Unanswered Questions
1,161 questions with no upvoted or accepted answers
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Localization of gravitational energy-momentum in plane waves
Dirac ("General Theory of Relativity") shows that in the case of a weak gravitational plane wave, the Einstein pseudo-energy tensor ${t_\mu}^\nu$ has the (approximate) form of a tensor in ...
- 366
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How to derive Smarr formula for Kerr Black Hole?
Following is the Smarr formula for Kerr Black Hole
$$M=\frac{\kappa A}{4\pi}+2 \Omega J $$
where $\kappa, \Omega$, $J$ and $A$ are surface gravity, angular velocity, angular momentum and surface area ...
- 59
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End points of event horizon
I am reading The Nature of Space and Time by S. W. Hawking. In the last paragraph on page 16 he said that:
event horizon may have past end points but don't have any future end points
I understand ...
- 207k
2
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BTZ black hole as a quotient of AdS space
I am trying to understand this paper 1 and trying to reproduce some calculations and had some questions about that. In section 3.2, page 12, eq. 3.9, the authors are writing normal geodesics of an ...
- 207k
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Energy of the gravitational field within a sphere of radius $R$ in the Schwarzschild metric
The Landau-Lifshitz energy-momentum pseudotensor $t^{μν}$ is defined by
$$16πt^{μν}
= -2G^{μν} - g^{-1} \left[ -g \left( g^{μν}g^{αβ} - g^{μα}g^{νβ} \right) \right]_{,αβ}$$
where $g=\text{det}[g^{μν}]...
- 366
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Question about the toroidal magnetic field in quasars and the role of an ergosphere
1) Introduction
Most of astrophysical bodies (in this context: formed stars, young stellar objects and black holes) produce or are immersed in a non-zero magnetic field $\vec{B}$. It is common, since ...
- 28.4k
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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 ...
- 207k
2
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Quantum field expansion and bogoliubov coefficients in the interior of a rotating black hole
I am trying to quantize a real scalar field in the interior of a rotating black hole (3+1 D, asymptotically flat). My question is regarding the modes of the radial part of the equation (obtained after ...
- 107
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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 ...
- 770
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The data file of the LISA Interferometer results
How to extract the data of the strain versus frequency plot of the Laser Interferometer Space Antenna (LISA): Figure (2) in this paper:
https://arxiv.org/abs/1702.00786
The paper doesn't contain any ...
- 207k
2
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Robin conditions from action principle
Consider the Lagrangian density
$$L(\tilde{\phi}, \nabla \tilde{\phi}, \tilde{g}) = \tilde{g}^{\mu \nu} \nabla_{\mu} \tilde{\phi} \nabla_{\nu} \tilde{\phi} + \xi \tilde{R} \tilde{\phi}^2$$
with $\...
- 743
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How to plot the curve of the gravitational wave energy density giving the data of the strain versus frequency
I want to plot the curve of energy density ($\Omega$) of the gravitational waves versus frequency that are predicted by the Einstein telescope. But in the ET pages:
https://moscow.sci-hub.se/4444/...
- 395
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Is there a database or catalog of all black hole candidates?
I am searching for a catalog, list, database, etc. That should show astronomical observations of known black hole candidates. I am primarily interested in knowing the mass of these candidates.
I have ...
- 207k
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Gravitational Wave Impact on Connected Particles
We understand that when a gravitational wave passes through a setup with two freely falling particles, it causes them to oscillate and change the distance between them. However, if the two particles ...
- 139
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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 ...
