The causal hierarchy of spacetimes

Abstract

The full causal ladder of spacetimes is constructed, and their updated main properties are developed. Old concepts and alternative definitions of each level of the ladder are revisited, with emphasis in minimum hypotheses. The implications of the recently solved ``folk questions on smoothability'', and alternative proposals (as recent isocausality), are also summarized.

Latex2e, 63 pages, 14 figures, uses psfrag. Contribution to the Proceedings of the ESI semester ``Geometry of Pseudo-Riemannian Manifolds with Applications in Physics'' (Vienna, 2006). Some erratas corrected and other modifications, including two references. This version matches the one to be published at the proceedings