A wooden frame supported an elliptical-shaped structure, 20 feet high, 6 feet wide at the ends and 25 feet across the middle. It contained 6 short tons of uranium metal, 50 short tons of uranium oxide and 400 short tons of graphite, at an estimated cost of $2.7 million. According to Robert Crease, CP-1 and preceding piles were "the largest unbonded masonry structures since the pyramids.

On December 2, 1942, Fermi announced that the pile had gone critical at 15:25. Fermi switched the scale on the recorder to accommodate the rapidly increasing electric current from the boron trifluoride detector. He wanted to test the control circuits, but after 28 minutes, the alarm bells went off to notify everyone that the neutron flux had passed the preset safety level, and he ordered Zinn to release the zip. The reaction rapidly halted. The pile had run for about 4.5 minutes at about 0.5 watts. Wigner opened a bottle of Chianti, which they drank from paper cups.

This was an enormous undertaking in a relatively short amount of time, even during wartime. I can hardly fathom the scale and urgency of these operations. I suppose the Russians invested similarly massive resources to build their own A-bomb after the war.

Interestingly, it was believed at the time that German scientists were also very close to producing a nuclear weapon. As was later discovered after the war, they were not.

Behind that phrase is a whole story in itself, covered in the book "Wizards of Oz How Oliphant and Florey helped win the war and shape the modern world" by Brett Mason.

Mark Oliphant was heading a lab and tasked Otto Frisch and Rodolf Perierls with figuring out whether an atomic bomb was possible, as they were not cleared to work on radar. They concluded it was possible and wrote a two part memorandum: 'On the Construction of a "Super bomb"; based on a Nuclear Chain Reaction in Uranium' and 'Memorandum on the Properties of a Radioactive "Super-bomb"' [1,2]

Oliphant sent this report up the chain and it lead to the formation of the MAUD committee in the UK. The UK didn't have the resources to build an atomic bomb, so what was known was sent to the US. Oliphant hopped on a plane and did a tour of the US, doing technology transfer, mainly for radar, but also for an atomic bomb. Most people in the US ignored the MAUD report and Oliphant could not get traction on the atomic side. In desperation Oliphant breached security and briefed Ernest Lawrence who at the time was not cleared, also providing him with a summary of the MAUD report. Robert Oppenheimer joined the discussion between Oliphant and Lawrence. Lawrence phoned Arthur Compton in Chicago. From there the USA listened.

[1] https://web.stanford.edu/class/history5n/FPmemo.pdf

[2] https://en.wikipedia.org/wiki/Frisch%E2%80%93Peierls_memoran...

Nevertheless, I remember asking him what was it like to actually work on the project. He said that it was far less Hollywood-esque than many would imagine -- at least for him. He was just given math/engineering problems and was asked to solve them with no context. He never knew what he was truly working on, why he was working on these problems, etc.. The work was pretty isolating and contact was with others was pretty minimal. I do know that he met both Von Neumann and Oppenheimer on at least one occasion which is pretty awesome.

I wish I could find some records, but I do not even know where to look.

"Need 10+ years of experience in nuclear detonation device."

https://www.bbc.com/future/article/20250829-the-bomber-that-...

spoiler:

probably the biggest engineering problem was the explosive lens

>Because the field was so new, using only recently-discovered natural phenomena that were poorly understood, a great deal of effort was needed to resolve this uncertainty along numerous technological axes. Thus the Manhattan Project involved a large amount of trial and error experimentation, and of pursuing multiple paths of technological development —

>It’s this last difficulty that is most relevant for other technological development projects. Developing other technologies doesn’t necessarily require building enormous, industrial scale industrial facilities to even begin, and doesn’t necessarily require rapidly proceeding before the proper information and supporting technologies are available. But it will almost certainly require investigating various promising paths of development, partially-informed groping around until the right combination of methods and components is discovered. Indeed, this sort of exploration is the very essence of technological development.

>resolving this uncertainty, and figuring out what a technology should actually be, is hard. The Manhattan Project had some of the most brilliant scientific minds in the world working on it, but even with this collective brainpower it was far from clear what the best route to the bomb was.

>Not all technologies will require expensive physical facilities to produce, or require extremely rapid, expensive development. But resolving the uncertainty inherent in a new technology — figuring out what, exactly, the arrangement of phenomena needs to be to achieve some goal, and how that arrangement can be achieved — is part of the fundamental nature of creating a new technology.

Never thought this kind of approach would be allowed to fade so far from what it once was. Almost nobody is even trying to carry the torch any more.