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June 2 - 4, 1947: The Shelter Island Conference

Discussing physics informally (left to right): R. Feynman, H. Feshbach, J. Schwinger. Reprinted from Shelter Island II
Discussing physics informally (left to right): R. Feynman, H. Feshbach, J. Schwinger. Reprinted from Shelter Island II

In 1947, physics in America was just getting back to normal after the disruption of World War II. Duncan MacInnes, a physical chemist at the Rockefeller Institute, Karl K. Darrow, the permanent secretary of the American Physical Society, and others conceived the idea of organizing a series of small conferences to address the most important research questions of the day. The Shelter Island Conference was the first of these, and the main topic was the status of quantum electrodynamics (QED), the theory that describes the interaction of electrons with photons, and therefore underlies all of chemistry, atomic physics, and optics.

The rules of QED had been known since the early days of quantum mechanics, having been formulated by Fermi, Dirac and others. But it was also known that as soon as one went beyond the lowest order of perturbation theory, the predictions ceased to make sense, seemingly giving divergent answers for physical quantities. Physicists had wrestled with these issues during the thirties, and had largely put them aside during the wartime period. At the Shelter Island Conference, 24 scientists, most of them theoretical physicists, gathered to take serious stock of the situation.

The trip to the conference site was not uneventful. The meeting was to take place at the Ram's Head Inn on Shelter Island, located between the twin forks of Long Island. Most of the participants gathered on June 1 in Manhattan, and boarded a bus that then headed east. As it proceeded across Long Island, it was accosted by a police escort, which eventually led it to a restaurant where a banquet had been prepared for the scientists-a tribute organized by a member of the local chamber of commerce, who, having served in the Pacific during the war, felt that the atomic bomb had saved his life and wanted to express his gratitude. At that moment physics may have reached the apogee of its public reputation in this country.

The conference itself brought together established physicists who had made their reputations in the thirties, such as Bethe, Weisskopf, Rabi and Oppenheimer, together with the emerging stars of the next generation, like Feynman and Schwinger. Among the most interesting news was the report by Willis Lamb of his recent work at Columbia in which he had measured a tiny difference in energy between the 2S and 2P levels of hydrogen. The Dirac equation predicts an exact degeneracy; it was known that QED gave a correction to this, but it was, of course, infinite. However, stimulated by this report, on the train ride back from the conference Bethe was able, with the aid of a few ad hoc assumptions, to perform a calculation in agreement with Lamb's result. Within a year or two, the work of Schwinger, Feynman, Dyson, and Tomonaga (much of whose work had been done in isolation in Japan during the war) brought QED into a fully relativistic and consistent form, with prescriptions for renormalization that removed all infinities from observable quantities. Today QED is the most successful theory science has ever produced, having been verified in some cases to an accuracy of 12 decimal places.

To read more about the Shelter Island Conference, see the essay by Silvan S. Schweber in "Shelter Island II," R. Jackiw et al. eds, MIT Press, Cambridge MA (1985).

Birthdays for June:
June 13 — James Clerk Maxwell (1831)
June 13 — Luis Alvarez (1911)
June 14 — C. A. de Coulomb (1736)
June 28 — Maria Goeppert-Mayer (1906)

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Editor: Alan Chodos
Associate Editor: Jennifer Ouellette