Symmetry, Integrability and Geometry: Methods and Applications (SIGMA)


SIGMA 12 (2016), 082, 49 pages      arXiv:1602.08104      http://dx.doi.org/10.3842/SIGMA.2016.082
Contribution to the Special Issue on Tensor Models, Formalism and Applications

Quantum Cosmology from Group Field Theory Condensates: a Review

Steffen Gielen a and Lorenzo Sindoni b
a) Theoretical Physics, Blackett Laboratory, Imperial College London, London SW7 2AZ, UK
b) Max Planck Institute for Gravitational Physics, Am Mühlenberg 1, 14476 Golm, Germany

Received February 29, 2016, in final form August 12, 2016; Published online August 18, 2016

Abstract
We give, in some detail, a critical overview over recent work towards deriving a cosmological phenomenology from the fundamental quantum dynamics of group field theory (GFT), based on the picture of a macroscopic universe as a ''condensate'' of a large number of quanta of geometry which are given by excitations of the GFT field over a ''no-space'' vacuum. We emphasise conceptual foundations, relations to other research programmes in GFT and the wider context of loop quantum gravity (LQG), and connections to the quantum physics of real Bose-Einstein condensates. We show how to extract an effective dynamics for GFT condensates from the microscopic GFT physics, and how to compare it with predictions of more conventional quantum cosmology models, in particular loop quantum cosmology (LQC). No detailed familiarity with the GFT formalism is assumed.

Key words: group field theory; quantum cosmology; loop quantum gravity.

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