All Questions
15
questions
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0
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81
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Photon speed for an observer at the photon sphere [closed]
I am asked to compute the orbital period of a photon, in the Scwarzschild spacetime, at the photon sphere for an observer at the same radius, $r^\star=3M$. I have computed the result, $\Delta T=6\pi M$...
25
votes
3
answers
8k
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Why don't we put satellites into an orbit where there is (almost) no time dilation/contraction compared to Earth's surface?
Consider:
On this image, if I understand correctly, the time dilation diagram is shown depending on the height for circular orbits. First in low orbit, time slows down relative to the surface due to ...
0
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0
answers
69
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Special relativity in orbit
I am writing something for school where I need to calculate the time dilation difference between Earth and Mars. First I calculated the difference from the gravity of the planets itself + that of the ...
- 131
1
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0
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42
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How would a super long object orbiting a black hole be affected by time dilation? [closed]
Assume there is a long enough rod orbiting a black hole.
Such that the time dilation occurring on the two ends of the rod is noticeably different.
So, for example, the end that's closer to the black ...
- 11
9
votes
2
answers
1k
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Time dilation in an elliptical orbit
What would be the approach for finding the degree of time dilation for a star at any point in a general elliptical orbit around a supermassive black hole? Ideally I would be looking to work this out ...
- 133k
0
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0
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32
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How do (if) the relative paces of time differ in these circular motions?
I) Imagine two equal masses tied tethered together by a rope in empty space. The rotate around their COM in the middle of the rope. The masses don't cause gravity.
The masses don't move wrt one ...
0
votes
2
answers
577
views
Time dilation inside International Space Station
SR tell us that inside ISS time is running slower than on the earth. But velocity is relative. We can choose to consider either ISS or earth to be at rest. An observer inside ISS sees the earth ...
- 455
0
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1
answer
1k
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What is the orbital angular velocity of a satellite?
Angular velocity ω is by definition the runned angle $dθ$ per time $dt$ elapsed: $ω=dθ/dt$. If the time elapsed in a specific point on the earth's surface is $dt$, the dilated time elapsed on ...
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-2
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1
answer
174
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Is Sergei Krikalev living slightly in the future, or is his body just younger than it otherwise would have been? [closed]
Due to cosmonaut Sergei Krikalev's time on board space station Mir in Earth orbit, the combined effects of velocity and gravity have caused him to experience an accumulated 20 milliseconds of time ...
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1
vote
1
answer
224
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Reconciling Wikipedia formulae for time dilation due to gravity and velocity
Wikipedia "Time dilation" shows the formula $\sqrt{ 1-v^2-v_e^2-v_r^2.v_e^2/(1-v_e^2) } $
where v is (perhaps) the 3D speed, $v_e$ is the Newtonian escape speed, $v_r$ is the radial speed.
...
- 2,403
2
votes
10
answers
913
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Relative clock speeds of two satellites with same but opposite direction orbits
Naïve reasoning: consider two satellites A and B that are in almost identical but opposite direction orbits, just not colliding. When A meets B, B is going past at a good speed, hence its clock is ...
1
vote
1
answer
229
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Time dilation in orbit [duplicate]
When orbiting a massive object, perhaps a neutron star, you maintain your altitude while at the same time you are close to a very strong gravitational field. Being in orbit, and being in free fall is ...
- 482
3
votes
1
answer
204
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Relativistic effects of an orbit around sun in a different direction than Earth
If I manage to orbit around the sun at the same speed but in a different direction than the earth, will I perceive the time on earth going faster or slower than my own time? And what about people on ...
- 71
8
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3
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3k
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Why we don't see time dilation in stars orbiting black hole?
We have images of stars orbiting black holes or black holes destroying near stars, but why do we see the stars moving normally? I mean, if time dilation does exist, shouldn't we see that stars slow ...
- 417
4
votes
3
answers
260
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Does gravitational time dilation affect apparent mass?
Suppose I'm on a highly elliptical orbit around some massive body. As I get closer, I start to experience time dilation due to the object's gravitational field - time starts passing slower for me than ...
- 171