Cillian Murphy said yes to Oppenheimer before he’d read a single page of the script. Nolan flew to Dublin to hand him a copy, printed on red paper so it couldn’t be photocopied. From that point on Murphy disappeared for six months. He dropped about 28 pounds, ate so little that Emily Blunt said it was “like, one almond” most nights, and skipped every single cast dinner. Matt Damon said they invited him every night. He never came. He was in the bath learning lines. He read American Prometheus, the Pulitzer-winning biography the film was based on. He read the Bhagavad Gita, a Hindu holy text that Oppenheimer quoted after watching the first nuclear bomb test. Then he found old recordings of the real Oppenheimer giving physics lectures and started walking beaches near his home in Ireland, reciting them out loud to his dog Scout. At one point he hit a scene where Oppenheimer gives a lecture in Dutch. He asked Nolan what they’d do about it. Nolan: “You mean what are YOU going to do about that.” So Murphy got the film’s cinematographer, who happens to be Dutch, to record the lines into his phone. Slowed the audio way down. Spent three weeks memorizing the whole thing. Robert Downey Jr. said the rest of the cast would plan weekend trips around Santa Fe while Murphy would just go, “I have to learn 30,000 words of Dutch. Have a nice time.” The weight loss got competitive. His own words: “You become competitive with yourself a little bit, which is not healthy. I don’t advise it.” During the 57-day shoot he pulled 18-hour days and said he hit a zone where food just stopped mattering. Nolan kept the air conditioning cranked during the interrogation scenes because the character is being humiliated, and Murphy was so hungry and so cold it actually helped the performance. The real Oppenheimer lived the same way. Ran on cigarettes and double-strength martinis. Throat cancer killed him at 62. Murphy’s wife Yvonne once described what happens when a character finally leaves him. Her words from his years playing Tommy Shelby on Peaky Blinders: “OK. Tommy’s gradually leaving. I’m getting Cillian back.” Murphy puts it his own way. “I cancel reality for a while.” Oppenheimer won 7 Oscars and pulled in $950 million at the box office. It gave Murphy his first Best Actor win after decades in the business. So when a doctor asks how he copes with playing deeply traumatized characters and he laughs and calls being a doctor “a real job,” he means every word. The job costs him six months inside someone else’s head, a body he has to starve into someone else’s shape, and a family that has to wait for him to come home.