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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
The simplest, quickest, and surest means to becoming known as a virtuous person is to work on yourself, to actually be virtuous. Examine each virtue, and you will see that they all were achieved with work and exercise. —SOCRATES
A Calendar of Wisdom
Leo Tolstoy and Peter Sekirin
Over the last few days, I have been able to see my life as from a great altitude, as a sort of landscape, and with a deepening sense of the connection of all its parts. This does not mean I am finished with life. On the contrary, I feel intensely alive, and I want and hope in the time that remains to deepen my friendships, to say farewell to those I love, to write more, to travel if I have the strength, to achieve new levels of understanding and insight. This will involve audacity, clarity, and plain speaking; trying to straighten my accounts with the world. But there will be time, too, for some fun (and even some silliness, as well). I feel a sudden clear focus and perspective. There is no time for anything inessential.
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