Comments by "Keit Hammleter" (@keithammleter3824) on "Why Einstein Thought Nuclear Weapons Were Impossible" video.

Gee this guy Veritasium talks nonsense. He said nuclear power is a knife edge situation, i.e., teetering on going bang. This clearly isn't so. For one, they are operated well below critical mass (There may be enough mass of the right isotope, but it is distributed over a large volume mixed with other stuff), so can't go bang. If you read anything about water moderated reactors, for example, you learn that water absorbs neutrons in proportion to its temperature, this means the reactor power level rises in beautiful proportion to control rod position (control rods are movable neutron absorbers), as increased reaction raises water temperature which slows down the reaction. It is a form of what is called a negative feedback loop. The control rods can typically control the reaction rate smoothly from beyond the design maximum down to a tiny fraction of that, practically zero. He said Einstein claimed nuclear power and bombs are not possible. Just when and where did Einstein say this? In what publication and in what context? I know that at one point he said it couldn't be done YET. Naturally it had to be figured out, which was not easy. Einstein famously wrote a letter to the US president to tell him that nuclear bombs are possible, and he better put resources into design and building one before an enemy does. Thus the Manhattan Project was begun. I have a book on Einstein that includes a reproduction of this letter. But Veritasium is the guy who posted a video claiming that electric energy is not transported in wires, and included a whole lot of mistaken nonsense about propagation in transmission lines, so perhaps his videos are some kind of leg pull.
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@langdalepaul He's posted other videos in which he gets things horribly wrong. He's the type of guy who reads a text book and thinks he understands the subject, but he doesn't have the training and experience. He recites, badly, old theories. A bit like a street cleaner reading a old book on brain surgery he found in the public library, and attempting to explain how its done without knowing medical knowledge has changed.
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@1over137 : It's very very difficult actually. Look at how long it took the boffins in the Manhattan Project to figure it out. The trouble is, with just two subcritical masses, at best you only get a few hundfed tonnes TNT equivalent, not the 20-30 thousand tonnes equivalent that the Manhattan Project produced for Japan, as it only converts a tiny fracttion of the uranium into energy. Much more likely is that you don't get the trigger explosion and timing just right, enough heat is generated to vaporise some of the uranium and the gas blows the masses apart again, and you just get a lot of radioactivity scattered about without the big bang. and the 2 bits of enriched uranium will put out enough neutrons to kill you. People think that nuclear bombs are 2 equal chunks of uranium forced together in a strong tube to get critical mass, not realising that was a decoy story published by the US just after the bombs were dropped on Japan - they had to give the public something. The real way uranium bombs worked (using a multitude of uranium pieces) remained secret until about 1980.
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