The spy who loved humanity

A new biography of Klaus Fuchs, the celebrated physicist who passed nuclear secrets to the Soviet Union, forces readers to rethink their idea of what constitutes treason

Klaus Fuchs is a forgotten name except among historians of the Cold War and espionage and among those who have a special interest in ''bomb physics’’ which is the shorthand for the science – especially physics and mathematics --- that went into the making of the atom and hydrogen bombs. There was a time, however, in the early 1950s when Klaus Fuchs was headline news. In January 1950, he confessed that he had passed on to the Soviet Union top secret information regarding the making of the bombs. It was only then that people outside a select group of scientists