Limits on CP invariance in general relativity

The test of the equivalence principle pointed out by Longo and by Krauss and Tremaine can be easily extended to comparing the infall velocities of matter and antimatter. The very close coincidence in arrival times for neutrinos and antineutrinos places strong constraints on the coupling of gravitational interactions to matter and antimatter. The relative difference in gravitational delay is less than 5×${10}^{\mathrm{-}6}$.