All Questions
589
questions
0
votes
0
answers
16
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Spinning top moving in curved spacetime
If I have a spinning top in empty space, it would take work to change the orientation of the angular momentum vector of the top. Suppose I throw a spinning top in flat space such that the direction of ...
- 1,222
-3
votes
0
answers
64
views
Does Mass Actually Displace Space-Time, or does Mass only Distort it?
1. Question
Given the plethora of space-time illustrations, there is a sense that space-time is actually being displaced by mass, (planets). But on its face, this doesn't really make sense because ...
- 87
4
votes
1
answer
402
views
What is the geometry of light cones if space is curved/non-Euclidean?
In light cone diagrams, the plane corresponding to the present is always the Euclidean one, but what if space is curved? Now, I've also seen diagrams where spacetime is supposed to be regarded as ...
CommunityBot
- 1
81
votes
17
answers
59k
views
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 ...
- 6,217
5
votes
3
answers
239
views
How did Einstein figure out mass (and hence energy) bends spacetime?
I can understand that once I fix the velocity of light at $c$, there is a relative variation in space-time based on special relativity (inertial frame of reference). It's not clear to me how Einstein ...
- 131
0
votes
0
answers
40
views
Extrinsic Curvature in a conformally-flat spacetime that is also asymptotically-flat spacetime
I would appreciate if someone can confirm or correct my understanding of extrinsic-curvature (as in the ADM 3+1 decomposition of spacetime) when dealing with a conformally-flat spacetime.
(I updated ...
- 21
7
votes
7
answers
11k
views
Does time dilation cause gravity as explained in this video?
Watch it around 2:00 minutes. https://youtu.be/gcvq1DAM-DE
Do objects move closer to Earth because they experience time at different rates, really? Does it make sense? The video also represents the ...
- 1
-3
votes
3
answers
76
views
Does Matter Cause Curvature or Vice-Versa [closed]
From the way explanations about gravity-acceleration-curvature equivalence are usually phrased here or elsewhere, it would appear many or most think that matter causes space-time curvature.
I cannot ...
- 1,897
1
vote
3
answers
430
views
Local inertial frames, and locally flat geometry, taylor expanding metric coefficients
In general relativity, if there is a line element of the form $$ds^2 = [f(u, v)]du^2 + [h(u, v)]dvdu + [w(u, v)]dv^2$$ which I believe corresponds to metric coefficients $$g_{00} = f(u, v)$$ $$g_{01} =...
CommunityBot
- 1
7
votes
2
answers
378
views
Test-particles motion in general space-time with *torsion* : geodesics or auto-parallel curves?
Consider a general curved space-time with torsion. In the standard Einstein-Cartan-Kibble-Sciama theory (ECKS or ECSK), torsion is non-dynamical and doesn't propagates in free space. But a more ...
- 2,093
2
votes
2
answers
917
views
Theoretically, can perfectly flat space exist in the universe?
According to general relativity, mass and energy cause the curvature of space. To have perfectly flat space, there must be a completely empty vacuum state with no mass or energy.
Theoretically, is it ...
- 13.1k
71
votes
2
answers
9k
views
Is spacetime flat inside a spherical shell?
In a perfectly symmetrical spherical hollow shell, there is a null net gravitational force according to Newton, since in his theory the force is exactly inversely proportional to the square of the ...
- 19
3
votes
3
answers
1k
views
Locally flatness in general relativity
My professor made following statement:
The spacetime of GR is curved in the presence of strong gravitational fields. The effects of curvature
manifest themselves at large ...
- 36
0
votes
1
answer
2k
views
2D space-time curvature [closed]
Actually, why is the space-time curvature considered 2D plane. As 2-D dimensional space-time curve is used to explain why moon revolves around the earth stating because the massive objects wraps the ...
- 1
26
votes
10
answers
13k
views
How do black holes move if they are just regions in spacetime?
If black holes are just regions of spacetime, how can black holes even move? When matter moves through spacetime, it bends the spacetime around it, but if black holes are just regions of spacetime, ...
- 358k