Loop quantum gravity: An Outside view

Nicolai, H.; Peeters, K.; Zamaklar, M.

Abstract

We review aspects of loop quantum gravity in a pedagogical manner, with the aim of enabling a precise but critical assessment of its achievements so far. We emphasize that the off-shell ('strong') closure of the constraint algebra is a crucial test of quantum spacetime covariance, and thereby of the consistency, of the theory. Special attention is paid to the appearance of a large number of ambiguities, in particular in the formulation of the Hamiltonian constraint. Developing suitable approximation methods to establish a connection with classical gravity on the one hand, and with the physics of elementary particles on the other, remains a major challenge.

Citation

Nicolai, H., Peeters, K., & Zamaklar, M. (2005). Loop quantum gravity: An Outside view. Classical and Quantum Gravity, 22(19), 193-247. https://doi.org/10.1088/0264-9381/22/19/r01

• Journal Article Type: Article
• Publication Date: 2005-10
• Deposit Date: Apr 27, 2007
• Journal: Classical and Quantum Gravity
• Print ISSN: 0264-9381
• Electronic ISSN: 1361-6382
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 22
• Issue: 19
• Pages: 193-247
• DOI: https://doi.org/10.1088/0264-9381/22/19/r01