Measurement of the neutron electric dipole moment
A permanent electric dipole moment (EDM) of a particle with spin violates time reversal symmetry. To date no finite EDM has been measured yet despite considerable search efforts world-wide and in various systems. The limits provide severe constraints on the Standard Model of Particle Physics and on theories beyond it. The most sensitive search for the EDM of the neutron is being pursued at PSI. I will present an introduction to the field of EDM research and its present status, and give the latest update from the effort at PSI including a new result on ultra-light axion dark matter.