All Questions
Tagged with spacetime black-holes
64
questions
163
votes
9
answers
40k
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Does someone falling into a black hole see the end of the universe?
This question was prompted by Can matter really fall through an event horizon?. Notoriously, if you calculate the Schwarzschild coordinate time for anything, matter or light, to reach the event ...
- 358k
13
votes
4
answers
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Can a black hole be explained by Newtonian gravity?
In the simple explanation that a black hole appears when a big star
collapses under missing internal pressure and huge gravity, I can't see
any need to invoke relativity. Is this correct?
- 1,436
22
votes
3
answers
6k
views
If the observable universe were compressed into a super massive black hole, how big would it be?
I understand only a little of general relativity, but that's why I'm here! :)
Consider the hypothetical situation of some extra-terrestrial intelligence pushing all the mass in the observable ...
user756
17
votes
6
answers
2k
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Is it possible for one black hole to pull an object out of another black hole?
Suppose we have a spacecraft just inside the event horizon of a black hole, struggling to escape, but slowly receding into it. Another (bigger) black hole expands until its event horizon includes the ...
- 2,784
17
votes
3
answers
1k
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A Sphere of Black Holes
Imagine a sphere of black holes surrounding a piece of space. Will this piece be separated from the rest of normal spacetime (at least for some time, till these black holes finally attracted ...
- 982
17
votes
2
answers
5k
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Space falling faster than light after it falls inside the event horizon of a black hole?
Typing my question directly so people know what I am asking, afterwards providing background and context.
Q: What does it mean when space is falling, faster than light?
(I am specifically wondering ...
- 398
29
votes
4
answers
6k
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Could the black hole in the center of the galaxy be a white hole?
In the center of the galaxy there is a strong radio source which we call Sagittarius A*. Based on the high speed and orbit of nearby stars we have calculated that something with the mass of more than ...
- 1,141
11
votes
1
answer
2k
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Do black holes exist in 1+1 dimensional spacetime?
I'm currently working in 1+1 dimensional spacetime and would like to know if black holes can exist in such a manifold? I think they can because the Schwarzchild metric has the coordinate singularity, ...
- 477
3
votes
5
answers
3k
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Time paradox inside a black hole
At the event horizon of a black hole, time and the spatial direction toward the center exchange places. The direction inside the black hole from the event horizon to the the singularity in the center ...
- 12.7k
3
votes
4
answers
2k
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Time inside a Black hole
If time stops inside a black hole, due to gravitational time dilation, how can it's life end after a very long time? If time doesn't pass inside a black hole, then an event to occur inside a black ...
- 558
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
vote
2
answers
652
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Can a sufficiently large black hole be singularity-free?
This came to me after reading that a black-hole that has the mass of the observable universe will also have an event horizon that covers the observable universe.
Since the definition of a black hole ...
- 589
1
vote
1
answer
435
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If a black hole is just warped spacetime, then where is the electric charge?
I've heard Kip Thorne repeatedly state that matter is destroyed when a black hole is created, that all you are left with is distorted spacetime.
"The idea that black holes are made from very ...
- 51
21
votes
3
answers
6k
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How does the Penrose diagram for a spinning black hole differ in realistic scenarios (formed by stellar collapse)?
The Penrose diagram for a non-spinning Schwarzschild black hole is
Notably, there is a second universe "on the other side" of the black hole. However, actual black holes form by stellar collapse, and ...
- 11.6k
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.
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