Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Reflections on "Making the Atomic Bomb", published by boazbarak on August 17, 2023 on LessWrong.

[Cross posted on windowsontheory; see here for my prior writings]

[it appears almost certain that in the immediate future, it would be] possible to set up a nuclear chain reaction in a large mass of uranium by which vast amounts of power and large quantities of new radium-like elements would be generated.- Letter from Albert Einstein (prepared by Leo Szilard) to F.D. Roosevelt, August 1939

Do you know, Josef Vassarionovich, what main argument has been advanced against uranium? "It would be too good if the problem could be solved. Nature seldom proves favorable to man." - Letter from Georgi Flerov to Joseph Stalin, April 1942.

I've heard great things about Richard Rhodes' "The Making of the Atomic Bomb." Finally, on vacation, I managed to read it. (Pro-tip: buy the Kindle version - the hard copy is far too big to lug around.) It's as great as people say. Can't recommend it enough. I can't remember when, if ever, I've read a book that combines so well popular science and history. Indeed, the Atomic bomb is the one setting where the precise details of the smallest particles have profoundly impacted human history.

Here are some quick thoughts after reading the book. (Warning: spoilers below for people who don't know how WWII ended.)

The level of investment in the Manhattan Project was truly staggering.

I knew it but didn't fully grasp this. This is not just the numbers ($2B, which was almost 1 percent of GDP at the time) but also the project's sheer size, employing more than 100,000 people, and the massive construction of buildings, factories, and roads at multiple sites. As just one example, when they didn't have enough copper, the treasury department lent the project 15,000 tons of silver to be used in the electromagnetic separation plant (to be later melted and returned after the war).

Much of this cost was due to the compressed schedule.

The staggering cost was mainly due to the need to get the bomb done in time to use in the war. Time and again, whenever the project faced a choice between approaches A, B, or C, they chose to pursue all three in parallel, so if two failed, they could still go ahead. Whenever there was a choice between saving money or time, they opted for the latter. The fact that the cost was primarily due to time is also evidenced by the fact that, following the war, many countries could set up their own atomic bomb programs or reach the threshold of doing so at a much lower cost.

This seems to be a general principle in technological innovation: the cost of achieving a new advance decreases exponentially in time. Thus, achieving X transitions over time from being impossible to being inevitable. This is related to Bill Gates' famous quote that in technology, we tend to overestimate progress in two years and underestimate progress in ten years.

The Manhattan Project was trying to achieve the Atomic bomb just at the cusp of it being possible. The project got going when General Groves was appointed (September 1942), and it took a little less than three years until the successful test (July 1945). Of course, they could have started much earlier: Einstein and Szilard sent their famous letter to Roosevelt in August 1939. The "impossible vs. inevitable" phenomenon is manifested in another way. The U.S. drastically underestimated how long it would take for the Soviet Union to achieve the bomb (even considering the Soviet advantages due to spying, which the Americans should at least have partially anticipated as well).

The government fully trusted the scientists on the science.

The project was authorized primarily based on pen and paper calculations. At the time the project was approved, no chain reaction had been demonstrated, and the total quantity of Uranium 23...