Perfect fluid with shear viscosity and spacetime evolution

Abstract

We investigate the anisotropic evolution of spacetime driven by perfect fluid with off-diagonal shear-viscosity components. We consider the simplest form of the equation of state for fluid, for which the pressure and the shear stress are proportional to the energy density individually. At late times, compared with the usual Friedmann universe, we find that the spacetime expands less rapidly as the energy density drops faster due to the transfer to the shear stress. Very interestingly, for some ranges of the equation-of-state parameters, we find that the initial big-bang singularity can be removed.