Wave Fronts in a Causality-Violating Gödel-Type Metric

Figure 5

Wave fronts of null geodesics emitted by an observer at the origin at eight successive times. These wave fronts show bifurcations due to the non-causal nature of the time coordinate of the time coordinate shown in Figure 1. Each entire wave front of constant time, including the disconnected sections, are inside the causal boundary circle of radius .