All Questions
26
questions
1
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0
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50
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Does gravity accelerate you towards the geodesic of light between you and the mass?
If there's a planet far away, you will accelerate straight towards it due to gravity. If you place a Schwarzschild black hole right in the middle between you and the planet (the distance between the ...
- 171
17
votes
2
answers
5k
views
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
7
votes
3
answers
1k
views
How massive objects affect distance measurements, or "But how far away is a black hole singularity, really?"
My question basically boils down to: Is the singularity of a black hole infinitely far away?
I think questions like mine have been asked before, but they encounter responses like "no meaningful ...
- 215
2
votes
3
answers
527
views
Would our orbit really remain the same if the sun were a black hole of equal mass?
There seems to be an idea floating around that the sun could be replaced by anything of equal mass with no consequence to our orbit.
It seems to me that if the mass of the sun were confined to a ...
- 47
4
votes
1
answer
277
views
Why does Kip Thorne claim spacetime warping itself contains energy?
Kip Thorne, in this public lecture, says
that a black hole is kept together by the energy of the warping of space.
Quote around 8:00-8:30 :
"in this case, the energy [which keeps a black hole ...
- 53
0
votes
0
answers
36
views
If frequency shift is positive then how to interpret it?
Let say lightning is happening at $r=r_{A}$ from center of gravity and our observer at $r=r_{B}$ with $r_{A}>r_{B}$ then if we get frequency shift is positive (by considering let say schwarzschild ...
1
vote
1
answer
279
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Kruskal coordinates from GR field equations
The "usual" way (as I've seen in most text books) of dealing with Schwarzschild spacetime is to start with Schwarzschild coordinates, then explore the nature of coordinate singularity at $r=...
- 1,632
3
votes
1
answer
127
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A space ship has maximum proper acceleration of $a_0$. How close can it fall freely towards a black hole before it can no longer accelerate away?
Edit: To clarify, all motion is radial only.
Classically, the answer to this is pretty obvious. You just find the distance from the black hole at which the gravitational acceleration matches $a_0$ and ...
- 1,307
0
votes
2
answers
133
views
What would happen to a long ruler in a strong gravitational field?
So, let's say that we have an incredibly long, virtually indestructible ruler. We have advanced enough to move it wherever we want. Let's also say that we have another, identical ruler of the same ...
- 365
2
votes
0
answers
56
views
Exponentially small effects in black hole physics
On page 60 of the following paper1, it is written:
But in gravity, due to exponentially small effects of $O(\exp(−Area/G_N ))$, associated with black-hole physics, even these dressed versions of ...
- 649
0
votes
1
answer
33
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Black Holes - behaviour of masses perpendicular to accretion disk [duplicate]
If the accretion disk is on the (x,y) plane of an orthogonal reference frame what happens to objects outside the (x,y) plane (e.g. objects on the z-axis) ? In other words why is the accretion disk a ...
- 17
1
vote
1
answer
84
views
Does spacetime itself fall towards gravitational bodies? [closed]
John Wheeler said “Matter tells spacetime how to curve and spacetime tells matter how to move.”
So, when objects fall to Earth they travel along the spacetime curves that they and all the surrounding ...
- 740
0
votes
1
answer
68
views
What determines intensity + range of a gravity field?
Related questions..
How does the Sun's gravity extend out millions of miles to influence the far reaches of our solar system?
Reference: movie - "Interstellar", 2014 Nolan) / How does a ship ...
- 55
0
votes
1
answer
192
views
Does spacetime interval at event horizon become light-like for all trajectories?
I have been reading up few papers against the black hole paradigm specifically ECO, and i came across the argument raised by them that at r = 2GM, ds does indeed vanish. Is it correct? Please provide ...
- 134
3
votes
1
answer
112
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How one pair of Schwarzschild coordinates can specify 2 different points on a manifold?
My question is regarding Schwarzschild solution. I always heard that coordinate chart is a one to one map from a manifold to real numbers. But when we look inside the black hole using Kruskal ...
- 51