Cillian Murphy has branded J Robert Oppenheimer “naïve” for thinking he could end “all wars” by inventing the atomic bomb.

The 47-year-old ‘Peaky Blinders’ actor studied and dieted for months in preparation for playing the scientist in Christopher Nolan’s ‘Oppenheimer’ blockbuster, and added his hard drinking and womanising – as well as the torment he felt after creating the bomb – made him “contradictory” and “complex”.

He told NME about Oppenheimer: “I do think that he believed it would be the weapon to end all wars.

“He thought that (having the bomb) would motivate countries to form a sort of nuclear world governance.

“He was naïve. Chris (Nolan) used this amazing phrase. We were talking about Oppenheimer’s arc and he said, ‘You know, he’s dancing between the raindrops morally.’ That unlocked something in my mind when I was preparing.”

Quantum physicist Oppenheimer oversaw the creation of the atomic bomb for the US Government, two of which were dropped on Japanese cities Hiroshima and Nagasaki in 1945, killing an estimated 220,000 people.

He spent the rest of his life campaigning for disarmament and was left disgusted at the weapon he called his “gadget”.

Cillian read the Bhagavad Gita in preparation for the role, the 700-page Hindu religious text the physicist famously quoted from when he said: “Now I am become Death, the destroyer of worlds.”

He researched for six months before filming began in February 2022, and during the 67-day production regularly worked 18-hour days.

Cillian was also said to have eaten only an almond or stick of celery a day to get hard-drinking Oppenheimer’s gaunt look.

He added even though he needed a break after the role, he hasn’t let it weigh on him.

Cillian said: “You always have to take a holiday after a job. It’s not because… as some journalists like to think, you’re a method actor or whatever.

“It’s because you give so much time to the job and then suddenly you stop. You have all this displaced energy, you know, so you kind of don’t know what to do with yourself… but I’m a very easy going sort of person. It doesn’t weigh me down.”