Geoff Brumfiel

You know, you think a nuclear test and it's like a mushroom cloud over the desert. But that was actually just a very brief period that those above ground tests were happening. It was mostly in the 1950s and it stopped because of radioactive fallout. The wind was carrying radioactive material much further than expected. And it started showing up on fishing boats.

In milk and baby teeth, places nobody wanted it. So in 1963, the world's nuclear power signed a treaty to move testing deep underground. And it kept going that way all the way until the end of the Cold War.

In milk and baby teeth, places nobody wanted it. So in 1963, the world's nuclear power signed a treaty to move testing deep underground. And it kept going that way all the way until the end of the Cold War.

In milk and baby teeth, places nobody wanted it. So in 1963, the world's nuclear power signed a treaty to move testing deep underground. And it kept going that way all the way until the end of the Cold War.

I spoke to Hans Christensen with the Federation of American Scientists. He tracks nuclear weapons all over the world, and he says there were two big reasons.

I spoke to Hans Christensen with the Federation of American Scientists. He tracks nuclear weapons all over the world, and he says there were two big reasons.

I spoke to Hans Christensen with the Federation of American Scientists. He tracks nuclear weapons all over the world, and he says there were two big reasons.

It was this growing power of supercomputers. They could now take these supercomputers and simulate nuclear testing in silicon.

It was this growing power of supercomputers. They could now take these supercomputers and simulate nuclear testing in silicon.

It was this growing power of supercomputers. They could now take these supercomputers and simulate nuclear testing in silicon.

Yeah, and that actually takes us to the first stop on this whole nuclear testing road trip.

Yeah, and that actually takes us to the first stop on this whole nuclear testing road trip.

Yeah, and that actually takes us to the first stop on this whole nuclear testing road trip.

I traveled out to Lawrence Livermore National Laboratory in California, and I got to see their newest computer where they do what they call the button-to-boom calculations.

I traveled out to Lawrence Livermore National Laboratory in California, and I got to see their newest computer where they do what they call the button-to-boom calculations.

I traveled out to Lawrence Livermore National Laboratory in California, and I got to see their newest computer where they do what they call the button-to-boom calculations.

It's inside a secure vault. The computer is called El Capitan.

It's inside a secure vault. The computer is called El Capitan.

It's inside a secure vault. The computer is called El Capitan.

Terry Quinn oversees high-performance computing at Livermore, and she showed us around. Now, this machine uses advanced processors, similar to those used for generative AI, actually. LCAP can do more than two quintillion calculations per second. Wow. That's two exaflops for those in the supercomputing game. And its only job is to calculate, you know, a nuclear weapon's detonation.