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Cosmic rays opposed to accelerators. Pair theory


Physics in the early 1930s. Discovery of the neutron
John Wheeler Scientist
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At that time, physics was, I would say, much simpler than it is today. Elementary particle physics was trivial compared to what it is now, with just a few particles and known behaviors. Condensed matter physics had not reached its present state of sophistication. Superconductivity still was to be explained. And the structure of atoms and molecules seemed a matter of detail, not of principle. No great principle had to be uncovered there. But the number one question at that time, to me, was nuclear physics; how did Neutrons and Protons in an atomic nucleus behave? This is something like condensed matter physics on a reduced scale; instead of the billions of particles in a solid area, you had maybe 100 or 200 or only four particles in an atomic nucleus. The forces were not so well known as those in condensed matter physics where it was simply electric force between an electron and a nucleus, but these neutrons and protons gave us a family of just two particles, and what would happen? Well, it was at this time that Artificial Radioactivity was discovered, inducing radioactivity by bombarding one particle with another. It was this time that the neutron was discovered. Already, while I was a graduate student at Johns Hopkins, the news came in about the discovery of the neutron. I feel very stupid because I gave one of the reports of our student seminars a summary of a paper in which something had been knocked on by something invisible. This was really the discovery of the neutron, but I didn't have sense enough to see that that's what it was. And neither did anybody else at that time. As soon as the neutron was discovered, all hell broke loose. I remember, my friend and graduate student colleague, Bob Murray, telling me with great amusement about somebody putting a source of neutrons in St. James' Park in London, and rowing away with a row boat and seeing if the detector could move faster than the particles. So nuclear physics, to me, looked like the doorway to learning new facts about nature. But you were- But I didn't see any great point of principle involved. It was more a question of figuring out what the Law of Force was and using existing principles then to predict what would happen.

John Wheeler, one of the world's most influential physicists, is best known for coining the term 'black holes', for his seminal contributions to the theories of quantum gravity and nuclear fission, as well as for his mind-stretching theories and writings on time, space and gravity.

Listeners: Ken Ford

Ken Ford took his Ph.D. at Princeton in 1953 and worked with Wheeler on a number of research projects, including research for the Hydrogen bomb. He was Professor of Physics at the University of California and Director of the American Institute of Physicists. He collaborated with John Wheeler in the writing of Wheeler's autobiography, 'Geons, Black Holes and Quantum Foam: A Life in Physics' (1998).

Duration: 4 minutes, 30 seconds

Date story recorded: December 1996

Date story went live: 24 January 2008