All Questions
Tagged with gravity general-relativity
2,007
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Why does the wavelength of gravitational waves increase with larger energy?
Gravitational and electromagnetic waves are quite similar, as both are fundamental force waves that travel at the speed of light and have no limit to their range, but when it comes to electromagnetism,...
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Einstein's equation of gravitation field [duplicate]
I'm looking for the reason why there is the number eight $8$ at the r.h.s. of EI:
$$R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}=\frac{8\pi G}{c^2}T_{\mu\nu}.$$
My attempt was to take the limit of this equation ...
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On the existence of Gravitational energy in GR [duplicate]
I was reading this paper that puts forward the argument that Gravitational energy in GR is unnecessary and doesn't exist and that got me wondering if this is a fringe theory or what exactly is the ...
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Does dark matter have mass?
When trying to understand what dark matter is, it is helpful to know that some properties of it can already be derived from various observations, such as, it only interacting via gravity and no other ...
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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 ...
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How is Gravity, assuming only General Relativity, *not* like Centrifugal Force?
It is common to state that "Gravity is not a force" due to its interpretation as a curvature effect in general relativity. By this, is it right to say that gravity is a fictitious force due ...
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Can there be structures made from neutrinos that can have angular momentum?
Would it be possible to eventually have structures made from neutrinos somewhere in the universe, as it is indicated in this question (Are neutrino stars theoretically possible?), like halos of ...
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Suppose a shell of a sphere formed by matter and with large radius, start afterwards to diminish the radius, give $E=mc^2$ the system stops
Thinking in classical mechanics terms but with the knowledge that $E=mc^2$ let's make the below thought:
Suppose you have a shell of a sphere formed by a mass uniformly distributed over the surface of ...
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Do two bodies with the same mass but different volumes, exert the same gravitational pull?
Asking this strictly from GR, not Newtonian gravity. I am not well versed with GR, so let me know if my question fundamentally misunderstood the concepts of GR, but if there are two independent bodies,...
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So just because gravity "merely" bends space and isn't "really" a force at a distance - isn't it still a thing at a distance? [closed]
As a preamble, just for clarity as far as I can remember (I was awfully drunk) I have a degree in physics, math and comp sci: my point is "here's a probably stupid question at the level of person ...
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If gravity is not a force, what makes massive objects spheroid?
For most of my life, the explanation given for why celestial bodies like stars, planets, etc. are round is due to gravitational force. Simply put, if an object has enough mass, it will, in turn, have ...
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How does gravity act and propagate in a 2+1D universe?—Newtonian versus general relativity
In a hypothetical 2+1D universe:
if we apply the Newtonian concept of gravity, we might expect that the gravitational force between two mass points with a distance of $r$ would diminish linearly with ...
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How is Wald deriving this Gauge condition: $\partial^b\, \overline{\gamma}_{ab} = 0$?
R. Wald in Section#4.4 of his book General Relativity derives the EFE in the case of a weak gravitational field by taking the curved spacetime metric $g_{ab}$ to be a "small" perturbation $\...
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Confusion over what constitutes a uniform gravitational field in relativity
Suppose we have some observer moving upwards with a constant proper acceleration, by the equivalence principle this is the same as the observer remaining stationary in a gravitational field, like ...
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Relation between the number of curvature functions and dimensions in GR
I am reading Weinberg's Gravitation and Cosmology. On page 10, it reads
In $D$ dimensions there will be $D(D+1)/2$ independent metric functions $g_{ij}$, and our freedom to choose the $D$ coordinates ...
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