Loop quantum gravity: an outside view
By H. Nicolai, Kasper Peeters, M. Zamaklar. 2005
200 citations recorded by the source corpus.
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.
Subfields: Applied Mathematics, Statistical and Nonlinear Physics
View Paper: https://www.semanticscholar.org/paper/d9de5a0cb243892b930c801ee19327f1ded7bc92
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In Applied Mathematics
In Statistical and Nonlinear Physics
- M. Niedermaier
- R. Loll
- Martin Reuter
- J. Jurkiewicz
- Gianluca Calcagni
- J. Ambjørn
- S. Shankaranarayanan
- Golam Mortuza Hossain
Citations in the corpus
- Loop Quantum Cosmology (2005, background): “Since many reviews of full loop quantum gravity [172, 195, 22, 174, 161] as well as shorter accounts [9, 10, 173, 190, 167, 198] are already available, we describe here only those properties which will be essential later on.”
- The Asymptotic Safety Scenario in Quantum Gravity (2006, background): “The dynamics formulated in terms of the Hamiltonian constraint thus must be automatically well-defined on the above kinematical arena (see [151, 173] for a discussion of the ambiguities in such constructions).”
- Spherically symmetric quantum geometry: Hamiltonian constraint (2005, unknown): “in [62].”
- Reconstructing the universe (2005, methodology): “ctice complicated by the fact that some explicit results about the quantum dynamics of the proposed quantum gravity theory must be known. For example, this is not yet the case in loop quantum gravity [2, 3, 4] or in four-dimensional spin foam models for gravity [5]. In the method of Causal Dynamical”
- Towards understanding the ultraviolet behavior of quantum loops in infinite-derivative theories of gravity (2014, background): “For instance, the entireformulation of LQG is based on non-local objects, such as Wilson loops and fluxes coming from the gravitational field.”
- Anomaly freedom in perturbative loop quantum gravity (2008, background): “Some rare solvable systems can be studied by exact effective equations without truncation, which in cosmology is realized for a flat isotropic model sourced by a free, massless scalar [6].”