The electron dipole moment—A case history

FEB 01, 1966

The anomalous magnetic moment of the electron is of great significance in the study of elementary particles and quantum electrodynamics. The history of its discovery is in large part the story of a technique:—the use of molecular beams—which was not invented for the specific purpose hut which did, by permitting a discrepancy to appear where none was expected, answer an unasked question.

DOI: 10.1063/1.3048048

Polykarp Kusch

THE ELECTRON is one of the fundamental particles in the universe and is likely to remain one. It is as abundant as any other particle with the possible exception of the neutrino. There may be more neutrinos around, but I am not expert on that question. The electron has a definite charge and a definite rest mass.

References

1. Reprints of both Thomson’s and Millikan’s papers appear in Great Experiments in Physics. Morris Shamos, Ed. Henry Holt, New York, 1959.
2. As is true of almost every major event in the history of physics, the proposals of Goudsmit and Uhlenbeck were not made without some previous provocative suggestions. See, for instance, Whittaker, A History of the Theories of Aether and Electricity, Vol. II, pages 133, 134. Harper, New York, 1960.
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6. The emphasis on the molecular‐beam magnetic‐resonance method as a generalized spectrometric procedure is not made in the early papers. In 1939 Rabi, Millman, Kusch, and Zacharias (Phys. Rev. 55, 526) discussed the trajectories of molecules in a system of inhomogeneous magnetic fields and, very importantly, the process of changing the orientation of a magnetic dipole in a magnetic field.
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More about the Authors

Polykarp Kusch. Columbia University.