By Gill Pringle at CinemaCon, Las Vegas

Amidst all the frivolity and festive spirit at CinemaCon – the annual convention held in Las Vegas where the major film studios gather to present their upcoming slates – Christopher Nolan was in a somber mood as he took the stage to unveil dramatic new footage from Oppenheimer, his sweeping biopic of J. Robert Oppenheimer, the American physicist who helped create the atomic bomb.

The World War II-set drama stars long time Nolan collaborator Cillian Murphy as Oppenheimer, known as the “father of the atomic bomb” for his role in the Manhattan Project.

Nolan, who has been critical of streamers and is a major advocate for the big screen, took to the stage to huge applause from the crowd of cinema owners from around the world. “I know of no more dramatic tale with higher stakes,” he said.

The gripping footage looked at a moment in history which has always fascinated Nolan, namely, when Oppenheimer knew that testing the atomic bomb might ignite the atmosphere and destroy the world, but he hit the button anyway.

You could cut the tension with a knife, as audiences saw – for the first time – footage outlining how Oppenheimer creates a bomb with the potential to lead to unthinkable loss of life and destruction.

We saw scenes of the physicist’s team engaged in the top-secret work of bomb-making, but the movie also spins forward in time to a point where Russia has developed its own atomic technology, triggering suspicions of espionage at Los Alamos in New Mexico, US.

Nolan said that the film’s protagonist made decisions that still reverberate to this day.

“Like it or not, J. Robert Oppenheimer is the most important person who ever lived,” said the revered filmmaker. “He made the world that we live in for better or for worse. His story has to be seen to be believed.”

Likewise, the cast has to be seen to be believed, with Nolan’s opus filled with performances from A-listers Matt Damon, Florence Pugh, Rami Malek, Dane DeHaan, Kenneth Branagh and Casey Affleck.

Gary Oldman brings gravitas as US president Harry S Truman and Emily Blunt plays Kitty, Oppenheimer’s traumatised wife.

A gaunt and barely recognisable Robert Downey Jr. portrays US Major General Lewis Strauss, a member of the Atomic Energy Commission.

The film is one of the most ambitious big studio summer releases in years. It’s a season that’s usually reserved for tentpole action movies and superhero flicks, but Oppenheimer grapples with far weightier themes, not to mention a scientific development that re-shaped the course of history. Oppenheimer guided the Manhattan Project as the head of the Los Alamos Laboratory, before becoming a critic of weapons of mass destruction.

“His story is both dream and nightmare,” Nolan said. “I know of no more dramatic tale with higher stakes, twists and turns and ethical dilemmas. … The finest minds in the country were in a desperate race against the Nazis to harness the power of the atom in World War II.”

The movie was shot in 70mm with Imax cameras, and the trailer that Nolan shared toggled between smoky black-and-white and colour with impeccable production design.

A big fan of Black and White, Nolan even joked, “Don’t worry, there’s not too much Black and White.”

Murphy – a veteran of previous Nolan films including Dunkirk, Inception and as The Scarecrow in the Dark Knight trilogy – looks eerily similar to the real Oppenheimer as seen in archival imagery.

The Irish actor certainly conveys the haunted air of a man who unleashed an awesome weapon, a destroyer of worlds. But when the Manhattan Project was launched during World War II, control of civilisation did hang in the balance.

“I don’t know if we can be trusted with such a weapon. But I know the Nazis can’t,” says Murphy’s Oppenheimer.

Celebrated for his Hollywood blockbusters with complex – some might say “confusing” – storytelling, Nolan, 52, is considered to be one of the most acclaimed filmmakers of his generation.

Certainly, the box office agrees, and his films have grossed US$5 billion worldwide.