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To numerically evolve the full Einstein equations (or modifications thereof), simulations of cosmological spacetimes must rely on a particular formulation of the field equations combined with a specific gauge/frame choice. Yet truly…

General Relativity and Quantum Cosmology · Physics 2023-06-30 Anna Ijjas

Gravitational waves sourced by amplified scalar perturbations are a common prediction across a wide range of cosmological models. These scalar curvature fluctuations are inherently nonlinear and typically non-Gaussian. We argue that the…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-10 A. J. Iovino , S. Matarrese , G. Perna , A. Ricciardone , A. Riotto

The geodesic equations for the general case of diagonal metrics of static, spherically symmetric fields are calculated. The elimination of the proper time variable gives the motion equations for test particles with respect to coordinate…

General Physics · Physics 2015-03-09 Franz-Günter Winkler

The emission of gravitational waves from a system of massive objects interacting on elliptical, hyperbolic and parabolic orbits is studied in the quadrupole approximation. Analytical expressions are then derived for the gravitational wave…

Astrophysics · Physics 2010-04-21 Salvatore Capozziello , Mariafelicia De Laurentis

We present a mathematical theory of dynamical fluctuations for the hard sphere gas in the Boltzmann-Grad limit. We prove that: (1) fluctuations of the empirical measure from the solution of the Boltzmann equation, scaled with the square…

Analysis of PDEs · Mathematics 2022-08-26 Thierry Bodineau , Isabelle Gallagher , Laure Saint-Raymond , Sergio Simonella

The Einstein-Langevin equation is a perturbative correction to the semiclassical Einstein equation which takes into account the lowest order quantum fluctuations of the matter stress-energy tensor. It predicts classical stochastic…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Rosario Martin , Enric Verdaguer

Physical scenarios, leading to highly energetic stochastic gravitational waves backgrounds (for frequencies ranging from the $\mu$Hz up to the GHz) are examined. In some cases the typical amplitude of the logarithmic energy spectrum can be…

High Energy Physics - Phenomenology · Physics 2016-11-03 Massimo Giovannini

Using Euler's equations of motion and the Hamiltonian formulation, we obtain the equations of motion of systems with internal angular momentum that are moving with respect to a given reference frame, when subjected to a torque which is…

Classical Physics · Physics 2007-05-23 M. Dorado

The Gerlach and Sengupta (GS) formalism of coordinate-invariant, first-order, spherical and nonspherical perturbations around an arbitrary spherical spacetime is generalized to higher orders, focusing on second-order perturbation theory.…

General Relativity and Quantum Cosmology · Physics 2009-11-11 David Brizuela , Jose M. Martin-Garcia , Guillermo A. Mena Marugan

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 2015-05-13 B. L. Hu , E. Verdaguer

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 2016-10-19 B. L. Hu , E. Verdaguer

Through averaging the Einstein equations over transverse gravitational perturbations it is obtained a closed system of two ordinary differential equations describing macroscopic cosmological evolution of the isotropic space-flat Universe…

General Relativity and Quantum Cosmology · Physics 2016-08-24 Yurii Ignat'ev

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

The interval approach to computation of dynamics of celestial bodies in the planetary problem has been considered. It is based on the refusal from idealization of infinitely high resolving capacity of measuring tools, and forms an…

Space Physics · Physics 2010-02-17 Valeriy V. Petrov

Perturbations in a universe with matter and cosmological constant are computed in terms of the primordial scalar perturbation up to second order. The calculation is easy -- a generalization of the spherical dust solution. Our expression…

Astrophysics · Physics 2007-05-23 Andrei Gruzinov

We study the wave equations with various spins on the background of the general spherically symmetric spacetime. We obtain the unified expression of the Teukolsky-like master equations and the corresponding radial equations with the general…

General Relativity and Quantum Cosmology · Physics 2023-10-04 Ya Guo , Hiroaki Nakajima , Wenbin Lin

Assuming a classical statistical system of point particles the fundamental equations of continuum thermomechanics (continuity equation, equation of motion, and energy equation) shall be derived exactly. The macroscopic state functions…

Statistical Mechanics · Physics 2010-06-03 Walter Noll

Stochastic geometric mechanics (SGM) is known for its potential utility in quantifying uncertainty in global climate modelling of the Earth's ocean and atmosphere while also preserving the fundamental advective transport properties of ideal…

Fluid Dynamics · Physics 2023-08-30 Darryl D. Holm , Erwin Luesink

The equation describing the stochastic motion of a classical particle in 1+1-dimensional space-time is connected to the Dirac equation with external gauge fields. The effects of assigning different turning probabilities to the forward and…

High Energy Physics - Theory · Physics 2016-09-06 Jae-weon Lee , Eok Kyun Lee , Hae Myoung Kwon , In-gyu Koh , Yeong Deok Han

The conditions of thermodynamic equilibrium, local thermodynamic equilibrium, and statistical equilibrium are discussed in detail. The equations of statistical equilibrium and the supplementary equations are shown together with the…

Solar and Stellar Astrophysics · Physics 2015-05-19 Jiri Kubat