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You would jump through fire for Oppenheimer


Inside a nuclear bomb: the plutonium pit
Jeremy Bernstein Scientist
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As I said, it was about the size and weight of a bowling ball. Now, I was so ignorant; I sort of knew it was plutonium. I think I knew, maybe I didn't know but it was something like that. I was so ignorant that I did not ask the obvious question, which was why was it so light. A solid sphere, like a bowling ball of plutonium, would have weighed hundreds of pounds and I couldn't possibly have lifted it, but I could lift it and hold it in my hand. So the obvious question was, why was it so light? And if I had asked that question, I either would have been thrown out or certainly not given an answer. The answer was obviously that it was hollow, it was a hollow sphere of plutonium, and the next question was, why was it hollow? Well, it was hollow because they were testing one of those boosted weapons, which light hydrogen isotypes and the like are inserted in one form or another in the interior of the weapons, and when the pit is imploded and the fission begins then fusion is induced.

So you have… it's a mixture of a fission and a boosted device, in which there is fusion. It's not a proper hydrogen bomb, but it uses the same principle. And then this fusion produces a blast of energetic neutrons, which enhances the fission. So... it's a fusion-boosted device. That's what was being tested. Of course, I would not have been told that, I would have probably been sent away, but I didn't ask the question because I didn't know that was the question to ask.

Born in 1929, Jeremy Bernstein is an American physicist, educator and writer known for the clarity of his writing for the lay reader on the major issues of modern physics. After graduating from Harvard University, Bernstein worked at Harvard and at the Institute of Advanced Studies at Princeton. In 1962 he became an Associate Professor of Physics at New York University, and later a Professor of Physics at Stevens Institute of Technology in Hoboken, a position he continues to hold. He was also on the staff of The New Yorker magazine.

Listeners: Christopher Sykes

Christopher Sykes is an independent documentary producer who has made a number of films about science and scientists for BBC TV, Channel Four, and PBS.

Tags: plutonium, weapons, hydrogen isotopes, fission, fusion, hydrogen bomb

Duration: 1 minute, 59 seconds

Date story recorded: 15th June 2011

Date story went live: 08 September 2011