Incompatible moments A spinning charge (left) acts like a loop of current to produce a magnetic dipole moment (blue arrow). Distorting the electron's charge distribution (middle) produces an electric ...

More information: Li-Ren Liu et al, Measurement of the electric dipole moment of AlCl by Stark-level spectroscopy, Physical Review A (2025). DOI: 10.1103/hwwm-1mn7 ...

Yet theories that include additional, yet-to-be-detected particles predict a much larger dipole moment. Physicists have been searching for this dipole moment for 50 years.