The background field approximation in (quantum) cosmology

  title={The background field approximation in (quantum) cosmology},
  author={R. Parentani},
  journal={Classical and Quantum Gravity},
  • R. Parentani
  • Published 2000
  • Physics
  • Classical and Quantum Gravity
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 equation leads to the Schrodinger equation in a background geometry. In particular, we investigate the problem of the choice of the background and that of the corrections to the Schrodinger equation associated with this choice. To this end, we first work classically. We determine when the total action, a… Expand
8 Citations
Gauge Fixing and the Semiclassical Interpretation of Quantum Cosmology
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 theExpand
Semiclassical momentum representation in quantum cosmology
It is well-known that the standard WKB approximation fails to provide semiclassical solutions in the vicinity of turning points. However, turning points arise in many cosmological scenarios. In aExpand
On the semiclassical approach to quantum cosmology: relational particle model
The emergent semiclassical time approach to resolving the problem of time in quantum gravity involves heavy slow degrees of freedom providing via an approximately Hamilton–Jacobi equation anExpand
On the phenomenology of quantum gravity : stability properties of Hawking radiation in the presence of ultraviolet violation of local Lorentz invariance
In this thesis, we study several features of Hawking radiation in the presence of ultraviolet Lorentz violations. These violations are implemented by a modified dispersion relation that becomesExpand
Emergent semiclassical time in quantum gravity: I. Mechanical models*
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
Emergent semiclassical time in quantum gravity: II. Full geometrodynamics and minisuperspace examples
I apply the preceding paper's emergent semiclassical time approach to geometrodynamics. The analogy between the two papers is useful at the level of the quadratic constraints, while I document theExpand
Tempus Post Quantum. ii. Semiclassical Machian Emergent Time
We now contemplate dealing with frozen quantum wave equations by finding an emergent time once already at the quantum level, within semiclassical quantum cosmology’s physical regime of interest. ThisExpand
Relational particle models. II. Use as toy models for quantum geometrodynamics
Relational particle models are employed as toy models for the study of the problem of time in quantum geometrodynamics. These models' analogue of the thin sandwich is resolved. It is argued that theExpand


The validity of the Background Field Approximation
In the absence of a tractable theory of quantum gravity, quantum matter field effects have been so far computed by treating gravity at the Background Field Approximation. The principle aim of thisExpand
Particle creation and non-adiabatic transitions in quantum cosmology
Abstract The aim of this paper is to compute transition amplitudes in quantum cosmology. To this end, we apply a double adiabatic development to the solutions of the Wheeler-DeWitt equation. We workExpand
Time in semiclassical gravity.
  • Brout, Venturi
  • Physics, Medicine
  • Physical review. D, Particles and fields
  • 1989
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
Quantum gravitational corrections to the functional Schrödinger equation.
We derive corrections to the Schr\"odinger equation which arise from the quantization of the gravitational field. This is achieved through an expansion of the full functional Wheeler-DeWitt equationExpand
Origin of structure in the Universe.
A scale-free spectrum of density perturbations which could account for the origin of galaxies and all other structure in the Universe is obtained. Expand
Note on the semiclassical approximation in quantum gravity.
We reexamine the semiclassical approximation to quantum gravity in the canonical formulation, focusing on the definition of a quasiclassical state for the gravitational field. It is shown that aExpand
Time in Cosmology
The notion of time in cosmology is revealed through an examination of transition matrix elements of radiative processes occurring in the cosmos. To begin with, the very concept of time is delineatedExpand
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
The recoils of a dynamical mirror and the decoherence of its fluxes
Abstract In order to address the problem of the validity of the “background field approximation”, we introduce a dynamical model for a mirror described by a massive quantum field. We analyze theExpand
Dust as a standard of space and time in canonical quantum gravity.
  • Brown, Kuchar
  • Physics, Medicine
  • Physical review. D, Particles and fields
  • 1995
The particles of dust introduce into space a privileged system of coordinates that allows the supermomentum constraint to be solved explicitly and yields a formally conserved inner product that can be written in terms of either the instantaneous state functionals or the solutions of constraints. Expand