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Summary Article: Szilard, Leo (1898-1964)
From The Hutchinson Dictionary of Scientific Biography

Place: Hungary

Subject: biography, physics

Hungarian physicist and one of the 20th century's most original minds. He made major contributions to statistical mechanics, nuclear physics, nuclear engineering, molecular biology, political science, and genetics but was best known for his work on nuclear chain reaction. He was a central figure in the Manhattan Project and after the war became a strong proponent of the peaceful uses of atomic energy.

Leo Szilard was born in Budapest, the oldest of three children of a Jewish architect and engineer. A sickly child, he was mostly taught at home by his mother. He started studying electrical engineering in Budapest but his studies were interrupted when he was drafted into the Austro-Hungarian army in World War I. In 1920 he continued his studies in Berlin at the Technische Hochschule but transferred to read physics at the university, receiving a doctorate in 1922. His PhD thesis was on thermodynamics and the continuation of this work led to the publication of a famous 1929 paper establishing the connection between entropy and information. This was a forerunner to the theory of cybernetics.

In Berlin he was a research worker at the Kaiser Wilhelm Institute and a Privatdozent (unpaid lecturer) at the university. He worked on X-ray crystallography with Herman Marks and began work on patenting some of his pioneering inventions which included a prototype of the modern nuclear particle accelerator. With Albert Einstein he patented an electromagnetic pump for liquid refrigerants, which is still used in nuclear reactors today.

In 1933, Szilard fled Hitler's Germany for the UK, working in the field of nuclear chain reactions at St Bartholomew's Hospital in London and the Clarendon Laboratory, Oxford. This work led to the establishment of the Szilard-Chambers reaction and the discovery of the emission of neutrons from beryllium. When Szilard emigrated to the USA in 1938, he learned that Otto Hahn and Lise Meitner had discovered fission in Germany. Recognizing the significance of this he persuaded Einstein (who commanded world respect) to write to President Roosevelt, warning him of the possibility of atomic bombs and encouraging him to develop them before the Germans did. This was the start of the Manhattan Project and initiated a programme that was to culminate in the dropping of a nuclear bomb on Hiroshima in Japan in 1945.

Szilard started work immediately at Columbia University to demonstrate the fission process and measure the number of neutrons released. In 1942 he joined Enrico Fermi at Chicago University, where they worked on the first controlled chain reaction on 2 December 1942. Fermi and Szilard were awarded the patent for the nuclear fission reactor in 1945. In the last months of the war, Szilard and others made a futile attempt to dissuade President Truman from dropping the bomb on Hiroshima, predicting the nuclear stalemate that would follow.

After the war Szilard moved into molecular biology, becoming professor of biophysics at Chicago in 1946. He was also prominent in the campaign for nuclear-arms control and in 1962 he founded the Council for a Livable World, a Washington lobby on arms control. He joined the Salk Institute of Biological Sciences at La Jolla in California in 1956, where he worked on genetics and immunology until his death on 30 May 1964.

Szilard was a fellow of the American Physical Society and the American Academy of Arts and Sciences and he received the Einstein Award in 1958 and the Atoms for Peace Award in 1959.

© RM, 2018. All rights reserved.

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