Jul 27, 2023
How does ‘Oppenheimer’ re
The acclaimed director tells National Geographic he was determined not to use CGI—and to hew as closely as possible to real life in his telling of the story. Here’s how he pulled it off. Christopher
The acclaimed director tells National Geographic he was determined not to use CGI—and to hew as closely as possible to real life in his telling of the story. Here’s how he pulled it off.
Christopher Nolan knew that the scene of the Trinity test in his epic film Oppenheimer had to be a showstopper. After all, the real Trinity test was the detonation of the first atomic bomb—and a transformative moment in world history. It ushered in a new era of technology and introduced a nuclear threat to humanity that can never be reversed.
Seconds before 5:30 on the morning of July 16, 1945, the bomb exploded in the New Mexico desert, generating a blinding burst of light and a shockwave felt a hundred miles away. In just seven minutes, it blossomed into a mushroom-shaped cloud surging more than 38,000 feet into the sky. It left a crater one-half mile wide and eight-feet deep, made of a radioactive green glassy substance known as trinitite. Horrific as it was, the test was considered a success: less than a month later the U.S. dropped atomic bombs on Hiroshima and Nagasaki forcing Japan to surrender and ending World War II.
The complicated legacy and ethical dilemmas wrought by the creation of the atomic bomb would haunt theoretical physicist J. Robert Oppenheimer, whose efforts to develop the bomb alongside his team of scientists on the Manhattan Project is at the center of Oppenheimer.
(Who is Oppenheimer? The controversial man behind the atomic bomb.)
Replicating the Trinity test for cinema was a challenge, even for Nolan, a writer-director known for big-spectacle films—he even blew up a real Boeing 747 in his 2020 movie Tenet rather than using CGI (computer-generated imagery). Nolan also made the decision not to use CGI for Oppenheimer because “it would have felt too safe,” he tells National Geographic.
“The Trinity test in the movie had to be horrifying and make a statement about what Oppenheimer had released on the world. It had to feel lethal. It had to have beauty and evoke awe, but it also had to be terrifying at the same time.”
Historical accuracy can be tricky in films and is subject to nitpicking. (Some viewers, for example, pointed out that Oppenheimer depicted American flags emblazoned with 50 stars at a time when it really had 48 stars.) But Nolan says his goal was to ensure accuracy without the 100-million-dollar film feeling like a caricature of an earlier time.
Beyond telling the story of the race to develop the first atomic bomb, Oppenheimer recounts the journey of J. Robert Oppenheimer (played by Cillian Murphy), his anguish over creating a weapon that could potentially destroy civilization, and the political climate that turned him into a pariah accused of being a Communist sympathizer.
Based on the 2005 Pulitzer Prize-winning novel American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Martin J. Sherwin and Kai Bird, the movie went to great lengths for accuracy. They filmed inside historic buildings, based a number of characters on the real scientists of the Manhattan Project, and used dialogue that came directly from a U.S. Senate hearing, declassified FBI documents, and other archival records.
(Oppenheimer: The secrets he protected and the suspicions that followed him.)
“I couldn’t find a single historical error in the movie,” says Bird, who read Nolan’s screenplay early on and consulted on Oppenheimer. Even Oppenheimer’s signature fedora passed the accuracy test: Costume designer Ellen Mirojnick reached out to hat makers in New York and Italy until she finally found the perfect silhouette at legendary Baron Hats in Los Angeles.
Scouting locations took the team throughout the western U.S. and finally back to northern New Mexico, where the Army’s real top-secret Manhattan Project was located at Los Alamos National Laboratory.
Constructing the world of Oppenheimer fell to production designer Ruth De Jong, who drew up an elaborate recreation of Los Alamos, then rendered it as a giant 3D model. But upon realizing that recreating a full-scale replica with interiors and exteriors would be hugely expensive, she came up with the idea to shoot most of the interiors in existing buildings from the era.
Scenes were shot inside the original house where Oppenheimer and his wife, Kitty (Emily Blunt) lived and at the Institute for Advanced Study in Princeton, New Jersey, where Oppenheimer and Albert Einstein worked together after World War II. Oppenheimer’s office had been remodeled and looked too modern, so the production team staged Einstein’s office and used it as Oppenheimer’s in the movie.
“Is our Los Alamos an exact replica?” says De Jong. “No, we came up with ideas to emotionally transport the viewers back to that era and time and be accurate in that sense with the material choices and color palettes. This is our version.”
Simulating the Trinity test was even more challenging. The original Trinity site is still an operational Army base, about 260 miles from Los Alamos, where the top-secret Manhattan Project was based. But it wasn’t available when the production needed it for filming. Instead, the filmmakers re-created its 100-foot steel tower and concrete bunker at Ghost Ranch, a vast 21,000-foot expanse of desert in Belen, New Mexico.
Contrary to some absurd internet chatter, Nolan did not detonate a real atomic bomb to achieve the stunning visuals in the movie. The process for creating the simulated Trinity test began with visual effects supervisor Andrew Jackson and special effects supervisor Scott Fisher conducting experiments of all kinds: They smashed ping pong balls together, threw paint at a wall, and concocted luminous magnesium solutions, then filmed them on small digital cameras super close-up at various frame rates.
Ultimately, to achieve the Trinity explosion the team detonated and photographed their own 200-foot-high explosion in the desert, positioning cameras close to the blast so it would feel even larger. They ignited the explosion with a combination of TNT, black powder, gasoline, magnesium, and aluminum powder, then incorporated elements such as shock waves, lighting effects, molten metal, and other pyrotechnics in the final edit to add to the large-scale simulated explosion.
(‘A ball of blinding light’: Atomic bomb survivors share their stories.)
Meanwhile, De Jong worked with set decorators and fabricators to build a replica of the “Gadget,” the nickname scientists gave to the bomb. They drew on diagrams and illustrations published in an old book they found about atom bombs. “We followed how the first Gadget was designed and created the device, and that’s what you see in the film,” says De Jong.
Nolan had only basic knowledge of Oppenheimer and the Manhattan Project when he began working on the screenplay for the movie. But his interest in the physicist’s life grew when actor Robert Pattinson—who isn’t in Oppenheimer but had worked with Nolan on an earlier movie—gave him a book of Oppenheimer’s speeches.
In preparing to write the screenplay, Nolan immersed himself in research, reading American Prometheus, which became the bible for the film, and other materials. In 2021, he made an unannounced visit to the Los Alamos History Museum taking the standard tour, then returning several times to use the archives.
As Nolan studied Oppenheimer, he began to see the profundity of the Trinity test: Even with calculations from the world’s most brilliant scientists, there was a possibility that the bomb would ignite a fire in the atmosphere that could destroy the planet. Through this lens, Nolan began to view Oppenheimer as the most important person in human history.
(How the advent of nuclear weapons changed the course of history.)
One of the most challenging parts of making Oppenheimer, Nolan says, was figuring out how to show what was going on in Oppenheimer’s mind.
“There had to be a strong connection between Oppenheimer’s interior state and the ultimate manifestation of his work on the grandest level possible,” he says. “There is a vibration to energy that relates to Oppenheimer’s own neurotic state as a young man.”
Some of the techniques the special effects team used to show the bomb’s power were also used to portray Oppenheimer’s inner world and thought processes—explosions, waves, and particles, and the classic vision of electrons spinning around.
In a way, making Oppenheimer was in itself a giant science experiment. Throughout the process, from writing the screenplay to directing the film, Nolan says he never felt pressured to be an expert in quantum physics himself. Instead, he views his role as that of an interpreter of the science on behalf of moviegoers.
“My approach on all issues, not just science but also historical accuracy, is to try to understand reality and come away with the essential elements to make something clear and comprehensive for my audience,” he says.