Boron contamination of graphite also slowed the Manhattan Project:
"
Fermi writes that "The results of this experiment was [sic] somewhat discouraging" presumably because of the absorption of neutrons by some unknown impurity. So, in December 1940 Fermi and Szilard met with Herbert G. MacPherson and V. C. Hamister at National Carbon to discuss the possible existence of impurities in graphite. During this conversation it became clear that minute quantities of boron impurities were the source of the problem.
"
Sounds like a good time travel story: the mission is to go back in time and plant a single uranium cube, to be found ~80 years hence, to convince people that the German bomb project was doomed so that– ahh, but let's not spoil it! :)
Clickbait antidote: The cubes revealed only that the uranium was a bit less dense than textbook values because of tiny internal voids.
That measurement fed a computer model, but if I'm reading the article right, most of the work was actually based on wartime records on heavy water and graphite. Anyway, the model showed they would have needed twice the uranium and heavy water they actually had.
IIRC, US Colonel Hogan got Luftwaffe Colonel Klink to drink a bunch of that heavy water as a cure for baldness as a truckful of it transited through Stalag 13.
Phew, that underground mission was more important than I thought!
Since Norsk Hydro was mentioned in the article, I have to mention in turn one of my favorite books ever: The Winter Fortress by Neil Bascomb. It's the true story of the Norwegian commando sabotage of the heavy water plant. Short version: after a failed attempt by the English, some locals who'd fled to England and received training parachuted in, blew it up, and then skied to neutral Sweden. Legends, the lot of them: they froze their balls off and didn't have enough to eat, but they pulled it off.
Every time I re-read it, it makes me want to take up nordic skiing. It is absolutely up there on my list of greatest true stories ever told with Touching the Void, The Emerald Mile, and a select few others.
This story is also covered in The Bastard Brigade, which details many other Allied attempts to sabotage the Germany nuclear program. Fun fact: Heisenberg was close to being assassinated by a famous baseball player (Mo Berg). Very entertaining and interesting book.
As a snowboarder I was reluctant, but got into it a few years ago. We pull our young daughter in a chariot with skis about 10km into a little cabin by a river with a wood stove.
Cheese, salami and hot chocolate and we make the return loop. Three evenings a week all winter long is a great way to spend time outside.
Building a reactor was a step on the way to building a bomb.
Two isotopes were used for fission bombs in WWII: Uranium 235 and Plutonium. More than 99% of naturally occurring Uranium is Uranium 238, which will not sustain a chain reaction necessary for a bomb. There are only trace amounts of Plutonium in nature, but it can be produced in reactors that use U238 for fuel. So, to make a fission bomb you need to either separate U235 from U238 or build a reactor to create Plutonium.
It's worth noting that the shortage of heavy water was no accident. The Allies sabotaged the heavy water production facility in Norway that Germany relied on[1].
In the context of the time, those US scientists that built a reactor were all in for nuclear energy and absolutely 100% did not think that a nuclear weapon was economically feasible.
"Economically feasible" meaning maybe, perhaps, theoretically possible but even if so astronomically expensive in time, money, and physical resources.
It took the UK/CA/AU Tube Alloys group to find ways to make a weapon more practical, and multiple letters, attempts, and a one on one press the flesh tour to convince the US nuclear types that a weapon was both possible and achievable.
If you go to the Los Alamos Science Museum you can see an original letter from Albert Einstein where he proposed that a nuclear bomb could be fit on a ship and sailed into harbor in 1938. A ship-sized nuclear bomb was not of interest to President Roosevelt at the time for a likely good reason. It's only when the UK realized that it wasn't a ship size. It was something that you could drop from a conventional airplane bomber of the day that the US became interested.
Seen it, read it, and aware of why it was ignored at the time - the ability to make such a weapon, as relayed by Einstein, was a hearsay tale of speculation.
Some time later Mark Oliphant visited the US in person and walked key people through a circles and arrows on chalkboard breakdown of how such a thing would be actually possible.
It was also a failure of imagination. A ship sized tsar bomba at the time would still be quite interesting - armor the ship like a Iowa class (or more), and give it an automated navigator (very doable at the time, plus or minus a mile or two), and it’s a war ender.
Wait until the wind is right, add some of the right contaminants, and you wouldn’t need to do so to poison all of Germany for at least a generation.
Also, Tokyo Bay.
For the Axis powers, it would be an even easier sell of course.
At least if any of them could believe - or even imagine - that it actually could exist or be as devastating as it was of course. And frankly, unless you saw the footage of an actual Tsar Bomba, how could anyone?
Footage of the actual Tsar Bomba has no scale, detonating as it did high up in the atmosphere - for anyone watching it might have been a really big or really small explosion.
For the first bomb ever made to immediately jump to Tsar Bomba size, or for it to utilise an understanding of fallout and contaminants that didn't exist prior to the Castle Bravo tests seems ... unlikely.
In general the take was that human created nuclear weapons were infeasible (regardless of design) because of what was thought to be the barrier to cross to achieve a chain reaction.
The Frisch–Peierls memorandum changed that understanding ... provided that reading of the FP-memorandum was convincingly conveyed to people that made things happen, what Einstein put to paper (and was ignored) and that Oliphant pushed through in person.
Little Boy on Hiroshima was a gun design, a grossly inefficient McGyver that used some 64 kilograms of enriched uranium to successfully convert less than half a gram to energy.
Fat Man on Nagasaki was an implosion device - a necessary design change due to simply not having enough uranium or an enrichment pipeline to sustain the needs of a gun design.
The first device detonated, at Trinity in the USofA, was an implosion device, created to test the more difficult design.
Further, there was an abandoned / discarded "Thin Man" device IIRC.
These were all alternative implementations that were pursued after the FP-memorandum was pushed about to make the case that weapons were apparently possible rather than not yet achievable - the prevailing belief in the US prior to Oliphant doing the rounds.
As I said above - and perhaps you might like to try a primary source rather than wikipedia ?
These weapons were, however, as different as their monikers imply. Little Boy was a uranium, gun-type weapon, whereas Fat Man was a plutonium, implosion-style weapon. Two types were needed because there was only enough uranium for one gun-type weapon, and the U.S. government knew it would need to make more than one weapon.
Awesome article and interesting to see Heisenberg get it wrong. It really was a perfect situation for the US because we could get all the radioactive material with little issue.
A clean reminder that logistics is everything.
Also cool that the author is married to Sean Carroll.
It mega-helped that Edgar Sengier saw the importance of uranium ore and shipped 1200 tons of it out of the Congo to New York before the U.S. government even realized it would need it.
Relatively recently, recordings were released of conversations between captured Nazi scientists held at a house in the UK (I think I saw it on HN). They were housed together and the house was bugged purposely to capture casual conversation for intelligence purposes.
IIRC one conclusion they/some of the scientists drew was that the culture of the Nazi regime - the paranoia, fear, and violence - made a project on that scale impossible. Enough talented, high-ego people could not work together on project that large and demanding.
Also, IIRC, when the Hiroshima bomb was announced, many couldn't believe it. They had been working on a power generation reactor as a first step - though I'm not sure the OP fits that story?
Also, maybe Heisenberg didn't want to succeed? Has that ever been resolved to some degree?
The sheer economic costs of the manhattan project were prohibitive to a nation like Germany, even if they'd managed to build a functional project team.
(how many nations had 14,700 tons of silver lying around)
A nation like Germany on the cusp of losing a war sure. The opposite scenario of Germany controlling all the resources of Europe and Africa is a scary proposition.
> The opposite scenario of Germany controlling all the resources of Europe and Africa is a scary proposition.
It shouldn't be. In WW2, in 1942, Germany did essentially control all of Europe, save only the UK. And at the height of its power, Germany's vast industrial machine produced roughly on par with the UK. Not the entire British Empire, just UK.
It turns out that the Nazis were complete incompetent buffoons when it came to economic management. Their grand master plan for Europe was to overrun the east, not for some vast rich treasure trove of minerals to fuel an industrial juggernaut, but to plop down more homesteads to feed their inefficient agricultural economy. And even if the Nazis had a grand plan to become an industrial juggernaut, they still faced the prospect of the industrial juggernaut par excellence, the US.
I don't believe the silver was strictly necessary. Copper windings would have worked for the calutron. Silver was used because copper was not as easily available at the time. But the point is valid. The project was originally British, moved to the US for economic reasons.
> one conclusion they/some of the scientists drew was that the culture of the Nazi regime - the paranoia, fear, and violence - made a project on that scale impossible
This makes me think about the pervasive classification and paranoia in the "defense" contractors supporting the US Department of "Defense". Any information that's classified, even at the lowest "confidential" level, is only provided on a "need-to-know" basis. And unclassified projects are sort of looked down on, so there's a perverse incentive to classify more than necessary. This "secretive, isolationist approach" seems like it probably prevents a lot of groups from "sharing information or resources", in the article's words (though it concludes that wasn't the biggest problem facing the German effort).
When sharing classified information that someone might not need to know might be a crime, and might get your clearance pulled even if it's not, the incentives run strongly counter to sharing information. Consequently, I confidently claim that there are very, very few people in a position to serendipitously make significant discoveries that involve combining two or three different classified facts.
(I don't actually know this, because I don't know any classified facts.)
Maybe this is part of the sclerosis that causes the US defense-industrial complex to "basically produce useless junk", in the words of Les Earnest (https://www.youtube.com/watch?v=Ych6pvLMKCU), and which prompts Sergey Tovkach to say, "There isn’t a single Western drone that’s proven itself effective in this conflict." (https://www.youtube.com/watch?v=RmfNUM2CbbM). Maybe that's why Russian propaganda in 02024 reported that Ukraine had to withdraw the USA-made M1A1 tanks far from the front (https://www.youtube.com/watch?v=aCIN-t3VxJ0).
> Also, maybe Heisenberg didn't want to succeed? Has that ever been resolved to some degree?
From the Farm Hall transcripts, it seems that Heisenberg was "happy" to have been working on a reactor and not a bomb, but from context, this seems less like an objection to the principle of working on a weapon and more like gratitude that the Allies couldn't hang him for working on an atomic bomb. Recall that the conversations took place after Germany had been utterly defeated and the scientists were prisoners at the mercy of the British--prisoners in a gilded cage, but prisoners nonetheless.
" Fermi writes that "The results of this experiment was [sic] somewhat discouraging" presumably because of the absorption of neutrons by some unknown impurity. So, in December 1940 Fermi and Szilard met with Herbert G. MacPherson and V. C. Hamister at National Carbon to discuss the possible existence of impurities in graphite. During this conversation it became clear that minute quantities of boron impurities were the source of the problem. "
https://en.wikipedia.org/wiki/Nuclear_graphite
That measurement fed a computer model, but if I'm reading the article right, most of the work was actually based on wartime records on heavy water and graphite. Anyway, the model showed they would have needed twice the uranium and heavy water they actually had.
Phew, that underground mission was more important than I thought!
Every time I re-read it, it makes me want to take up nordic skiing. It is absolutely up there on my list of greatest true stories ever told with Touching the Void, The Emerald Mile, and a select few others.
https://www.abebooks.com/Winter-Fortress-Epic-Mission-Sabota...
[1] https://en.wikipedia.org/wiki/Kon-Tiki_expedition
As a snowboarder I was reluctant, but got into it a few years ago. We pull our young daughter in a chariot with skis about 10km into a little cabin by a river with a wood stove.
Cheese, salami and hot chocolate and we make the return loop. Three evenings a week all winter long is a great way to spend time outside.
The Germans tried to build a reactor, not a bomb, or am I wrong?
Two isotopes were used for fission bombs in WWII: Uranium 235 and Plutonium. More than 99% of naturally occurring Uranium is Uranium 238, which will not sustain a chain reaction necessary for a bomb. There are only trace amounts of Plutonium in nature, but it can be produced in reactors that use U238 for fuel. So, to make a fission bomb you need to either separate U235 from U238 or build a reactor to create Plutonium.
It's worth noting that the shortage of heavy water was no accident. The Allies sabotaged the heavy water production facility in Norway that Germany relied on[1].
________________________
[1]https://en.wikipedia.org/wiki/Norwegian_heavy_water_sabotage
[1] https://en.wikipedia.org/wiki/Chicago_Pile-1 [2] https://en.wikipedia.org/wiki/Hanford_Site
"Economically feasible" meaning maybe, perhaps, theoretically possible but even if so astronomically expensive in time, money, and physical resources.
It took the UK/CA/AU Tube Alloys group to find ways to make a weapon more practical, and multiple letters, attempts, and a one on one press the flesh tour to convince the US nuclear types that a weapon was both possible and achievable.
Some time later Mark Oliphant visited the US in person and walked key people through a circles and arrows on chalkboard breakdown of how such a thing would be actually possible.
Also, Tokyo Bay.
For the Axis powers, it would be an even easier sell of course.
At least if any of them could believe - or even imagine - that it actually could exist or be as devastating as it was of course. And frankly, unless you saw the footage of an actual Tsar Bomba, how could anyone?
For the first bomb ever made to immediately jump to Tsar Bomba size, or for it to utilise an understanding of fallout and contaminants that didn't exist prior to the Castle Bravo tests seems ... unlikely.
Were both judged infeasible for different reasons? Perhaps uranium purification challenges and the implosion required for plutonium?
The Frisch–Peierls memorandum changed that understanding ... provided that reading of the FP-memorandum was convincingly conveyed to people that made things happen, what Einstein put to paper (and was ignored) and that Oliphant pushed through in person.
Little Boy on Hiroshima was a gun design, a grossly inefficient McGyver that used some 64 kilograms of enriched uranium to successfully convert less than half a gram to energy.
Fat Man on Nagasaki was an implosion device - a necessary design change due to simply not having enough uranium or an enrichment pipeline to sustain the needs of a gun design.
The first device detonated, at Trinity in the USofA, was an implosion device, created to test the more difficult design.
Further, there was an abandoned / discarded "Thin Man" device IIRC.
These were all alternative implementations that were pursued after the FP-memorandum was pushed about to make the case that weapons were apparently possible rather than not yet achievable - the prevailing belief in the US prior to Oliphant doing the rounds.
[1] https://en.wikipedia.org/wiki/Thin_Man_(nuclear_bomb)
A clean reminder that logistics is everything.
Also cool that the author is married to Sean Carroll.
IIRC one conclusion they/some of the scientists drew was that the culture of the Nazi regime - the paranoia, fear, and violence - made a project on that scale impossible. Enough talented, high-ego people could not work together on project that large and demanding.
Also, IIRC, when the Hiroshima bomb was announced, many couldn't believe it. They had been working on a power generation reactor as a first step - though I'm not sure the OP fits that story?
Also, maybe Heisenberg didn't want to succeed? Has that ever been resolved to some degree?
(how many nations had 14,700 tons of silver lying around)
It shouldn't be. In WW2, in 1942, Germany did essentially control all of Europe, save only the UK. And at the height of its power, Germany's vast industrial machine produced roughly on par with the UK. Not the entire British Empire, just UK.
It turns out that the Nazis were complete incompetent buffoons when it came to economic management. Their grand master plan for Europe was to overrun the east, not for some vast rich treasure trove of minerals to fuel an industrial juggernaut, but to plop down more homesteads to feed their inefficient agricultural economy. And even if the Nazis had a grand plan to become an industrial juggernaut, they still faced the prospect of the industrial juggernaut par excellence, the US.
The war machine is what changed that - that and not being reachable by enemy bombers, and hence not bombed to bits.
Germany started middling and ended destroyed.
This makes me think about the pervasive classification and paranoia in the "defense" contractors supporting the US Department of "Defense". Any information that's classified, even at the lowest "confidential" level, is only provided on a "need-to-know" basis. And unclassified projects are sort of looked down on, so there's a perverse incentive to classify more than necessary. This "secretive, isolationist approach" seems like it probably prevents a lot of groups from "sharing information or resources", in the article's words (though it concludes that wasn't the biggest problem facing the German effort).
When sharing classified information that someone might not need to know might be a crime, and might get your clearance pulled even if it's not, the incentives run strongly counter to sharing information. Consequently, I confidently claim that there are very, very few people in a position to serendipitously make significant discoveries that involve combining two or three different classified facts.
(I don't actually know this, because I don't know any classified facts.)
Maybe this is part of the sclerosis that causes the US defense-industrial complex to "basically produce useless junk", in the words of Les Earnest (https://www.youtube.com/watch?v=Ych6pvLMKCU), and which prompts Sergey Tovkach to say, "There isn’t a single Western drone that’s proven itself effective in this conflict." (https://www.youtube.com/watch?v=RmfNUM2CbbM). Maybe that's why Russian propaganda in 02024 reported that Ukraine had to withdraw the USA-made M1A1 tanks far from the front (https://www.youtube.com/watch?v=aCIN-t3VxJ0).
See Anathem for more on this.
From the Farm Hall transcripts, it seems that Heisenberg was "happy" to have been working on a reactor and not a bomb, but from context, this seems less like an objection to the principle of working on a weapon and more like gratitude that the Allies couldn't hang him for working on an atomic bomb. Recall that the conversations took place after Germany had been utterly defeated and the scientists were prisoners at the mercy of the British--prisoners in a gilded cage, but prisoners nonetheless.