  The model of Lorentzian three-dimensional dynamical triangulations provides a
non-perturbative definition of three-dimensional quantum gravity. The theory
has two phases: a weak-coupling phase with quantum fluctuations around a
``semiclassical'' background geometry which is generated dynamically despite
the fact that the formulation is explicitly background-independent, and a
strong-coupling phase where ``classical'' space disintegrates into a foam of
baby universes.
