In DepthPhysics

The electron is still round—for now

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Science  27 Oct 2017:
Vol. 358, Issue 6362, pp. 435
DOI: 10.1126/science.358.6362.435

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In a series of ever-more-sensitive experiments, researchers have established that if the shape of the electron has any distortion at all, the bulge must be smaller than 1 thousand trillion trillionths of a millimeter (10-27 mm). Now, a group at the JILA research institute in Boulder, Colorado, has a new approach that could help reduce the uncertainty still further—and perhaps reveal an actual distortion, known as an electric dipole moment (EDM). Scientists usually think of the electron as an exceedingly, if not infinitely, small and uniform sphere of negative charge, but a nonzero EDM would mean that charge is distributed unevenly. This tiny spatial asymmetry would have far-reaching implications, challenging physicists' simplest model of particles and forces and helping explain why the universe today contains far more matter than antimatter.

  • * Edwin Cartlidge is a science journalist in Rome.