  Double field theory proposes a generalized spacetime action possessing
manifest T-duality on the level of component fields. We calculate the
cosmological solutions of double field theory with vanishing Kalb-Ramond field.
It turns out that double field theory provides a more consistent way to
construct cosmological solutions than the standard string cosmology. We
construct solutions for vanishing and non-vanishing symmetry preserving dilaton
potentials. The solutions assemble the pre- and post-big bang evolutions in one
single line element. This novel feature provides a natural way for the theory
to contain extra dimensions. Our results show a smooth evolution from an
anisotropic early stage to an isotropic phase without any special initial
conditions in contrast to previous models. In addition, we demonstrate that the
contraction of the dual space automatically leads to both an inflation phase
and a decelerated expansion of the ordinary space during different evolution
stages.
