3d Lorentzian, dynamically triangulated quantum gravity

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.