Projection diagrams

Abstract

In this chapter we show that one can usefully represent classes of non-spherically symmetric geometries in terms of two-dimensional diagrams, called projection diagrams, using an auxiliary two-dimensional metric constructed out of the spacetime metric. Whenever such a construction can be carried out, the issues such as stable causality, global hyperbolicity, the existence of event or Cauchy horizons, the causal nature of boundaries, and the existence of conformally smooth infinities become evident by inspection of the diagrams.