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We consider scalar perturbations of energy-density for a class of cosmological models where an early phase of accelerated expansion evolves, without any fine-tuning for graceful exit, towards the standard Friedman eras of observed universe.…

General Relativity and Quantum Cosmology · Physics 2011-05-10 S. Capozziello , G. Lambiase , G. Scarpetta

Recently, we presented a unified way of analysing classical cosmological perturbation in generalized gravity theories. In this paper, we derive the perturbation spectrums generated from quantum fluctuations again in unified forms. We…

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

By making use of a class of steep exponential type of potentials, which has been recently used to describe quintessential inflation, we show how a unified picture for both inflation, dark energy and dark matter can emerge entirely through…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-20 Gustavo B. F. Lima , Rudnei O. Ramos

At Planck-scale, spacetime is "foamy" due to quantum fluctuations predicted by quantum gravity. Here we consider the possibility of using spacetime foam-induced phase incoherence of light from distant galaxies and gamma-ray bursters to…

Astrophysics · Physics 2009-11-07 Y. Jack Ng , W. A. Christiansen , H. van Dam

Quantum mechanics is considered to arise from an underlying classical structure (``hidden variable theory'', ``sub-quantum mechanics''), where quantum fluctuations follow from a physical noise mechanism. The stability of the hydrogen ground…

Quantum Physics · Physics 2009-11-11 Th. M. Nieuwenhuizen

We show that high energy scattering is a statistical process essentially similar to reaction-diffusion in a system made of a finite number of particles. The Balitsky-JIMWLK equations correspond to the time evolution law for the particle…

High Energy Physics - Phenomenology · Physics 2009-11-10 E. Iancu , A. H. Mueller , S. Munier

If spacetime undergoes quantum fluctuations, an electromagnetic wavefront will acquire uncertainties in direction as well as phase as it propagates through spacetime. These uncertainties can show up in interferometric observations of…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Y. Jack Ng

In this paper, utilizing M{\o}ller's energy-momentum complex, we explicitly evaluate the energy and momentum density associated with a metric describing a four-dimensional, Schwarzschild-like, spacetime derived from an effective gravity…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Th. Grammenos , I. Radinschi

Previously defined covariant and gauge-invariant perturbation variables, representing, e.g., the fractional spatial energy density gradient on hypersurfaces of constant expansion, are used to simplify the linear perturbation analysis of a…

Astrophysics · Physics 2009-10-30 Winfried Zimdahl

As in an earlier paper we start from the hypothesis that physics on the Planck scale should be described by means of concepts taken from ``discrete mathematics''. This goal is realized by developing a scheme being based on the dynamical…

High Energy Physics - Theory · Physics 2016-09-06 Manfred Requardt

We show that quantum properties of spacetime, encoded by noncommutativity at the Planck scale, lead to a generalized time evolution of quantum systems in which pure states can evolve into mixed states. Specifically, a decoherence mechanism…

General Relativity and Quantum Cosmology · Physics 2023-01-27 Michele Arzano , Vittorio D'Esposito , Giulia Gubitosi

We consider a Hamiltonian system of particles, interacting through of a smooth pair potential. We look at the system on a space scale of order {\epsilon}^1, times of order {\epsilon}^2, and mean velocities of order {\epsilon}, with…

Mathematical Physics · Physics 2023-05-11 Raffaele Esposito , Rossana Marra

Possibly, the most general action in the background of isotropic and homogeneous space-time has been considered to study the quantum evolution of the early universe, apart from a cosmological constant. The hermiticity of the effective…

High Energy Physics - Theory · Physics 2020-10-30 Ranajit Mandal , Dalia Saha , Mohosin Alam , Abhik Kumar Sanyal

We provide a class of QFTs which exhibit dissipation above a threshold energy, thereby breaking Lorentz invariance. Unitarity is preserved by coupling the fields to additional degrees of freedom (heavy fields) which introduce the rest…

High Energy Physics - Theory · Physics 2008-11-26 Renaud Parentani

Extracting governing physical laws from computational or experimental data is crucial across various fields such as fluid dynamics and plasma physics. Many of those physical laws are dissipative due to fluid viscosity or plasma collisions.…

Computational Physics · Physics 2026-02-11 Yubin Lu , Xiaofan Li , Chun Liu , Qi Tang , Yiwei Wang

We consider scalar perturbations of energy--density for a class of cosmological models where an early phase of accelerated expansion evolves, without any fine--tuning for graceful exit, towards the standard Friedman eras of observed…

General Relativity and Quantum Cosmology · Physics 2007-05-23 S. Capozziello , G. Lambiase , G. Scarpetta

We derive a formula that defines quantum fluctuations of energy in subsystems of a hot relativistic gas. For small subsystem sizes we find substantial increase of fluctuations compared to those known from standard thermodynamic…

High Energy Physics - Phenomenology · Physics 2021-12-15 Arpan Das , Wojciech Florkowski , Radoslaw Ryblewski , Rajeev Singh

We review a few topics in Planck-scale physics, with emphasis on possible manifestations in relatively low energy. The selected topics include quantum fluctuations of spacetime, their cumulative effects, uncertainties in energy-momentum…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Y. Jack Ng

The new, complex-dynamical mechanism of the universal gravitation naturally incorporating dynamical quantization, wave-particle duality, and relativity of physically emerging space and time (quant-ph/9902015,16) provides the realistic…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Andrei P. Kirilyuk

In most current models of inflation based on a weakly self-coupled scalar matter field minimally coupled to gravity, the period of inflation lasts so long that, at the beginning of the inflationary period, the physical wavelengths of…

High Energy Physics - Theory · Physics 2008-11-26 Jerome Martin , Robert H. Brandenberger