Oppenheimer was educated at Harvard, then travelled to Europe, working on quantum mechanics and awarded a PhD in 1927. Returning home he continued his research and in 1930 demonstrated that Dirac's atomic energy equations allowed for the existence of a positively charged electron. He thereby 'predicted' the positron, which would be discovered and named two years later.

For the next two years Oppenheimer headed the Los Alamos project that pioneered the atomic bomb. The quotation which ran through his mind at the time of the test - 'I am become death, the destroyer of worlds' - reflects his ambivalent attitude towards nuclear weaponry. He was part of a scientific panel which recommended a 'populated military target' for the bomb, but he was against the development of the hydrogen bomb after the war, and counselled caution in weapons development.

This reticence, coupled with his youthful Communist sympathies, helped earn him powerful enemies. In 1953, in the midst of the McCarthy incriminations, Oppenheimer had his security clearance stripped, being told his loyalty was in question. It was never restored, although long afterwards the government sought to make amends by presenting him with the Fermi award in 1963. He told President Johnson: 'I think it is just possible that it has taken some charity and some courage for you to make this award today'.