All Questions
134
questions
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Black Hole Formation -- How Can an Event Horizon be Observed to Grow? [duplicate]
This is a question about black hole formation. To be clear, I’m not suggesting that black holes don’t form. It’s that I’m having trouble with the accepted explanation so there’s a flaw in my logic ...
- 21
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0
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48
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What is the difference between Hawking radiation and a black hole laser?
While reading this paper (https://arxiv.org/abs/1409.6550), I got a little bit puzzled: what is the difference between Hawking radiation and a black hole laser? Is it the same thing? From my ...
- 159
3
votes
1
answer
150
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Do black holes evaporate prior to crossing their event horizon? [duplicate]
Bob falls into a black hole, watched by Alice who is far away.
Alice sees Bob asymptotically approach the event horizon while his clock asymptotically approaches 12:00 noon as his image redshifts (...
- 161
1
vote
2
answers
78
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Probability of a primordial black hole absorbing background radiation?
I'm thinking of the early universe when there was a lot of energetic radiation around. A primordial black hole (PBH) that would be about to evaporate completely about now, would have an initial mass ...
- 6,112
1
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104
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Can black holes exchange Hawking radiation, avoiding complete evaporation?
I was wondering if it would be possible that, as a black hole radiates its mass as Hawking radiation, another black hole could absorb that radiation and then when the second black hole radiates its ...
- 2,462
9
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4
answers
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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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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 ...
2
votes
0
answers
33
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Gray body factors of PBH's - radial equation approximation (Page 1976)
I'm deriving the results of the Page paper: "Particle emission rates from a black hole: Massless particles from an uncharged, nonrotating hole*" (https://doi.org/10.1103/PhysRevD.13.198). At ...
- 21
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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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49
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About the geometric optics approximation in Hawking radiation
I have read Hawking's famous paper Particle creation by Black Holes (Ref. 1) and I have some doubts about the geometric optics approximation and its implications in the argument being made. The ...
- 1,989
1
vote
2
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110
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If Hawking radiation is observer dependent then is the mass of a black hole too?
I have read this question (in the comments):
Late response, but the energy really comes from the gravitational field, which exists outside the event horiz0n and in space. This field is what lets us ...
- 29k
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 ...
1
vote
0
answers
67
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Hairy black hole
I was wondering why it is said that if a black hole has hair we can measure its charge at infinity, where does this statement come from?
It doesn't seem right to me because solutions to KG equation ...
- 63
4
votes
0
answers
76
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Where from Hawking radiation actually arise?
Where from Hawking radiation actually arise? I would like to connect the answer with the technical derivation along the lines of the original calculation by Hawking (a modern account of which is given ...
- 785
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2
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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 ...
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