All Questions
589
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How to mathematically describe the process of spacetime curvature?
I guess as a result of the energy-momentum tensor $T_{\mu\nu}$ coupling to a flat Minkowski metric, $\eta_{\mu\nu}$, the flat metric can become that of a curved spacetime, $g_{\mu\nu}$. How can one ...
- 357
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1
answer
67
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How would objects move in a linear gravitational field?
In General Relativity, gravity is described as the curvature of spacetime caused by mass. This curvature is often visualized as a straight path bending due to a warped surface. My question is: If, ...
- 87
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votes
1
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33
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Measuring distances between the stars
If we know how far away are the two known stars from Earth, then is it a safe bet that we can know how far apart those two stars are from each other using sine rules? Does that mean we must first ...
- 13k
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Are there any ways to conceptualize the relationship between gravity and space-time other than curvatures?
This might sound like a random question, but it came to me while I was trying to conceptualize the size of the universe and started thinking of entire galaxies resembling grands of sand floating ...
1
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1
answer
67
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Why does trajectory in the space curved by gravity, depend on the speed?
I am sorry about the probably naiive nature of this question (I am a software eng, not a physics student):
I (think I) understand the popular curved "trampoline" model of 2-dimensional space,...
- 13
1
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2
answers
85
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What is Dirac's reasoning when saying parallel displacement creates vector field with vanishing covariant derivative?
Section 12 of Dirac's book "General Theory of Relativity" is called "The condition for flat space", and he is proving that a space is flat if and only if the curvature tensor $R_{\...
- 43
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2
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77
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Gravitational field of the star changes the paths of light rays, how is this observed during eclipse?
The gravitational field of the star changes the paths of light rays in space-time from what they would have been had the star not been present. I understand that the light cones are bend slightly ...
- 103
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How does Einstein's spacetime curvature theory for gravity actually makes sense? [duplicate]
I have a lot of confusion understanding the concept that a mass creates a curvature in the space time and other small masses gets attracted towards big masses since they starts falling inside that ...
1
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1
answer
97
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Limit of gravity
Is there any limit to the bending of spacetime due to gravity?
I have been reading about wormholes and how they bend spacetime and connect two systems. But if there is no limit to gravity, we can ...
0
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3
answers
133
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What is spacetime like according to general relativity? [duplicate]
It is often said that matter curves space (or rather spacetime) in general relativity.
But why should matter curve space one way and not the other way? So it seems like a metaphor, I guess.
I read ...
- 15
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1
answer
102
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Flat space between colliding black holes
When 2 black holes approach each other, they both bend space in an opposite direction. There must always be a flat space between 2 colliding black holes.
However, I heard that they actually merge, ...
- 187
4
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4
answers
826
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Why do we call the Riemann curvature tensor the curvature of spacetime rather than the curvature tensor of its tangent bundle?
I was studying the mathematical description of gauge theories (in terms of bundle, connection, curvature,...) and something bothers me in the terminology when I compare it with general relativity.
In ...
- 123
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1
answer
71
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Does the variation of $I$ yield Bach tensor？
For $$I_1=\int \sqrt{-g}C_{abcd}C^{abcd}d^4x,$$ where $C_{abcd}$ is the Weyl tensor. If we neglect the Gauss-Bonnet term this can be reduced to $$I_2=2\int \sqrt{-g}(R^{ab}R_{ab}-\frac {1}{3} R^2)d^4x....
- 75
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84
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Definition of asymptotically flat spacetime
Following the definition in Wald's book on general relativity, in page 276 asymptotically flat spacetimes are defined using conformal isometry with conformal factor $Ω$.
Then one of the requirements ...
- 1,734
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How does a curvature in time equate to Newtonian gravity? [duplicate]
I often read that a curvature in time (the rate at which clocks tick) near a massive object, is considered to be the source of Newtonian gravity.
This got me wondering, does General Relativity use the ...
