All Questions
Tagged with spacetime event-horizon
108
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
20
votes
2
answers
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Chasing someone who has fallen into a black hole
Assume that my friend and I decided to explore a black hole. I parked the spaceship in a circular orbit safely away from the horizon. He puts on his spacesuit with a jet pack and carefully travels ...
- 427
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 ...
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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 ...
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11
votes
1
answer
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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, ...
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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
11
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3
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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
10
votes
2
answers
796
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What is the region of space that exists at the center of mass of merging black holes?
The title of the question does not allow enough characters for a clear statement of the question. This is the question:
Imagine that a series of black holes are converging toward a common center of ...
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9
votes
2
answers
898
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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
8
votes
2
answers
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A naïve question about spacetime singularities
Very little that I know about general relativity is that there are solutions of its equations with singularities, and these are interpreted as black holes.
Mathematically, the most widespread kind of ...
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7
votes
1
answer
356
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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
7
votes
5
answers
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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
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 ...
6
votes
2
answers
653
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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 ...
- 1,187
6
votes
0
answers
262
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Why are there multiple universes in the Reissner-Nordström solution?
I am trying to make sense of the Penrose diagram of a non extremal Reissner-Nordström spacetime, that is, the solution with two horizons. The coordinates are
$$ v'=\text{exp}\left(\frac{r_+-r_-}{2r_+^...
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