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Klaus Fuchs

Klaus Fuchs was a gifted physicist who made major contributions to the Manhattan Project in the theory of gaseous diffusion cascades, and in implosion theory. However, he is best known for his role as a voluntary spy for Russia.

Fuchs was born in 1911 in Rüsselsheim, Germany. He studied at both Leipzig and Kiel Universities, where he became heavily involved with the Social Democratic Party of Germany and the Communist Party of Germany. However, a violent confrontation in 1933 with the new Nazi government caused him to flee to France and then Great Britain, where he earned his Ph.D. in physics at the University of Bristol in 1937 and took a DSc at the University of Edinburgh.

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When World War II broke out, Fuchs was interned on Canada's Isle of Man with other German citizens living in Britain. However, an Edinburgh collegue, Max Born, intervened on his behalf and Fuchs was released after only six months. He was immediately recruited by fellow German-born British physicist Sir Rudolf Peierls to conduct British atomic bomb research, and upon his agreement, was granted British citizenship. In 1941 he established a USSR contact and began transmitting British nuclear secrets to the Soviet Union.

Peierls and Fuchs were soon transferred to the United States to work on the Manhattan Project, first at the University of Chicago, and later in the Theoretical Physics division in Los Alamos, New Mexico under Hans Bethe. There, he made major contributions to the Manhattan Project in the theory of gaseous diffusion cascades, and in implosion theory. Fuchs also used his Manhattan Project post to gather information about uranium-235 and the United States' stockpiles of it for the Soviets, which they then used to calculate how many functional warheads the US must have. Fuchs also transmitted all the information he could find about recent work towards the production of a hydrogen bomb, though research at the time was so undeveloped that it is now largely thought that this information did not particularly help Russia.

Fuch's contact in Los Alamos, codenamed "Raymond," turned out to be Harry Gold, who was a chief witness in the trial of Julius and Ethel Rosenberg. His identity was revealed when, shortly after returning to the United Kingdom in 1946, Fuchs was confronted by military intelligence officers who had broken Soviet ciphers. After a long interrogation, he confessed, believing it would save him from the death penalty. However, because the UK had not been at war with the Soviet Union at the time of Fuch's betrayal of military secrets, the maximum sentence was only fourteen years in prison.

Fuchs was stripped of his British citizenship and served nine and a half years in Wakefield Prison. Upon his release, he returned to Germany, where he lived in Dresden and continued his scientific career until his death in 1988.