  In the context of homogeneous and isotropic superstring cosmology, the
T-duality symmetry of string theory has been used to argue that for a
background space-time described by dilaton gravity with strings as matter
sources, the cosmological evolution of the Universe will be nonsingular. In
this Letter we discuss how T-duality extends to brane gas cosmology, an
approximation in which the background space-time is again described by dilaton
gravity with a gas of branes as a matter source. We conclude that the arguments
for nonsingular cosmological evolution remain valid.
