TOPICAL REVIEW: Loop quantum gravity: an outside view
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.
- Publication:
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Classical and Quantum Gravity
- Pub Date:
- October 2005
- DOI:
- 10.1088/0264-9381/22/19/R01
- arXiv:
- arXiv:hep-th/0501114
- Bibcode:
- 2005CQGra..22R.193N
- Keywords:
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- High Energy Physics - Theory;
- General Relativity and Quantum Cosmology
- E-Print:
- 57 pages, 11 figures