Causality-Violating Lorentzian Manifolds Admitting a Shear-free Timelike Flow

The Godel spacetime is an important cosmological solution of Einstein's field equations of gravitation. Although it does not offer a viable description of the physical universe, it illustrates the theoretical possibility of time travel. This work investigates world models similar to the Godel spacetime with particular emphasis on relations between kinematical properties (shear, vorticity, acceleration, expansion) and causality violation, i.e., the formation of closed timelike curves.