Christopher Nolan takes us inside creating Oppenheimer's atomic bomb explosion

On the morning of July 16, 1945, theoretical physicist J. Robert Oppenheimer oversaw the detonation of the first atomic bomb in the New Mexico desert, a momentous event and an awful, awe-inspiring one to witness. In Kai Bird and Martin J. Sherwin's 2005 book American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer, the authors describe how the explosion from the Trinity test resulted in white light filling the sky to such an extent that one of the other scientists present, chemist James Conant, momentarily thought "something had gone wrong" and that the entire world had "gone up in flames."

When director Christopher Nolan set out to make Oppenheimer (out July 21), which is based on Bird and Sherwin's book, he knew that one of his toughest tasks would be recreating that pivotal moment in the history of the titular scientist — played in the film by Cillian Murphy — and of the human race. As the filmmaker explains in EW's Around the Table, where he was joined by stars Murphy, Emily Blunt, Matt Damon, and Robert Downey Jr., "We always knew that the Trinity test would have to be a showstopper. It's the fulcrum that the whole story turns on."

Nolan had used computer graphics to depict a nuclear explosion in his 2012 superhero film The Dark Knight Rises but was determined to eschew CG-trickery this time around, believing it could not adequately recreate the visceral threat apparent in film footage of the actual Trinity test. The director explains that he enlisted the help of visual effects supervisor Andrew Jackson, who won an Oscar for his work on Nolan's previous movie Tenet, soon after completing the screenplay. "When I finished the script, one of the first people I showed the script to was my visual effects supervisor," says Nolan. "I wanted to take CG off the table and see if he could come up with real-world methodologies for producing the effect of the first atomic blast." Nolan also asked Jackson to try to show Oppenheimer's thought processes which would be ultimately depicted in the movie via abstract but spectacular imagery. "I wanted to try and look into Oppenheimer's mind [with] symbolic imagery and visualizations of the quantum world," says the director. "Andrew Jackson understands the computer world but he also understands the analog world. He's wonderful with that. And so he spent months and months and months doing all these experiments and figuring out all these methods, some very, very small and microscopic, some of them absolutely colossal."

Production designer Ruth De Jong and special effects supervisor Scott Fisher were responsible for constructing the physical bomb, or "gadget" as the scientists call the device in the film. Nolan gleefully reveals that the pair built a complete recreation of the bomb, despite the filmmaker telling them it was unnecessary to do so. "When we were trying to make our budget work, it was like, well, what do you need to see of the gadget itself?" explains the director. "I was like, well, we only see it in these shots and those shots. They ignored that completely, and they built the entire thing in exacting detail, so that we were then free to shoot the entire process, the shrink wrapping on it as it comes up in the truck that gets cut off, the way that the different modules are inserted in and wired up. We were able to build the tension up to the detonation by showing that process that they went through."

And where is the movie version of the bomb now? In Nolan's garage, where he reportedly keeps the Batmobile? "I do not have it in my garage, but it's around somewhere," he says.

Nolan added a further element of authenticity to proceedings by filming his actors in the scenes before, during, and after the explosion in Belen, N.M., northwest of the actual test site.

"Ruth De Yong [built] the bunkers as they would have been so we could shoot in the middle of the night, in the desert, in the real places, and get [the actors] there to really experience some measure of what that tension would have been like that the weeks building up [to] that crazy night sort of building up," he says. "We were very fortunate, the weather did all the things we needed it to do. On cue! It was really wonderful. I'm rumored to be lucky with weather. I think we make our own luck, though, because we always shoot, no matter what the weather, we don't stop, we don't wait. On Interstellar, they kicked us off the glacier finally [because of bad weather] and we shot in the car park. The thing is, we're always prepared to try and use what nature gives us to give us a real texture, and in the case of the New Mexico desert it just paid such dividends. All of it just informs the whole drama of the piece, and the build-up to Trinity is the key — it's really all about the tension leading up to it, and the process that they went through."

Oppenheimer drops in theaters July 21.

See Nolan and his cast reveal more about the making of Oppenheimer in the full Around the Table video below.

EW's Around the Table interview was conducted prior to the start of the SAG-AFTRA strike.

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