  In most of the literature on granular gases it is assumed that the
restitution coefficient \epsilon, which quantifies the loss of kinetic energy
upon a collision is independent on the impact velocity. Experiments as well as
theoretical investigations show, however, that for real materials the
restitution coefficient depends significantly on the impact velocity. We
consider the diffusion process in a homogeneous granular gas, i.e. in a system
of dissipatively colliding particles. We show that the mean square displacement
of the particles changes drastically if we take the impact velocity dependence
of \epsilon into account. Under the oversimplifying assumption of a constant
coefficient one finds that the particles spread in space logarithmically slow
with time, whereas realistic particles spread due to a power law.
