How the Oppenheimer atomic bomb explosion was done without CGI

Oppenheimer is Christopher Nolan’s most impressive movie to date, and it comes with an extraordinary promise: the Trinity Test’s atomic bomb explosion recreated without CGI – so, how did they do it?

Nolan, armed with his trusty DP Hoyte van Hoytema and composer Ludwig Göransson, hone in on your senses Oppenheimer; the sub-atomic, gargantuan crashing of visuals and sound is a knowing assault on every fibre of your being.

Of course, it somewhat culminates in the titular physicist’s headline event: the Trinity Test, aka the first detonation of an atomic bomb on US soil, taking place in the New Mexico desert on July 16, 1945.

In a movie full of jaw-dropping moments, this is the one audiences are filing into IMAX theaters to see from the outset, especially as it was pulled off without CGI – so, how the hell did they do it?

Oppenheimer DOP explains atomic bomb explosion without CGI

Contrary to popular belief, Nolan didn’t detonate an actual atomic bomb in Oppenheimer. “Obviously, we couldn’t make an explosion the size of the actual explosion so we used trickery,” Hoytema explained to Variety.

Assisted by special effects supervisor Scott Fisher and visual effects supervisor Andrew Jackson, they began conducting a number of “science experiments… we built aquariums with power in it. We dropped silver particles in it. We had molded 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.”

“We had long shutter speeds, short shutter speeds, wide negative color, negative overexposure, underexposure. It was like a giant playground for all of us,” the DP added.

While there are real, enormous blasts in the movie, more than a few moments are smaller than they appear. “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,” Fisher told SYFY.

The recipe for that specific eye-melting, ultra-radiant quality of an atomic boom included gasoline, propane, black powder, aluminium powder, and magnesium flares – however, much like Nolan, Hoytema is keen to keep some of the sequence’s secrets.

“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,” Hoytema explained.

While taking part in the latest Wired Autocomplete Interview, Nolan also 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.”

Oppenheimer is in cinemas now. You can check out our other coverage below:

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