Gauge Fixing and the Semiclassical Interpretation of Quantum Cosmology

@article{Chataignier2019GaugeFA,
  title={Gauge Fixing and the Semiclassical Interpretation of Quantum Cosmology},
  author={Leonardo Chataignier},
  journal={Zeitschrift f{\"u}r Naturforschung A},
  year={2019},
  volume={74},
  pages={1069 - 1098}
}
Abstract We make a critical review of the semiclassical interpretation of quantum cosmology and emphasise that it is not necessary to consider that a concept of time emerges only when the gravitational field is (semi)classical. We show that the usual results of the semiclassical interpretation and its generalisation known as the Born–Oppenheimer approach to quantum cosmology can be obtained by gauge fixing, both at the classical and quantum levels. By “gauge fixing,” we mean a particular choice… Expand
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References

SHOWING 1-10 OF 169 REFERENCES
Notes on Semiclassical Gravity
Abstract In this paper we investigate the different possible ways of defining the semiclassical limit of quantum general relativity. We discuss the conditions under which the expectation value of theExpand
Fermions in quantum cosmology.
  • D'Eath, Halliwell
  • Physics, Medicine
  • Physical review. D, Particles and fields
  • 1987
TLDR
The extension of the ideas of quantum cosmology and, in particular, the proposal of Hartle and Hawking for the boundary conditions of the Universe, to models which incorporate fermions in a realistic manner is considered, finding this to imply that the fermion modes start out in their ground state. Expand
Observables in classical canonical gravity: folklore demystified
We give an overview of some conceptual difficulties, sometimes called paradoxes, that have puzzled for years the physical interpetation of classical canonical gravity and, by extension, the canonicalExpand
Semiclassical Approximation for Gravity and the Issue of Back Reaction
Semiclassical approximations, which are useful in the study of a quantum system interacting with a classical system, are studied and compared. A toy quantum mechanical model with two degrees ofExpand
EMERGENT SEMICLASSICAL TIME IN QUANTUM GRAVITY
The emergent semiclassical time approach to resolving the problem of time in quantum gravity is considered in the arena of relational particle toy models. In situations with ‘heavy’ and ‘light’Expand
The background field approximation in (quantum) cosmology
We analyse the Hamilton-Jacobi action of gravity and matter in the limit where gravity is treated at the background field approximation. The motivation is to clarify when the Wheeler-DeWitt equationExpand
Time in semiclassical gravity.
  • Brout, Venturi
  • Physics, Medicine
  • Physical review. D, Particles and fields
  • 1989
TLDR
It is shown that cosmology as a theory of the mean is meaningful and the Schr\"odinger equation for matter is obtained in conformity with previous work where these particular questions were not addressed. Expand
On the modification of the cosmic microwave background anisotropy spectrum from canonical quantum gravity
We evaluate the modifications to the cosmic microwave background anisotropy spectrum that result from a semiclassical expansion of the Wheeler-DeWitt equation. Recently, such an investigation in theExpand
On the semiclassical limit of the Wheeler-DeWitt equation
The authors continue their investigation of approximation schemes for obtaining semiclassical Einstein equations with a backreaction, starting from the Wheeler-DeWitt equation. The analysis isExpand
Unitary and nonunitary evolution in quantum cosmology
We analyse when and why unitarity violations might occur in quantum cosmology restricted to minisuperspace. To this end we discuss in detail backscattering transitions between expanding andExpand
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2
3
4
5
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