"It was a race to build this weapon, and he thought if Hitler had it first, he would use it to win the war for fascism, which would be a terrible, tragic outcome. So, he felt compelled to do this," Bird said. "Immediately after Hiroshima, he fell into a deep depression… he spent the rest of his life trying to warn humanity about the dangers of these weapons and the need to control them, so he had a very complicated relationship to this terrible thing that he himself was responsible for building."
Granger – Historical Picture Archive/Alamy
When the Soviets exploded their first atomic bomb in 1949, US President Harry Truman ordered American scientists to embark on a new programme to build a hydrogen bomb, whose nuclear explosion could be 1,000 times more powerful than an atomic bomb. Oppenheimer, the government's chief scientific advisor on nuclear policy and defence, objected on moral and practical grounds, reportedly telling Truman, "I feel I have blood on my hands." Oppenheimer's defiance ultimately made him a chief target of the US' anti-communist hysteria during the Cold War. In the spring of 1954, he endured an exhaustive four-week interrogation that questioned his US loyalty and ultimately stripped him of his security clearance. (The US government would ultimately clear his name 68 years later.)
According to Bird, a now-fully-white-haired Oppenheimer was left "humiliated, terribly wounded and physically and psychologically exhausted". So, that summer, the disgraced physicist left his Princeton, New Jersey, home, boarded a 72ft ketch with his wife and two children and set sail for St John.
"He was escaping – escaping the notoriety of being the father of the atomic bomb, but also the notoriety that plagued him after the '54 trial, the suspicions of disloyalty, of being a Communist or perhaps a spy," Bird said. "When they saw the island for the first time, [Oppenheimer] fell in love with St John … so, he went back the following year and eventually found some property on the beach and built a very simple, spartan cabin, and it's where he spent the rest of his life – you know, many months of the year, both in the winter, but sometimes in the spring and summers … it wasn't about penance; it was about getting back to the physicality of the natural world."