All Questions
Tagged with gravity reference-frames
22
questions
32
votes
4
answers
22k
views
Does gravity slow the speed that light travels?
Does gravity slow the speed that light travels? Can we actual measure the time it takes light from the sun to reach us? Is that light delayed as it climbs out of the sun's gravity well?
- 1,011
10
votes
9
answers
4k
views
Why and when can the Earth be considered an inertial reference frame?
The question has been asked (e.g., here and here), but I would like to get a more definitive and mathematically formal answer.
The Earth rotates around its axis, around the Sun, and participates in ...
- 60.4k
5
votes
2
answers
5k
views
When objects fall along geodesic paths of curved space-time, why is there no force acting on them?
On cseligman.com, it is written that
So, we see things falling with an acceleration which we call the acceleration of gravity,and thinking that we live in a straight line , uniformly moving or ...
user36790
25
votes
4
answers
7k
views
If gravity is not a force, then how come gravitational assists work?
I have learned about general relativity and how gravity arises from spacetime curvature. And I have always been taught that gravity is not a real force in the sense that
$$\frac{dp}{dt} = 0$$
And from ...
- 1,896
87
votes
6
answers
9k
views
If gravity is a pseudoforce in general relativity, then why is a graviton necessary?
As far as I’m aware, gravity in general relativity arises from the curvature of spacetime and is equivalent to an accelerated reference frame. Objects accelerating in a gravitational field are in fact ...
- 2,123
8
votes
2
answers
569
views
Mach's principle and a reference frame for acceleration
Although there are different statements of Mach's principle, one statement could be that acceleration is meaningless unless it can be defined relative to something. The distance stars provide a fixed ...
- 13.7k
5
votes
1
answer
365
views
Explanation for "if all accelerated systems are equivalent, then Euclidean geometry cannot hold in all of them"
I'm doing an EPQ (mini college research paper) on gravity, and I found a site that explained things in simple terms. I am having trouble understanding how Einstein came to his revelation space-time ...
3
votes
2
answers
558
views
The Michelson-Morley experiment
A fundamental assumption in special relativity is that the speed of light is constant in all inertial reference frames, which was first established empirically via the Michelson-Morley experiment. ...
- 304
0
votes
2
answers
330
views
Earth as inertial reference frame: finite radius effects
In a recent question I tried to clarify under what conditions the Earth can be considered as an inertial reference frame. The opinions, summarized in my own answer to the cited question, are that
...
- 60.4k
9
votes
3
answers
1k
views
Can we determine an absolute frame of reference taking into account general relativity?
Given that acceleration induces measurable physical effects, would it be correct to say that there should be an absolute inertial frame of reference? I know that one cannot distinguish a priori ...
- 127
5
votes
2
answers
214
views
Comoving system of expanding or collapsing dust-like particles
I have a question on co-moving and synchronized reference systems. I read the corresponding section (97) in Landau/Lifshitz's second book "Field Theory" on it.
In particular it is said that space ...
- 9,778
5
votes
1
answer
3k
views
How to explain centripetal force in terms or relativity
At the end of a video of dropping a ball and feathers in a vacuum, Brian Cox explains that the Ball and Feathers, as understood in terms of General Relativity, aren't falling. (apologies I can only ...
- 153
4
votes
2
answers
245
views
Time dilation for non-physicists
Apologies in advance, as I'm not a physicist, and may use terms incorrectly.
In the movie Interstellar, the planet Miller has a time dilation of one hour to seven Earth years. This has brought up ...
- 151
4
votes
1
answer
3k
views
Relativity - Am I accelerating while standing on earth?
So I understand how a free-falling object in a gravitational field is "at rest" or has an inertial reference frame, but I cannot figure out why an object hovering in a gravitational field is supposed ...
- 239
3
votes
2
answers
4k
views
How much Gravity is required to stop time?
Clocks free of gravitational influence run faster than those experiencing gravity. Is it possible for gravitational influence to bring time to a stop? Additionally can acceleration affect clocks in ...
- 470