arXiv:2008.07837v2 [gr-qc] 1 Jun 2021 Cosmological implications of the hydrodynamical phase of group field theory Luciano Gabbanelli a, * and Silvia De Bianchi b,c, † a Institut de F´ ısica d’Altes Energies (IFAE), Universitat Aut` onoma de Barcelona, Campus UAB 08193 Bellaterra (Barcelona), Spain. b Department of Philosophy, University of Milan, Via Festa del Perdono, 7 20122 Milan, Italy. c Department of Philosophy, Universitat Aut` onoma de Barcelona, Building B Campus UAB 08193 Bellaterra (Barcelona), Spain. Abstract In this review we focus on the main cosmological implications of the Group Field Theory approach, according to which an effective continuum macroscopic dynamics can be extracted from the underlying formalism for quantum gravity. Within this picture what counts is the collective behaviour of a large number of quanta of geometry. The resulting state is a condensate-like structure made of “pre-geometric” excitations of the Group Field Theory field over a no-space vacuum. Starting from the kinematics and dynamics, we offer an overview of the way in which Group Field Theory condensate cosmology treats solutions for the homogeneous and isotropic universe. These solutions including a bounce, share with other quantum cosmological approaches the resolution of the singularity characterizing general relativity. Contrary to what is usually done in quantum cosmology, in GFT cosmology no preliminary symmetry reduction is needed for this purpose. We conclude with a discussion of the limits and future perspectives of the Group Field Theory approach. 1 Introduction The goal of the present paper is to review some essential properties of Group Field Theory (GFT) and GFT condensate cosmology in an accessible way from a non-specialist’s perspec- tive, and with a non-GFT audience in mind. For a review with an internalist perspective see [1]. Our purpose is to underline the physical consequences of the formalism and to discuss some results that go beyond quantum cosmology and invite conceptual innovation. Although the general formalism of GFT is deeply related to Loop Quantum Gravity (LQG), tensor models and lattice quantum gravity, in the sense that all these theories share the formulation in terms of discrete and combinatorial structures rather than continuum variables (such as a * luciano.gabbanelli@uab.cat † silvia.debianchi@unimi.it 1