  There are interesting parallels between the physics of heavy ion collisions
and cosmology. Both systems are out-of-equilibrium and relativistic fluid
dynamics plays an important role for their theoretical description. From a
comparison one can draw interesting conclusions for both sides. For heavy ion
physics it could be rewarding to attempt a theoretical description of fluid
perturbations similar to cosmological perturbation theory. In the context of
late time cosmology, it could be interesting to study dissipative properties
such as shear and bulk viscosity and corresponding relaxation times in more
detail. Knowledge and experience from heavy ion physics could help to constrain
the microscopic properties of dark matter from observational knowledge of the
cosmological fluid properties.
