[HN Gopher] What John von Neumann Did at Los Alamos (2020)
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What John von Neumann Did at Los Alamos (2020)
Author : fanf2
Score : 58 points
Date : 2024-04-07 16:42 UTC (6 hours ago)
(HTM) web link (3quarksdaily.com)
(TXT) w3m dump (3quarksdaily.com)
| credit_guy wrote:
| 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 wrote:
| 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.
| 082349872349872 wrote:
| see also https://en.wikipedia.org/wiki/Klara_Dan_von_Neumann
|
| Lagniappe: http://anappendage.blogspot.com/2010/02/autofac-by-
| phillip-k...
| ChrisArchitect wrote:
| (2020)
|
| Some discussion then:
| https://news.ycombinator.com/item?id=28673376
| literallycancer wrote:
| I like how in the thread from 2021 all the Westerners still
| think Russia/the Soviets are normal and proposing a first
| strike before they acquire their own bomb is somehow incorrect.
| nmwnmw wrote:
| Highly recommend The Man from the Future: The Visionary Life of
| John von Neumann by Ananyo Bhattacharya. Talks about this time
| plus many of his other contributions to e.g. game theory.
| surprisetalk wrote:
| If you're looking for a dramatic, fictionalized biography of Von
| Neumann and surrounding characters, I highly recommend The
| MANIAC:
|
| https://bookshop.org/p/books/the-maniac-benjamin-labatut/196...
| jonplackett wrote:
| I'm curious, since I never studied maths past A level.
|
| Is there a difference to the way it's taught now compared to
| whenever von Neumann was studying.
|
| What I mean is, the way I was taught maths and science in general
| was with a feeling of "look we basically know everything just
| learn this and you'll be fine".
|
| Rather than that there are MASSIVE open questions and things we
| don't understand at all. Please learn maths and physics and fix
| them, will you?
|
| I'm basically curious how a fairly young person gets into their
| head a thought like "Hey, why don't I just revolutionise a few
| things? That seems totally reasonable for me to do that."
| tekla wrote:
| Some people just seem to be born with the gift and are simply
| better.
|
| I recommend reading about Srinivasa Ramanujan
|
| https://en.wikipedia.org/wiki/Srinivasa_Ramanujan
| jonplackett wrote:
| This is fascinating. Thanks for sharing.
| mycologos wrote:
| Ramanujan is an interesting comparison. He was an outstanding
| mathematician, but it feels like his prowess came from a deep
| love of math and concomitant time spent on it. There's an
| anecdote somewhere about child Ramanujan working his way
| through thousands of elementary lemmas for fun, and I wonder
| if this gave him the almost occult intuitive ability reported
| by his collaborators. The stories about him have a tone of
| awe, but not fear.
|
| In some contrast, von Neumann seems to have been able to take
| his enormous fluid intelligence and speed and apply it to
| pretty much whatever problem he decided, and he did it across
| many areas, including non-scientific ones. The stories about
| him are tinged with a little unease, and it's a little harder
| to see the human underneath his achievements.
| chpatrick wrote:
| https://en.wikipedia.org/wiki/The_Martians_(scientists)
|
| There was an incredible cadre of scientists from Hungary in the
| early 20th century. Sadly they were exiled by fascism.
| javajosh wrote:
| One wonders what fascism could have done had it not alienated
| intellectuals. But one also wonders if that alienation is
| core to fascism, even definitive. Fascism is notoriously hard
| to define, but "alienates the best thinkers" seems like a
| good litmus test.
| mhh__ wrote:
| It's hard to imagine von Neumann not being great today (I think
| some stories are probably made up, but he was obviously in the
| top 1 minds of his era), but it is probably true that the
| "easy" stuff has been mined - where I would define easy as
| things that can stem from an application of brains around the
| coffee table rather than intense application of years of
| whittling at the conference stage.
| randcraw wrote:
| BTW, the author of this piece is an amazing writer. The rest of
| his blog and the blog roll at 3quarksdaily are worth a closer
| look.
| RcouF1uZ4gsC wrote:
| von Neumann was the genius's genius.
|
| Even the people a at Los Alamos had a suspicion that von Neumann
| operated on a different level from themselves.
|
| From wikipedia:
|
| Nobel Laureate Hans Bethe said "I have sometimes wondered whether
| a brain like von Neumann's does not indicate a species superior
| to that of man".[29] Edward Teller observed "von Neumann would
| carry on a conversation with my 3-year-old son, and the two of
| them would talk as equals, and I sometimes wondered if he used
| the same principle when he talked to the rest of us."
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