All Questions
Tagged with spacetime event-horizon
24
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
17
votes
6
answers
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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
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
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
11
votes
3
answers
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Is the edge of our Hubble Sphere within our Cosmic Event Horizon and why?
I was recently shown a pretty cool video about common cosmological misconceptions. It got me reviewing the different between event horizon (current distance within which we will see/interact), ...
- 14.2k
6
votes
1
answer
473
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Why can't light travel past the event horizon?
Since the event horizon is defined as the boundary within which the escape velocity is greater than the speed of light, and escape velocity is the speed required for that object to reach infinity away ...
3
votes
1
answer
452
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Where does the parallel universe in the Penrose diagram come from?
In this diagram, as well as our universe, you have a parallel universe.
Where does this come from? Is this just a artifact of the diagram, or is it predicted by the maths in some sort.
- 2,908
1
vote
2
answers
1k
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If spacetime can expand faster than the speed of light, then can a black hole do that too?
I have read this question:
Yes, the expansion of space itself is allowed to exceed the speed-of-light limit because the speed-of-light limit only applies to regions where special relativity – a ...
- 29k
0
votes
2
answers
1k
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About the 1D singularity of black hole [duplicate]
I saw some responses here saying that the singularity into the black hole is one dimension object so my question is : is it possible that the singularity is simply a merger of the 4 dimensions of the ...
- 145
11
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3
answers
2k
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Closed timelike curves in the region beyond the ring singularity in the maximal Kerr spacetime
The region beyond the ring singularity in the maximal Kerr spacetime is described as having closed timeline curves. Why and/or how is the question.
Now if you look a Kruskal-Szkeres Diagram (or a ...
- 25.7k
9
votes
2
answers
898
views
Is it possible the space-time manifold itself could stop at a black hole's event horizon?
This is a repost of a question I saw here:
Could the spacetime manifold itself end at the event horizon?
which was closed because it apparently didn't seem clear as to what the poster there was ...
- 20.6k
7
votes
5
answers
1k
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How do we expect distance measurements to compare inside and outside the event horizon of a black hole?
I've read that as one approaches the event horizon of a black hole, time is dilated relative to time measured farther away from the event horizon (clocks tick slower near the event horizon).
I've ...
- 11.7k
7
votes
1
answer
356
views
Equilibrium for a rope hanging in a Schwarzschild spacetime
Update: Trimok and MBN helped me solve most of my confusion. However, there is still an extra term $-(2/r)T$ in the final result. Brown doesn't write this term, and it seems physically wrong.
Update #...
user4552
6
votes
2
answers
653
views
Can one define a flow of spacetime?
One often reads things like, 'At the event horizon, the flow of spacetime exceeds the local speed of light.' But is this actually correct? Can you mathematically define some sort of spacetime flow ...
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