All Questions
114
questions
3
votes
2
answers
669
views
When do we talk about spaghettification or pancakification in black holes?
So I've been doing some research for a while now, and yesterday came across the video of PBS space time talking about what happens to quantum information in a black hole. In the thought experiment ...
0
votes
2
answers
57
views
When it comes to getting closer to the Schwarzschild radius, how is discrete a limit?
From Keeton (2014) in Principles of Astrophysics: Using Gravity and Stellar Physics to Explore the Cosmos, Gravitational time dilation near a large, slowly rotating, nearly spherical body, such as the ...
2
votes
0
answers
68
views
Is there a formula relating the rate/speed a black hole event horizon will grow, to the density of the medium surrounding it?
I am thinking about the average density of the space around the black hole, not the density immediately adjacent to the event horizon which might be different. It will probably be best to model the ...
- 131
0
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2
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179
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How do we know that a black hole radius is not significantly contracted for a stationary outside observer?
It is my understanding that just as special relativity contracts length with velocity general relativity contracts length with gravity. Would this mean the radius of a BH is smaller than it would ...
- 1,348
0
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1
answer
116
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Time required to reach Black Hole's Event Horizon from outsider perspective?
Let's imagine a pair of particles that is entangled. One (call it $P_1$) is released and then falls to a black hole from a distant $x_0$, (for example $x_0=5r_s$) and velocity $v_0(=1/2c)$, while the ...
1
vote
0
answers
49
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In the reference frame of an observer an arbitrarily large distance away, can event horizons form in finite time? [closed]
There are similar questions answered already but the answers disagree. I understand that simultaneity/time is local in GR and that in a given region of space, an event horizon and singularity can form ...
- 11
4
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3
answers
1k
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Will a distant observer really see an object that has fallen close to a black hole freeze in time?
I'm currently taking my first course in general relativity, and I was wondering:
We know from the schwarzschild metric that for a (far away) observer looking at an object falling towards a black hole, ...
0
votes
1
answer
74
views
What happens if we throw the observer in a black hole?
Sorry if this sounds like a silly question, but what would happen if a scientist observes Schrodinger's cat alive, but is then thrown into a black hole before he has leaked any information to the ...
- 589
1
vote
1
answer
168
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Does a geodesic exist that will take someone across the event horizon?
I saw the movie "Interstellar" a few years back, and was amazed that Cooper was able to fall from 1 AU into a black hole before his daughter turned 110. Intuitively, I would think that there ...
- 69
2
votes
2
answers
118
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If, relative to us, objects never cross the event horizon, does this imply that we cannot observe a black hole grow? [duplicate]
From what I understand relativity predicts that outside observers would never observe external objects actually crossing into the event horizon, due to time dilation.
How does that can reconciled with ...
- 169
1
vote
3
answers
109
views
Why do we See Black Holes?
The image of things falling into a Black Hole stays frozen on the event horizon forever. So how is it that we don't see the image of a dying star where a Black Hole formed?
We see the black, with an ...
- 61
1
vote
1
answer
293
views
Would something falling into a black hole appear to be flattened to an outside observer?
At the event horizon, time essentially stops. An outside observer would never see you cross the event horizon, as my understanding goes.
But in that case, how would this work out if I imagine the ...
- 1,009
1
vote
3
answers
413
views
Would someone falling into or orbiting a black hole see themselves?
Spacetime is extremely curved in the vicinity of a black hole. When a light ray is targeted close to a black hole, it is curved to a significant angle. This angle increases as the target is pointed ...
- 1,223
0
votes
1
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150
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If I jump into a black hole one million years after another person, how do we end up relative to one another in space and time? [duplicate]
Imagine we live eternally and can survive tidal forces. Say, we are point-particles.
From a fixed distance someone jumps into a black hole. I wait a million years and jump from the same position.
How ...
- 81
2
votes
2
answers
245
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What is the perceived shape of a non-spinning black hole as it is approached at high velocities?
The question and answer at What is the shape of a black hole? states that an event horizon " is indeed a sphere." But if it is approached at high velocity, does the traveler calculate that ...
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