The 2-dimensional version of causal set quantum gravity has proved to be a useful testing ground for the full theory. It exhibits a phase transition which interpolates between a continuum phase and a "crystalline" non-manifoldlike phase. These phases play an important role in determining the nature of the Hartle-Hawking wavefunction. Combining analytic and numerical techniques we find that the wave function has a low temperature peak over causal sets which exhibit physically interesting behaviour. In particular, they show a rapid spatial expansion with respect to the discrete proper time, as well as a high degree of spatial homogeneity. While our results are limited to 2 dimensions they provide a concrete example of the role played by non-perturbative quantum gravity in generating the initial conditions for our observable universe.
Time: 3pm, Thursday 30th June 2016
Place: Lecture Room, 1st Floor, School of Theoretical Physics, DIAS, 10 Burlington Road, Dublin 4