WORMHOLES WITH A PAST

We discuss Minkowski space interpretations of euclidean solutions which provide semiclassical approximations to quantum processes. In particular, we consider wormhole and euclidean bounce solutions. We argue that the semiclassical description involves an instantaneous discontinuity in the Minkowski signature classical evolution and that the euclidean solutions provide final and initial value data on either side of this discontinuity. In the case of the de Sitter wormhole and bounce solutions, we resolve the problem of having a single maximal surface on the euclidean solution which must provide both past and future data across the Minkowski signature discontinuity. © 1990.