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We study the conditions under which thermal fluctuations generated in the contracting phase of a non-singular bouncing cosmology can lead to a scale-invariant spectrum of cosmological fluctuations at late times in the expanding phase. We…

High Energy Physics - Theory · Physics 2009-08-05 Yi-Fu Cai , Wei Xue , Robert Brandenberger , Xinmin Zhang

For a freely evolving granular fluid, the buildup of spatial correlations in density and flow field is described using fluctuating hydrodynamics. The theory for incompressible flows is extended to the general, compressible case, including…

Statistical Mechanics · Physics 2009-10-30 T. P. C. van Noije , M. H. Ernst , R. Brito

Context: Strings and other alternative theories describing the quantum properties of space-time suggest that space-time could present a foamy structure and also that, in certain cases, quantum gravity (QG) may manifest at energies much…

General Relativity and Quantum Cosmology · Physics 2011-09-29 Fabrizio Tamburini , Carmine Cuofano , Massimo Della Valle , Roberto Gilmozzi

We investigate the dominant physical effects of superhorizon fluctuations in a flat FLRW universe, focusing on whether the combined evolution of scalar and tensor adiabatic modes in the near-horizon regime could lead to geometries beyond…

General Relativity and Quantum Cosmology · Physics 2025-04-02 Jorge Noreña , Thiago S. Pereira , Sean K. Reynolds

In this work, I review some aspects concerning the evolution of quantum low-energy fields in a foamlike spacetime, with involved topology at the Planck scale but with a smooth metric structure at large length scales, as follows. Quantum…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Luis J. Garay

We compute the fluctuations in gravitational lens image positions and time delay caused by large scale structure correlations. We show that these fluctuations can be expressed as a simple integral over the density power spectrum. Using the…

Astrophysics · Physics 2008-11-26 Uros Seljak

We propose an effective field theory describing the time dependent fluctuations of electrons in conducting systems, generalizing the well known kinetic theory of fluctuations. On several examples, we show its equivalence, (when quantum…

Mesoscale and Nanoscale Physics · Physics 2009-03-22 D. B. Gutman , A. D. Mirlin , Yuval Gefen

We establish a fluctuation-correlation theorem by relating the quantum fluctuations in the generator of the parameter change to the time integral of the quantum correlation function between the projection operator and force operator of the…

Quantum Physics · Physics 2009-10-31 Arun K. Pati

In this paper, we study the effect of thermal fluctuations on the thermodynamics of a black geometry with hyperscaling violation. These thermal fluctuations in the thermodynamics of this system are produced from quantum corrections of…

High Energy Physics - Theory · Physics 2017-08-24 Behnam Pourhassan , Mir Faizal , Sudhaker Upadhyay , Lina Al Asfar

We analyze the thermal fluctuations of a free, conformally invariant, Maxwell quantum field (photon) interacting with a cosmological background spacetime, in the framework of quantum field theory in curved spacetimes and semiclassical and…

General Relativity and Quantum Cosmology · Physics 2025-07-01 Markus B. Fröb , Dražen Glavan , Paolo Meda

The influence of quantum fluctuations of the electromagnetic field on the propagation of a polarized light wave in a nonlinear dielectric is investigated. It is shown that in some cases, the fluctuations couple to the optical nonlinearities…

Quantum Physics · Physics 2019-07-17 V. A. De Lorenci , L. H. Ford

Quantum vacuum fluctuations of the electromagnetic field result in two signatures on a harmonically trapped charged particle: a shift from the natural trap frequency and generation of quantum coherences. We assess the role of the…

Quantum Physics · Physics 2024-12-17 Aaron Malcolm , B. Sharmila , Zhi-Wei Wang , Animesh Datta

The curved spacetime induced by gravitational waves can give rise to visual effects such as geometric distortions and redshift structures in the observed image. By establishing a mapping from the object's surface coordinates to the…

General Relativity and Quantum Cosmology · Physics 2024-04-12 Ke Wang , Chao-Jun Feng

Extra-galactic sources of photons have been used to constrain space-time quantum fluctuations in the Universe. In these proposals, the fundamental "fuzziness" of distance caused by space-time quantum fluctuations has been directly…

High Energy Astrophysical Phenomena · Physics 2015-06-24 Yanbei Chen , Linqing Wen , Yiqiu Ma

A non-perturbative study on the quantum fluctuations of light ray propagation through a quantum region of spacetime is long overdue. Within the theory of Lorentzian simplicial quantum gravity, we compute the probabilities for a test light…

General Relativity and Quantum Cosmology · Physics 2022-06-14 Ding Jia

In generic models of cosmological inflation, quantum fluctuations strongly influence the spacetime metric and produce infinitely many regions where the end of inflation (reheating) is delayed until arbitrarily late times. The geometry of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Sergei Winitzki

We consider the effects of entanglement in the initial quantum state of scalar and tensor fluctuations during inflation. We allow the gauge-invariant scalar and tensor fluctuations to be entangled in the initial state and compute…

High Energy Physics - Theory · Physics 2017-01-13 Nadia Bolis , Andreas Albrecht , R. Holman

We present a brief overview of some key concepts in the theory of generalised complex manifolds. This new geometry interpolates, so to speak, between symplectic geometry and complex geometry. As such it provides an ideal framework to…

Mathematical Physics · Physics 2015-08-21 P. Fernandez de Cordoba , J. M. Isidro

With a modulated oscillator, we study several effects of quantum fluctuations far from thermal equilibrium. One of them is quantum heating, where quantum fluctuations lead to a finite-width distribution of a resonantly modulated oscillator…

Mesoscale and Nanoscale Physics · Physics 2017-09-15 Vittorio Peano , M I Dykman

The phenomenology for the deep spatial geometry of loop quantum gravity is discussed. In the context of a simple model of an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Seth A. Major