Feature

Sizing up the Electron

Measuring the inner shape of the famous particle could help solve a cosmic mystery

By Alexandra Witze

- More than 2 years ago

Long thought to be a simple speck of negative charge, the humble electron may be hiding one more surprise in its depths.

Detecting an electric dipole moment would mean electrons, which buzz about atomic nuclei, have internal structure. © galinka86/dreamstime.com

HINTS IN TIME Reversing time (by switching the direction of a particle’s spin) changes the direction of the magnetic dipole (blue) but not the electric dipole (green).