All Questions
82
questions
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What are regular event horizons?
I am studying uniqueness theorems of Black Holes and I often see the word "regular event horizon" instead only event horizon. Many textbooks and literature do not define this term. Please ...
- 59
9
votes
4
answers
3k
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Is it possible to have a stable black hole that does not evaporate?
Black holes would presumably evaporate in the long future via Hawking radiation.
However is this inevitable? Or are there any mechanisms that would compensate the lost mass due to Hawking radiation ...
- 2,462
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votes
0
answers
57
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Scattering approach for massless scalar Hawking radiation and Bogoliubov coefficients in Schwarzschild metric
Reflection coefficient from the scattering approach in tortoise coordinates, looks exactly like relationship between modulus squared of Bogoliubov coefficients. However I'm not able to figure out a ...
0
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0
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45
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What is the difference between the cosmological and the black hole horizons in thermodynamics?
I want to know the different thermal behaviors between cosmological and black hole horizons, such as temperature, entropy and so on.
- 113
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41
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Why are greybody factors necessary when dealing with Hawking radiation?
According to Wikipedia, greybody factors are corrections to the black hole Hawking radiation spectrum. They say that at the horizon the emission is that of a perfect black body, but the gravitational ...
- 22.1k
1
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32
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How increase in area of the horizon implies that the horizon in spacelike using Raychaudhuri equation?
In a talk The enigma of black hole horizons, (at 24:37), it is said that
"Raychaudhuri equation implies, if the flux into H is positive, area increases and horizon is spacelike".
How ...
- 293
1
vote
0
answers
32
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Understanding Haywards trapping gravity
In the paper General Laws of Black hole Dynamics, Hayward has proposed a formula for trapping gravity of an outer trapping horizon given by
$\kappa$ = $\frac{1}{2}$ $\sqrt{-e^f \mathcal{L}_- \Theta_+}$...
- 293
1
vote
0
answers
25
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Do all small-large AdS black hole phase transitions have swallow tail like behaviour for the Free Energy v/s Temperature plot?
In the literature the swallow tail like behaviour is prominently seen for small-large AdS black hole phase transition for the Free Energy vs Temperature Plot. Recently I was trying to reproduce the ...
- 193
1
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36
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Conformal mapping of Euclidean Schwarzschild AdS black hole
I have been trying to understand this for some time. given the Euclidean S-AdS black hole metric,
$$ ds^2 = f(r)d\tau^2 + \frac{1}{f(r)} dr^2 + r^2d\Omega^{2}_{D-2} $$
From what I understand this has ...
3
votes
1
answer
151
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What size is the smallest black hole stable at Standard temperature & pressure?
I have seen several questions regarding the size of the absolute smallest black hole, the smallest stable black hole and similar. These made me wonder; what is the smallest stable black hole if it is ...
3
votes
0
answers
79
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Past null horizon
What are past null horizons and future null horizons? Are they the same as past event horizons and future event horizons? The literature on Black Holes often uses these terms but I don’t get it. ...
- 59
3
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0
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32
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Question on apparent super efficiency of the magnetic penrose process
Accordingly to this paper $[1]$, the efficiency of the so called Magnetic Penrose Process (MPP) is, for supermassive black holes of mass $M∼10^{10} M_{\odot}$ immersed in a magnetic field having $B∼10^...
- 3,085
1
vote
2
answers
434
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Does the interior volume of a black hole grow forever?
Recently, I was reading about a article which tells about something known as "Susskind Complexity". The article states that the interior volume of a black hole grows forever.
How/why does ...
user355398
1
vote
0
answers
18
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Ergodicity and spin connections at the event horizon
Hawking famously relates the entropy $S$ to the surface area of a black hole $A$ as $S=A/4$. Should I be thinking of the entropy as the number of possible configurations of a spin connection at the ...
- 241
2
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0
answers
50
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Hawking Temperature for a hairy BTZ Black Hole
The metric of a hairy Black Hole is given by:
$$ds^2 = \frac{L^2}{z^2}\biggl(-g(z) dt^2 + \frac{e^{2 A(z)}}{g(z)} dz^2 +d\varphi^2\biggr), $$
where $L$ is the AdS length taken to be $1$,$A(z)$ is the ...
- 193