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. "

https://en.wikipedia.org/wiki/Nuclear_graphite

This is central to the plot of D: Heavy Water, Neal Stephenson's second installment of the Bomb Light Trilogy.

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.

https://www.abebooks.com/Winter-Fortress-Epic-Mission-Sabota...

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.

The obvious question to me is whether Heisenberg got it wrong on purpose.

Anyone interested in the bomb should read 'And the Devil Reached Towards the Sky, an oral history of the atomic bomb.'

It's full of fun anecdotes and asides...like when they 'found' tuns of uranium ore in NY...or the aforementioned acquisition of silver from Treasury.

There are classic bureaucratic things...like when they issued a check for millions and specified 'no questions asked.' Then the guy called with questions. Or how Groves' people and Treasury tried to figure out how many ounces were in a ton.

"As the German scientists were racing against time,"

The Germans tried to build a reactor, not a bomb, or am I wrong?

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.

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?

Why famous scientists supported Nazi regime? Aren't scientists supposed to be smart?