The Asymptotic Safety scenario predicts that the deep ultraviolet of Quantum
Einstein Gravity is governed by a nontrivial renormalization group fixed point.
Analyzing its implications for cosmology using renormalization group improved
Einstein equations we find that it can give rise to a phase of inflationary
expansion in the early Universe. Inflation is a pure quantum effect here and
requires no inflaton field. It is driven by the cosmological constant and ends
automatically when the renormalization group evolution has reduced the vacuum
energy to the level of the matter energy density. The quantum gravity effects
also provide a natural mechanism for the generation of entropy. It could easily
account for the entire entropy of the present Universe in the massless sector.Comment: 17 pages, 4 figures, Invited contribution to the special issue of
Entropy on "Entropy in Quantum Gravity
