'Oppenheimer' fact v. fiction: What the movie got right and wrong according to a nuclear historian

• Warning: Minor spoilers ahead for Christopher Nolan's "Oppenheimer", which has 13 Oscar nominations.
• J. Robert Oppenheimer was an immensely complex figure, and the movie's based on a biography of him.

Christopher Nolan's movie "Oppenheimer" tells the story of J. Robert Oppenheimer. As the director of the Manhattan Project's Los Alamos Laboratory in the 1940s, the physicist is known as the "father of the atomic bomb."

Though mainly focused on a handful of years of his life, the film packs in a good deal of science, politics, and romantic relationships.

"Historians sometimes call him a complicated figure," Alex Wellerstein, a historian of science and nuclear technology and professor at the Stevens Institute of Technology, said of Oppenheimer. "You cannot come up with a simple version of him."

Heavily based on "American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer" by Kai Bird and Martin Sherwin, the movie stays pretty faithful to the man's eventful, unusual life.

But that doesn't mean there aren't some exaggerations or inconsistencies. Wellerstein helped us separate fact from fiction in "Oppenheimer."

Fact: Oppenheimer did try to poison his tutor (but Niels Bohr wasn't there)

While studying at Cambridge in the mid-1920s, Oppenheimer was able to meet many important physicists, including Patrick Blackett, "whom I liked very much," he later wrote.

In "American Prometheus," Bird and Sherwin write that Oppenheimer admired Blackett, who would become his tutor. But the future Nobel Prize winner was a practical, hands-on physicist who pushed his student to do lab work that Oppenheimer found difficult. He preferred going to lectures and reading.

During his time in England, Oppenheimer was living in a "miserable hole" of an apartment and would roll around on the floor in agony some days. Finally, he got so fed up that he put chemicals in Blackett's apple. Oppenheimer's grandson has disputed the incident, saying there's no record of it.

In the movie, Niels Bohr nearly takes a bite out of the apple, but that scene was invented for dramatic effect. (It was Ernest Rutherford who introduced Oppenheimer to Bohr.)

One of Oppenheimer's biographers wrote that Cambridge officials learned of the incident, and Oppenheimer's father convinced them not to press charges. Instead, Oppenheimer was put on probation and had to see a psychiatrist.

Fact: Oppenheimer did deliver a lecture in Dutch

According to "American Prometheus," "Oppenheimer astonished his peers by giving a lecture in Dutch," only six weeks after he arrived in Leiden, Holland.

"I don't think it was very good Dutch, but it was appreciated," Oppenheimer said.

He had a short-lived relationship with a woman there, who may have helped him learn the language, biographer and physicist Abraham Pais wrote.

In the movie, it only takes Oppenheimer six weeks to learn Dutch. But Wellerstein points out that he could have spent time learning the language ahead of time. That summer, Oppenheimer spent a couple of weeks in New Mexico recuperating from tuberculosis.

In between reading Baudelaire and e.e. cummings, who's to say he wasn't brushing up on his Dutch?

Fact: The Oppenheimers had Haakon Chevalier raise their son, Peter, for a while

In 1941, when Peter Oppenheimer was just two months old, Robert and Kitty left him with Haakon and Barbara Chevalier for two months, according to "American Prometheus." Robert explained that his wife was exhausted, and the two went to the family's ranch, Perro Caliente, near Los Pinos, New Mexico.

But the movie links the arrangement with Kitty's drinking by showing Robert dropping Peter off after a scene in which Kitty is drunk and frustrated with having to care for the baby all day, alone.

Fact: Germany wasn't ready to build an atomic bomb

In September 1943, Niels Bohr made a narrow escape from Nazi-occupied Denmark via Sweden. A few months later, Bohr arrived in Los Alamos, ready to tell Oppenheimer and the rest about his 1941 meeting with German physicist Werner Heisenberg.

In the movie, after peppering Bohr with questions, Oppenheimer is satisfied that Heisenberg took a "wrong turn" somewhere, and the Germans were sufficiently far enough behind the Americans if they were indeed making an atomic bomb.

It's a simplified version of reality, but it's mainly correct, Wellerstein said. "They do have a very small-scale nuclear reactor project, which is never going to make a bomb at its present size," he said.

But it wouldn't be until nearly a year later, in November 1944, that the Allies would find definitive proof that the Germans were still in the early stages of development.

Fact: Oppenheimer mocked Strauss about isotopes

Physicist David Hill testified at a Senate hearing for Lewis Strauss' nomination to President Dwight D. Eisenhower's Cabinet. He said that most scientists would prefer Strauss no longer be in government, as "Oppenheimer" depicts.

But it was David Inglis, chairman of the Federation of American Scientists, who said Strauss, out of "personal vindictiveness," had targeted Oppenheimer, Time magazine reported. Inglis also discussed Strauss' opposition to shipping isotopes to Europe for medical purposes.

Much is made in the film about Oppenheimer mocking Strauss' concerns, saying that "you can use a bottle of beer for atomic energy" and that isotopes were less important than electronic devices but "more important than a sandwich." The line comes from an Atomic Energy Committee joint committee session in 1949.

What Oppenheimer actually said was isotopes were "less important than, let us say, vitamins, somewhere in between." The line did get laughs.

Likely fact: Oppenheimer estimated only 20,000 people would die from an atomic bomb

When discussing the potential effects of the atomic bomb in the movie, Oppenheimer estimates the number of dead at 20,000 to 30,000.

"I've never seen anything that suggested they had any real methodology," Wellerstein said. He notes that it's hard to find references to that number beyond physicist Arthur Compton saying that Oppenheimer told him he thought the number would be around 20,000.

Fact: A big thunderstorm delayed the Trinity Test

It wasn't just for dramatics that "Oppenheimer" depicted a heavy thunderstorm as the scientists and military rushed to prep the bomb for the Trinity Test.

It was initially scheduled for 4 a.m. and was pushed an hour and a half because of the weather.

Oppenheimer makes an oracle-like prediction in the film that the storm will pass, but there was a meteorology team, led by Jack Hubbard, who said the same thing in real life.

Army Lt. Gen. Leslie Groves apparently threatened to hang Hubbard if his weather predictions were wrong, but the skies did clear.

Fact: Feynman did watch the Trinity Test from behind a windshield

Physicist Richard Feynman recalled getting into a truck to watch the atomic bomb test from behind a windshield because he said it would protect him from the ultraviolet radiation.

"I'm probably the only guy who saw it with the human eye," he said, while everyone else watched through dark glasses.

Fact: Oppenheimer never said publicly he regretted dropping the bomb

Strauss rages in the film that Oppenheimer would "do it all over" and never said he regretted dropping the atomic bomb.

"That's 100% true" that Oppenheimer never said anything like that publicly, Wellerstein said. But he wishes the film depicted someone else saying it, instead of "the guy who you're painting as a totally unreliable snake."

But, Wellerstein said, Oppenheimer did feel remorse about not being able to stop the arms race: "He regretted what came next, and he did a lot of work to try and avoid that."

Fact: Oppenheimer was a dilettante

When listing the concerns fellow scientists raised about Oppenheimer being named director of the Los Alamos lab in the movie, Groves calls Oppenheimer a "dilettante" who "couldn't run a hamburger stand".

Wellerstein calls that a fair assessment. Oppenheimer would often jump from topic to topic, depending on what his students were working on.

"Oppenheimer was interested in everything," Robert Serber, one of his students, said. A single session might include a discussion of electrodynamics, cosmic rays, and nuclear physics.

If it weren't for the atomic bomb, Oppenheimer would likely be best known for bolstering theoretical physics at the University of California, Berkeley. Many of his students went on to do important work, including David Bohm, Philip Morrison, and Willis Lamb.

"That's a big legacy," Wellerstein said.

Fact: Oppenheimer was ahead of his time on black holes

The day Hitler invaded Poland, Oppenheimer and his student Hartland Snyder published an important paper about "heavy stars" running out of fuel and collapsing. The paper followed up on the work of several other scientists, but Oppenheimer didn't publish on the topic again.

Theoretical physicist Kip Thorne describes how "truly strange" other scientists found this concept at the time. Even John Wheeler, who popularized the term "black hole" in 1967, fought against the idea in the 1950s.

Roger Penrose described black holes in 1964, for which he would win the Nobel Prize in 2020. After his win, Penrose cited Oppenheimer and Snyder's paper as one of the inspirations for his research.

Fact: The sound of the bomb came long after the explosion during the Trinity Test

The film recreates the Trinity Test with a ball of fire and plumes of smoke and Cillian Murphy reciting Oppenheimer's famously quoting the Bhagavad Gita, "Now I am become Death, the destroyer of worlds."

It's eerily silent. Then comes the blast wave that knocks some onlookers over and a tremendous, startling boom.

There really was quiet after the bomb exploded. "Finally, after about a minute and a half, there's suddenly a tremendous noise — BANG — and then a rumble, like thunder," Feynman remembered later.

Fiction: People didn't notice an explosion in the middle of the desert

"Oppenheimer" doesn't zoom out beyond the scientists and military members who watch the Trinity Test at various distances, but the brightness of the flame, the sound of the explosion, and the shaking caused by the blast wave didn't go unnoticed.

The force blew out windows in nearby cities. Amarillo, Texas, residents could see the flash from over 280 miles away.

The government planted a story that an ammunition magazine had exploded but that no one was hurt.

Fiction: They knew the bomb was going to end the war

"In the movie, they make it seem like that the reason they're using the bomb is because they don't want to invade Japan, and that is just not actually how it was discussed at the time," Wellerstein said. "That's an after-the-fact rationalization that was created later."

In December 1946, physicist Karl T. Compton wrote in The Atlantic that dropping the bombs was a "calculated gamble" and that Secretary of War Stimson and others hoped it would end the war.

Fiction: Stimson spared Kyoto because he honeymooned there

Selecting the targets for the atomic bombs was a complicated process that involved many people, including Oppenheimer and Secretary of War Henry Stimson. "Stimson is a very interesting character, and he gets turned into a sort of caricature" in the movie, Wellerstein said.

During the meeting depicted in "Oppenheimer," Stimson says they shouldn't bomb Kyoto because of its cultural significance and because he and his wife went there after they got married. "He visited Kyoto, that's for sure, but I don't think he took a honeymoon there," Wellerstein said.

The decision was more nuanced and complicated, he said, and had far-reaching consequences for the cities that were bombed.

Fiction: Oppenheimer was sidelined because he was thinking about the long-term implications of nuclear weapons

"Oppenheimer" also sets up its main character as a bit of a lone wolf, the only one in the meetings with Groves and Stimson asking questions about the long-term implications of nuclear weapons.

"This was not some sort of fringe position that only Oppenheimer had," Wellerstein said. "He definitely played a role in advocating it, but it was very well received and other people had the same idea and lots of people took it really seriously at the highest levels of government."

That included Stimson, who brought those concerns to President Harry Truman, Wallenstein said.

Fiction: Oppenheimer consulted Einstein about Teller's calculations

Edward Teller, who went on to invent the hydrogen bomb, certainly did raise concerns that a nuclear weapon could ignite the Earth's atmosphere with devastating consequences.

"I didn't believe it from the first minute," Hans Bethe later said.

But it wasn't Albert Einstein who Oppenheimer went to. "Einstein wouldn't have been any good for that anyway," said Wellerstein. "It's the wrong kind of science."

Instead, Oppenheimer consulted Compton, according to "American Prometheus."

Bethe's calculations did show there was a "near-zero" possibility of such a catastrophe happening. And Enrico Fermi really did take bets on Teller's theory before the Trinity Test, according to Bethe.

Fiction: Oppenheimer remained anti-H-bomb

In the movie, Roger Robb, the special counsel at Oppenheimer's security clearance hearing, shouts at Oppenheimer over his contradictory positions on the hydrogen bomb. Oppenheimer did support Teller's research and later changed his mind.

There were a few reasons why Oppenheimer was hesitant about an H-bomb, including that there were limited resources for weapons development after the war. "He's not saying don't make weapons," Wellerstein said. "He's saying, 'Let's make more of the weapons we already have and not waste material on weapons that might not work.'"

But then, Teller and Stanislaw Ulam made a breakthrough on their hydrogen bomb research, and Oppenheimer was "almost thrilled," according to AEC commissioner Gordon Dean.

"When he is in favor again, it's already sort of a fait accompli," Wellerstein said. At that point, Oppenheimer felt it was better to be the first once again.

Fiction: Charlotte Serber was Oppenheimer's secretary

At one point in the film, Oppenheimer asks Charlotte Serber to make a call for him, implying she's his secretary. But Serber worked as a librarian for Los Alamos' "secret library."

In real life, Oppenheimer recruited the wife of physicist Robert Serber because she wasn't a professional librarian and therefore wouldn't mind cutting "the necessary corners." While Charlotte Serber spent a brief time working with Oppenheimer's secretary, she eventually became busy enough with the library and classified files to have a staff of 12.

Because of Charlotte's political leanings and that of her family, the FBI kept a file on her and her husband and wiretapped the couple. It was actually Oppenheimer who told Groves that she might have been a communist, though he didn't think she was affiliated with the party any longer.

"It's one of the things that makes him a complicated guy," Wellerstein said, "is he's ratting out all the people around him to try and look reliable to the security people."