All Questions
65
questions
1
vote
0
answers
50
views
Does gravity accelerate you towards the geodesic of light between you and the mass?
If there's a planet far away, you will accelerate straight towards it due to gravity. If you place a Schwarzschild black hole right in the middle between you and the planet (the distance between the ...
- 171
1
vote
0
answers
31
views
Gravitational Time Dilation: How to find the time difference between orbits at different radii? [closed]
I want to calculate the difference in time measured by a clock at on earths surface (r=6000km), and a geostationary satellite (r=26000km). My approach is as follows:
For simplicity, we consider curves ...
- 11
4
votes
2
answers
628
views
GR contribution to time dilation when both clocks are falling freely
When reading simplified explanations of time dilation experienced by satellites, such as those used for the GPS and other satellite navigation systems, the time dilation is often presented as having ...
1
vote
1
answer
63
views
Definition of surface gravity via the non-affine geodesic equation
I have found a discrepancy in the way different sources define surface gravity (or derive) via the non-affine geodesic equation satisfied by the a Killing vector $\xi$ on a Killing Horizon (KH), up to ...
- 1,989
0
votes
4
answers
244
views
Can Schwarzschild acceleration be written in exact form as a function of position and velocity vector?
For the special case of only one massive point-shaped or spherically symmetric non-rotating body and a small "test mass" body under general relativity the movement of that small body is ...
- 729
1
vote
0
answers
161
views
Why does general relativity assume that the torsion is equal to zero?
I do not understand why the torsion is set equal to zero in the general theory of relativity. The geodesics would be the same. Is there even a way to test it?
Pg 250 from the 2017 edition of MTW says
...
- 391
0
votes
0
answers
53
views
Question on gravity and spacetime curvature [duplicate]
In General Theory of Relativity, it is explained that the fabric of reality i.e. spacetime bends around objects with mass, and that curvature causes other objects to come close to/ fall towards the ...
2
votes
1
answer
74
views
When observers moving along different geodesics meet locally, can they detect one another's acceleration?
Consider two free-falling observers in the Earth's gravitational field, A and B, who meet at point C, where A orbits the Earth at a constant radius from the Earth's center, and B falls towards the ...
- 5,318
1
vote
1
answer
121
views
Earth surface acceleration and inertial geodesics
I hope this is an appropriate question for this forum. It is one I have struggled with for a while.
I read that in GR gravity is not a force, and that the apparent force we feel and can measure (eg ...
- 11
-3
votes
3
answers
229
views
Why is light not affected by gravity?
If a rocket needs to go to mars, it needs to go through a specific trajectory. But i can see the sun straight where it is, so light does not obey gravity?
- 121
1
vote
0
answers
65
views
What would the Raychaudhuri Equation be for accelerated geodesics?
What would the Raychaudhuri Equation be for accelerated geodesics? Suppose we are not able to assume the geodesic equation but rather have to assume for some tangent vector $u^\alpha$
$$u^\alpha\...
- 11
1
vote
0
answers
50
views
Which curve has the maximum proper length? [closed]
Below is a spacetime diagram in the rest frame of a lab on Earth (with a gravitational field). Which of the worldlines shown below has the greatest proper time?
My attempt: B, because $d\tau=\sqrt{1-...
- 131
0
votes
1
answer
92
views
Are photons affected by "temporal gravity?"
Since objects follow geodesics in spacetime, that is the locally shortest path, it would seem to me that unless objects move, they do not trace any path at all. In other words, if I'm stationary on ...
- 47
1
vote
1
answer
60
views
How can we describe the class of trajectories around a point mass in general relativity?
As per the answers to this post, a Newtonian gravitational trajectory of a test particle about an ideal isolated point mass is always a conic section.
An ideal point mass in GR is a black hole, either ...
- 2,475
1
vote
0
answers
146
views
Equivalence Principle: Uniform to Non-uniform gravitational fields
2Einstein in his 1916 GR paper describes the equivalence principle and makes a case for general relativity i.e a person in a non-inertial frame is equivalent to a person in a uniform gravitational ...
- 141