Perturbing a quantum gravity condensate

Gielen, Steffen

Abstract

In a recent proposal using the group field theory approach, a spatially homogeneous (generally anisotropic) universe is described as a quantum gravity condensate of
“atoms of space”, which allows the derivation of an effective cosmological Friedmann equation from the microscopic quantum gravity dynamics. Here we take a first step towards the study of cosmological perturbations over the homogeneous background. We consider a state in which a single “atom” is added to an otherwise homogeneous condensate. Backreaction of the perturbation on the background is negligible and the background dynamics can be solved separately. The dynamics for the perturbation takes the form of a quantum cosmology Hamiltonian for a “wave function”, depending on background and perturbations, of the product form usually assumed in a Born-Oppenheimer approximation. We show that the perturbation we consider corresponds to a spatially homogeneous metric perturbation, and for this case derive the usual procedures in quantum cosmology from fundamental quantum gravity.

Citation

Gielen, S. (2015). Perturbing a quantum gravity condensate. Physical Review D - Particles, Fields, Gravitation and Cosmology, 91(4), Article 043526. https://doi.org/10.1103/physrevd.91.043526

• Journal Article Type: Article
• Acceptance Date: Jan 8, 2015
• Online Publication Date: Feb 20, 2015
• Publication Date: Feb 15, 2015
• Deposit Date: Oct 23, 2018
• Publicly Available Date: Oct 23, 2018
• Journal: Physical Review D
• Print ISSN: 1550-7998
• Electronic ISSN: 1550-2368
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 91
• Issue: 4
• Article Number: 043526
• DOI: https://doi.org/10.1103/physrevd.91.043526
• Public URL: https://nottingham-repository.worktribe.com/output/1180923
• Publisher URL: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.043526