  Quantum gravity may shed light on the prehistory of the universe. Quantum
corrections to gravity affect the dynamics of the expansion of the universe.
Their influence is studied on the example of the exactly solvable quantum
model. The corrections to the energy density and pressure lead to the emergence
of an additional attraction (like dark matter) or repulsion (like dark energy)
in the quantum system of the gravitating matter and radiation. The model
explains the accelerating expansion (inflation) in the early universe (the
domain of comparatively small values of quantum numbers) and a later transition
from the decelerating expansion to the accelerating expansion of the universe
(the domain of the very large values of quantum numbers) from a single
approach. The generation of primordial fluctuations of the energy density at
the expense of the change of sign of the quantum correction to the pressure is
discussed.
