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Semiclassical Einstein-Langevin equations for arbitrary small metric perturbations conformally coupled to a massless quantum scalar field in a spatially flat cosmological background are derived. Use is made of the fact that for this problem…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Antonio Campos , Enric Verdaguer

Environment interaction may induce stochastic semiclassical dynamics in open quantum systems. In the gravitational context, stress-energy fluctuations of quantum matter fields give rise to a stochastic behaviour in the spacetime geometry.…

General Relativity and Quantum Cosmology · Physics 2011-04-15 Albert Roura , Enric Verdaguer

We give a summary of the status of current research in stochastic semiclassical gravity and suggest directions for further investigations. This theory generalizes the semiclassical Einstein equation to an Einstein-Langevin equation with a…

General Relativity and Quantum Cosmology · Physics 2008-11-26 B. L. Hu

Whereas semiclassical gravity is based on the semiclassical Einstein equation with sources given by the expectation value of the stress-energy tensor of quantum fields, stochastic semiclassical gravity is based on the Einstein- Langevin…

General Relativity and Quantum Cosmology · Physics 2007-05-23 B. L. Hu , E. Verdaguer

We discuss Einstein-Klein-Gordon system in an environment of an infinite number of scalar fields leading to an external thermal noise. In the lowest order of metric and field perturbations the quadratic fluctuations consist of a sum of…

General Relativity and Quantum Cosmology · Physics 2019-05-22 Z. Haba

We present an extension of the semiclassical Einstein equations which couples n-point correlation functions of a stochastic Einstein tensor to the n-point functions of the quantum stress-energy tensor. We apply this extension to calculate…

General Relativity and Quantum Cosmology · Physics 2015-03-10 Nicola Pinamonti , Daniel Siemssen

In studying temperature fluctuations in the cosmic microwave background Weinberg has noted that some ease of calculation and insight can be achieved by looking at the structure of the perturbed light cone on which the perturbed photons…

General Relativity and Quantum Cosmology · Physics 2021-05-19 Asanka Amarasinghe , Philip D. Mannheim

Quantum gravitational effects in loop quantum cosmology lead to a resolution of the initial singularity and have the potential to solve the horizon problem and generate a quasi scale-invariant spectrum of density fluctuations. We consider…

Astrophysics · Physics 2008-11-26 Joao Magueijo , Parampreet Singh

The semiclassical Einstein-Langevin equations which describe the dynamics of stochastic perturbations of the metric induced by quantum stress-energy fluctuations of matter fields in a given state are considered on the background of the…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Rosario Martin , Enric Verdaguer

We consider the classical stochastic fluctuations of spacetime geometry induced by quantum fluctuations of massless non-conformal matter fields in the Early Universe. To this end, we supplement the stress-energy tensor of these fields with…

General Relativity and Quantum Cosmology · Physics 2008-11-26 E. Calzetta , A. Campos , E. Verdaguer

The noise kernel is the vacuum expectation value of the (operator-valued) stress-energy bi-tensor which describes the fluctuations of a quantum field in curved spacetimes. It plays the role in stochastic semiclassical gravity based on the…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Nicholas G Phillips , B. L. Hu

Using the concept of open systems where the classical geometry is treated as the system and the quantum matter field as the environment, we derive a fluctuation-dissipation theorem for semiclassical cosmology. This theorem which exists…

General Relativity and Quantum Cosmology · Physics 2008-11-26 B. L. Hu , Sukanya Sinha

We study the back reaction of a thermal field in a weak gravitational background depicting the far-field limit of a black hole enclosed in a box by the Close Time Path (CTP) effective action and the influence functional method. We derive…

General Relativity and Quantum Cosmology · Physics 2011-04-15 Antonio Campos , B. L. Hu

This paper delineates the first steps in a systematic quantitative study of the spacetime fluctuations induced by quantum fields in an evaporating black hole under the stochastic gravity program. The central object of interest is the noise…

General Relativity and Quantum Cosmology · Physics 2008-11-26 B. L. Hu , Albert Roura

The back-reaction of a classical gravitational field interacting with quantum matter fields is described by the semiclassical Einstein equation, which has the expectation value of the quantum matter fields stress tensor as a source. The…

General Relativity and Quantum Cosmology · Physics 2008-11-26 E. Verdaguer

An important yet perplexing result from work in the 90s and 00s is the near-unity value of the ratio of fluctuations in the vacuum energy density of quantum fields to the mean in a collection of generic spacetimes. This was done by way of…

General Relativity and Quantum Cosmology · Physics 2023-01-10 Hing-Tong Cho , Jen-Tsung Hsiang , Bei-Lok Hu

At the mesoscopic scales --- which interpolate between the macroscopic, classical, geometry and the microscopic, quantum, structure of spacetime --- one can identify the density of states of the geometry which arises from the existence of a…

General Relativity and Quantum Cosmology · Physics 2018-12-19 T. Padmanabhan

In inflationary cosmological models driven by an inflaton field the origin of the primordial inhomogeneities which are responsible for large scale structure formation are the quantum fluctuations of the inflaton field. These are usually…

General Relativity and Quantum Cosmology · Physics 2009-02-20 Albert Roura , Enric Verdaguer

In the first part of this paper, we show that the semiclassical Einstein-Langevin equation, introduced in the framework of a stochastic generalization of semiclassical gravity to describe the back reaction of matter stress-energy…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Rosario Martin , Enric Verdaguer

We discuss the stability of semiclassical gravity solutions with respect to small quantum corrections by considering the quantum fluctuations of the metric perturbations around the semiclassical solution. We call the attention to the role…

General Relativity and Quantum Cosmology · Physics 2007-05-23 B. L. Hu , Albert Roura , Enric Verdaguer
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