Gravitation and electromagnetic wave propagation with negative phase velocity

Abstract

Gravitation has interesting consequences for electromagnetic wave propagation in vacuum. The propagation of plane waves with phase velocity directed opposite to the time-averaged Poynting vector is investigated for a generally curved spacetime. Conditions for such negative-phase-velocity (NPV) propagation are established in terms of the spacetime metric components for general and special cases. Implications of the negative energy density of NPV propagation are discussed. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.