Who was Oppenheimer? The true story you need to know before watching the film

The historian behind Christopher Nolan’s blockbuster gives us the lowdown

Phil de Semlyen
Written by
Phil de Semlyen
Global film editor
Photograph: Universal PicturesCillian Murphy as J Robert Oppenheimer

Christopher Nolan’s Oppenheimer is about to hit cinemas – and like the British filmmaker’s last blockbuster, Tenet, its title will come with a question mark for some moviegoers. Who was J Robert Oppenheimer, the man played by Cillian Murphy in the film, and what did he do?

Happily, unlike Tenet, which we still don’t understand, we’ve found someone to fill in the blanks on the life of this iconic quantum physicist and A-bomb pioneer ahead of the film’s release. Pulitzer-winning historian Kai Bird co-wrote his biography, ‘American Prometheus: The Triumph and Tragedy of J Robert Oppenheimer’, the book on which Nolan’s new movie is based. He answers the big questions about the hero of 2023’s smartest and most gripping movie.

Is Oppenheimer based on a true story?

Yes, and the movie cleaves closely to the facts of Robert Oppenheimer’s well-documented life. ‘Oppenheimer is regarded as the father of the Atomic bomb,’ says his biographer Kai Bird. ‘He was one of America’s leading physicists and was on the cutting edge of quantum physics in the 1920s and ’30s.’ 

What was the Manhattan Project?

Oppenheimer’s greatest achievement – and the meat of the movie – came when he was asked to run America’s wartime A-bomb project in New Mexico, the top-secret Manhattan Project. It was a race against time against Nazi scientists that he won for his country, explains Bird. ‘He was the director of the Los Alamos secret city that produced “the gadget” in two and a half years.’ 

What’s the story of Oppenheimer?

‘There’s a great arc to it,’ says Bird, ‘from the triumph [of the war years] to the tragedy of what America did to him in the era of the McCarthy witchhunts.’ In 1945 Oppenheimer was a national hero who had helped his country win the war, his face adorning the covers of Time and Life magazines. ‘Just nine years later, he was hauled before a kangaroo court, humiliated and stripped of his security clearance,’ explains Bird. ‘He became a public non-entity.’

Photograph: Melinda Sue Gordon/Universal PicturesFlorence Pugh plays Oppenheimer’s lover Jean Tatlock in the film

What was Robert Oppenheimer really like, IRL?

'He was deeply charismatic, and attractive to women,’ says Bird. ‘He wasn’t just a nerdy personality – he loved French literature and British poets and the novels of Ernest Hemingway, and he acquired a fascination for Hindu mysticism.’ The historian is full of praise for Murphy’s performance. ‘He plays Oppenheimer as a very intense personality, which is exactly right: he was very intense and thoughtful, a man full of contradictions who was fragile and sensitive but also strong. [The actor] captures the complexity of the man.’

Life Magazine
Photograph: Life MagazineOppenheimer was a Life magazine cover star in 1949

Did he like being called ‘Oppie’?

‘I think he did,’ says Bird of the nickname used by Oppenheimer’s closest friends and students. ‘It originated after he moved from Cambridge to go study in Germany. He was in Holland and someone started calling him “Opje” and it slowly translated into “Oppie”.’ Not everyone used the nickname, notes the biographer. ‘His wife called him Robert.’

How did Oppenheimer feel about the bomb?

Conflicted, in a word. ‘He had very mixed emotions,’ says Bird. ‘He’d worked very hard to produce this “gadget”. His motivation was that he believed his counterparts in Germany were capable of bringing Hitler the bomb and he understood what a terrible outcome that would be. But he was also aware that it would be mostly civilian victims of this weapon if it was ever used, because it would be used on a city.’ 

Photograph: Universal PicturesCillian Murphy with the first A-bomb in ‘Oppenheimer’

Did the ‘poisoned apple’ incident in the movie actually happen?

The movie opens with Oppenheimer as a Cambridge undergraduate injecting his tutor’s apple with cyanide in a fit of pique, before hastily binning the fruit and rescuing the man from certain death. Bird can’t vouch for the incident’s historical accuracy – ‘Maybe it was a metaphor,’ he says, ‘although Oppenheimer told his friends that story’ – but he says that it captures an emotional truth about the young Oppie. ‘He was a fragile young man and he had a near-nervous breakdown. He was suspended from Cambridge and put on probation, although we don’t know exactly what happened because his Cambridge records were destroyed.’

What happened to Oppenheimer after the war?

He was brought low by America’s anti-communist fervour of the late ’40s. His own left-wing ties – he’d been in a relationship with Jean Tatlock, a communist organiser played by Florence Pugh in the film – and his outspoken concerns about nuclear proliferation left him vulnerable to the McCarthyite witch hunts. He was eventually forced to attend a jumped-up security hearing. ‘He spent the rest of his life after 1945 trying to grapple with the implications of what he had produced as a scientist,’ says Bird. ‘He was very intolerant of authority and arrogance, and as a result he made some powerful political enemies.’

Photograph: Universal PicturesCillian Murphy’s Oppenheimer takes the plaudits at Los Alamos

Did the President really call him a ‘cry baby’?

Yes! As Nolan’s film shows in a gripping Oval Office scene, Oppenheimer blew his meeting with President Truman by seizing the moral high ground in their discussion of the A-bomb. ‘It was a disaster of a meeting,’ says Bird. ‘Truman told an aide: “I don't want to see that cry baby scientist ever again.”’

Oppenheimer is in cinemas worldwide Jul 21. ‘American Prometheus: The Triumph and Tragedy of J Robert Oppenheimer’ by Kai Bird and Martin J Sherwin is available now.

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