Having worked with Christopher Nolan on six films, beginning with Batman Begins, Cillian Murphy is one of the acclaimed filmmaker’s most frequent collaborators. With his leading turn alongside Nolan in Oppenheimer, however, Murphy transcended his previous supporting player status, taking center stage as the father of the atomic bomb. Not taking the opportunity for granted, he thrust himself into a rigorous regimen of preparation in order to play the role, which continued throughout the film’s shooting schedule and demanded the utmost dedication as he transformed himself both mentally and physically. According to his co-stars, Emily Blunt and Matt Damon, Murphy’s commitment to Oppenheimer was so intense that they rarely, if ever, saw the actor outside working hours, but his hard work would ultimately pay off in droves.
How Did Cillian Murphy Prepare to Play J. Robert Oppenheimer?
Having accepted the role of J. Robert Oppenheimer before laying eyes on Christopher Nolan’s screenplay, Cillian Murphy knew he’d have his work cut out for him. Headlining an ambitious three-hour biopic would likely give even the most experienced performers a moment of pause, but Murphy relished the opportunity and dove in headfirst for a 5-month preparation period. Aside from reading Kai Bird and Martin Sherwin‘s American Prometheus, the 2005 biography upon which Oppenheimer is based, the actor familiarized himself with the Bhagavad Gita, the Hindu text the physicist famously drew from when he witnessed the 1945 Trinity Test. Murphy also prepared for the role by reading and listening to Oppenheimer’s lectures, often reciting them to his dog as they strolled down beaches, but these immersive measures arguably paled in comparison to the physical challenges he’d face.
To capture Oppenheimer’s trademark thin, gaunt physical appearance — likely a product of his reliance on cigarettes and martinis — Murphy maintained a strict diet before and during production. “I had to lose quite a bit of weight,” he told The New York Times, referring to Oppenheimer as “very slim, almost emaciated” and saying further of the process, “You become competitive with yourself a little bit which is not healthy. I don’t advise it.” While Murphy has declined to comment on exactly how much weight he lost for the role, his commitment to the film’s physical demands was perfectly evident to his co-stars, with Emily Blunt jokingly observing that he survived on “an almond every day.”
Cillian Murphy Isolated Himself While Filming ‘Oppenheimer’
Considering he’d landed what’s arguably the role of a lifetime, playing one of the most consequential figures in human history, Cillian Murphy’s dedication to Oppenheimer wasn’t limited to research and physical transformation. Throughout filming, the actor kept a low profile among his fellow cast and crew, isolating himself and rarely socializing with others. As Emily Blunt recalls, “The sheer volume of what he had to take on is so monumental,” adding that Murphy often skipped out on meals with his co-stars. “His brain was just too full,” echoed Matt Damon.
Though Murphy was undoubtedly pushing himself to his performative limits with Oppenheimer, Nolan’s fast-paced approach to shooting kept the actor in a constant state of intellectual engagement, physical movement, and creative adrenaline. “You sleep for a few hours, get up, bang it again,” he told The Guardian. “I was running on crazy energy. I went over a threshold to where I was not worrying about food or anything.”
Fortunately for Murphy, his dedication to the film was highly rewarding, resulting in what’s arguably a career-best performance. Driven by a seemingly obsessive, near-manic energy that walks a fine line between brilliance and madness, the actor’s acclaimed turn as J. Robert Oppenheimer is, in hindsight, reflective of the hard work he put into it. In that sense, Christopher Nolan’s fast-paced working methods were essential in keeping Murphy in a particular mental and physical state, depriving him of idle time and any petty distractions that might compromise his focus. While such an approach to making Oppenheimer was likely an exhaustive one for Murphy, his commitment to the role paid off in droves when it won him the Academy Award for Best Actor.
Oppenheimer is available to watch on Prime Video in the U.S.
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