Related papers: Cosmological apparent and trapping horizons
We disclose the deep connection between the thermodynamics and gravity in a general braneworld model with curvature correction terms on the brane and in the bulk, respectively. We show that the Friedmann equations on the 3-brane embedded in…
The thermodynamical properties of dark energy are usually investigated with the equation of state $\omega =\omega_{0}+\omega_{1}z$. Recent observations show that our universe is accelerating, and the apparent horizon and the event horizon…
The analysis of phase transitions in cosmological spacetimes shows that their existence requires a time-dependent apparent horizon radius, which in turn implies an equation of state different from that of a dark energy fluid. This condition…
We have considered the flat FRW model of the universe which is filled with only dark energy. The general descriptions of first and second laws of thermodynamics are investigated on the apparent horizon and event horizon of the universe. We…
This paper proves a theorem about the existence of an apparent horizon in general relativity, which applies equally well to vacuum configurations and matter configurations. The theorem uses the reciprocal of the surface-to-volume ratio of a…
The question that continues to hinge the interrelation between cosmology and thermodynamics is broadly described as -- what is the form of horizon entropy that links the Friedmann equations for a "$general$" gravity theory with the…
We discuss some of the drawbacks of using event horizons to define black holes. The reasons are both practical, physical and theoretical. We argue that locally defined trapping horizons can remedy many of these drawbacks. We examine of the…
The concept of smooth deformations of a Riemannian manifolds, recently evidenced by the solution of the Poincar\'e conjecture, is applied to Einstein's gravitational theory and in particular to the standard FLRW cosmology. We present a…
It was shown by Tsallis and Cirto that thermodynamical entropy of a gravitational system such as black hole must be generalized to the non-additive entropy, which is given by $S_h=\gamma A^{\beta}$, where $A$ is the horizon area and $\beta$…
Numerical studies of gravitational collapse to black holes make use of apparent horizons, which are intrinsically foliation-dependent. We expose the problem and discuss possible solutions using the Hawking quasilocal mass. In spherical…
Gravitational perturbations of flat Minkowski space make the Rindler horizon dynamical: the horizon satisfies mechanical laws analogous to the ones followed by black holes. We describe the gravitational perturbation of Minkowski space using…
We consider the cosmology that results if our observable universe is a 3-brane in a higher dimensional universe. In particular, we focus on the case where our 3-brane is located at the $Z_2$ symmetry fixed plane of a $Z_2$ symmetric…
Does a dynamical black hole embedded in a cosmological FRW background emit Hawking radiation where a globally defined event horizon does not exist? What are the differences to the Schwarzschild black hole? What about the first law of black…
In the context of modified $f(R)$ gravity, we attempt to study the thermodynamic properties of the evolving Lorentzian wormholes at the apparent horizon. It is shown that the wormhole can be derived from a particular $f(R)$ model in the…
General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degrees of freedom in the extended effective field theory of gravity generated by the…
Recently, Almheiri et. al. argued, via a delicate thought experiment, that it is not consistent to simultaneosuly require that (a) Hawking radiation is pure, (b) effective field theory is valid outside a stretched horizon and (c) infalling…
In this letter we explore the foundations of entropic cosmology and highlight some important flaws which have emerged and adopted in the recent literature. We argue that, when applying entropy and temperature on the cosmological horizon by…
The dynamics of apparent and event horizons of various black hole spacetimes, including those containing distorted, rotating and colliding black holes, are studied. We have developed a powerful and efficient new method for locating the…
A general definition of a black hole is given, and general `laws of black-hole dynamics' derived. The definition involves something similar to an apparent horizon, a trapping horizon, defined as a hypersurface foliated by marginal surfaces…
Adopting the Landau-Lifshiftz method of classical fluctuations we determine the statistical average strength of the fluctuations of the energy flux on the apparent horizon of a homogeneous and isotropic universe described by Einstein…