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Then a member of the newly arrived British mission made a proposal that paid his mission’s way. James L. Tuck was a tall, rumpled Cherwell protégé from Oxford who had worked in England developing shaped charges for armor-piercing shells. A shaped charge is a charge of high explosive arranged in such a way—usually hollowed out like an empty ice cream cone with the open end pointed forward—that its normally divergent, bubble-shaped shock wave converges into a high-speed jet. Such a ferocious jet can punch its way through the thick armor of a tank to spray death inside. It had just become clear from theoretical work that the several diverging shock waves produced by multiple detonators in Neddermeyer’s experiments reinforced each other where they collided and produced points of high pressure; such pressure nodes in turn caused the jets and irregularities that spoiled the implosion. Rather than continue trying to smooth out a colliding collection of divergent shock waves, Tuck sensibly proposed that the laboratory consider designing an arrangement of explosives that would produce a converging wave to begin with, fitting the shock wave to the shape it needed to squeeze. Such explosive arrangements were called lenses by analogy with optical lenses that similarly focus light. No one wanted to tackle anything so complex so late in the war. Geoffrey Taylor, the British hydrodynamicist, arrived in May to offer further insight into the problem. He had developed an understanding of what came to be called Raleigh-Taylor instabilities, instabilities formed at the boundaries between materials. Accelerate heavy material against light material, he demonstrated mathematically, and the boundary between the two will be stable. But accelerate light material against heavy material and the boundary between the two will be unstable and turbulent, causing the two materials to mix in ways extremely difficult to predict. High explosive was light compared to tamper. All of the tamper materials under consideration except uranium were significantly lighter than plutonium.
Making of the Atomic Bomb
Richard Rhodes
It is still a fairly astounding notion to consider that atoms are mostly empty space, and that the solidity we experience all around us is an illusion. When two objects come together in the real world—billiard balls are most often used for illustration—they don't actually strike each other. “Rather,” as Timothy Ferris explains, “the negatively charged fields of the two balls repel each other . . . were it not for their electrical charges they could, like galaxies, pass right through each other unscathed.” When you sit in a chair, you are not actually sitting there, but levitating above it at a height of one angstrom (a hundred millionth of a centimeter),
A Short History of Nearly Everything
Bill Bryson
Chinese office workers can be annoying in the way they carefully dole out job‐related information, and sometimes even the most innocent of questions is treated with great caution. During a holiday period, I asked one woman who worked in an American client's office when the office would return to work. “Is everyone back on Tuesday?” I asked. “Is that what you heard?” she responded. This was common treatment in China. The woman did not wish to contradict something that a coworker might have said. Years ago, in my own office, I had such issues with communication. “Do you have the file on that plywood?” I asked a colleague. “File?” she responded. “Yes,” I said. “The plywood file.” “Plywood?” she asked. She had been working on nothing else for two weeks, so the reference was clear. Thinking that perhaps I had been mumbling, I clearly enunciated my words this time. “Yes, the file on plywood.” It took me years to work out that this was no more than a delay tactic. While I was asking (and repeating) my benign question, the office worker's head was spinning: Why is he requesting the file? Why now? Is this a trap? Does he suspect something wrong with my work? Should I buy time and review the data? Maybe the information is good and he will make the faux pas of complimenting me in front of my colleagues, who already despise me for my diligence. He seems the sort who would make that kind of mistake. What if my colleagues become envious? Better to appear reluctant to hand over the file at least, just in case. Like Deep Blue working out its next chess move, she was running scenarios and calculating odds.
What's Wrong With China
Paul Midler
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