Cillian Murphy and Florence Pugh had to complete an 'outrageously silly' test together before filming their Oppenheimer nude scene.

Premiering the same day as Barbie, Christopher Nolan’s upcoming film tells the story of American scientist J. Robert Oppenheimer and his role in developing the atomic bomb which was used in World War II – for which he became titled as the ‘father of the atomic bomb’.

And not only will we get an eyeful of science and cigarettes, but we can also expect a right old eyeful of Murphy and Pugh.

The Irish actor plays the titular role with Midsommar’s Pugh playing his ex-fiancée, Jean Tatlock.

Although there’s a huge amount of secrecy around the hotly-anticipated film, a piece by The Guardian revealed it will feature ‘prolonged full nudity’ between the pair.

Plus, there’s going to be sex and ‘complicated scenes with star Emily Blunt who plays his wife, Kitty Oppenheimer.

Universal Pictures

This will be the first time such saucy scenes and R-rated content will feature in a Nolan film – the director responsible for the likes of Inception and The Dark Knight Rises.

And ahead of all this ‘nudity’ and ‘complication’ taking place, the actors had to complete ‘chemistry tests’.

Although the Murphy told The Guardian he’s under ‘strict instructions’ to not ‘give away’ any of the content, he did spill the beans on the tests he took with both Pugh and Blunt.

“They put two actors in a room to see if there’s any spark, and have all the producers and director at a table watching,” he said.

“I don’t know what metric they use, and it seems so outrageously silly, but sometimes you get a chemistry and nobody knows why.”

The Peaky Blinders actor described the film as ‘sometimes like a thriller, sometimes like a horror’.

And a rarity for Nolan, it’s features lurrvvvve.

The director previously told Wired: “The love of the characters, the love of the relationships, is as strong as I’ve ever done.”

Universal Pictures

Murphy also warned Oppenheimer is going to ‘knock people out’ with how ‘provocative and powerful’ it is.

“What [Nolan] does with film, it f**ks you up a little bit,” the actor said.

One thing he did reveal about the content though hardly comes as a surprise.

We watched him play Tommy Shelby for nearly 10 years where we was constantly puffing on cigarettes. And he’ll be doing the same in this major role too.

Before dying of cancer in 1967, the ‘atomic bomb father’ consumed very little else other than cigarettes and martinis.

Murphy said: “I’ve smoked so many fake cigarettes for Peaky and this. My next character will not be a smoker. They can’t be good for you. Even herbal cigarettes have health warnings now.”