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We investigate the geometrical and physical structures of a pseudo-symmetric spacetime $(PS)_4$ with timelike vector under the condition of conformal flatness. We classify it into two possible types: constant Ricci scalar and closed…

General Relativity and Quantum Cosmology · Physics 2021-12-09 Avik De , Simran Arora , Uday Chand De , P. K. Sahoo

Hydrodynamics is a universal effective theory describing relaxation of quantum field theories towards equilibrium. Massive QFTs in de Sitter spacetime are never at equilibrium. We use holographic gauge theory/gravity correspondence to…

High Energy Physics - Theory · Physics 2017-07-05 Alex Buchel

In this work, we analyse static spherically symmetric solutions in the framework of mimetic gravity, an extension of general relativity where the conformal degree of freedom of gravity is isolated in a covariant fashion. Here we extend…

General Relativity and Quantum Cosmology · Physics 2018-12-13 Ratbay Myrzakulov , Lorenzo Sebastiani , Sunny Vagnozzi , Sergio Zerbini

Present investigation devoted to the dynamical study of Relativistic Hydrodynamics with some thermodynamical characteristics in $f(R,G)$ gravity towards spatially homogeneous isotropic cosmological model filled with isotropic fluid. We…

General Physics · Physics 2020-04-09 S. H. Shekh , Simran Arora , V. R. Chirde , P. K. Sahoo

We develop a geometric framework for irreversible transport phenomena in which macroscopic evolution equations arise from the combined structure of a thermodynamic state metric and an Onsager-based dissipation metric. The construction…

Fluid Dynamics · Physics 2026-01-14 Sami Lakka

It is very likely that the quantum description of spacetime is quite different from what we perceive at large scales, $l\gg (G\hbar/c^3)^{1/2}$. The long wave length description of spacetime, based on Einstein's equations, is similar to the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 T. Padmanabhan

This paper presents an in-depth exploration of timelike free geodesics in spatially curved Friedmann-Lema\^itre-Robertson-Walker (FLRW) spacetime. A unified approach for these geodesics encompassing both radial and non-radial trajectories…

General Relativity and Quantum Cosmology · Physics 2024-02-13 Omar Nemoul , Hichem Guergouri , Jamal Mimouni

It is easy to reason that gravity might be the effect of a fluid in disguise, as it will naturally arise in emergent gravity models where gravity is due to the effect of some fundamental particles, with the latter expected to behave…

General Relativity and Quantum Cosmology · Physics 2023-01-16 Jianwei Mei

It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher's Information Matrix. In this work we…

Mathematical Physics · Physics 2015-08-27 A. Bravetti , C. S. Lopez-Monsalvo , F. Nettel

Self-similar spacetimes are of importance to cosmology and to gravitational collapse problems. We show that self-similarity or the existence of a homothetic Killing vector field for spherically symmetric spacetimes implies the separability…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Sanjay M. Wagh , Keshlan S. Govinder

In this paper, the generalized second law (GSL) of thermodynamics and entropy is revisited in the context of cosmological models in Gauss-Bonnet gravity with the boundary of the universe is assumed to be enclosed by the dynamical apparent…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Hossein Farajollahi , Amin Salehi

We present a general framework for reconstructing effective Hamiltonians from known gravitational energy density profiles in curved spacetime. Starting from local thermal equilibrium and Liouville dynamics, we establish an inverse procedure…

General Relativity and Quantum Cosmology · Physics 2025-08-12 Davood Momeni

In this paper we consider a semitetrad covariant decomposition of spherically symmetric spacetimes and find a governing hyperbolic equation of the Gaussian curvature of two dimensional spherical shells, that emerges due to the…

General Relativity and Quantum Cosmology · Physics 2022-11-23 Sayuri Singh , Dharmanand Baboolal , Rituparno Goswami , Sunil D. Maharaj

We develop a geometric formulation of fluid dynamics, valid on arbitrary Riemannian manifolds, that regards the momentum-flux and stress tensors as 1-form valued 2-forms, and their divergence as a covariant exterior derivative. We review…

Fluid Dynamics · Physics 2022-06-14 Andrew D. Gilbert , Jacques Vanneste

In this paper, we study the discrete classical phase space of loop gravity, which is expressed in terms of the holonomy-flux variables, and show how it is related to the continuous phase space of general relativity. In particular, we prove…

General Relativity and Quantum Cosmology · Physics 2013-04-04 Laurent Freidel , Marc Geiller , Jonathan Ziprick

One field of fluid dynamics concerns the search for variational principles. So far, the Hamiltonian view and Riemannian geometry has been applied to find geodesics for hydrodynamic systems. Compared to Riemannian geometry sub-Riemannian…

Fluid Dynamics · Physics 2022-03-08 Annette Müller , Peter Névir

We construct a unified framework of geometrodynamics based on the Finsler geometry to reveal the relationship between spacetime and dynamics.The Lagrangian of electron in electromagnetic field as the Finsler function gives the Finslerian…

Mathematical Physics · Physics 2026-01-13 Mingwei Zhou , Shi-Dong Liang

The quantum mechanics description of a physical object stretched in space and stable in time from the relativistic space-time properties point of view, introduced in special theory of relativity, is considered and analysed. The mathematical…

Quantum Physics · Physics 2007-05-23 Andrey V. Novikov-Borodin

We prove a theorem that generalizes Schmidt's Subspace Theorem in the context of metric diophantine approximation. To do so we reformulate the Subspace theorem in the framework of homogeneous dynamics by introducing and studying a slope…

Number Theory · Mathematics 2021-02-08 Emmanuel Breuillard , Nicolas de Saxcé

We investigate the emergence of cosmic hysteresis in cyclic bouncing cosmologies within the framework of $f(R)$ modified gravity theories. Building upon previous studies that explored hysteresis phenomena in braneworld and…

General Relativity and Quantum Cosmology · Physics 2025-06-12 Aritra Sanyal