All Questions
587
questions
0
votes
0
answers
37
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 ...
- 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 ...
- 115
5
votes
3
answers
180
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
2
votes
2
answers
914
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 ...
- 197
2
votes
1
answer
68
views
Understanding Wormholes Geometrically
Is the folding sheet analogy really that good for understanding what a wormhole is? After all, space-time curvature doesn't require any ambient space (it's intrinsic), as such a picture would suggest. ...
- 323
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, ...
- 403
1
vote
0
answers
48
views
How can you use gravity while trying to model gravity? [duplicate]
So consider the usual pop-science spacetime model, a bowling ball on a trampoline. Apparently, the ball should sink into the trampoline, causing a dip in the fabric which causes nearby objects to fall ...
- 141
-7
votes
1
answer
135
views
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 ...
- 994
-1
votes
1
answer
53
views
If an area in 2D cannot be curved and finite is the same regarding the space of our pressumed 3D universe?
Is the sentence in the title right that our universe is infinite? And if so does it mean that stars are not evenly distributed along our universe but they all move from a populated centre to a fairly ...
- 2,245
1
vote
1
answer
54
views
Does the Weyl tensor amount to tidal effects of gravity?
The Ricci tensor, for the spacetime surrounding the Earth, is zero, so the spacetime around the Earth is Ricci-flat.
The Riemann tensor though is not zero since spacetime certainly is curved. This ...
- 450
2
votes
2
answers
111
views
Why does the warping of spacetime make objects move closer together?
I understand why the warping of spacetime affects moving objects, but why would it affect stationary ones if it even does? Would two completely stationary objects not move closer together because they ...
18
votes
2
answers
3k
views
How does spacetime curve around an object in superposition?
I'm trying to learn quantum mechanics and this is a question that came to mind. I tried searching for it online, but I couldn't find a good answer (or at least one I could understand). From what I ...
- 191
0
votes
1
answer
59
views
Are gravitons suggested as the cause of matter curving space?
My understand is that GR says that mass curves space but it does not say why or how this occurs. Is the idea of gravitons that they are the entities that actually affect space?
- 2,224
0
votes
0
answers
72
views
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 ...
- 337
1
vote
1
answer
67
views
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, ...
- 85