Friedmann equations from nonequilibrium thermodynamics of the Universe: A unified formulation for modified gravity

Teo

2017

Class. Quantum Grav.

756

657

We review recent developments on the thermodynamics of black holes in extended phase space, where the cosmological constant is interpreted as thermodynamic pressure and treated as a thermodynamic variable in its own right. In this approach, the mass of the black hole is no longer regarded as internal energy, rather it is identified with the chemical enthalpy. This leads to an extended dictionary for black hole thermodynamic quantities, in particular a notion of thermodynamic volume emerges for a given black hole spacetime. This volume is conjectured to satisfy the reverse isoperimetric inequalityan inequality imposing a bound on the amount of entropy black hole can carry for a fixed thermodynamic volume. New thermodynamic phase transitions naturally emerge from these identifications. Namely, we show that black holes can be understood from the viewpoint of chemistry, in terms of concepts such as Van der Waals fluids, reentrant phase transitions, and triple points. We also review the recent attempts at extending the AdS/CFT dictionary in this setting, discuss the connections with horizon thermodynamics, applications to Lifshitz spacetimes, and outline possible future directions in this field.

Section: Thermodynamics Of De Sitter Black Holesmentioning

confidence: 99%

Black hole chemistry: thermodynamics with Lambda

Kubizňák

Teo

2017

Class. Quantum Grav.

756

657

“…Our knowledge of thermodynamic volume, and more generally the thermodynamic behaviour of asymptotically de Sitter (dS) black holes, for which Λ > 0, is significantly more sparse [47,[50][51][52][53][54][55]]. Yet their importance to cosmology and to a posited duality between gravity in de Sitter space and conformal field theory [56] make them important objects of investigation.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic volume of cosmological solitons

Mbarek

2017

Physics Letters B

We present explicit expressions of the thermodynamic volume inside and outside the cosmological horizon of Eguchi-Hanson solitons in general odd dimensions. These quantities are calculable and well-defined regardless of whether or not the regularity condition for the soliton is imposed. For the inner case, we show that the reverse isoperimetric inequality is not satisfied for general values of the soliton parameter a, though a narrow range exists for which the inequality does hold. For the outer case, we find that the mass M out satisfies the maximal mass conjecture and the volume is positive. We also show that, by requiring M out to yield the mass of dS spacetime when the soliton parameter vanishes, the associated cosmological volume is always positive.

“…Our knowledge of the thermodynamic behaviour of asymptotically de Sitter (dS) black holes, for which Λ > 0, is significantly more sparse [29][30][31][32][33][34][35]. Yet their importance to cosmology and to a posited duality between gravity in de Sitter space and conformal field theory [36] make them important objects of investigation.…”

Section: Introductionmentioning

confidence: 99%

Reverse Hawking-Page phase transition in de Sitter black holes

Mbarek

2019

J. High Energ. Phys.

In the context of black hole chemistry, we study the thermodynamics of asymptotically de Sitter black holes with conformal scalar hair in Einstein gravity. The hair parameter allows us to attain thermodynamic equilibrium between the event horizon and the cosmological horizon. We find that the system of the black hole and the de Sitter space surrounding it undergo a "Reverse" Hawking-Page phase transition provided we consider the grand-canonical ensemble. arXiv:1808.03349v2 [hep-th]