Gravity and Nonequilibrium Thermodynamics of Classical Matter

Abstract

Renewed interest in deriving gravity (more precisely, the Einstein equations) from thermodynamics considerations [1, 2] is stirred up by a recent proposal that 'gravity is an entropic force' [3] (see also [4]). Even though I find the arguments justifying such a claim in this latest proposal rather ad hoc and simplistic compared to the original one I would unreservedly support the call to explore deeper the relation between gravity and thermodynamics, this having the same spirit as my long-held view that general relativity is the hydrodynamic limit [5, 6] of some underlying theories for the microscopic structure of spacetime - all these proposals, together with that of [7, 8], attest to the emergent nature of gravity [9]. In this first paper of two we set the modest goal of studying the nonequilibrium thermodynamics of classical matter only, bringing afore some interesting prior results, without invoking any quantum considerations such as Bekenstein-Hawking entropy, holography or Unruh effect. This is for the sake of understanding the nonequilibrium nature of classical gravity which is at the root of many salient features of black hole physics. One important property of gravitational systems, from self-gravitating gas to black holes, is their negative heat capacity, which is the source of many out-of-the ordinary dynamical and thermodynamic features such as the non-existence in isolated systems of thermodynamically stable configurations, which actually provides the condition for gravitational stability. A related property is that, being systems with long range interaction, they are nonextensive and relax extremely slowly towards equilibrium. Here we explore how much of the known features of black hole thermodynamics can be derived from this classical nonequilibrium perspective. A sequel paper will address gravity and nonequilibrium thermodynamics of quantum fields [10].

25 pages essay. Invited Talk at Mariofest, March 2010, Rosario, Argentina. Festschrift to appear as an issue of IJMPD

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Cited by in corpus (24)

• Emergent perspective of Gravity and Dark Energy
• Emergence of Cosmic Space and the Generalized Holographic Equipartition
• Conservative entropic forces
• Thermodynamical instabilities of perfect fluid spheres in General Relativity
• Entropic Corrections to Coulomb's Law
• Trapped surfaces and emergent curved space in the Bose-Hubbard model
• Thermodynamic properties, thermal image and phase transition of Einstein-Gauss-Bonnet black hole coupled with nonlinear electrodynamics
• Thermodynamics and galactic clustering with a modified gravitational potential
• Newtonian Semiclassical Gravity in the Ghirardi-Rimini-Weber Theory with Matter Density Ontology
• Machian Origin of the Entropic Gravity and Cosmic Acceleration
• The cosmological constant: A lesson from the effective gravity of topological Weyl media
• Emergent Cosmos in Einstein-Cartan Theory
• On entropic gravity: the entropy postulate, entropy content of screens and relation to quantum mechanics
• On the Dynamics of the Ensemble of Particles in the Thermodynamic Model of Gravity
• Cosmological parameters from the thermodynamic model of gravity
• Dynamical Vacuum Compressibility of Space
• Box of Ideal Gas in Free Fall
• Emergence from irreversibility
• Thermodynamical features of Verlinde's approach for a non-commutative Schwarzschild-anti-deSitter black hole in a broad range of scales
• Emergence: Key physical issues for deeper philosophical inquiries
• Zeroth Law in Quantum Thermodynamics at Strong Coupling: `in Equilibrium', not `Equal Temperature'
• Modeling the Past Hypothesis: A Mechanical Cosmology
• Entropic force law in the presence of a noncommutative inspired spacetime for a solar system scale
• Thermodynamics and phase transitions of black holes in contact with a gravitating heat bath