Black hole thermodynamics

2021 ◽  
pp. 301-316
Author(s):  
Andrew M. Steane
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Black Hole Thermodynamics ◽  
Unruh Effect ◽  
Area Theorem ◽  
Hawking Effect ◽  
Precise Calculation ◽  
Radiation Entropy ◽  
Penrose Process

The chapter presents the Penrose process, Hawking radiation, entropy and the laws of black hole thermodynamics. The Penrose process is derived and the area theorem is stated. A heuristic argument for the Hawking effect is given, emphasising a correct grasp of the concepts and the nature of the result. The Hawking effect and the Unruh effect are further discussed and linked together in a precise calculation. Evaporation of black holes is described. The information paradox is presented.

scholarly journals HORIZON MASS THEOREM

2005 ◽  
Vol 14 (12) ◽  
pp. 2219-2225 ◽  
Author(s):  
YUAN K. HA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Uniqueness Theorem ◽  
Hawking Radiation ◽  
General Theorem ◽  
Positive Energy ◽  
Singularity Theorem ◽  
Area Theorem ◽  
Classical Black Holes ◽  
The Uniqueness Theorem

A new theorem for black holes is found. It is called the horizon mass theorem. The horizon mass is the mass which cannot escape from the horizon of a black hole. For all black holes, neutral, charged or rotating, the horizon mass is always twice the irreducible mass observed at infinity. Previous theorems on black holes are: (i) the singularity theorem, (ii) the area theorem, (iii) the uniqueness theorem, (iv) the positive energy theorem. The horizon mass theorem is possibly the last general theorem for classical black holes. It is crucial for understanding Hawking radiation and for investigating processes occurring near the horizon.

scholarly journals HEAD-ON COLLISION AND MERGING ENTROPY OF BLACK HOLES: RECONSIDERATION OF HAWKING'S INEQUALITY

2013 ◽  
Vol 22 (07) ◽  
pp. 1350050 ◽  
Author(s):  
MASARU SIINO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Upper Bound ◽  
Gravitational Radiation ◽  
High Energy ◽  
Black Hole Thermodynamics ◽  
Black Hole Horizon ◽  
Energy Ratio ◽  
Area Theorem ◽  
Numerical Investigations

We evaluate the amount of energy that can be converted into gravitational radiation in head-on collision of black holes. We estimate it by the area theorem of black hole horizon incorporating merging entropy of colliding black holes from a viewpoint of black hole thermodynamics. Then we obtain an upper bound of energy ratio of the gravitational radiation which is smaller than the upper bound originally derived by Hawking. The fact that this estimation is not inconsistent with the results of both numerical investigations in low- and high-energy head-on collision implies that thermodynamics of coalescing black holes requires the contribution of the merging entropy.

Some applications

2020 ◽  
pp. 85-114
Author(s):  
Piotr T. Chruściel
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Wave Equation ◽  
Black Hole Thermodynamics ◽  
Splitting Theorem ◽  
Short Discussion ◽  
Area Theorem ◽  
Black Hole Spacetimes ◽  
Singularity Theorems ◽  
Incompleteness Theorems

The aim of this chapter is to present key applications of causality theory, as relevant to black-hole spacetimes. For this we need to introduce the concept of conformal completions, which is done in Section 3.1. We continue, in Section 3.2, with a review of the null splitting theorem of Galloway. Section 3.3 contains complete proofs of a few versions of the topological censorship theorems, which are otherwise scattered across the literature, and which play a basic role in understanding the topology of black holes. In Section 3.4 we review some key incompleteness theorems, also known under the name of singularity theorems. Section 3.5 is devoted to the presentation of a few versions of the area theorem, which is a cornerstones of ‘black-hole thermodynamics’. We close this chapter with a short discussion of the role played by causality theory when studying the wave equation.

On the reality of Hawking radiation

2019 ◽  
Vol 28 (16) ◽  
pp. 2040001
Author(s):  
Asghar Qadir
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Theory ◽  
Hawking Radiation ◽  
Black Hole Thermodynamics ◽  
The Public ◽  
Roger Penrose ◽  
The Subject

Hawking radiation caught the imagination of the public and physicists alike, because it seemed so counter-intuitive. By their very definition, black holes were supposed to endlessly absorb, but never emit, matter and energy. Yet, Hawking argued that taking Quantum Theory into account, they would radiate. The further belief was that Bekenstein and Hawking had developed the field of Black Hole Thermodynamics. Here I want to correct this impression and give due credit to Roger Penrose for founding the subject. Further, I discuss the question of whether Hawking radiation should be expected to really exist, arguing that there is reason to doubt it.

scholarly journals BLACK HOLES WITHOUT BOUNDARIES

2008 ◽  
Vol 17 (13n14) ◽  
pp. 2359-2366 ◽  
Author(s):  
ALEX B. NIELSEN
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Gravity ◽  
Hawking Radiation ◽  
Information Loss ◽  
Black Hole Thermodynamics ◽  
Event Horizons ◽  
Central Singularity ◽  
Trapping Horizon ◽  
Trapping Horizons

We discuss some of the drawbacks of using event horizons to define black holes and suggest ways in which black holes can be described without event horizons, using trapping horizons. We show that these trapping horizons give rise to thermodynamic behavior and possibly Hawking radiation too. This raises the issue of whether the event horizon or the trapping horizon should be seen as the true boundary of a black hole. This difference is important if we believe that quantum gravity will resolve the central singularity of the black hole and clarifies several of the issues associated with black hole thermodynamics and information loss.

scholarly journals Effect of the inner horizon on the black hole thermodynamics: Reissner–Nordström black hole and Kerr black hole

2021 ◽  
pp. 2150177
Author(s):  
G. E. Volovik
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Kerr Black Hole ◽  
Black Hole Thermodynamics ◽  
Spherically Symmetric ◽  
Schwarzschild Black Hole ◽  
Inner Horizon ◽  
Hole Charge

For the Schwarzschild black hole, the Bekenstein–Hawking entropy is proportional to the area of the event horizon. For the black holes with two horizons, the thermodynamics is not very clear, since the role of the inner horizons is not well established. Here we calculate the entropy of the Reissner–Nordström black hole and of the Kerr black hole, which have two horizons. For the spherically symmetric Reissner–Nordström black hole, we used several different approaches. All of them give the same result for the entropy and for the corresponding temperature of the thermal Hawking radiation. The entropy is not determined by the area of the outer horizon, and it is not equal to the sum of the entropies of two horizons. It is determined by the correlations between the two horizons, due to which the total entropy of the black hole and the temperature of Hawking radiation depend only on mass M of the black hole and do not depend on the black hole charge Q. For the Kerr and Kerr–Newman black holes, it is shown that their entropy has the similar property: it depends only on mass M of the black hole and does not depend on the angular momentum J and charge Q.

scholarly journals Islands and stretched horizon

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Yoshinori Matsuo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Entanglement Entropy ◽  
Total System ◽  
Island Rule ◽  
Asymptotically Flat ◽  
Flat Spacetime ◽  
Ads Spacetime ◽  
Hole Geometry

Abstract Recently it was proposed that the entanglement entropy of the Hawking radiation contains the information of a region including the interior of the event horizon, which is called “island.” In studies of the entanglement entropy of the Hawking radiation, the total system in the black hole geometry is separated into the Hawking radiation and black hole. In this paper, we study the entanglement entropy of the black hole in the asymptotically flat Schwarzschild spacetime. Consistency with the island rule for the Hawking radiation implies that the information of the black hole is located in a different region than the island. We found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. This implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. Thus the surface would be interpreted as the stretched horizon. This structure also resembles black holes in the AdS spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the AdS spacetime and the flat spacetime.

scholarly journals Islands and Page curves of Reissner-Nordström black holes

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Xuanhua Wang ◽  
Ran Li ◽  
Jin Wang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Entanglement Entropy ◽  
Additional Term ◽  
Current Case ◽  
Information Paradox ◽  
Extremal Surface ◽  
Four Dimensions ◽  
Black Hole Information

Abstract We apply the recently proposed quantum extremal surface construction to calculate the Page curve of the eternal Reissner-Nordström black holes in four dimensions ignoring the backreaction and the greybody factor. Without the island, the entropy of Hawking radiation grows linearly with time, which results in the information paradox for the eternal black holes. By extremizing the generalized entropy that allows the contributions from the island, we find that the island extends to the outside the horizon of the Reissner-Nordström black hole. When taking the effect of the islands into account, it is shown that the entanglement entropy of Hawking radiation at late times for a given region far from the black hole horizon reproduces the Bekenstein-Hawking entropy of the Reissner-Nordström black hole with an additional term representing the effect of the matter fields. The result is consistent with the finiteness of the entanglement entropy for the radiation from an eternal black hole. This facilitates to address the black hole information paradox issue in the current case under the above-mentioned approximations.

scholarly journals Black hole superradiance as a probe of ultra-light new particles

2016 ◽  
Vol 12 (S324) ◽  
pp. 273-278
Author(s):  
Robert Lasenby
Keyword(s):  
Beyond Standard Model ◽  
Black Holes ◽  
Black Hole ◽  
Standard Model ◽  
Gravitational Wave ◽  
Exponential Growth ◽  
Gravitational Radiation ◽  
Bound States ◽  
Penrose Process ◽  
Energy And Momentum

AbstractBosonic fields around a spinning black hole can be amplified via ‘superradiance’, a wave analogue of the Penrose process, which extracts energy and momentum from the black hole. For hypothetical ultra-light bosons, with Compton wavelengths on ≳ km scales, such a process can lead to the exponential growth of gravitationally bound states around astrophysical Kerr black holes. If such particles exist, as predicted in many theories of beyond Standard Model physics, then these bosonic clouds give rise to a number of potentially-observable signals. Among the most promising are monochromatic gravitational radiation signals which could be detected at Advanced LIGO and future gravitational wave observatories.

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