The Los Alamos physicist who handed the Soviets the atomic bomb
Klaus Fuchs did vital calculations for the first nuclear weapons at Los Alamos while secretly feeding the Soviet Union details of the project for seven years. After the Cold War, Russian sources openly admitted he gave them the fission bomb. He served nine years in a British prison, then became a senior scientist in East Germany.
Fuchs was born in 1911 in Rüsselsheim, the son of a Lutheran pastor, Emil Fuchs, who became a pacifist, a socialist and eventually a Quaker. The children were taunted at school over their father's politics and came to share them. At university in Leipzig and Kiel, Fuchs joined the Social Democrats, but was expelled in 1932 for offering to speak for the Communist candidate in the presidential election, and he and all three siblings joined the Communist Party. He was once beaten and thrown into a river at a Nazi rally.
On a train to Berlin in February 1933 he read about the Reichstag fire, guessed the left would be blamed, and quietly took off his hammer-and-sickle pin. After months in hiding he reached England that September. Nevill Mott took him on at Bristol, where he earned a doctorate in 1937, and he later worked with Max Born in Edinburgh. His family in Germany suffered badly: his father was jailed for a month, and his siblings were imprisoned for smuggling Jews and regime opponents out of the country through a car rental business.
When war broke out Britain interned him on the Isle of Man and then in Canada. Returning in 1941, he became assistant to Rudolf Peierls on Tube Alloys, the British bomb project, and began passing secrets to Moscow through Ursula Kuczynski, a Soviet military intelligence officer codenamed Sonya. In 1943 he went with Peierls to New York for the Manhattan Project, and from August 1944 he worked in the theoretical division at Los Alamos, contributing to the first bombs and early hydrogen bomb designs.
In January 1950 he confessed to spying since 1942. A British court sentenced him to fourteen years and he lost his citizenship. Released after nine, he moved to East Germany in 1959, joined its Academy of Sciences and the ruling party's central committee, and served as deputy director of a nuclear physics institute in Dresden until retiring in 1979. He died in 1988.
Source: Klaus Fuchs
