All Questions
109
questions
2
votes
1
answer
76
views
How to properly combine kinetic and gravitational time dilation effect?
I developed a time dilation calculator that includes both kinetic (Lorentz Factor) and gravitational (Schwarzschild Metric Formula) factors to assess the time difference between Earth and satellites. ...
1
vote
0
answers
64
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Is it possible to know if you're moving or standing still due to the definition of Einsteins equivalence principle?
I have a question regarding Einstein's theory of relativity.
Einstein's equivalence principle states that locally it's not possible to tell if you're accelerating or being stationary in a ...
- 23
0
votes
0
answers
36
views
Measurement of the velocity of a celestial body by means of (relativistic and classical) gravitational effects on clocks
Imagine a planet with the same properties as Earth, this time moving in an elliptical orbit around a black hole of a large number of solar masses. Also imagine that the surface of this planet is as ...
- 95
0
votes
2
answers
645
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Can we regard metric as the Higgs field of gravity?
The longer version of the question is: should we regard special relativity just as a spontaneous symmetry breaking phase of general relativity, driven by the non-zero vacuum expectation value (VEV) of ...
- 4,452
-4
votes
1
answer
88
views
Why we need time dimension for general relativity?
May sound strange but why GR came up with the 4th dimension ( ct ) while same results could be obtained by making a postulate like : space ( and not spacetime ) shrinks around a mass-energy component. ...
- 291
1
vote
2
answers
56
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What effects do we have to take in account to calculate the total precession of a gyroscope orbiting close to a black hole?
I've read about the Lense–Thirring precession which applies to bodies orbiting rotating masses. But there is also the geodetic effect (de Sitter precession), which is caused by the curvature of ...
0
votes
0
answers
40
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Does a tangential vector experience length contraction when moved in radial direction through Schwarzschild metric?
Let's have a look at the Schwarzschild solution. Let's consider only the spatial part since my question is only regarding length contraction.
There is the coefficient of the radial component, it's $\...
- 93
1
vote
1
answer
188
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Null surfaces in Lorentzian manifold
Null Hypersurface of Lorentzian Manifold: A hypersurface that admits a null-like normal vector field($N^a$) to it. i.e. $g_{ab}N^a N^b=0$ (metric signature$(-1,1,1,1,...)$)
In Minkowski spacetime the ...
- 27
1
vote
1
answer
124
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How is this approximation of gravity involving Rindler coordinates valid?
I have seen that it is possible to approximate the metric in the presence of a gravitational field by the Rindler metric:
Does a uniform gravitational field exist? Is there any acceleration in a ...
- 8,640
0
votes
1
answer
61
views
Is the law of the lever equation the same in classical physics as in relativity ? Why?
In classical mechanics the balancing lever equation (law of the lever) is
$$M_1 a = M_2 b$$
Where $M_1$ is the mass at a distance $a$ from the fulcrum and $M_2$ is the mass at a distance $b$ from the ...
- 926
0
votes
0
answers
58
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The Relation Between Maxwell's Equations and the Equations of Gravitoelectromagnetism
Under certain conditions, it is possible to approximate the effects of the theory of relativity through equations very similar to those of Maxwell, but for gravity. In these equations, our "...
1
vote
0
answers
65
views
What would the Raychaudhuri Equation be for accelerated geodesics?
What would the Raychaudhuri Equation be for accelerated geodesics? Suppose we are not able to assume the geodesic equation but rather have to assume for some tangent vector $u^\alpha$
$$u^\alpha\...
- 11
1
vote
0
answers
62
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Is Einstein's GR field equations covariant under local diffeomorphisms?
Given that a local diffeomorphism is not necessarily a [global] diffeomorphism, I wonder if Einstein's GR in covariant under local diffeomorphisms of a Lorenzian manifold?
If so, why do we interpret ...
- 1,268
0
votes
1
answer
52
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On the distances on the earth's Surface as seen from a spatial external observer in general relativity
Recently I was thinking about general relativity, I was wondering what distances would look like on the earth's surface seen from outer space, according to general relativity time passes more slowly ...
- 29
3
votes
1
answer
121
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Does positive pressure due to fast-moving particles create an attractive gravitational force in general relativity despite not having more true mass?
Matthew O'Dowd of PBS Spacetime explained, in his old video on dark energy and the cosmological constant, that even if a region of space has the same total energy and mass density as another, it will ...
- 4,509