Oppenheimer: Cillian Murphy Was Committed To Christopher Nolan's 'Behemoth Ask'

As one of the lead creators of atomic weaponry, J. Robert Oppenheimer is among the most notable and controversial human beings ever to walk planet Earth. Therefore, bringing him to the big screen in Christopher Nolan's "Oppenheimer" and exploring his psyche as he inched closer and closer to completing such world-devastating weapons couldn't have been an easy task for actor Cillian Murphy. Nevertheless, the frequent Nolan collaborator didn't back down from the acting challenge, going above and beyond to fulfill the director's monumental ask of bringing the infamous physicist to life.

"Oppenheimer" star Robert Downey Jr. sat down with People and explained the incredible commitment Murphy displayed while filming "Oppenheimer." "I have never witnessed a greater sacrifice by a lead actor in my career...He knew it was going to be a behemoth ask when Chris called him. But I think he also had the humility that is required to survive playing a role like this," Downey said, recalling that Murphy frequently had to turn down fun exploits away from the set to focus on more tedious tasks like learning 30,000 Dutch words to enhance his performance.

Unsurprisingly, RDJ isn't the only "Oppenheimer" actor who left the film's set blown away by the hard work Murphy put into his portrayal of the title character.

In addition to Robert Downey Jr., "Oppenheimer" star Florence Pugh also offered up words of praise for Cillian Murphy. She told People, "Every single day, he shows up knowing every single possible way, intonation, inflection of how to bring this character to life. That was hugely impressive to me. There's a reason why he is one of the greats." Thus, given his unrivaled dedication to his craft and impressive body of past work, Pugh shared that she was eager to work with Murphy as soon as the chance arose. She cited it as one of the best acting experiences she's had so far in her silver screen run.

Emily Blunt gave Murphy plenty of credit as well, likening his preparation work to Meryl Streep's on the set of "The Devil Wears Prada." She recalls that he had to totally detach himself from the rest of the cast and crew to dig deep into the characterization of J. Robert Oppenheimer. "He had such a monumental undertaking. And he could only eat, like, an almond every day. He was so emaciated," she said, noting that in addition to taking on a whole new mindset to become Oppenheimer, Murphy also transformed himself physically (via extratv on YouTube).

Like with any biographical film, finding the right actors is paramount to the success of the overall endeavor. For the lead especially, the casting has to be just right, and in the case of "Oppenheimer," it's safe to say Cillian Murphy was the right call. He went through rigorous preparation to excel in the title role once the cameras started rolling, and considering the glowing endorsements from his fellow actors, his hard work paid off. Of course, in the eyes of Christopher Nolan, Murphy was undoubtedly the person for the job from the start.

"I've been staring at the cover of the book ['American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer' by Kai Bird and Martin J. Sherwin] for so many months, and there's this photograph, black and white, a light blue-eyed stare, very intense, of this guy. And I thought, 'Well, I know who could do that,'" Nolan told The Hollywood Reporter of how he came to cast Murphy as the lead of "Oppenheimer." Thus, he grabbed his script and got on a plane to Ireland, where he met with Murphy and presented him with the document. Murphy read it as Nolan awaited his thoughts, and the rest is history.

At this stage in his career, Cillian Murphy is no stranger to working with Christopher Nolan. The two have collaborated on several projects over the years, though "Oppenheimer" is Murphy's first time serving as a lead for the seasoned director. Not only is that a tough position to be in, but he also had to take on the role of J. Robert Oppenheimer, which comes with no shortage of baggage on its own. So, as soon as Murphy took the role, he got right to work doing as much studying as possible to cultivate an attention-commanding performance.

Speaking with Collider, Murphy explained, "[Nolan] said, 'I'm making this movie about Oppenheimer, and I would like you to play Oppenheimer.' It's a big shock, and a very pleasant one, but then you kind of go, 'Okay, now I have a lot of work to do.'" Between that conversation and the start of filming, Murphy only had six months to learn as much as he could about Oppenheimer, his mindset during World War II, and the complex work he and his team of scientists were committed to at the time, among other things. While he wishes he had more time, he made the six-month window work.

For those looking to see all of Cillian Murphy's hard work in action, "Oppenheimer" is now playing exclusively in theaters.