All Questions
15
questions
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1
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114
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Dimension of mass of black hole in natural unit
I am reading articles on superradiance, specifically, massive scalr field in Kerr geometry. https://journals.aps.org/prd/abstract/10.1103/PhysRevD.22.2323
One assumption of the article is $$\mu M\ll1,$...
- 442
5
votes
3
answers
717
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Are there fields (of any kind) inside a black hole?
It is said that nothing escapes from black holes, not even light. All particles are now thought to be excitation of different fields (electric field, electromagnetic field, photon field, etc).
Does it ...
- 137
2
votes
1
answer
208
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Scalar product of fields in Schwarzschild space-time
The scalar product of fields in curved space-time is defined by (Birrel, Davies)
$$\left(\phi_{1}, \phi_{2}\right)\equiv-\mathrm{i} \int_{\Sigma} \phi_{1}(x) \overset{\leftrightarrow} {\partial_\mu}\...
- 339
0
votes
1
answer
122
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Black Hole S-Matrix
I am reading arXiv:2006.03606 where through Eq. (1.1) they say that the transition amplitude for collapse of matter from initial state $\Psi_{i}$ into a black hole and eventually evaporation of black ...
- 648
0
votes
1
answer
86
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quantum fluctuations at the horizon
So suppose we have a black hole with hair, that is a background solution in our field theory that describes a black hole spacetime and in which a field coupled to gravity has a non zero configuration.
...
- 1,874
2
votes
0
answers
98
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What's the difference, if any, between Soft Hair & Quantum Hair
In the early 90s, John Preskill, Sidney Coleman, Frank Wilzcek and Lawrence Krauss presented a series of papers [1][2][3] on Quantum Hair on Black Holes due to Cosmic strings in a number of ways ...
- 425
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votes
1
answer
152
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Why do we use Schwarzschild solution as background when applying QFT to black hole?
Schwarzschild solution is classical, so it does not allow for violation of energy conditions to allow for Hawking radiations. So what justifies its use in QFT for a black hole?
- 173
2
votes
0
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162
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About the origin of the thermality in Unruh effect
It's normally understood that the thermal response in Unruh effect is related with the horizon of an accelerated observer so that part of the information is unaccessable.
In this paper, Rovelli ...
- 1,548
1
vote
0
answers
168
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Phenomena in the intersection of general relativity and quantum mechanics
I am looking for physical phenomena that have aspects involving both general relativity and quantum mechanics.
The only example I know is Hawking radiation. While black holes are objects that cannot ...
- 315
4
votes
1
answer
593
views
Black hole thermodynamics in a time dependent metric
For a time dependent space time metric, to get the thermodynamics, does the standard procedure of Wick rotating the time, and then calculating the free energy, work ?
- 336
5
votes
1
answer
1k
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Solving Klein-Gordon equation in the Rindler coordinates - the Unruh effect
I am reading 't Hooft's notes on Black Holes. I want to find the solutions of the Klein-Gordon equation $(\tilde{x},\tilde{y}, \rho, \tau)$ in the Rindler coordinates which are $$x=\tilde{x}\,\,\,\,\ ...
user7757
5
votes
3
answers
1k
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Hawking Radiation: how does a particle ever cross the event horizon?
The heuristic argument for Hawking Radiation is, that a virtual pair-production happens just at the event horizon. One particle goes into the black hole, while the other can be observed as radiation.
...
- 644
7
votes
1
answer
357
views
Hawking radiation: direct matter -> energy conversion?
When a black hole evaporates, does it turn all the matter that has fallen in directly to energy, or will it somehow throw back out the same kind of matter (normal or anti) that went in?
- 345
18
votes
3
answers
2k
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Why is there a flux of radiation in the Hawking effect but not in the Unruh effect? (and other questions)
This question is slightly related to this one Do all massive bodies emit Hawking radiation?, which I think was poorly posed and so didn't get very useful answers. There are several questions in this ...
- 8,800
28
votes
3
answers
4k
views
No hair theorem for black holes and the baryon number
The no hair theorem says that a black hole can be characterized by a small number of parameters that are visible from distance - mass, angular momentum and electric charge.
For me it is puzzling why ...
- 6,480