Crystalline Gravity

by Gerard 't Hooft (Institute for Theoretical Physics, University of Utrecht)

Wednesday 17 Sept 2008, 14:00 → 15:00 Europe/Zurich

TH Theory Conference Room (CERN)

Matter interacting classically with gravity in 3+1 dimensions usually gives rise to a continuum of degrees of freedom, so that, in any attempt to quantize the theory, ultraviolet divergences are nearly inevitable. In this talk, we investigate matter of a form that only displays a finite number of degrees of freedom in compact sections of space-time. In finite domains, one has only exact, analytic solutions. This is achieved by limiting ourselves to straight pieces of string, surrounded by locally flat sections of space-time, much like defects in a crystal. Globally, however, the model is not finite, because solutions tend to generate infinite fractals. The model is not (yet) quantized, but could serve as a stepping stone for quantum models. The analogy with crystals becomes more evident if one restricts oneself to discrete subgroups of the Lorentz group.

Slides tHooft.pdf tHooft.ppt