Short Wave - 'Oppenheimer' And The Science Of Atomic Bombs

Episode Date: July 21, 2023

Christopher Nolan's new film 'Oppenheimer' chronicles the life and legacy of J. Robert Oppenheimer, the first director of Los Alamos National Laboratory and so-called "Father of the Atomic Bomb." The movie does not shy away from science — and neither do we. We talked to current scientists at Los Alamos about the past and present science of nuclear weapons like the atomic bomb.Read more about the Manhattan Project.Want us to cover other historical science or science in pop culture? Email us at [e-mail] — we'd love to hear from you!See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

Before we begin, we have a content warning. This episode talks about the film Oppenheimer and acknowledges the death and destruction that resulted from the U.S. dropping atomic bombs on two Japanese cities. Here's our episode. You're listening to Shortwave from NPR. In December 1938, scientists in Nazi Germany

made a breakthrough that alarmed other scientists around the globe. Like Leo Zillard, he was a Hungarian, Jewish, physicist living in the U.S., and almost immediately he and another physicist, Enrico Fermi, set out to conduct independent experiments to confirm this breakthrough. Nuclear fission. The first piece of the atomic bomb puzzle. It was possible. Zillard became so worried that in August of the following year,

he wrote a letter for his friend Albert Einstein to sign and send directly to the president of the United States. The letter warned that, quote, extremely powerful bombs of a new type may thus be constructed. The letter prompted President Roosevelt to create the advisory committee on uranium. It would soon morph into a much bigger project, the Manhattan Project. The Manhattan Project was a top secret program established during World War II to essentially design and build and deliver a combat unit to end World War II.

Ellen McGee is a historian at Los Alamos National Lab in New Mexico. One of the several sites where research for the project was conducted. She says the Manhattan Project was a massive effort that relied on many brilliant technical and scientific minds from around the world. Over the course of the next few years, over half a million people would be involved in the project, from scientists to other workers to political leaders. The scientists were contributing a lot of the theoretical ideas, but there were a lot of other people. with hands-on work to actually make the weapons a reality, including women who were working as technicians behind the fence. Some of the Hispanic villagers whose lands were appropriated,

they came and worked during the Manhattan Project at Los Alamos and continued to be a very important part of the workforce today. Enter the father of the atomic bomb, Robert Oppenheimer, Initially, consulting on a small part of the project, he would eventually become the first director of Los Alamos National Lab, the site in charge of building and testing an atomic bomb. He was, by all accounts, brilliant, possibly even a genius. But he could also be a little bit impatient or arrogant. But he could sit and listen to other people talking about the science. And then he would summarize and then also bounce ideas off of people so that he was really like a synthesizer or like a catalyst. A catalyst to the Trinity test, the plutonium bomb test that was completed July 16, 1945.

Today on the show, the legacy of the Manhattan Project. We talk about the science and the impact of atomic bombs, how the U.S. nuclear weapons program works now, And after all that, what it was like to be on the set of the movie Oppenheimer? I'm Regina Barber. You're listening to Shortwave, the science podcast from NPR. On the morning of August 6, 1945, the United States dropped an atomic bomb on the Japanese city of Hiroshima. And three days later, a second on the city of Nagasaki. It's estimated that more than 100,000 people died as a result of the initial impact, heat, and radiation of the two weeks. bombs, with some estimates surpassing 200,000 after days and months.

The bomb dropped on Hiroshima was made with uranium. The bomb dropped on Nagasaki used plutonium. Both of the atomic bombs the U.S. used were fission bombs. Fission is basically what it sounds like. It's cutting the atoms apart using smaller particles like neutrons, and when you split them apart, part of what comes out of that is energy. That's Anita Carrasco-Gorego. She's a weapons engineer at Los Alamos National Laboratory in New Mexico.

And she says to make the bomb, the Manhattan Project scientist needed to use something called fissile material. That sort of unstable isotope of uranium or plutonium, that's what fissile material is. So it's able to be put into a fusion or fission-type reaction. And it's surrounded by high explosives. And it has to be enough high explosives to drive that material. and compress that material small enough and fast enough to a high enough density to create those fission reactions. The bombs dropped on Japan were the first and only two atomic bombs in history used as weapons.

But thousands of nuclear tests have been conducted around the world, which showered the Earth with radioactive particles. In the years following, the world's nuclear powers signed a treaty prohibiting atmospheric testing, but they kept testing underground. Then in 1992, the U.S. voluntarily halted underground testing as well. And because of that, as a weapons engineer, Anita doesn't run physical tests on the U.S. nuclear weapons stockpile. That is what came out of the test ban treaty, is the SSP or the Stockpiles Assamint Program, in which we use the testing available to us to compare back to underground testing. So that is, in essence, what we do here is we use very powerful computer. to analyze any changes in the stockpile so that we can tell the weapon will work should we need it.

That means upgrading aging equipment or replacing faulty parts. And to make sure the stockpile is operational without nuclear testing, Anita and her colleagues run additional experiments. We go through centrifuge experiments. We do thermal experiments. And we have a whole series of just the high explosives, just that, no plutonium, nothing else. and we just test how that is aging, how the detonation wave is moving across the high explosive, or we test the detonators. If we see something weird, we see if they're still going to function like they're supposed to. Data from these experiments are then fed into very complex simulations,

used by computational physicists at Los Alamos like Shane Fogarty. You need temperatures, densities, and material properties of all the different things in your simulation. You have to model many different physics factors in hydrodynamics. All these different individual physics models have to all come together for one solution to what that material is doing at any given time in your simulation. Scientists then check the results of the simulations against old nuclear test data. And once a year, all the work put into nuclear testing from thousands of the lab's employees goes to one person, Tom Mason.

Tom Mason, the director of Los Alamos National Lab, we all give to him work and he certifies. He signs a letter to the president that says our... Of the United States. Of the United States, yes, that our nuclear stockpile is both safe and reliable. In addition to his regular work at Los Alamos, helping to certify the nuclear stockpile of the U.S., Shane was also cast as an extra, in the film. Because the movie is about Robert Oppenheimer, who worked at Los Alamos National

Lab, much of the movie was filmed in New Mexico, and the filmmakers wanted actual scientists to play extras in the movie. Shane played an attendee and actually talked with Killeen Murphy, who played Oppenheimer, and Robert Downey Jr., who played the chairman of the U.S. Atomic Energy Commission, Lewis Strauss. As soon as I mentioned that I was a scientist, they really jumped on that and asked me a lot of questions, which is super fun. You know, Robert Downey Jr. is asking me about the formation of the moon debating the prospects for nuclear fusion as a viable mechanism to produce energy for our world. And he was at times much more informed than I was at the current state of like nuclear fusion. Shane's wife, Erica, a computational astrophysicist at Los Alamos

National Lab, was also offered a part as an extra. But while I got cast as an attendee, she was cast as a wife. She declined. She likened her feelings of being cast as that 40's wife to how she feels when she's sometimes addressed as Mrs. rather than doctor. Many white men were cast in the movie because many people of color and women who worked on the project were usually not in positions of power and historically not recognized for their contributions.

Shane says that's not how Los Alamos National Laboratory looks today. I was participating in a scene where you have the most powerful and influential scientific decision makers at the time in America, and they're preparing to advise the president of the United States. So I thought you could kind of see a sort of ceiling manifest itself there when you look around the table and there are literally zero women at the table. And no people of color. No, no. Not at all. So, yeah, that was for me a stark difference between then and now. One thing that hasn't changed over the years, the moral complexity of working on nuclear weapons.

Both Anita and Shane do their work with the hope that atomic weapons will never be used again. I understand the moral struggle. I mean, I was not born in a world where we were in the middle of a world war. So I don't necessarily know those struggles that go on. in a time of war. So I think trying to understand what that means and why they were developed is difficult, but they're here. And it's not just us who have them.

And what we're doing here is we're now managing it responsibly, right? But, of course, never wanting it to have to be used is the goal. There are no greater stakes than working on nuclear weapons, though maybe someone working on climate change would disagree. So how do I feel? Yeah, I would say a mixture of nervous that my work has importance, but also a sense of pride and that I'm doing meaningful work that affects the real world and hopefully for the better. It's a struggle that many scientists depicted in the movie grappled with two,

including Oppenheimer. He hoped that the simple knowledge that the U.S. had these weapons would be deterrent enough. When he realized it wasn't, he argued against an arms race before ultimately exploring the idea of disarmament, a topic which is still very much debated, even today. Special thanks to Tara Jostenko and Laura Malayne for helping shape this episode. We'll have links on our website if you want to learn more about the Manhattan Project or the U.S. nuclear weapons program. This episode was produced by Burley McCoy, edited by our managing producer Rebecca Ramirez and fact-checked by Britt Hansen. The audio engineer was Robert Rodriguez.

Beth Donovan is our Senior Director of Programming and our Senior Vice President of Programming is Anya Grenman. I'm Regina Barber. Thanks for listening to Shortwave from NPR.