Nolan continued to request additional pieces of music as he began editing “Oppenheimer,” which led to so much music being included in the finished film. To set up the third act that deals more with Oppenheimer’s political downfall, Göransson was tasked with crafting a “20-minute piece of music with a lot of action and high stakes.” Then, Nolan requested another musical section that came in at around fifteen minutes in length. Despite the amount of music featured, Göransson and an orchestra somehow managed to record the entire score within five days. “It was a tremendous, crazy recording session, and we had a lot of music to record in a very short amount of time,” said Göransson. “But we did it with an incredible group of live musicians.”
In one scene early on, the towering physicist Niels Bohr (Kenneth Branagh) tells Oppenheimer that it’s more important to “hear the music” of theoretical physics instead of worrying so much about the math. For that sequence, Göransson wrote a two-minute piece with 21 tempo changes. During the recording session, Göransson assumed they would have trouble recording the piece, but his wife Serena, who is also an accomplished violinist, made a suggestion. “I thought we had to do it in segments and record it bar by bar,” he said. “But Serena said, ‘They’re great musicians, why don’t we try different recording techniques and figure out how to do it in one continuous take?’ So, we figured out a way to do it, and that’s why you hear this crazy energy that is causing that momentum.”
That momentum and the changes in tempo allowed the music to represent what was happening inside the raging mind of Oppenheimer, which was a fairly frightening proposition at times.