All Questions
240
questions
2
votes
4
answers
187
views
Necessity of Singularity in General Relativity
The Schwarzschild solution is the standard example used to describe a black hole, its important points being the event horizon and the central singularity. But this solution is derived by assuming an ...
- 9,500
0
votes
3
answers
186
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Is the size of a black hole singularity smaller than a fundamental particle?
I am wondering about the size of a black hole singularity. We know that a classical black hole is infinitely dense. I am not asking about size of event horizon. I am asking about actual size of the ...
0
votes
0
answers
72
views
Where is the mass in a Black Hole without a "central" curvature singularity?
Not all black holes have a curvature singularity at their center (an example). But in principle, I thought that the curvature singularity was a direct result of the fact that the mass is concentrated ...
- 770
0
votes
2
answers
105
views
Realistic black holes
If I understand the answers provided in this Link Why singularity in a black hole, and not just "very dense"?
Then the singularity at $r=0$ may just be a mathematical artifact, and may not ...
26
votes
10
answers
13k
views
How do black holes move if they are just regions in spacetime?
If black holes are just regions of spacetime, how can black holes even move? When matter moves through spacetime, it bends the spacetime around it, but if black holes are just regions of spacetime, ...
- 403
6
votes
2
answers
1k
views
What happens to the ring singularities when two Kerr black holes merge?
Imagine two Kerr black holes with ring singularities oriented in different axes (e.g. one horizontal and the other one vertical). If they merge, what will happen to these singularities? Will they form ...
- 185
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votes
1
answer
78
views
What are spinning black holes orbiting?
I have seen depictions of spinning black holes with the "singularity" spinning around a center of rotation in a flat plane, or moving around an imaginary sphere. Is there anything in the ...
- 1
3
votes
6
answers
1k
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Singularity of a black hole: point or solid sphere? [duplicate]
A black hole is defined by its event horizon. The event horizon has a Schwarzschild radius of,
$$r_s=\dfrac{2GM}{c^2}$$
Technically, this means that any body of mass, $M$, with a radius smaller than ...
- 33
0
votes
1
answer
77
views
Regularization of black hole singularities
Hi I have a question: when dealing with the gravitational Lorentz factor from schwarzchild solution to EFE, used in defining gravitaional time dilation and one encounters singularities at $r=0$ or $r=...
5
votes
2
answers
151
views
Is the Schwarzschild singularity a limit of the Kerr singularity?
In a Schwarzschild black hole, the singularity is spacelike. In a Kerr black hole, it is timelike.
Is there any continuous transformation between those solutions? Can the Schwarzschild solution be ...
- 203
1
vote
0
answers
50
views
2
votes
1
answer
163
views
Why domain of Kerr black hole includes negative values for $r$ coordinate?
I understand the domain of $t$ is all real numbers but mathematically, how to prove the domain of $r$ coordinate is also all real numbers except $r=0$ when $\theta = \pi/2$. I know that we get two ...
- 59
0
votes
1
answer
150
views
Black holes, singularities and topology in relativity
General relativity is defined on a base manifold which, viewed as a topological space, is simply connected (which means there's no holes). However, we know that inside a black hole there's a ...
- 309
6
votes
1
answer
262
views
How to find that there is a conical singularity in the BTZ black hole?
Considering a non-rotating and non-charged 2+1 dimensional black hole, known as the BTZ black hole which obtained by adding a negative cosmological constant $\Lambda=-\frac{1}{l^2},l\ne0$ to the ...
0
votes
1
answer
63
views
Don't Geodesics change due to other geodesics?
So the geodesics that point towards the Earth brings space-time towards the Earth and then back out again, but then the moon has its own geodesics so wouldn't it be kind of like geodesics affecting ...
- 1,534