%0 Journal Article %T Refractive gravitational waves and quantum fluctuations %A John W. Barrett %J Physics %D 2000 %I arXiv %X Refractive gravitational waves are a generalisation of impulsive waves on a null hypersurface in which the metric is discontinuous but a weaker continuity condition for areas holds. A simple example of a plane wave is examined in detail and two arguments are given that this should be considered a solution of Einstein's vacuum field equations. The study of these waves is motivated by quantum gravity, where the refractive plane waves are considered as elementary quantum fluctuations and the `area geometry' of a null hypersurface plays a primary role. %U http://arxiv.org/abs/gr-qc/0011051v1