  In Brane Gas Cosmology (BGC) the initial state of the universe is taken to be
small, dense and hot, with all fundamental degrees of freedom near thermal
equilibrium. This starting point is in close analogy with the Standard Big Bang
(SBB) model. In the simplest example, the topology of the universe is assumed
to be toroidal in all nine spatial dimensions and is filled with a gas of
$p$-branes. The dynamics of winding modes allow, at most, three spatial
dimensions to become large, providing a possible explanation to the origin of
our macroscopic (3+1)-dimensional universe. Specific solutions are found within
the model that exhibit loitering, i.e. the universe experiences a short phase
of slow contraction during which the Hubble radius grows larger than the
physical extent of the universe. This phase is studied by combining the dilaton
gravity background equations of motion with equations that determine the
annihilation of string winding modes into string loops. Loitering provides a
solution to the brane problem (generalised domain wall problem) in BGC and the
horizon problem of the SBB scenario. In BGC the initial singularity problem of
the SBB scenario is solved, without relying on an inflationary phase due to the
presence of the T-duality symmetry in the theory.
