Cosmological and black hole horizon fluctuations

Ford, L. H.; Svaiter, N. F.

doi:10.1103/physrevd.56.2226

Cited by 90 publications

(85 citation statements)

References 18 publications

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“…The other question which deserves further study is the procedure employed to deal with the runaway solutions discussed in Appendix E. The order reduction prescription is rather drastic as its net outcome is to discard entirely the contribution from the dissipation kernel ͑as far as the expectation value and the symmetrized two-point correlation func- 8 The imaginary part can be easily obtained from the expectation value for the commutator of the metric perturbations, which is given by 2i͓G ret (xЈ,x)ϪG ret (x,xЈ)͔, as briefly explained in Appendix C. 9 In those references dealing with stochastic gravity this term is usually called the dissipation term by analogy with QBM models. tion are concerned͒, which encodes the averaged back reaction of the matter fields on the metric perturbations.…”

Section: Discussionmentioning

confidence: 99%

Induced quantum metric fluctuations and the validity of semiclassical gravity

2004

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We propose a criterion for the validity of semiclassical gravity ͑SCG͒ which is based on the stability of the solutions of SCG with respect to quantum metric fluctuations. We pay special attention to the two-point quantum correlation functions for the metric perturbations, which contain both intrinsic and induced fluctuations. These fluctuations can be described by the Einstein-Langevin equation obtained in the framework of stochastic gravity. Specifically, the Einstein-Langevin equation yields stochastic correlation functions for the metric perturbations which agree, to leading order in the large N limit, with the quantum correlation functions of the theory of gravity interacting with N matter fields. The homogeneous solutions of the Einstein-Langevin equation are equivalent to the solutions of the perturbed semiclassical equation, which describe the evolution of the expectation value of the quantum metric perturbations. The information on the intrinsic fluctuations, which are connected to the initial fluctuations of the metric perturbations, can also be retrieved entirely from the homogeneous solutions. However, the induced metric fluctuations proportional to the noise kernel can only be obtained from the Einstein-Langevin equation ͑the inhomogeneous term͒. These equations exhibit runaway solutions with exponential instabilities. A detailed discussion about different methods to deal with these instabilities is given. We illustrate our criterion by showing explicitly that flat space is stable and a description based on SCG is a valid approximation in that case.

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Section: Discussionmentioning

confidence: 99%

Induced quantum metric fluctuations and the validity of semiclassical gravity

2004

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“…The "effective medium" is only an averaged description. Stochastic fluctuations are expected to occur, for example, in the arrival time of photons coming from point sources [24,25]. To next order, the corrections are proportional to…”

Section: Discussionmentioning

confidence: 99%

One-loop graviton corrections to Maxwell’s equations

Dalvit

Mazzitelli²,

Molina-Parı́s³

2001

Phys. Rev. D

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We compute the graviton induced corrections to Maxwell's equations in the one-loop and weak field approximations. The corrected equations are analogous to the classical equations in anisotropic and inhomogeneous media. We analyze in particular the corrections to the dispersion relations. When the wavelength of the electromagnetic field is much smaller than a typical length scale of the graviton two-point function, the speed of light depends on the direction of propagation and on the polarisation of the radiation. In the opposite case, the speed of light may also depend on the energy of the electromagnetic radiation. We study in detail wave propagation in two special backgrounds, flat Robertson-Walker and static, spherically symmetric spacetimes. In the case of a flat Robertson-Walker gravitational background we find that the corrected electromagnetic field equations correspond to an isotropic medium with a time-dependent effective refractive index. For a static, spherically symmetric background the graviton fluctuations induce a vacuum structure which causes birefringence in the propagation of light. PACS number(s): 04.60.-m, 11.15.Kc.

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“…Fluctuation of the horizon are more difficult to calculate, and are a topic of ongoing research [30,31,32].…”

Section: Black Hole Fluctuationsmentioning

confidence: 99%

Quantum Stress Tensor Fluctuations and their Physical Effects

Ford

2008

AIP Conference Proceedings

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We summarize several aspects of recent work on quantum stress tensor fluctuations and their role in driving fluctuations of the gravitational field. The role of correlations and anticorrelations is emphasized. We begin with a review of the properties of the stress tensor correlation function. We next consider some illuminating examples of non-gravitational effects of stress tensors fluctuations, specifically fluctuations of the Casimir force and radiation pressure fluctuations. We next discuss passive fluctuations of spacetime geometry and some of their operational signatures. These include luminosity fluctuations, line broadening, and angular blurring of a source viewed through a fluctuating gravitational field. Finally, we discuss the possible role of quantum stress tensor fluctuations in the early universe, especially in inflation. The fluctuations of the expansion of a congruence of comoving geodesics grows during the inflationary era, due to non-cancellation of anticorrelations that would have occurred in flat spacetime. This results in subsequent non-Gaussian density perturbations and allows one to infer an upper bound on the duration of inflation. This bound is consistent with adequate inflation to solve the horizon and flatness problems.

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Cosmological and black hole horizon fluctuations

Cited by 90 publications

References 18 publications

Induced quantum metric fluctuations and the validity of semiclassical gravity

Induced quantum metric fluctuations and the validity of semiclassical gravity

One-loop graviton corrections to Maxwell’s equations

Quantum Stress Tensor Fluctuations and their Physical Effects

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