I. Rienäcker

Catching a whisper in the middle of a noisy train station: that's roughly the challenge facing physicists searching for the neutron's electric dipole moment. This is a tiny shift of charge inside the particle. If it exists, it breaks the symmetry between matter and antimatter and could explain why our world exists at all.

The neutron, a particle inside the atomic nucleus, can live in two worlds: ours and a mirror one. The mirror world has its own neutron twin, invisible to our instruments. If an ordinary neutron sometimes hops to the mirror world and back, some neutrons in a trap would seem to dissolve into thin air.