  In cosmology, it has been a long-standing problem to establish a
\emph{parameter insensitive} evolution from an anisotropic phase to an
isotropic phase. On the other hand, it is of great importance to construct a
theory having extra dimensions as its intrinsic ingredients. We show that these
two problems are closely related and can naturally be solved simultaneously in
double field theory cosmology. Our derivations are based on general arguments
without any fine-tuning parameters. In addition, We find that when we begin
with FRW metric, the full spacetime metric of DFT totally agrees with
\emph{Kaluza-Klein theory}. There is a visible and invisible dimension exchange
between the pre- and post-big bangs. Our results indicate that double field
theory has profound physical consequences and the continuous
$O\left(D,D\right)$ is a very fundamental symmetry. This observation reinforces
the viewpoint that symmetries dictate physics.
