Group field theory cosmology

This thesis explores the cosmological sector of group field theory (GFT) which is a proposal for a theory of quantum gravity. We provide an overview of GFT and introduce the framework necessary to study cosmology in the context of GFT. We discuss two approaches to GFT cosmology in detail.

Firstly, we study the canonical approach where one implements the canonical quantisation program for a GFT coupled to one or more massless scalar fields. The main result is that we are able to derive equations for the volume which take the same functional form as the Friedmann equations from classical cosmology in certain limits.

Secondly, we employ a certain method of studying quantum systems with constraints in the context of GFT cosmology. We accomplish this by identifying a subset of one-body operators of the GFT with the classical observables. The resulting dynamics allow us to identify one of the operators with the extrinsic curvature of classical cosmology.