Oppenheimer: The Emotional Reason Why Christopher Nolan Cast His Daughter

"Oppenheimer" might just be Christopher Nolan's most emotional film yet, for a very specific reason.

The British director always goes for bold choices. Whether it's turning eccentric DC villains like Scarecrow and Bane into grounded, believable characters with his "Dark Knight" trilogy, or choosing to make his films as unintelligible as possible, Nolan is always swinging for the fences. And the truth is, he very rarely misses, as almost all of his films have proven to be commercial and critical successes.

After thrilling audiences with 2020's time-travel spy flick "Tenet," Nolan is set to debut "Oppenheimer," a three-hour epic that dissects J. Robert Oppenheimer, the father of the atomic bomb. Starring Cillian Murphy in the titular role, "Oppenheimer" is Nolan's riskiest play yet, but it seems to have paid off. Early reactions to the star-studded biopic are overwhelmingly positive, with many going so far as to call it Nolan's best. While "Oppenheimer" will certainly receive a few nods come awards season, there's a very particular reason why the film is special to Nolan.

While speaking with The Telegraph, the British filmmaker revealed that his daughter, Flora, is in "Oppenheimer." She plays an unnamed woman who appears to Oppenheimer in a vision, one where the scientist sees the physical impacts of his invention. In short: he witnesses the woman get her face blown off by the atomic bomb. For Nolan, casting his daughter in the role was a spur-of-the-moment decision, but one that left him emotional, thinking about the impact that nuclear detonation can bring. "But the point is that if you create the ultimate destructive power it will also destroy those who are near and dear to you," the director told the outlet. "So I suppose this was my way of expressing that in what, to me, were the strongest possible terms."

Blowing up his daughter was a last-minute decision

Once again, Christopher Nolan proves that he's completely dedicated to his craft. What other director would film a sequence involving their daughter blowing up, just so they could experience the emotional trauma of nuclear armageddon?

During his conversation with The Telegraph, Nolan made it clear that he tries not to analyze his own intentions, which makes sense considering that casting his daughter was a last-minute decision. His daughter had time off from university and decided to spend time with her father on the film's set. "We needed someone to do that small part of a somewhat experimental and spontaneous sequence," the director explained to the outlet, saying that "it was wonderful to just have her sort of roll with it." While his daughter's cameo in "Oppenheimer" appears to be brief, it'll definitely be one that sticks out for fans who know the context behind it.

But Nolan isn't just obsessed with going through the same pain that Oppenheimer went through — he's also interested in ensuring that his film is as accurate as possible. While Nolan has flirted with historical films in the past, "Oppenheimer" is the director's first true biopic, which makes the stakes extremely high. While speaking with Total Film magazine, the director opened up about how accuracy was the name of the game, confirming that the film features a recreation of the first Trinity test, the first-ever nuclear detonation — no, Nolan didn't use a real nuclear bomb. The director is particularly pleased with how the film doesn't use CGI, explaining how practical effects made Oppenheimer's ruminations all the more powerful. "I said, 'Okay, what we need in this film is a thread between the interior process of Oppenheimer, his imagining, his visualizing of atoms, molecules, those interactions, those energy waves,'" the director told Collider.

Christopher Nolan's films have always been about family

With such an emphasis on practicality, one can only imagine the emotional response Christopher Nolan had to watching his daughter get burned up alive due to the atomic bomb. Putting himself through these emotions isn't foreign to Nolan, as the director has always used his films as a vehicle to ruminate on his children.

If there's one thing the "Memento" filmmaker loves, it's being a dad. Or, at least, that's what his films convey. While fatherhood is common throughout his "Dark Knight" trilogy, it's his sci-fi films "Interstellar" and "Inception" which primarily focus on this recurring theme. Both films deal with lead protagonists trying their darnedest to return to their children despite larger-than-life circumstances. "Interstellar," in particular is about the emotional relationship between a father and daughter, who try and find each other through space and time. "Oppenheimer" and "Interstellar" also have one thing in common: both films feature Flora Nolan. In "Interstellar," Nolan's daughter has a brief cameo as a girl on a truck.

Nolan has always been open about the relationship he has with his children, telling The Guardian that he feels guilty for leaving his family behind when it comes to shooting films. "There is a lot of guilt for that," Nolan expressed. "The very sadness of saying goodbye to people is a massive expression of the love you feel for them." It's no surprise that so many of Nolan's films focus on characters dealing with children. With "Oppenehimer," Nolan takes his relationship one step further, imagining a scenario where his daughter is eviscerated by the world's deadliest weapon.

"Oppenheimer" hits cinemas on July 21.