Oppenheimer becomes Christopher Nolan's first R-rated movie in 21 years

It’s official: Oppenheimer will be R-rated when it’s released in cinemas later this year.

The highly anticipated film will be the first by director Christopher Nolan to receive the adult rating in over 20 years.

However, it’s not the only impressive thing about the upcoming movie - which tells the story of the first detonation of a nuclear weapon.

Starring Robert Downey Jr, Florence Pugh and Cillian Murphy as titular scientist J Robert Oppenheimer, the biopic even recreated the first dentation without CGI.

It’s unsurprising given Nolan’s commitment to practical effects, with the filmmaker flipping a real semi-truck in The Dark Knight Rises.

Speaking about his latest project, the legendary director explained how he and his production team achieved the incredible effects in Oppenheimer.

He told Games Radar's Total Film: "I think recreating the Trinity test [the first nuclear weapon detonation, in New Mexico] without the use of computer graphics, was a huge challenge to take on.

"It’s a story of immense scope and scale. And one of the most challenging projects I’ve ever taken on in terms of the scale of it, and in terms of encountering the breadth of Oppenheimer’s story.

“There were big, logistical challenges, big practical challenges.”

AJ Pics / Alamy Stock Photo

Given the scale of the story, the director was committed to pulling out all the stops for Oppenheimer.

This included the film gaining an R-rating, which was Nolan’s first since 2002’s Insomnia.

Nolan also confirmed that Oppenheimer is the longest movie of his career yet, with a runtime just shy of the three-hour mark.

Even the footage was huge with impressive effects being captured on Imax film, resulting in what Associated Press called ’11 miles of film stock’ which weighed ‘600 pounds’.

However, Nolan wanted to use Imax to help viewers ‘immerse them in the world of the film’ and get the ‘feeling of 3D without the glasses’.

“We knew that this had to be the showstopper,” he told AP.

Previously, the director has been criticised for the sound in his other films, with audiences complaining that they couldn’t parts of Tenet’s dialogue.

However, it seems that Oppenheimer’s sound will be blowing the roof off cinemas when it finally arrives on the big screen.

Nolan added: “We’re able to do things with picture now that before we were really only able to do with sound in terms of an oversize impact for the audience - an almost physical sense of response to the film.”

Oppenheimer is set to be released in cinemas on 21 July.