All Questions
9
questions
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66
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How can Planck-length elements exists in spacetime? [duplicate]
My question is simple, how can the theory of finite-sized elements (Planck-sized elements) in spacetime be correct, when you find the number $\pi$ in the Schwartzchild representation of the black hole,...
- 143
1
vote
1
answer
137
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A Question About the Surface of a Black Hole Singularity
In Kip Thorne's book, Black Holes and Time Warps, he states that the mass of the core of a star shrinks until quantum gravity takes over. And then discusses that at this distance, the singularity ...
- 2,706
2
votes
2
answers
183
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Black holes with no space-time or no space-time only (metric)? [closed]
It is generally accepted that a black hole can be defined as a trapped surface or region of space-time where gravity is so intense that light can not escape. Another definition is that a black hole is ...
- 6,611
5
votes
1
answer
236
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Black hole formation from radiation in a box
In a paper I am currently studying (here), it was assumed that a black hole can form from a pure state of radiation in a box.
Abstract:
INFORMATION IN BLACK HOLE RADIATION
arXiv:hep-th/9306083
If ...
- 2,849
1
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0
answers
91
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BMS supertranslations and integral identity in arXiv:1603.07706
Looking at the paper 1603.07706 we see that infinitesimal BMS supertranslations are generated by:
$$
\xi = f\partial_u - \frac{1}{r}\left(D^zf\partial_z + D^\bar{z}f\partial_\bar{z}\right) + \frac{1}{...
- 570
16
votes
2
answers
7k
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What are BMS supertranslation symmetries?
What are BMS supertranslation symmetries? I am studying soft hair on black holes and I need to learn BMS supertranslation symmetries.
- 373
0
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2
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349
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Space-time and gravitational fields
I am reading a book by Carlo Rovelli, Seven Brief Lessons On Physics, and would like to check if I have understood something. Apologies if my question is badly phrased, feel free to edit where ...
- 119
3
votes
2
answers
1k
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Can an object be infinitely small?
I read somewhere that the earth has to be smaller than 1 cm to become a black hole, according to Schwarzschild. Since big bang came from a singularity, I am wondering, is there any minimum volume for ...
- 33
1
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1
answer
162
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Classical black holes?
How big should the black hole be so we can consider it to be classical?
When they claim that we can not probe shorter distances than the Planck length, can it be true?
The argument says that, doing ...
- 2,586