Jeremy Bernstein 11–2007

Summary

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New Books Network Podcast: Jeremy Bernstein on Oppenheimer, Nuclear Weapons, and Proliferation

Episode Date: December 10, 2025
Guest: Jeremy Bernstein (archived 2007 lecture)
Host: New Books
Episode Theme: Exploring the life and legacy of J. Robert Oppenheimer, stories from the dawn of the atomic age, the technicalities and ethics of nuclear weapons, and the realities of global proliferation.

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Overview

This episode features the late physicist and writer Jeremy Bernstein, revisiting a 2007 lecture on J. Robert Oppenheimer, the Manhattan Project, and the rise of nuclear arms. Bernstein, who was both a contemporary and a chronicler of many nuclear-age figures, shares insights from his personal interactions, technical explanations of nuclear weapon-making, and reflections on proliferation, enriched with anecdotes and memorable humor.

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Key Discussion Points & Insights

1. Oppenheimer’s Genius and Los Alamos Culture

• Bernstein starts by debunking the myth that Los Alamos was overflowing with Nobel Prize winners; at the time, only three or four laureates were present, but many future recipients worked there (02:45).
• On Oppenheimer’s intellect:
  • “Oppenheimer was intellectually superior to everybody. He had the capacity of making instantaneous understanding of things... he had everything in his head.” (03:43, paraphrasing Hans Bethe)
• Anecdotes about Oppenheimer:
  • The “Added Cubit” lecture and the biblical reference to Matthew 6:27 (05:23).
  • Bernstein’s humorous exchange with Oppenheimer about the lecture title, with Oppenheimer noting Bernstein's rabbinical lineage (05:31).
  • Oppenheimer’s reaction at the Trinity test: “It worked and God did it work.” (07:06, Oppenheimer, as relayed by Frank Oppenheimer)

2. The Spread of Nuclear Weapons - A Satirical Song

• Interlude with Tom Lehrer’s song “Who’s Next?” satirizing the global spread of the bomb (08:30–09:32), underscoring the inherent absurdity and danger in nuclear proliferation.

3. The South African Nuclear Program: Lessons in Proliferation

• Key technical explanation: The difference between “fissionable” and “fissile” material, emphasizing the difficulty of enriching uranium to weapons-grade (11:11).
• South Africa uniquely built gun-type uranium bombs, making enough for six weapons before abandoning (12:04).
• On dismantling:
  • The process took four years, and uranium was partially repurposed for medical reactors, the rest placed under international supervision (13:30).
  • Notable involvement of A.Q. Khan, the Pakistani scientist who “opened a supermarket for selling nuclear material” (14:50).

4. Bernstein’s Personal Experience at Nuclear Weapons Tests

• Summer 1957 at Los Alamos: Bernstein receives “Q” clearance, reflecting on the oddities of security measures (16:08).
• At the Nevada Test Site:
  • Vivid recounting of witnessing a nuclear explosion:
    • “When I counted 10 and turned around, I saw a sight which can't get out of your mind... a livid fireball rising with colors of orange, red. A terrible, awesome, monstrous thing.” (21:56)
  • On the aftermath and the shock wave: “The shockwave at Hiroshima was 250 miles an hour and knocked over all the cooking stoves, which is what caused the firestorm in Hiroshima.” (23:42)
  • Reflects on the health impact on soldiers present at test sites and the government’s casual attitude (24:52).

5. Inside the Bomb Assembly Area

• Bernstein describes entering a facility with dozens of plutonium pits:
  • “All of them lined up on shelves enough to destroy a continent. I was, I remember, pretty shocked... Carson, observing this performance, picked one off the shelf and handed it to me, saying, 'don't drop this.' So I was holding this plutonium pit, which is a little bit warm to the touch, about the size and weight of a bowling ball.” (26:32)
• Brief literary aside about the surreal, almost mundane work environment: a technician filing explosives, a woman knitting beside him—at first doubted by fact-checkers, but confirmed later (28:18).

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Audience Q&A: Contemporary Proliferation, Iran, and Terror Threats

Iran’s Nuclear Ambitions

• On Iran’s enrichment efforts:
  • “I am quite certain that they’re working to get it... their cascade makes lightly enriched uranium... But once you have [4%], to go from 4% to 90% is much easier.” (29:22)
  • Notes Israel’s likely red lines: “I don’t think they'll let the Iranians have a weapon. I mean, look what they did in Syria a few weeks ago. They flattened what was presumably the beginning of a reactor.” (31:27)

Israel’s Nuclear Arsenal

• What is known (and unknown):
  • “They must have several hundred. I think they were self-produced. The French helped out in the beginning... They probably have boosted nuclear weapons.” (31:01)

Ease of Nuclear Weaponization

• On technical challenges:
  • “Making a crude weapon… the North Koreans tested the device and they got a half a kiloton. Now, everybody said, well, that's a crude weapon. Well, I like to think of it in terms of rider trucks... a 500 kiloton nuclear explosion is a very serious matter.” (32:47–33:59)
  • Uranium-based bombs described as “pretty straightforward to make a workable nuclear weapon.” (33:59)

Dirty Bombs and Terrorist Threats

• Clarifies what a “dirty bomb” is:
  • “What a dirty bomb is is that somebody goes into a hospital and gets a bunch of radioactive waste and sticks a high explosive around it... But that's not a nuclear weapon.” (37:32)
  • Suggests the main risk is from fissile material theft and states: “If a very well organized terrorist organization could buy the fissile material, then they could probably assemble it into a weapon.” (38:35)

State vs. Non-State Proliferation

• To build a “real” nuclear weapon requires a nation-state’s resources, but assembled bombs are plausible if fissile material is acquired illicitly (38:45–39:33).
• “There's a lot of this stuff floating around. I mean the Russians have tons and tons of fissile stuff. And how well is that guarded?” (39:33)

Proliferation Outlook

• Bernstein’s prediction for the next 50 years:
  • “In terms of proliferation, I think it's worrisome because a lot of crazy countries are now talking about getting nuclear weapons.” (36:32)
  • Finds North Korean partial disarmament encouraging, but is pessimistic overall, especially regarding Iran and the irrelevance of sanctions (36:32–37:32).

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Memorable Quotes & Notable Moments

• On Oppenheimer:
  • “He was always the smartest boy in the class. And this lasted throughout his entire life.” (04:32)
• On witnessing a nuclear blast:
  • “A sight which can't get out of your mind. Current horizon was a livid fireball rising with colors of orange, red. A terrible, awesome, monstrous thing.” (21:56)
• On proliferation and ease of weapon-making:
  • “Making a crude weapon… it's pretty straightforward to make a workable nuclear weapon. And I don't think you have to have a lot of great technical skills.” (33:59)
• On Iran:
  • “They have to be stopped. Although I don't know how to do that. I think that the Israelis will do it.” (29:59)

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Additional Insights and Ironies

• The “Plumbob” anecdote:
  • U.S. nuclear testers may have unintentionally launched the first human-made object into outer space—a manhole cover propelled by a test blast (41:28).
• The surreal juxtaposition:
  • Everyday life amid extinction-level tools: “This guy found this high explosion. She's knitting. It looked like a sweater... What a metaphor, man.” (28:21)

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Timestamps for Key Segments

• Oppenheimer and Los Alamos: 02:45–07:14
• Tom Lehrer’s satirical nuclear song: 08:30–09:32
• The South African nuclear program explained: 09:59–14:50
• Bernstein’s experience at Los Alamos and test site: 16:04–26:32
• Nuclear test witness, blast description: 21:56
• Audience Q&A on proliferation, Iran, Israel, dirty bombs: 29:20–41:28
• Manhole cover in space; ending anecdote: 41:28–42:37

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Tone and Style

Bernstein blends technical clarity, dry wit, and gentle self-deprecation, illuminating the moral complexity and persistent dangers posed by nuclear weapons:

“It's a very jolly way to end one of the most downrous of all the species. Thank you very much.” (42:37)

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For listeners curious about the human stories behind nuclear arms, the psychology of scientists, and the ongoing challenges of global armament, this episode is a sobering, insightful, and surprisingly entertaining journey through history and technical detail.

Transcript

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[C]

Welcome to the New Books Network.

[E]

Welcome to the New York Institute for the Humanities Podcast. I'm El Leo. In today's episode from the Vault, we revisit a 2007 presentation by Theoretical physicist and Institute fellow Jeremy Bernstein on J. Robert Oppenheimer, the atomic bomb, and and the nuclear arms race that followed. As a physicist, Bernstein made contributions to elementary particle physics and cosmology, working at institutions like the Institute for Advanced Study in Princeton, New York University, and Stevens Institute of Technology, where he became professor emeritus in 1967. Bernstein was a staff writer for the New Yorker for over three decades. He wrote regularly for the New York Review of Books, the Atlantic Monthly, and Scientific American, and authored over two dozen books, including Oppenheimer Portrait of an Enigma. He passed away on April 20, 2025, at the age of 95. Here he is in 2007, discussing the topics on which he made a great contribution and helped illuminate.

[C]

Let me Begin by telling you a couple of Oppenheimer. I would say that the fact that we got the atomic bomb in time to use it during the war. Was due partly to Oppenheimer's genius. And partly to General Groves. Anglophobia. I will explain that Anglophobia part in a minute. But people say that at Los Alamos. There were all these Nobel Prize winners and so on. Actually, there weren't all those Nobel Prize winners. I only could count actual Nobel Prize winners. At Los Alamos, maybe three or four. But what there were were future Nobel Prize winners. That was the part that was really amazing. There were just slews and slews of future Nobel Prize winners. Going all the way from Norman Ramsey, who's in his 90s, still going strong. Roy Glauber, who was the second youngest person of the technical staff at Los alamos. He was 18 when he went to Los Alamos in 1943. The second youngest. The youngest was his college roommate, Ted Hall. Who turned out to be one of the three Russian spies. The other spies were David Gold and, of course, Klaus Fuchs. Who turned over to the Russians the blueprint for, basically for the Nagasaki bomb. So there were all these incredibly brilliant people there. But Bethe, who was then not a Nobel Prize winner. Won a Nobel Prize afterwards. Always said that Oppenheimer was intellectually superior to everybody. He had the capacity of making instantaneous understanding of things. You'd get a sentence out, and he could fill out the whole paragraph. And he had everything in his head. He had all the details of the lab in his head. And he was always the smartest boy in the class. And this lasted throughout his entire life. And the anecdote I want to tell you has to do with Act 1963. He was giving a lecture at the National Book awards, spring of 1963. Which he called the Added Cubit. And he went to Columbia before he gave the lecture. To see his dear old friend Robbie. Who was the older brother that Oppie didn't ever have. With whom he could talk very straight. And when he was at Columbia, he was going around and asking everybody. I'm giving you a lecture called the Added Cubit. Can you tell me where it comes from? And of course, nobody could tell him where it came from. And he didn't say where it came from. Mal Ruderman, who was a professor at Columbia. Called me and said. Abenor has been around this morning. And he's asking everybody about this title, the Added Cubit. Do you know where it came from? I know where it came from, but I knew Where I could find out where it came from. I could call Robert Merton, because I knew he knew everything.

So I called Merton. I said, there's this lecture, blah, blah, blah. And Merton said, immediately Matthew 6, 2, 7.

When if you, by taking thought, can adjust the cubic to the added cubic, his stature, whatever, blah, blah, stature. You can't add to your stature by thinking about the cubic. That's the essence of it. Put, of course, in King James language. And I stored that piece of information away in my head, thinking I would tell Ruderman the next time I saw him. So if you ever were to be asked the question again, he could answer. Now. That very evening, as was my wont, in those days, when I just started writing for the New Yorker, a lot of us would gather at the Algonquin after hours, New Young writers, to commiserate about the latest atrocity William Shawn had pulled on us. I walk in the Algonquin, the elevator door opens, and out walks Oppenheimer and his wife, Kitty. He sees me and he says, I'm giving a lecture tonight called the Added Cubit. You should know this because your father is a rabbi. Now, there was a bit of not sequitur here, because it was the wrong testament, but I did not get into an argument. I just simply gave the answer. And he looked at me very strangely, and I never explained. A few years later, he died. He died in February of 67. And there was a very beautiful memorial at Princeton. It was on a very cold February day.

Many of us who had known him were invited to go out there. It was an impressive collection of speakers. And Bethes spoke and George Kennan spoke, Smyth spoke. Smyth actually never much liked Oppenheimer, but he felt that there was such an injustice with what happened to him during the McCarthy period. He spoke the Juilliard String Quartet.

And on the program it said that the music had been selected by George Balanchine. Now, there's a story there, which I don't have time to tell you, but that's a whole other story. But Oppenheimer was being, you know, the good host, even at the end. Afterwards, there was a reception at the Institute. Everybody was there, including Frank Oppenheimer, whom I knew he was Oppie's younger brother. He made the terrible mistake of going into physics and done. But I took the opportunity of asking Frank because I knew that at the Trinity test in July, where they tested the first bomb, I knew that Frank had been sitting next to his brother. And I wanted to know what Oppie said when it went off, because there's various things about the Bhagavad Gita. And one thing Frank said, what he said was it worked and God did it work. Then a clone was dropped on Nagasaki about a month later and the war was over. So those are the Oppenheimer anecdotes. Now I want to play a song because I think every lecture a nuclear weapon should have a song. And I think it should probably have this song.

[F]

First we got the bomb and that was good cause we love peace and motherhood. Then Russia got the bomb but that's okay we because the balance of power is maintained that way. Who's next?

France got the bomb but don't you grieve cause they're on our side. I believe China got the bomb but have no fears they can't wipe us out for at least five years. Who's next?

Haben Indonesia claim that they were gonna get one any day. South Africa wants two. That's right. One for the black and one for the white. Who's next?

Egypt's gonna get one too just to use on you know who. So Israel's getting tense, wants one in self defense. The Lord's our shepherd says the psalm but just in case we better get a bomb.

[C]

Who's next indeed. Tom was a very old friend of mine and he said that he been looking for something to replace Alabama and I suggested Hugo Chavez. He thought that was a little too now. So we compromised in Venezuela. But the South African one, we made a change here. The first part of it Tom put in. Japan will have its own device, all digital at half the price.

And then you remember South Africa wants two. That's right. One for the black, one for the white. Tom wrote his song in 1965. And in 1969 the South Africans began a nuclear program. They first said that they were going to use it for things like digging harbors. It was sort of like Henry Tellerson about plowshares. But after the Russians and their surrogates got into Angola, they said it was for deterrence. They were not kidding around. Let me tell you a little bit about the South African program because there are a lot of lessons to be learned from it. In the first place, the key thing in any nuclear weapons program is having the fissile material. There's a difference between something being fissionable and something being fissile. Something's fissionable. If you whack it with a neutron which is energetic enough, it splits, gives off more neutrons. Something that's fissile will split with a neutron of any energy and to make a weapon, you need a fissile nucleus. And the fissile nuclei that are important are isotope uranium 235 and the isotope plutonium 239.

Fortunately for all of us, plutonium does not exist as a natural element. It has to be made in reactors. So you have to have a whole reactor program make it. And the uranium you get out of a mine contains only a Small fraction of 235. Less than a percent. So you have to do something to change the percentage from less than a % to the 90% that's needed to make a weapon. So this brings up the whole issue of enrichment. And the South Africans used a method of enrichment which no other country ever used. It was a kind of centrifuge, except it wasn't exactly a centrifuge, but worked on the same principles. They made enough uranium 235 to manufacture six uranium bombs. They were what's called a gun assembly type, which is you take two subcritical masses, literally, usually in the bore of a cannon, you fire one against the other. When they conjoin, they become critical, then supercritical. Then the chain reaction starts, and you have the explosion. It's important to realize that all the nuclear energy in a nuclear weapons explosion is produced in a microsecond. All the activity happens in a microsecond. It's very fast. After the microsecond temperatures are produced, which are comparable to the interior temperature of the sun. Millions and millions of degrees. So the South Africans made enough of the stuff to make six nuclear weapons. And they were in the process of making seventh. When De Klerk in 1989, decided that they were going to abandon the program. There were a lot of things that he said about joining the world order and blah, blah, blah. So instructed to recall that Mandela was going to be let out in 1990. And the idea of giving the African Congress six nuclear weapons, I think did not sit very well with the departing white government. They abandoned the program. And then they had international inspectors who came to help them dismantle it. And dismantling one of these programs is not a trivial business. It took them four years to dismantle their program. I was in contact with a guy who directed their program at the end. Has a wonderful Afrikaans name of Waldo Stumpf. And Waldo swears that the South Africans never tested anywhere. But they had test facilities. So they had to destroy the test facilities. Then they had to deal with the uranium. What they claim is that they melted the uranium down. So it can never be Used for bombs again. And I emailed Waldo and I said, well, how much uranium did you have? He said, well, I can't tell you. It's a state secret. You can kind of figure it out because each other, each of these bombs required about 50 kilograms. So they had seven of them. That's 350 kilograms. I would figure that at least 400 kilograms of the stuff. That's a lot. So I said, what did you do with it? He said, well, we use some of it to fuel the safari reactor. They have a reactor which they're making medical isotopes. It's a big business in South Africa and the rest are under international guardianship. Nonetheless, after these years, there was still a resident of the program. This has to do with the Pakistani metallurgist Ekyu Khan, who came back to Pakistan with the plans for the modern ultracentrifuge and became the founding father of the Pakistani nuclear weapons program and then opened a supermarket for selling nuclear material. He actually had an office in Dubai and there was a price list. You would go and you just pick out what you wanted. And he sold the full menu to Gaddafi that included the centrifuges, uranium hexafluoride, which you put in the centrifuges plans for making the nuclear weapon. Once you had the stuff for a few hundred million dollars, and then Gaddafi decided to give it up. Before he decided to do that, he wanted stuff to be delivered. Now, Khan did not have material on hand. He just had this supermarket going in Dubai. So he outsourced the centrifuge stuff to a company in South Africa called Tradefin, which was run by a guy called Johann Meyer. Meyer's position is what centrifuges. All I know is that we sent a few tubes to Libya. He changed his tune when he was arrested in 2003, but that was his story. Tradefin still exists. They have a website. I email them periodically and ask whether they're still selling centrifuges. For some reason, they never answered the email. Now, in the time that remains, I want to tell you a little bit about my brief but very intense experience with nuclear weapons. In 1957.

After I've been a postdoc at Harvard for a couple of years.

Somebody suggested that I might like a summer job at Los Alamos as a summer intern. I don't know who suggested. It was probably Ken Bainbridge, who was chairman of the department, who had been in charge of the test site at Alamogordo where the first bomb, the gadget, was tested In July of 45 Bainbridge notoriously went over to Oppenheimer after the test and said to him, now we're all sons of pitches. And I suspect that it was Bainbridge who suggested that I be offered this job. I was very interested. I was curious. All these people around me had been to Los Alamos, and I'd read a lot about it. I was just curious to go. Just basic animal curiosity. You had to get a Q clearance, which was the fanciest clearance that the FBI offered. I just looked at what I filled out for them. You had to put everywhere you lived your whole life. I just looked at it recently, and they're places I live. Swear I never set foot in, but you have to write all these things out. And I had a great Aunt May, and I always hoped for the sake of the party. She wasn't a member, but she did subscribe to the Daily Worker and spoke darkly about the bosses. I think she was referring to her husband, who was a dentist. I thought, God, if the FBI finds out about Aunt May, I'll never get to Moss. They couldn't find out about Klaus Fuchs, nor could they find out about Ted Hall. They never found another one, Aunt May. And in some way that I don't remember, I got to Los Alamos. I don't know how I did. I didn't have a car, whether I took the train. There was no direct air flight. I don't really remember how I got there, nor do I remember what I did when I did get there. The place was really a closed city in 57, much more so than during the war. Because during the war, nobody but the people of Los Alamos and the Russians knew what was going on up there. But at 57, everybody knew what was going on up there. So the place was really closed, very tight. And I was assigned a room in a dormitory that was left over from the Second War. Really crummy dormitory. Then went to the T Division. And I had a friend, also postdoc from Harvard, was there, and we worked on a problem in elementary particle physics all summer. I had nothing to do with any weapons whatever. Everybody around us working on nuclear weapons. Everything was classified. There was a big need to know. You didn't need to know. Nobody told you. And we were working away. Toward the end of the summer, we produced a paper, and the head of the theory division, Carson Martin, was very pleased with us because he thought it was very nice to suddenly come out of Los Alamos was not weapons related. And then I made a great friend, a physicist called Francis Lowe. And Francis and I played a lot of tennis.

We played every week the end of the summer. Francis said, well, I can't play next week because I'm going to Mercury, Nevada to see bomb tests. I said, what? I didn't know you were working on weapons. He said, no, I'm not working on weapons. But Carson, Mark asked me, I'd like to see some bomb tests. I was curious. Yeah, I'd like to see some bomb test. He said, well, geez, can I see the bomb test? And he said, well, you have to go ask Carson. So I went to see Carson Park. As I said, he kind of liked what I thought. He said, yes, you can go and see them, providing you pay your own way, some airfares involved. Okay, fine. Carson had enough pool so he could command a light plane leaving from Postman Stamp airfield in Los Alamos, thanks to Albuquerque. And we flew to Santa Fe. We flew to Las Vegas. The Test site was 65 miles from Las Vegas. What do they say about Las Vegas? What happens here stays here. Well, I can tell you what happened in Mercury did not stay there. The fallout went all over the world. It said, tested that one summer, said to have induced 38,000 cases of thyroid cancer. So I can tell you that what was happening in Mercury did not stay Mercury. We got off the plane and I was very much under this aegis of need to know. It was very clear to me, without anybody saying to me anything, that you better not ask any questions because you don't need to know. Got off the plane, were met by a government car, taken immediately to a casino. It turned out that a mathematician the previous year had shown that if you played his system, you could beat casino blackjack in its spare time. The mainframe computer at Los Alamos, running millions of blackjack heads at night to show the system worked. And you were given a little white car which said, if the dealer shows this, you do that, you double down. So we all had little white cars. We all went to the casino, played blackjack. Max Frankel, the New York Times, was an atomic soldier. I'll tell you what that means. What it means is that a few years earlier he'd been detested as a soldier. Been marched up to ground zero, as these soldiers were. And he said he played a lot of blackjack. He feared he lost him up $10 during the period. They had a blue light which went on, which indicated the test was on the next day. One got a little sleep. Then about 4:30 quarter five, Carson got us up and we went over to a place where they had the local weatherman and the weatherman said he liked the winds. So a test was postponed. But at about 25 after 5, the test was on. Began counting down. And we were given very heavy dark things to put over our glasses. We were told to turn away from the direction of the explosion. The bomb was on a 700 foot tower. You could see the tower from where we were, I don't know how many miles, maybe four or five miles. We were told to turn around. We counted down to 10. Then there was a very bright flash reflected. And then we were told we could count 10 and turn around.

When I counted 10 and turned around, I saw a sight which can't get out of your mind. Current horizon was a livid fireball rising with colors of orange, red. A terrible, awesome, monstrous thing. And behind it the whole mountain of Joshua plants had lit up. So it was like some incredible pagan rite with this flame and all these Joshua plants illuminated. The next thing that happened was somewhat painful click in my ears. I didn't understand exactly what that was because I didn't know anything about the technology. Then there was an explosion and there was a noisy explosion at the Alamogordo test. The Times there was a pool correspondent, William L. Lawrence, and he had trouble. Oppenheimer assigned Feynman to him. So Feynman was his shepherd.

The test came, same sequence, and Lawrence, hearing the noise, said, what's that? And everybody has cited that as proof that Lawrence was a scientific boob. But it's actually a very good question involving the sequence of effects in the bomb dynamics. First the expanding fireball, then a shockwave comes out. The shockwave is supersonic and so it would arise first in the shockwave there was a wind which knocked down the chemist George Kissiot, Kisikovsky et al. Magoro. He was five miles away. It knocked him over and it produced a windstorm. The shockwave at Hiroshima was 250 miles an hour and knocked over all the cooking stoves, which is what caused the firestorm in Hiroshima. Then the mushroom cloud. And the mushroom cloud was not what I expected because I'd seen these pictures of these white mushroom clouds here one saw the bottom step because the mushroom cloud is the rising fireball like a blue, which is pulling up beneath it earth off the desert. So there's a black stem and then this sort of adder like thing hovering over us. And I didn't know what direction it was going to go. If it had come in our direction, we would have gone inside, went some other direction, probably to Las Vegas. Then we got some sleep and then heard the sound of helicopters. And I said to Carson, I said, they're flying. And Carson said, yes, they're flying and flying. I didn't know what they were flying. Oh, I forgot, though, to mention the soldiers and the helicopters. The test that I saw, which was called Smokey, I saw two tests, Smokey and Galileo. The Livermore tests were named after mountains, and the Los Alamos tests were named after scientists. And the test I saw them preparing was Galileo.

Los Alamos test, Livermore test was called Smoking. That was part of what was called Operation Plumb Bomb. And from May of that year till the following October, there were 29 explosions in Nevada. And at the particular test that I saw, they marched 3,000 soldiers to ground zero after the explosion to acclimatize them for what a nuclear war would be like. And that to fight one. These people had followed over the years. There's a book called Atomic Soldiers. As I said, Max Frackel, the New York Times guy, was one of them. A few years earlier, those people had health problems. They had higher than normal leukemia rates, that kind of thing. So they had health problems. But on the brief exposure that I had, I didn't have any problems. Then Carson took us on a tour, and the first place we went.

Was the tower where they were assembling the bomb for the test for the next day. It was 500ft, and then there was an open lift. It went up 500ft. And then the last part was a kind of ladder. I remember.

Goosebumps. Thinking about going up the ladder. I was not so much concerned about the bomb. I was concerned about the ladder. At the top of the ladder, there were several technicians who were assembling this bomb. And I heard the clacking of. I knew what the clacking was because I'd been in the cyclotron lab. I knew that was cryogenic. They were freezing. I didn't know why.

Then he went down. Then Carson took us to a very nondescript concrete blockhouse. No explanation.

Walked in. I looked around. I couldn't believe what I was seeing. On the shelves were the pits. Those are the spherical centerpieces of nuclear weapons. All of them lined up on shelves enough to destroy a continent. I was, I remember, pretty shocked. I remember moving back toward the door. I remember Francis was saying to me, moving back a couple of steps is not going to help if it goes off. Carson, observing this performance, picked one off the shelf and handed it to me, saying, don't drop this. So I was holding this plutonium pit, which is a little bit warm to the touch, about the size and weight of a bowling ball. If I had known anything, the question I would have asked is, why is it so light? Because plutonium is 16 times as dense as water. If something like this had been solid plutonium, it would have weighed several hundred pounds. And the question I should have asked, I wouldn't have gotten an answer, probably would have been arrested, is why is this so light? The answer is because it's hollow. Next question is, what do you put inside it? And then the answer is, you put inside it isotopes of hydrogen. And that's what the cryogenics were about. What was being tested were not pure fission weapons, but what are called boosted weapons, which consist of a mixture of fission fusion. So 65 miles from Las Vegas, they were testing miniature hydrogen bombs.

Then there was a table, and at the table there was a guy who was filing on pieces of high explosives that looked sort of like cheese. What they did is they had wedges of high explosives which they put around the plutonium pit, glued them in with great precision. They had to be all hand machined. Next to them was a woman.

Knitting.

In ice water. God, this is the way the world ends. This guy found this high explosion. She's knitting. It looked like a sweater. My recollection was green wool. Even then having a bit of a literary bent, you know, it's one of these things you could. What a metaphor, man. Later I wrote about some of this for the New Yorker and the checkers checked with Francis and Francis said, he's inveter then. Oh, there was no woman there made it up. So I wrote to Carson Mark and I said, Carson. Well, he didn't remember the. Said there were couples that worked at Mercury and maybe it was. And I then went to the checkers and I said, look, this one's on me. She was there. About a week before the thing went to press, I get a phone call from Frances saying, you're right, she was there. Well, I can tell you more, but I'm glad to answer.

[G]

Questions. If you can speculate about this.

[C]

I'd be very curious to.

[G]

Know. When you hear about discussions about.

[C]

Whether Iran will get the bomb, what does that arouse? I am quite certain that they're working to get it. I am quite certain that they have a cascade of 3,000 centrifuges. The way it's configured now does not make highly enriched uranium, makes lightly enriched uranium. The 4% enrichment which their cascade makes is what you need to run a power reactor. But once you have the 4%, to go from 4% to 90% is much easier than going from the 1% to the 4%. So the way that proliferation works, first you'd make enough 4% stuff to make a bomb and then you enrich it to 90%. Now we don't know whether the Iranians have secret enrichment sites. We don't know that almost by definition we do know they have one non secret site in Natanz, which is Isfahan, the city of the Blue Mosque. If all the lightly enriched uranium which they could make in a year were then enriched up to 90%, then they would have enough material for one weapon if it were well designed. But they want to go up to 50,000 centrifuges. If they have 50,000 centrifuges, they'll have enough material for several weapons a year. So I think they have to be stopped. Although I don't know how to do that. I think that the Israelis will do it. For better or worse. Yes. I'm asking what do you know about.

The beans were spilled because of this guy Vanunu? They must have several hundred. I think they were self produced. The French helped out in the beginning. The French helped make Dimona. Whether the French gave the Israelis the plans for the weapons, I don't know. The Israeli weapons are presumably plutonium because that's what you want the reactor for. I know they have tritium because they sold it to the South Africans. So they have tritium and deuterium. So they probably boosted nuclear weapons. Whether they ever tested is an interesting question. And that has to do with what's called the Vela incident, which has to do with a satellite that thought it might have detected something which people thought might be an Israeli test. Most people think that was not an Israeli test. They probably have not tested. On the other hand, the Hiroshima bomb was never tested either. I'm not sure that the testing of the full device is necessary if the parts have been tested. How many they have, I don't know. I once met Netano at a party before he was Netano. It's like saying you knew Doris Day before she was a virgin. I was introduced to him as a physicist and somebody he might like to talk to. But whatever. What he told me was this. He said if our back is errato the wall, we will use. That's a declared policy. The declared policy. 73 War the hangars were open, right? Right, Right. I don't think they'll let the Iranians have a weapon. I mean, look what they did in Syria a few weeks ago. They flattened what was presumably the beginning of a reactor. Is this technology.

Now well understood.

[G]

Enough that it doesn't take the kind of expertise it would have taken, say, the same 60s to make bombs. Is it something that's almost standardized in a.

[C]

Way? Yes. Making a crude weapon. And we have to be clear what's meant by a crude weapon. The North Koreans tested the device and they got a half a kiloton. Now, everybody said, well, that's a crude weapon. Well, I like to think of it in terms of rider trucks.

Timothy McVeigh had a rider truck full of high explosives, and he had two and a half tons. So a kiloton is what? 400 rider trucks? One kiloton. And this dud that the North Koreans tested was 500 kilotons. That's 500 times 400, which is some number of rider trucks. I cannot calculate in my head when people are talking about duds. To a weapons designer, this was a dud. To a person, a 500 kiloton nuclear explosion is a very serious matter given the fissile material, especially uranium. Plutonium is a harder material to deal with. Plutonium needed different technology with uranium. I think that it's pretty straightforward to make a workable nuclear weapon. And I don't think you have to have a lot of great technical.

[H]

Skills. I thought the eeriest thing about the story you told about seeing the test was the affectlessness on the part of everybody but yourself. In the story that is, your own fear came across really strongly. But what I'm wondering is, now looking back on it, since maybe you didn't ask yourself this at the time, what was Carson's motive in taking you and Francis there? I mean, did he want you to be frightened? Or was it just scientific knowledge that he was proudly sharing what was going on in human.

[C]

Him? In that case, I think he was giving Francis a treat. In my case, I asked and he agreed. Also have to understand a little the mindset. This was the middle of the Cold War. The weapons labs were very, very active. They were recruiting. They were working very hard. They had just made the hydrogen bombs. It was a very serious thing. And at Los Alamos, everybody around them was working on weapons. Jeremy, is it conceivable that ways could be devised that could prevent the changing of 4 to 90? The only way to stop that is to do something to interfere with the enrichment process. The enrichment process now of choice is that of the centrifuge. There are a variety of different ways, but what's Used now is the centrifuge, rather than destroying the centrifuge. I don't know of any. I don't know of any. Is it even theoretically possible?

Well, you have to. Maybe it's just a stupid question. No, it's not a stupid question, but you have to think of what the sequence is.

You get uranium out of a mine.

I didn't say this about the South Africans, but Valdo confirmed the following. The only South Africans who were allowed to work on the weapon itself were South Africans who had been born in South Africa. South Africans who were not born in South Africa were allowed to work on things peripheral to the weapons. For the weapons themselves, we didn't have to know the secrets of the weapons themselves. And black South Africans were allowed to dig the uranium. So out of the mine comes natural uranium, which is less than 1% of Uranium 235. If you don't want it to be enriched, then you don't give it to somebody who has enrichment facilities. Once you have an enrichment facility, cascades of centrifuges. Unless you stop the centrifuges, pretty hard to stop the thing from being.

[G]

Enriched. What thinks going to happen over the next 50 years in terms of.

[C]

Proliferation? In terms of proliferation, I think it's worrisome because a lot of crazy countries are not talking about getting nuclear weapons. The Egyptians, Venezuela. When I suggested Hugo Chavez, Tal said, well, it's a little too now. And then a couple of weeks later, Hugo Chavez went to Russia and started talking about making nuclear weapons. The Saudis are making noises. It is encouraging with North Koreans. They seem to be giving up the stuff. We don't know what they have. We know that A. Q Khan was active over there. We know he traded centrifuges for missiles. The Pakistani missiles are all North Korean missiles. He traded the Chinese for plans for the bomb. So we don't really know what the North Koreans have. Whether they have a centrifuge program, we don't know. But there are people now who are dismantling the reactor, so that's encouraging. The Iranians seem absolutely determined. And sanctions, Christ, I mean, the price of oil is $100 a barrel. What do you mean, sanctions?

I mean, they can buy and sell us. I have a question. What about the likelihood of what people call dirty bombs in the hands of terrorists and so forth? What's called a dirty bomb in that particular genre is not a nuclear weapon. What a dirty bomb is is that somebody goes into a hospital and gets a bunch of radioactive waste and sticks a high explosive around it, explodes it in the radioactive waste, goes all over the place. That would scare a lot of people. But it's not a very effective weapon. You just stay indoors for a couple of days, you're fine. It could happen. But that's not a nuclear weapon. Is it the case that nuclear weapons by the very nature, how they need to be developed and the money and the manpower and the equipment that really you need a nation state to be able to. What you need is somebody to produce the fissile material. If a very well organized terrorist organization could buy the fissile material, then they could probably assemble it into a weapon. The difficult stage is to get enough fissile material for uranium 235, you need about 50 kilograms. It's a little over 100 pounds of uranium 235. It's a pretty small size. It's like this 100 pounds of uranium. It's very dense, it's about 19 grams per cc. It's very dense. Just need about that much. So that's what you have to try to stop. But then they're kind of big and you have to deliver them somehow. Yes, but you could deliver pretty sizable bomb in a Rider truck. We have these Star Warian things about shooting this stuff. That's not what the issue is. The issue is that somebody smuggles something in a container, sticks it in a Rider truck, you know, so on and so on. There's a lot of this stuff floating around. I mean the Russians have tons and tons of fissile stuff. And how well is that guarded? We have a program, the Nunn Luger act has a program which we buy some stuff from the Russians, you know, but there are a lot of Russian technicians who are looking for work. And I think the North Koreans were selling, I think they were selling to the Syrians. That's what this reactor was about. The situation in Pakistan, of course, very scary because they have these weapons. And if Musharraf goes and is replaced by the mad people, I don't know what happens. But over the long run aren't.

[G]

The issue's much more game theoretic and about incentives? In other words, it's not at all surprising that Iran is seeking a nuclear weapon. It would almost be irrational for them not to. And during the days of the Shah there, there was even talk of Iran getting nuclear weapons. And the American attitude was a little more friendly towards that idea. I mean, regimes change, but national interests remain somewhat.

[C]

Stable. If the Iranians had a more congenial government and they wanted to work on nuclear energy, and they were willing to abide by their commitments to the international agencies. You have a different feeling about it. They're not congenial. They're not willing to abide by their commitments. They're doing many things in secret. And some of the things they're doing that we know about can only be explained if they're trying to make a weapon. You can argue that enriching uranium has a dual use, but they're also making spheres. That is only one use, and that use is to make it an implosion bomb. That's the only use for that. I think it was last week that Dennis and I here had a discussion in which Dennis said, everybody should have one. The Irish, and we should all have them, and so on. Well, you got to see one of them. People think of sort of this as a continuum. You start with a firecracker and hand grenade, but it's not a continuum. It's a quantum leap. I just wanted to perhaps end with.

A little story about that test series, the Plumbob. During the Plumb Bob series, they had all kinds of tests. They tested from balloons. They tested from caves. They tested, as we saw, from the two towers. They did one test which I described, boys will be boys test. The only thing I could think of is when we were kids growing up in Rochester, New York, on the 4th of July, we would take a firecracker, put it in a can, close the can, light the firecracker, stand back and see what would happen. And then, of course, the can go flying over the place. Very satisfying. What they did at Plumb Bob is they dug a shaft and they put on top of it a manhole, basically a large manhole. Put the bomb down there and blew it off. They calculated that the manhole would go off with something greater than the escape velocity for leaving the Earth, otherwise going to orbit. And nobody knows what happened because nobody's ever ready to find a manhole. The manhole disappeared. They did this a couple of months before Sputnik. And if it actually is in outer space, it was the first extraterrestrial.

It's a very jolly way to end one of the most downrous of all the species. Thank you very much.

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