All Questions
Tagged with black-holes general-relativity
2,485
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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 ...
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Orthogonal complement of null vector [closed]
I am trying to solve excercise 8.5 d) from Straumanns book on general relativity (here V is an n-dimensional Minkowski vector space):
Prove that the orthogonal complement of a null vector is an $(n-1)$...
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Derive metric tensor from frame fields [closed]
I am new to frame fields formalism. I want to ask if there is any way to derive metric tensor from given fuenfbein frame fields?
The problem I meet is $\rm AdS_5$ SUSY black hole solution in https://...
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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 ...
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3
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Photonic black holes
"Can a photon turn into a black hole?" - usually the answer to this question is - it can't, because it has zero rest mass. However, when we derive the Schwarzchild Metric initially the $2M$ ...
- 1,141
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WKB Approximation of the Quasinormal Mode Spectrum of the Poschl-Teller (PT) Potential
In Black Hole Spectroscopy, it is well known that the Pöschl-Teller (PT) potential behaves approximately, or similarly to the more complicated Regge-Wheeler (RW) Potential.
The WKB Approximation has ...
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Extreme Mass Ratio Inspirals and GWs cycles
I was reading through the following paper GRMHD study of accreting massive black hole binaries in astrophysical environment: A review. Therein, we have the following image
It is not quite clear how ...
- 1,213
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Binary black hole merging condition
Assuming two black holes with the same rest mass $m$ collid coming from infinity with velocity $v$ and impact parameter $b$. Lets ignore spin at first. For which values of $v$ and $b$ would these ...
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Black Hole Formation -- How Can an Event Horizon be Observed to Grow? [duplicate]
This is a question about black hole formation. To be clear, I’m not suggesting that black holes don’t form. It’s that I’m having trouble with the accepted explanation so there’s a flaw in my logic ...
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ADM mass calculation for 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 ...
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Conformal equivalent to Schwarzschild metric
Consider Schwarzschild spacetime in Eddington-Finkelstein coordinates $(v,r,\theta,\phi)$
$$g \enspace = \enspace -f(r) \, dv^2 + 2 \, dv \, dr + r^2 \, d\Omega^2 \quad , \qquad f(r) = 1 - \frac{2m}{r}...
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How come the magnetic field disappears when a neutron star becomes a black hole, while the rotation remains?
The only question I found is this one, but this considers as non-rotating neutron star collapsing:
Our final and most comprehensive test is represented by the collapse to a BH of a magnetized ...
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What is the difference between Hawking radiation and a black hole laser?
While reading this paper (https://arxiv.org/abs/1409.6550), I got a little bit puzzled: what is the difference between Hawking radiation and a black hole laser? Is it the same thing? From my ...
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When you are in a gravitational field, do object far away get physically closer to you as you get closer to the mass?
An observer A is close to a black hole and an observer B one light year away. They are both remaining at constant radial distance from the black hole. A is at 2 Rs away from the center of the black ...
- 161
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How to Understand Negative Energy in the Ergoregion?
I am trying to understand the Penrose process and having trouble explaining negative energy in the ergoregion.
How I interpret it is:
Energy is the dot product between the four momentum of the object ...
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