Cillian Murphy Doesn't Understand Oppenheimer's Physics Either – But He Did Learn Dutch

Don't ask Oppenheimer's leading man Cillian Murphy to explain the physics — theoretical or otherwise — behind the atomic bomb. He doesn't understand the logistics behind making J. Robert Oppenheimer's potential world-destroyer anymore than the audience. But the 47-year-old Irish actor, who's taking the reins of a Christopher Nolan project for the first time after years of collaboration, is no slouch. 

Not only do his co-stars have the highest regard for his work as both an artist and scene partner, but Murphy himself revealed to NBC Insider the level of dedication he gave to the starring role. 

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"It was ... six months, and I would have taken more [to prepare]," Murphy said. "You kind of just go at it. You break it down and say, 'Alright, we need to work on this today.' I used to set aside, 'I'll work on this for a week and I'll work on that for a week.'

"The Dutch, our [Director of Photography] Hoyte van Hoytema is Dutch so I got him to record the Dutch into my phone," he explained. "And then I slowed it down — you know how you can slow it down on your phone? And then I listened to it for like three [weeks]. I still remember that speech in Dutch, actually."

Murphy's longtime fans likely aren't surprised by his sheer determination to get the pronunciation down pat. In his best-known roles — as Birmingham gangster Tommy Shelby in Peaky Blinders or his other Nolan roles such as Batman Begins and Inception in which he's affecting an American accent — Murphy is something of a chameleon. So being able to memorize and spout out a bit of Dutch after listening to the words over and over again couldn't be that much work for his usual level of dedication. 

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Working on a Nolan set is, he admitted, a big help in getting into character, as well.

"He does make movies on a huge scale. The sets are extraordinary but it never feels like that when you're working in them because it feels very intimate and kind of private," he mused. "There's no video village or monitors, it's just him and his DP and the boom op and the actors. So it's very calm — incredibly calm and it feels very safe just to experiment and try stuff."

Oppenheimer premieres exclusively in theaters on July 21.

Reporting by Stephanie Gomulka.