When J Robert Oppenheimer travelled to New Mexico in 1942 to visit his best friend, he asked people to call him by a name that carefully masked his Jewish roots. He went by Robert Smith. It didn't stick, but this wasn’t the first time he had tried to mask his identity.

Throughout his life, he maintained that the J in J. Robert Oppenheimer didn’t stand for anything at all. But it did.

The man who called himself “destroyer of worlds,” and protagonist of the Nolan film Oppenheimer, was named after his father, Julius, but hid his name throughout his life to mask his Jewish roots.

His tendency to assimilate started with his background. Oppenheimer’s father was a member of the Ethical Culture movement in New York, a sort of “secularised version” of Reform Judaism.

Alex Wellerstein, a science historian at the Stevens Institute of Technology describes it as if "you took the basic ethical principles of Reformed Judaism and then sort of ditched all the religious stuff”.

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US nuclear physicist Julius Robert Oppenheime director of the Los Alamos atomic laboratory, testifying before the Special Senate Committee on Atomic Energy. (Photo by Keystone/Getty Images)

“On any kind of religious level, I don’t think he was religiously anything, Oppenheimer,” Wellerstein explains. But with a name like that, you can’t exactly escape your identity. “It’s totally unavoidable”. 

This was reflected in Nolan's film. The director made this clear in a scene depicting Oppenheimer’s first meeting with Lewis Strauss, one of the original members of the US Atomic Energy Commission – and the man who took Oppenheimer’s security clearance away in a McCarthyist show trial in 1954.

In the film, Nolan places Judaism clearly in the centre of their feud. Strauss pronounces his name Straws, in a Southern drawl. Oppenheimer tells him that whether its Oh-ppenheimer or Ah-ppenheimer, it doesn’t make a difference. “No matter how you say it, they know I’m Jewish”.

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Admiral Lewis Strauss (1896 - 1974), chairman of the United States Atomic Energy Commission, arrives at London Airport for a tour of British atomic energy plants, on 21st April 1955. (Photo by J. Wilds/Keystone/Hulton Archive/Getty Images)

Strauss wasn’t ashamed of his faith – and nor did he avoid it. In contrast to Oppenheimer’s assimilation into US culture, Strauss was deeply connected to his Jewish identity and served as president of Manhattan's Temple Emanu-El for ten years between 1938 and 1948.

The difference between the two men was not just their faith, but their class – something Nolan omits. The Jewish community in the US in the early 20th century was not a monolith, but comprised both assimilationist middle-class refugees and working-class, more observant Yiddish speakers.

Strauss grew up in the South. “He was an autodidact,” Wellerstein tells me, who “came from nothing”. He clung to his Judaism, even as he changed his name.

Oppenheimer’s well-off, Upper East Side family, in contrast, were “assimilationist,” Wellerstein says. Part of an earlier wave of Jewish immigrants from Germany, “they wanted to be seen as respectable,” and did that by downplaying their Jewishness. When they weren't allowed into Christian prep schools, they founded their own – Julius sent his son to one such school.

Oppenheimer’s assimilationist tendencies did not go unnoticed. In fact, they were celebrated by Gentiles throughout his life. On June 24, 1925, Percy Bridgman, his Harvard undergrad advisor, wrote Oppenheimer a letter of recommendation for the Cavendish laboratory in Cambridge.

“As appears from his name,” the letter reads, “Oppenheimer is a Jew, but entirely without the usual qualifications of his race. He is a tall, well set-up young man, with a rather engaging diffidence of manner”. Bridgman even noted his “perfectly prodigious power of assimilation”. 

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American atomic scientist Julius Robert Oppenheimer (1904 - 1967) arrives in Paris to give a series of lectures at the Faculty of Science. (Photo by Central Press/Getty Images)

Oppenheimer studied at Harvard at a time when Jews’ place at the institution was in question, marked by debates of Jewish quotas, something which Wellerstein says he was “clearly very affected by”. The atmosphere was hostile. “Do we need more Jews here?” they asked. “Do we have too many Jews here?” “This had a really profound impact on his sense of identity,” Wellerstein tells me.

Cambridge was no better. In fact, it was worse. “As tricky as being a Jew in the United States is, it’s super tricky at Cambridge,” Wallerstein explains. Confronted with overwhelming antisemitism – and the realisation that he wasn't quite cut out for experimental physics, at least at the time – Oppenheimer was driven to a nervous breakdown. 

But unlike Einstein, with whom he worked in Germany after leaving Cambridge, this exclusion didn’t push him away. Instead, Oppenheimer did what he did best – try again to assimilate. 

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German born American physicist Albert Einstein (1879 - 1955) awarded Nobel prize for physics (1921) at Princeton in New Jersey. (Photo by Doreen Spooner/Getty Images)

“For me, this is a really key part of Oppenheimer,” Wellerstein says. His identity crisis “is really important in deciphering why he is so needy of approval from the US government”. Although Nolan centres guilt over Hiroshima as the reason for his engagement with his security hearing, Wellerstein disagrees. “They don’t really get at what his internal conflict actually is,” he says. “In fact, they misidentify his internal conflict”. 

“He’s constantly not sure he’s good enough, or accepted enough,” says Wallerstein. He can’t walk away from his security clearance, because it’s his seal of approval – the ultimate letter of recommendation saying Don’t worry, you aren’t too Jewish to be one of us.

But he was. And even an upper-class upbringing, and a complete lack of engagement in politics – he said in his security hearing that he didn’t pay any attention to broader world politics until 1936 – couldn’t keep him sheltered from antisemitism. “It’s in the air,” Wellerstein says. “It’s in the air he’s breathing”. 

The antisemitism Oppenheimer faced throughout his life is something Nolan fails to properly grapple with. “If you want to have a deeper understanding of Oppenheimer as a person,” Wellerstein says, “you have to get deeper into spaces that sometimes make people, especially people who aren’t Jewish, uncomfortable”. That is, antisemitism, and the complex nature of Jewish identity. 

Not engaging with those complexities has consequences, too. The film was criticised for featuring white voices at the expense of others affected by the bomb including Japanese and Native Americans.

But six of the eight scientists who led the Manhattan project were Jewish, and their ethnicity was a key reason why they were in America building a bomb and not in Nazi-occupied Europe.

“A lot of European physicists’ Jewishness is not discussed in the context of the bomb,” says Wellerstein. “But it’s core to what a lot of them are doing, because a lot of them had to flee Europe because of Hitler”.

Engaging with the delicate debates around Judaism and race doesn’t seem to be something Nolan was comfortable doing. Oppenheimer's class, his faith, his ethnicity, and his character all formed part of his story, and taking out one element of that, or glazing over the rough edges of it, leaves the story open to accusations of being incomplete.

Oppenheimer, a movie about a Jewish scientist with explicitly anti-fascist and leftist values developing a weapon to attack Nazi allies, is white supremacy in 2023 https://t.co/ykdikLk5hk

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Jewish refugees were afraid in a way that Americans weren’t – it wasn’t just that, as Nolan makes clear, they empathised with Jews in Europe. “They took [the threat of losing the war] very seriously,” Wellerstein explains. “And they are the ones who pushed the Manhattan Project forward initially”.

“I’m often asked why so many scientists of that era were Jewish,” Rabbi Geoff Mitelman, the director of Sinai and Synapses, an organisation that bridges the scientific and religious worlds, tells me, “and why Jews embrace science so easily today – sometimes more easily than they embrace Judaism”.

He refers me to an explanation Isidor Rabi – a good friend of Oppenheimer – once gave. When he came home from school, his mother didn’t ask him what he’d learned. Instead, she would say: “Did you ask a good question today?”

“That kind of framing is deep in Jewish tradition,” Rabbi Mitelman says. “We’re trying to find better questions”. Nolan’s Oppenheimer is at its best – and its most Jewish – when it isn’t trying to tell you who J. Robert Oppenheimer was. The film shines when we are left with questions, not with answers – in the true spirit of Jewish conversation, you leave most enlightened when things are left less clear than before.