All Questions
Tagged with gravity general-relativity
2,007
questions
21
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3
answers
2k
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Can perfectly stable orbits exist in GR?
Defining "stable orbit" between two bodies as one where, in the absence of other bodies or non-gravitational forces, the distance stays between some value pair $r_{min}>0$ and $r_{max}$. ...
- 355
81
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17
answers
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How exactly does curved space-time describe the force of gravity?
I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or ...
- 6,112
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What is the cause of gravity according to general relativity? [duplicate]
The question is based on general relativity and it can help big bang theory.
- 207k
1
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1
answer
33
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Cause of Coordinate Acceleration in Free Fall [duplicate]
So I understand that objects in free fall are in an inertial frame, at rest in terms of relativity. However, from a person on the surface of earth, a falling apple is accelerating constantly until it ...
- 358k
1
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1
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Gauge invariance of linearized gravity with an arbitrary background spacetime
Consider here a background metric $g_{\mu\nu}$, we impose a perturbation $g_{\mu\nu}+\epsilon h_{\mu\nu}$ with $\epsilon\ll1$. Then we can write down the modified Einstein-Hilbert action with zero ...
CommunityBot
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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
8
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5
answers
1k
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Do you always experience the gravitational influence of other mass as you see them in your frame?
You see a galaxy far away. That galaxy is attracting you with a certain amount of gravity. I'm wondering if the gravity influence of the galaxy on you, as measured by you, always ends up being what ...
- 1,148
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3
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101
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What is the gravitational field of a hole in an infinite perfect crystal?
Or equivalently and more interestingly: In the early universe when there was uniform H/He gas everywhere, gravitational field was close to 0 everywhere. Every test particle was pulled from all sides ...
- 56.4k
0
votes
2
answers
60
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Confused about Weinberg's result of gravitational time dilation
I am reading Weinberg's Gravitation and Cosmology. In section 3.5, the author got a result$$\frac{dt}{\Delta t}=(-g_{00})^{-1/2}\tag{3.5.2}.$$Here $dt$ is the time interval of a stationary observer in ...
- 613
2
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3
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Is gravity a tensor?
All other fundamental forces are mediated by vector bosons. The Higgs boson is a scalar boson & the interaction it mediates isn't called as a force. A force is a vector in the usual description. ...
- 4,452
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0
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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
3
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0
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52
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Negative (absolute - not potential) energy of the gravitational field; how to generalize to GR?
Alan Guth gives a thought experiment to show that a gravitational field has negative energy. (See the picture below.) Consider a thin spherical shell of elastic, compressible matter, of radius $R_o$. ...
- 366
13
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3
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Why does angular momentum shorten the Schwarzschild Radius of a black hole?
Angular momentum causes the event horizon of a black hole to recede. At maximum angular momentum, $J=GM^2/c$, the Schwarzschild radius is half of what it would be if the black hole wasn't spinning.
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4
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Lorentz force error in the present 2024 version of the gravitoelectromagnetism Wikipedia page? [closed]
I noticed that the Gravitoelectromagnetism (GEM) Wikipedia page has been edited recently. The factor of 4 in the GEM Lorentz force equation is now missing. But the GEM field equations are identical to ...
- 207k
0
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1
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99
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How to derive the surface gravity in terms of redshift factor in static spacetime?
I am following Carroll's book "Spacetime and Geometry" p. 245-247. I have the following expression for the surface gravity of a Killing horizon:
$$\kappa^2=-\frac{1}{2}(\nabla_{\mu}K_{\nu})(\...
