REVIEW 5 cited by
Unimodular loop quantum gravity and the problems of time
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
Signed reviews
read the original abstract
We develop the quantization of unimodular gravity in the Plebanski and Ashtekar formulations and show that the quantum effective action defined by a formal path integral is unimodular. This means that the effective quantum geometry does not couple to terms in the expectation value of the energy-momentum tensor proportional to the metric tensor. The path integral takes the same form as is used to define spin foam models, with the additional constraint that the determinant of the four metric is constrained to be a constant by a gauge fixing term. We also review the proposal of Unruh, Wald and Sorkin- that the hamiltonian quantization yields quantum evolution in a physical time variable equal to elapsed four volume-and discuss how this may be carried out in loop quantum gravity. This then extends the results of arXiv:0904.4841 to the context of loop quantum gravity.
Forward citations
Cited by 5 Pith papers
-
Attracting without being attracted: Dark Matter as an aether wind
Dark matter may be a non-dynamical, non-conserved relic of broken diffeomorphism invariance that attracts normal matter but is not attracted, and a constant density of it produces flat rotation curves.
-
Canonical analysis of unimodular Pleba\'nski gravity
A canonical analysis of unimodular Plebański gravity shows that the Hamiltonian density is constrained only to be constant, promoting the cosmological constant to an integration constant.
-
Inflation in unimodular loop quantum cosmology
In unimodular loop quantum cosmology, an α-attractor potential allows a potential-energy-dominated bounce at the Planck scale that is consistent with CMB observations and may show quantum-gravity imprints.
-
Unimodular quantum cosmology in the connection representation: A minimal model
In a flat, empty unimodular quantum cosmology in connection variables, positive-cosmological-constant wave functions vanish at zero volume, while a negative cosmological constant is excluded by operator regularity and...
-
How to make a Universe
A canonical formalism links changing constants of nature to matter production, and an absorbing Markov chain model suggests fixed, diffeomorphism-invariant laws are the absorbing state that preserves the matter gained.
Discussion (0). Continue with ORCID to comment.