Wave Fronts in a Causality Violating Godel-Type Metric

The light-rays and wave fronts in a flat class of Godel-type metric are examined to reveal the causality violating features of the space-time. Non-causal features demonstrated by the development of unusual wave front singularities are shown to be related to the non-monotonic advance of time along the light rays, as measured by a system of observers at rest with respect to one another with synchronized clocks.