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The Einstein-Hilbert action has a bulk term and a surface term (which arises from integrating a four divergence). I show that one can obtain Einstein's equations from the surface term alone. This leads to: (i) a novel, completely self…

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

The Einstein-Hilbert action (and thus the dynamics of gravity) can be obtained by combining the principle of equivalence, special relativity and quantum theory in the Rindler frame and postulating that the horizon area must be proportional…

General Relativity and Quantum Cosmology · Physics 2009-11-07 T. Padmanabhan

This work comprises a study of the thermodynamic behavior of modified $f(\bar{R},\bar{T})$ gravity, which had been developed based on a non-canonical theory known as K-essence theory. In this development, we use the Dirac-Born-Infeld (DBI)…

General Relativity and Quantum Cosmology · Physics 2024-10-14 Arijit Panda , Goutam Manna , Saibal Ray , Maxim Khlopov , Praveen Kumar Dhankar

It has been known for a long time that Einstein's field equations when projected onto a black hole horizon looks very similar to a Navier-Stokes equation in suitable variables. More recently, it was shown that the projection of Einstein's…

General Relativity and Quantum Cosmology · Physics 2012-01-18 Sanved Kolekar , T. Padmanabhan

The paper deals with the calculation of the gravitational entropy in the context of teleparallel gravity for de Sitter space-time. In such a theory it is possible to define gravitational energy and pressure, thus we use those expressions to…

General Relativity and Quantum Cosmology · Physics 2016-07-20 S. C. Ulhoa , E. P. Spaniol

The work shows that the evolution of the field of the free Klein-Gordon equation (KGE), in the hydrodynamic representation, can be represented by the motion of a mass density subject to the Bohm-type quantum potential, whose equation can be…

General Physics · Physics 2019-04-10 Piero Chiarelli

It is often argued that {\it all the information of a gravitational theory is encoded in the surface term of the action}; which means one can find several physical quantities just from the surface term without incorporating the bulk part of…

General Relativity and Quantum Cosmology · Physics 2015-11-09 Bibhas Ranjan Majhi

I describe how gravitational entropy is intimately connected with the concept of gravitational heat, expressed as the difference between the total and free energies of a given gravitational system. From this perspective one can compute…

General Relativity and Quantum Cosmology · Physics 2022-10-12 R. B. Mann

There are two strong clues about the quantum structure of spacetime and the gravitational dynamics, which are almost universally ignored in the conventional approaches to quantize gravity. The first clue is that null surfaces exhibit…

General Relativity and Quantum Cosmology · Physics 2020-01-17 T. Padmanabhan

Using Relativistic Quantum Geometry we study back-reaction effects of space-time inside the causal horizon of a static de Sitter metric, in order to make a quantum thermodynamical description of space-time. We found a finite number of…

General Relativity and Quantum Cosmology · Physics 2020-01-08 Juan Ignacio Musmarra , Mauricio Bellini

The two surprising features of gravity are (a) the principle of equivalence and (b) the connection between gravity and thermodynamics. Using principle of equivalence and special relativity in the {\it local inertial frame}, one could obtain…

High Energy Physics - Theory · Physics 2009-11-07 T. Padmanabhan

Bearing the thermodynamic arguments together with the two definitions of mass in mind, we try to find metrics with spherical symmetry. We consider the adiabatic condition along with the Gong-Wang mass, and evaluate the $g_{rr}$ element…

General Relativity and Quantum Cosmology · Physics 2016-12-23 H. Moradpour , S. Nasirimoghadam

We explain how quantum gravity can be defined by quantizing spacetime itself. A pinpoint is that the gravitational constant G = L_P^2 whose physical dimension is of (length)^2 in natural unit introduces a symplectic structure of spacetime…

High Energy Physics - Theory · Physics 2014-11-21 Hyun Seok Yang

We clarify the problem in which occasions can gravitational force be regarded emergent from thermodynamics, by proposing an entropic mechanism that can extract the entropic gradient existing in spacetime, due to the variation of the…

High Energy Physics - Theory · Physics 2021-10-01 Yang An , Peng Cheng

Expanding the black hole thermodynamics from the horizon to achronal Cauchy hypersurface, the general relation between the Einstein equation and thermodynamics is established. Starting from trivial entropy that is generalized by…

High Energy Physics - Theory · Physics 2020-04-14 Jun Chen

I describe an approach which relates classical gravity to the quantum microstructure of spacetime. In this approach, the field equations arise from maximizing the density of states of the matter plus geometry. The former is identified using…

General Relativity and Quantum Cosmology · Physics 2017-08-22 Thanu Padmanabhan

We derive the equations of motion for Palatini F(R) gravity by applying an entropy balance law T dS= \delta Q+\delta N to the local Rindler wedge that can be constructed at each point of spacetime. Unlike previous results for metric F(R),…

General Relativity and Quantum Cosmology · Physics 2015-03-17 Goffredo Chirco , Christopher Eling , Stefano Liberati

We consider the energetics and thermodynamics of spacetimes with no horizons, but endowed with a preferred timelike junction surface. They could arise as a limiting case of the gravastar and other constructions regularizing the interior of…

General Relativity and Quantum Cosmology · Physics 2025-07-08 Raymond Isichei , João Magueijo

In a recent paper [arXiv:1001.0785], Verlinde has shown that the Newton gravity appears as an entropy force. In this paper we show how gravity appears as entropy force in Einstein's equation of gravitational field in a general spherically…

High Energy Physics - Theory · Physics 2010-04-14 Rong-Gen Cai , Li-Ming Cao , Nobuyoshi Ohta

A new definition of entropy is introduced using a model that simulates an expanding space-time compatible with the fundamental principle of cosmology. The entropy is obtained by mean of a state function that measures the variation of the…

General Physics · Physics 2024-05-01 Faycal Ben Adda