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Personal speculation: without John von Neumann's contributions to the Plutonium bomb, there's a good chance we would not have hydrogen bombs to this day. Here's

Personal speculation: without John von Neumann's contributions to the Plutonium bomb, there's a good chance we would not have hydrogen bombs to this day. Here's why: the US had already had a feasible bomb design, the Uranium-235 based bomb, that was dropped at Hiroshima. Not only that, but it had an alternative to the Plutonium bomb too, the U-233 bomb. Glenn Seaborg, the guy who discovered Plutonium and a bunch of other elements, was tasked with doing a feasibility study of a bomb with U-233. He found out it can be done, and sure enough, a few years after the war the US build such a bomb and tested it. It was not done because the Plutonium bomb became possible (with von Neumann's help). But again, if von Neumann had decided to spend his time on other problems, then the US could have focused on the U-233 bomb instead. This leaves us at the end of the war, when the Soviets decided to steal the secret and build their own bomb. Stalin decided they'll build an exact replica of the Nagasaki bomb, which they did and tested in 1949. If only U-233 and U-235 were on the table, they would have picked one of those, rather than explored an uncertain design. From uranium bombs to boosted uranium bombs there's a small step. So the world would have seen much bigger bombs than the ones dropped on Japan. Fission bombs were built and tested that got close to one megaton. But the hydrogen bomb is fundamentally an implosion bomb. The hydrogen bomb was a side-effect of the deeper understanding of the implosion design. In particular, the US figured out that if you can do implosion with conventional explosives, you can do it even better with nuclear explosives, so it designed and tested a two stage fission bomb, the Castle Nectar bomb. It's the only non-thermonuclear bomb ever detonated that had a yield above 1 MT (it was 1.8 MT). The research into this two-stage bomb is what Ulam was doing, and he told Teller that maybe what works for a second stage that is a fission bomb could work for a second stage that's a fusion bomb. Teller added his own insights, and eventually it was done.

philwelch 3y ago
Wikipedia claims that Von Neumann and Klaus Fuchs also had a preliminary design for a hydrogen bomb that also used the implosion bomb as a first stage, though in a different way than the Teller-Ulam design. Fuchs leaked the Neumann-Fuchs design to the Soviets along with everything else, but just like the US, the Soviets set it aside and independently came up with the Teller-Ulam design instead. So it would seem that, despite Teller and Ulam winning out, Von Neumann was still deeply involved in hydrogen bomb development beyond simply developing the prerequisite plutonium implosion bomb.
- refset 3y ago
  > Von Neumann was still deeply involved in hydrogen bomb development beyond simply developing the prerequisite plutonium implosion bomb This. https://en.wikipedia.org/wiki/John_von_Neumann https://en.wikipedia.org/wiki/John_von_Neumann > In 1955, von Neumann became a commissioner of the Atomic Energy Commission (AEC) > He used this position to further the production of compact hydrogen bombs suitable for intercontinental ballistic missile (ICBM) delivery > He was adamant that H-bombs delivered deep into enemy territory by an ICBM would be the most effective weapon possible It seems much of his life was dedicated to applying Game Theory.
barelyauser 3y ago
This is an absurd take, to say the least. It offends the intelligence of virtually everyone involved in the bomb development. Plutonium usefulness would be noticed eventually. Implosion of fusion fuel using X-Rays thermal transport would have been discovered as well. The world does not have a single point of failure based on a single person, like you paint it.
- silverquiet 3y ago
  Absurd isn't really the word I would use. I think it's more of a naive/common misconception about how science advances. People tend to think of a single genius making breakthroughs when in fact a lot of ideas were building on prior work and in collaboration with others; essentially the ideas eventually have their time, and you get a sense that the specific people who discovered them, while impressive, are a bit of a historical detail rather than an essential ingredient. To me, the biggest example would be evolution - Darwin was famous for it, but you will find others speculating about it before him, and famously he sat on his work and only published it once Alfred Russel Wallace was about to independently publish his discovery of the same phenomena "Connections" by James Burke is a wonderful documentary that first helped me to really understand this.
- credit_guy 3y ago
  Slow down a bit. First: it took many years for the Ulam-Teller design to be discovered. Teller came up with the idea of a fusion bomb in 1942. The actual Ulam-Teller design was invented in March 1951, basically 9 years later. In this 9 years, for at least 2 years, people were searching frantically for a workable design. It's very easy to say, after the fact, that "X-Rays thermal transport would have been discovered as well" because we know this is what worked in the end. But before the fact, nobody was looking for X-Ray implosion. Second: During WW2, plutonium was considered superior to uranium because it was cheaper to manufacture. U-235 was being manufactured via a very expensive separation process. But U-233 can be bred in a thorium reactor just like Plutonium is bred in a uranium reactor. They both come with their challenges (U-232 for U-233, Pu-240 for Pu-239), but in a scenario where the Manhattan project did not figure the implosion design in a hurry, the US would have shifted the resources to U-233. Here's a quote from wikipedia [1] > A declassified 1966 memo from the US nuclear program stated that uranium-233 has been shown to be highly satisfactory as a weapons material, though it was only superior to plutonium in rare circumstances. It was claimed that if the existing weapons were based on uranium-233 instead of plutonium-239, Livermore would not be interested in switching to plutonium. Now, I have no doubts that fission boosting would have been discovered. But with fission boosting, bombs would have gotten to the 1 MT yield, and that is plenty destructive for all war scenarios. Crucially, such a weapon did not need to use any type of implosion. In a scenario where the US does not develop the implosion knowledge because it can build a 1 MT weapon without, then it is not at all a given that someone else would have looked for an implosion-based design of a thermonuclear weapon. We would still have had the layer-cake design, but that is not a game changer, and it's not clear that the extra yield was worth the extra complexity. Now, in today's world: Most of US's nukes have yields around 100 kT [2]. They are thermonuclear but the same effect can be achieved with (boosted) fission bombs. The largest current US nuke, the B83, has a yield of 1.2 MT, but the US is looking to retire it, and replace it with B61, with a maximum yield of 400 kT. My point is that a superpower can service all its deterrence needs with nuclear weapons with yields that are achievable with boosted fission. Why did we then go and build thermonuclear monster bombs in the 50's and 60's? Because at the time the ICBM precision was limited, and you needed something with a mile-sized fireball to make up for the lack of precision. But the ICBM technology advanced at an incredible pace. If we had been 10 years late coming with the design for a thermonuclear bomb, it would not have been needed at all. Yet another thing is this: the destructive power of a nuke does not grow linearly with its yield. Ten bombs with a 100 kT yield are more destructive than on single bomb with a 1 MT yield. Oppenheimer knew that, and advised the US to focus on more rather than bigger. He was not listened to, and the US build both more and bigger. But we do know that you can devastate the world with 100 kT bombs, just as much as you can devastate it with 1 MT bombs. [1] https://en.wikipedia.org/wiki/Uranium-233#Weapon_material https://en.wikipedia.org/wiki/Uranium-233#Weapon_material [2] https://en.wikipedia.org/wiki/W76 https://en.wikipedia.org/wiki/W76
dilyevsky 3y ago
Implosion design would have been worked out eventually with JN or not. Computer models make this a lot easier and they probably could have gotten there even without via trial and error.
- Animats 3y ago
  There was a lot of trial and error involved. Huge numbers of explosive tests were made out in the desert. A technique was developed of taking X-ray movies of implosions to see what was going on in there.
  - dilyevsky 3y ago
    It think x-ray were early tests and later they switched to ionization chambers with a La-140 radioactive source aka RaLa experiments[0]. Wiki says they conducted a total of 254 tests which is huge amount of work but hardly huge number of tests. Guessing if they had to determine the shape and composition of charges experimentally, it would've probably taken thousands of tests and a few more years. [0] - https://en.wikipedia.org/wiki/RaLa_Experiment https://en.wikipedia.org/wiki/RaLa_Experiment
temporarely 3y ago
> the Soviets decided to steal the secret Did they decide or was it gifted to them? My speculation is that USSR supported creation of Israel as a quid pro quo.

philwelch 3y ago

Wikipedia claims that Von Neumann and Klaus Fuchs also had a preliminary design for a hydrogen bomb that also used the implosion bomb as a first stage, though in a different way than the Teller-Ulam design. Fuchs leaked the Neumann-Fuchs design to the Soviets along with everything else, but just like the US, the Soviets set it aside and independently came up with the Teller-Ulam design instead. So it would seem that, despite Teller and Ulam winning out, Von Neumann was still deeply involved in hydrogen bomb development beyond simply developing the prerequisite plutonium implosion bomb.

refset 3y ago
> Von Neumann was still deeply involved in hydrogen bomb development beyond simply developing the prerequisite plutonium implosion bomb This. https://en.wikipedia.org/wiki/John_von_Neumann https://en.wikipedia.org/wiki/John_von_Neumann > In 1955, von Neumann became a commissioner of the Atomic Energy Commission (AEC) > He used this position to further the production of compact hydrogen bombs suitable for intercontinental ballistic missile (ICBM) delivery > He was adamant that H-bombs delivered deep into enemy territory by an ICBM would be the most effective weapon possible It seems much of his life was dedicated to applying Game Theory.

barelyauser 3y ago

This is an absurd take, to say the least. It offends the intelligence of virtually everyone involved in the bomb development. Plutonium usefulness would be noticed eventually. Implosion of fusion fuel using X-Rays thermal transport would have been discovered as well. The world does not have a single point of failure based on a single person, like you paint it.

silverquiet 3y ago
Absurd isn't really the word I would use. I think it's more of a naive/common misconception about how science advances. People tend to think of a single genius making breakthroughs when in fact a lot of ideas were building on prior work and in collaboration with others; essentially the ideas eventually have their time, and you get a sense that the specific people who discovered them, while impressive, are a bit of a historical detail rather than an essential ingredient. To me, the biggest example would be evolution - Darwin was famous for it, but you will find others speculating about it before him, and famously he sat on his work and only published it once Alfred Russel Wallace was about to independently publish his discovery of the same phenomena "Connections" by James Burke is a wonderful documentary that first helped me to really understand this.
credit_guy 3y ago
Slow down a bit. First: it took many years for the Ulam-Teller design to be discovered. Teller came up with the idea of a fusion bomb in 1942. The actual Ulam-Teller design was invented in March 1951, basically 9 years later. In this 9 years, for at least 2 years, people were searching frantically for a workable design. It's very easy to say, after the fact, that "X-Rays thermal transport would have been discovered as well" because we know this is what worked in the end. But before the fact, nobody was looking for X-Ray implosion. Second: During WW2, plutonium was considered superior to uranium because it was cheaper to manufacture. U-235 was being manufactured via a very expensive separation process. But U-233 can be bred in a thorium reactor just like Plutonium is bred in a uranium reactor. They both come with their challenges (U-232 for U-233, Pu-240 for Pu-239), but in a scenario where the Manhattan project did not figure the implosion design in a hurry, the US would have shifted the resources to U-233. Here's a quote from wikipedia [1] > A declassified 1966 memo from the US nuclear program stated that uranium-233 has been shown to be highly satisfactory as a weapons material, though it was only superior to plutonium in rare circumstances. It was claimed that if the existing weapons were based on uranium-233 instead of plutonium-239, Livermore would not be interested in switching to plutonium. Now, I have no doubts that fission boosting would have been discovered. But with fission boosting, bombs would have gotten to the 1 MT yield, and that is plenty destructive for all war scenarios. Crucially, such a weapon did not need to use any type of implosion. In a scenario where the US does not develop the implosion knowledge because it can build a 1 MT weapon without, then it is not at all a given that someone else would have looked for an implosion-based design of a thermonuclear weapon. We would still have had the layer-cake design, but that is not a game changer, and it's not clear that the extra yield was worth the extra complexity. Now, in today's world: Most of US's nukes have yields around 100 kT [2]. They are thermonuclear but the same effect can be achieved with (boosted) fission bombs. The largest current US nuke, the B83, has a yield of 1.2 MT, but the US is looking to retire it, and replace it with B61, with a maximum yield of 400 kT. My point is that a superpower can service all its deterrence needs with nuclear weapons with yields that are achievable with boosted fission. Why did we then go and build thermonuclear monster bombs in the 50's and 60's? Because at the time the ICBM precision was limited, and you needed something with a mile-sized fireball to make up for the lack of precision. But the ICBM technology advanced at an incredible pace. If we had been 10 years late coming with the design for a thermonuclear bomb, it would not have been needed at all. Yet another thing is this: the destructive power of a nuke does not grow linearly with its yield. Ten bombs with a 100 kT yield are more destructive than on single bomb with a 1 MT yield. Oppenheimer knew that, and advised the US to focus on more rather than bigger. He was not listened to, and the US build both more and bigger. But we do know that you can devastate the world with 100 kT bombs, just as much as you can devastate it with 1 MT bombs. [1] https://en.wikipedia.org/wiki/Uranium-233#Weapon_material https://en.wikipedia.org/wiki/Uranium-233#Weapon_material [2] https://en.wikipedia.org/wiki/W76 https://en.wikipedia.org/wiki/W76

dilyevsky 3y ago

Implosion design would have been worked out eventually with JN or not. Computer models make this a lot easier and they probably could have gotten there even without via trial and error.

Animats 3y ago
There was a lot of trial and error involved. Huge numbers of explosive tests were made out in the desert. A technique was developed of taking X-ray movies of implosions to see what was going on in there.
- dilyevsky 3y ago
  It think x-ray were early tests and later they switched to ionization chambers with a La-140 radioactive source aka RaLa experiments[0]. Wiki says they conducted a total of 254 tests which is huge amount of work but hardly huge number of tests. Guessing if they had to determine the shape and composition of charges experimentally, it would've probably taken thousands of tests and a few more years. [0] - https://en.wikipedia.org/wiki/RaLa_Experiment https://en.wikipedia.org/wiki/RaLa_Experiment

temporarely 3y ago

> the Soviets decided to steal the secret Did they decide or was it gifted to them? My speculation is that USSR supported creation of Israel as a quid pro quo.