Inhomogeneous string cosmologies

We present exact inhomogeneous and anisotropic cosmological solutions of low-energy string theory containing dilaton and axion fields. The spacetime metric possesses cylindrical symmetry. The solutions describe ever-expanding universes with an initial curvature singularity and contain known homogeneous solutions as subcases. The asymptotic form of the solution neat the initial singularity has a spatially varying Kasner-like farm. The inhomogeneous axion and dilaton fields are found to evolve quasihomogeneously on scales larger than the particle horizon. When the inhomogeneities enter the horizon they oscillate as nonlinear waves and the inhomogeneities attentuate. When the inhomogeneities are small they behave as small perturbations of homogeneous universes. The manifestation of duality and the asymptotic behavior of the solutions are investigated.