Publication details for Kasper PeetersNicolai, H., Peeters, K. & Zamaklar, M. (2005). Loop quantum gravity: An Outside view. Classical and Quantum Gravity 22(19): 193-247.
- Publication type: Journal Article
- ISSN/ISBN: 0264-9381, 1361-6382
- DOI: 10.1088/0264-9381/22/19/R01
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
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.