the umbrella of the Manhattan Project. In the meantime, Szilard moved to join Enrico Fermi at the University of Chicago and it was here, at the end of 1942, in a squash court under the football stadium, that they successfully developed the world's first self-sustaining nuclear reactor. Szilard, who became an American citizen in 1943, continued to work on the Manhattan Project. In 1945, however, when the Western Allies began to believe that only the atomic bomb could bring the war against Japan to an end, Szilard and a number of other Manhattan Project scientists objected that it would be immoral to use it against populated targets.

Although he would continue to campaign against nuclear warfare for the rest of his life, Szilard now abandoned nuclear research. In 1946 he became Professor of Biophysics at the University of Chicago and devoted himself to experimental work on bacterial mutations and biochemical mechanisms, as well as theoretical research on ageing and memory.

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Principal Honours and Distinctions

Atoms for Peace award 1959.

Further Reading

Kosta Tsipis, 1985, Understanding Nuclear Weapons, London: Wildwood House, pp. 16–19, 26, 28, 32 (a brief account of his work on the atomic bomb).

A collection of his correspondence and memories was brought out by Spencer Weart and Gertrud W.Szilard in 1978.

CM