How Christopher Nolan actually recreated a real nuclear explosion without CGI

Christopher Nolan and his team have opened up on some of the ways that they managed to recreate a nuclear bomb without using CGI - without detonating an actual bomb, of course.

And those special effects came with a big promise – that the film would show a nuclear bomb explosion without using computer generated effects.

Nolan and his Director of Photography, Hoyte van Hoytema, were the masterminds behind this plan, and the pair set about recreating the Trinity Test that made Oppenheimer famous without blasting a gigantic crater in the Earth.

They still blasted some of it, though. Don’t worry about that.

In recreating events in New Mexico on 16 July 1945, the pair had to play with the scale of the explosion, as well as employing some other trickery too.

They didn’t explain all of their secrets – that would be no fun, would it? – but Hoytema did offer some of their methods up.

“Obviously, we couldn’t make an explosion the size of the actual explosion so we used trickery,” he told Variety.

They started with some ‘science experiments… we built aquariums with power in it. We dropped silver particles in it.

“We had moulded metallic balloons which were lit up from the inside.

“We had things slamming and smashing into one another such as ping-pong balls, or just had objects spinning.”

He added: “We had long shutter speeds, short shutter speeds, wide negative colour, negative overexposure, underexposure.

"It was like a giant playground for all of us.”

There are obviously some real explosions in the film, as special effects supervisor Scott Fisher explained: “We do them as big as we possibly can, but we do reduce the scale so it’s manageable.

"It’s getting it closer to the camera, and doing it as big as you can in the environment.”

In the concoction for their blasts, the team used gasoline, propane, black powder, aluminium powder, and magnesium flares.

They had to get the chemistry right to attempt to recreate the sheer power and blinding qualities of a genuine nuclear blast.

Hoytema added: “The Trinity Test was something that came together and was cobbled from the miniatures of that science experiment, under the guidance of Chris and my guidance, that we pushed slowly in certain directions in order to serve specific functions in these sequences.”

Giving his own take, Nolan said: “We don’t want to give away the tricks too much.

“We didn’t use CG, we tried to come up with methods from the visual effects and special effects department that were microscopic things that look huge, but also some giant big bangs out in the desert that were pretty spectacular to live through.”

Everyone seems to be pretty happy with what they’ve seen so far, and if you want to catch it for yourself you can watch Oppenheimer in cinemas now.