All Questions
65
questions
8
votes
5
answers
1k
views
Do you always experience the gravitational influence of other mass as you see them in your frame?
You see a galaxy far away. That galaxy is attracting you with a certain amount of gravity. I'm wondering if the gravity influence of the galaxy on you, as measured by you, always ends up being what ...
- 171
2
votes
1
answer
161
views
When you are in a gravitational field, do object far away get physically closer to you as you get closer to the mass?
An observer A is close to a black hole and an observer B one light year away. They are both remaining at constant radial distance from the black hole. A is at 2 Rs away from the center of the black ...
- 171
0
votes
1
answer
177
views
How is special relativity explained by general relativity?
To be more specific about this, I am under the below assumptions and then will explain my question further. Please let me know if any of the assumptions are incorrect.
(1) Special relativity describes ...
4
votes
1
answer
112
views
How to relate Riemannian and Lorentzian tetrad fields on the same manifold/spacetime?
Consider Gibbons and Hawkings paper wherein a Riemannian metric $\overset{\mathcal{R}}{g}_{\mu\nu}$ and everywhere well defined normalized line field $l_{\mu}$ on spacetime $M$ may be used to ...
- 2,847
0
votes
2
answers
75
views
General Relativistic version of the Lorentz factor
In curved spacetime, the Lorentz factor is different than that in flat spacetime.
Is there any expression that gives the Lorentz factor for any arbitrary metric tensor?
user355398
0
votes
1
answer
120
views
Stress-energy tensor in different reference frames and spacetime curvature
The components of the stress-energy tensor are different in different reference frames. Also there is no universal time, so values of energy will be different in different reference frames.
Via the ...
- 65
5
votes
1
answer
404
views
Physical Meaning of Pullback metric vs. Effective Spatial Metric
Consider a Riemannian Manifold with a metric tensor $g_{\mu\nu}$ and coordinates $(t, x^i)$. Let us assume that the spacetime is stationary, so $\partial_t g_{\mu\nu} = 0$. At a fixed coordinate time ...
- 709
3
votes
2
answers
533
views
Using time dilation to find universal frame of reference
Before I ask this question, I just want to clarify that I am by no means an expert and that this question most likely came about due to my ignorance on the subject. If this is the case, please let me ...
- 567
-1
votes
3
answers
421
views
How "accurately" does the CMB tell the age of the universe?
Just to clarify, I am not asking about clock accuracy per se at all. The reason I am asking this question stems from the fact that on this site, most questions about the age of the universe answer ...
- 29k
4
votes
3
answers
272
views
Can we think of space as any kind of aether in any way? [duplicate]
I am not asking about the Michelson-Morley experiment in any way. I am specifically asking, if space (including the fields that QFT describes) itself can be thought of as any kind of aether that ...
- 29k
6
votes
2
answers
751
views
Can a Kerr black hole be viewed as a Schwarzschild black hole by changing the frame of reference?
In a local universe empty of any matter except a Kerr black hole and an observer, that observer is spinning at the same rate as the black hole and observes it from a great distance directly above its ...
- 643
4
votes
5
answers
558
views
What is actually waving in a gravitational wave if spacetime is not a thing (just a mathematical construct)?
I have read this question:
except what is waving is spacetime itself.
Gravitational Wave - What is waving?
Is gravitational wave a new category of wave?
Yet none of the answers are satisfactory, ...
- 29k
0
votes
1
answer
262
views
Acceleration and reference frames in General Relativity
A person walks on Earth in a straight line, he says he is walking with uniform velocity. But I (from space) see him walking on a curved surface and say that he must be accelerating since he is ...
- 159
1
vote
1
answer
59
views
Is the earth's version of time dictated by the earth's speed? [closed]
Is time on earth, relative to everywhere else, dependent on the earth's speed? Earth rotates at a speed, it moves around the sun, the sun moves around the galaxy and the galaxy is also moving - is it ...
0
votes
1
answer
216
views
Acceleration/gravitation vs velocity and the Twin Paradox
I see in Professor Pogge’s explanation
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html dec. 2020.
that
“Because an observer on the ground sees the satellites in motion relative to ...
- 351