*Review* **Group Field Theory Condensate Cosmology: An Appetizer**

### **Andreas G. A. Pithis \* and Mairi Sakellariadou**

Department of Physics, King's College London, University of London, Strand, London WC2R 2LS, UK; mairi.sakellariadou@kcl.ac.uk

**\*** Correspondence: andreas.pithis@kcl.ac.uk

Received: 2 April 2019; Accepted: 8 June 2019; Published: 13 June 2019

**Abstract:** This contribution is an appetizer to the relatively young and fast-evolving approach to quantum cosmology based on group field theory condensate states. We summarize the main assumptions and pillars of this approach which has revealed new perspectives on the long-standing question of how to recover the continuum from discrete geometric building blocks. Among others, we give a snapshot of recent work on isotropic cosmological solutions exhibiting an accelerated expansion, a bounce where anisotropies are shown to be under control, and inhomogeneities with an approximately scale-invariant power spectrum. Finally, we point to open issues in the condensate cosmology approach.

**Keywords:** quantum geometry; quantum gravity; quantum cosmology; group field theory; loop quantum gravity

> Most important part of doing physics is the knowledge of *approximation*.

> > Lev Davidovich Landau
