  Renormalization group (RG) improved cosmologies based upon a RG trajectory of
Quantum Einstein Gravity (QEG) with realistic parameter values are investigated
using a system of cosmological evolution equations which allows for an
unrestricted energy exchange between the vacuum and the matter sector. It is
demonstrated that the scale dependence of the gravitational parameters, the
cosmological constant in particular, leads to an entropy production in the
matter system. The picture emerges that the Universe started out from a state
of vanishing entropy, and that the radiation entropy observed today is
essentially due to the coarse graining (RG flow) in the quantum gravity sector
which is related to the expansion of the Universe. Furthermore, the RG improved
field equations are shown to possess solutions with an epoch of power law
inflation immediately after the initial singularity. The inflation is driven by
the cosmological constant and ends automatically once the RG running has
reduced the vacuum energy to the level of the matter energy density.
