Cosmological implications of the hydrodynamical phase of group field theory

Abstract

In this review we focus on the main cosmological implications of the Group\nField Theory approach, according to which an effective continuum macroscopic\ndynamics can be extracted from the underlying formalism for quantum gravity.\nWithin this picture what counts is the collective behaviour of a large number\nof quanta of geometry. The resulting state is a condensate-like structure made\nof "pre-geometric" excitations of the Group Field Theory field over a no-space\nvacuum. Starting from the kinematics and dynamics, we offer an overview of the\nway in which Group Field Theory condensate cosmology treats solutions for the\nhomogeneous and isotropic universe. These solutions including a bounce, share\nwith other quantum cosmological approaches the resolution of the singularity\ncharacterizing general relativity. Contrary to what is usually done in quantum\ncosmology, in GFT cosmology no preliminary symmetry reduction is needed for\nthis purpose. We conclude with a discussion of the limits and future\nperspectives of the Group Field Theory approach.\n