EXISTENCE AND CAUSALITY OF CYLINDRICALLY SYMMETRICAL COSMOLOGICAL MODELS WITH ROTATING SPIN FLUIDS

Some recent articles have proposed expanding and rotating fluids with the Krechet-Godel metric as cosmological models. Here we show that, allowing a time-dependent scale factor for cylindrical Lewis-type geometries, the rotating spin fluids of Ray-Smalley and of Ray-Smalley-Krisch cannot be expanding in the framework of general relativity. We also found that for a subclass of these metrices, both spin fluids yield three kinds of solutions: stationary, Friedman and de Sitter. With respect to Lewis-type stationary metrics, we found that the Ray-Smalley spin fluid admits a stably causal inhomogeneous model with strong spin-vorticity coupling. The simplest solution given by the Ray-Smalley-Krisch spin fluid presents causality violation.