  We propose a theory of quantum gravity which formulates the quantum theory as
a nonperturbative path integral, where each spacetime history appears with a
weight given by the exponentiated Einstein-Hilbert action of the corresponding
causal geometry. The path integral is diffeomorphism-invariant (only geometries
appear) and background-independent. The theory can be investigated by computer
simulations, which show that a de Sitter universe emerges on large scales. This
emergence is of an entropic, self-organizing nature, with the weight of the
Einstein-Hilbert action playing a minor role. Also the quantum fluctuations
around this de Sitter universe can be studied quantitatively and remain small
until one gets close to the Planck scale. The structures found to describe
Planck-scale gravity are reminiscent of certain aspects of condensed-matter
systems.
