All Questions
40
questions
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
76
views
Is it more accurate to say space in a weaker gravitational field is contracted, or that time is faster?
Little thought experiment. An observer places a mirror and a clock 1 lightyear away from a black hole. He then goes in the black hole's gravitational field at a point where he sees the clock tick at 2 ...
- 171
2
votes
1
answer
776
views
The value of speed of light in different regions of spacetime
This question of mine started shaping in my head first while I was looking for the most fundamental answer for the speed of light's value and its property of being the limit.
I have convinced myself ...
- 23
0
votes
3
answers
201
views
Is it possible to prove from relativity that massless things have proper time of zero?
Is it possible to come to the conclusion that something massless has proper time of zero, thus moves at $c$? I have seen many arguments for why moving at the speed of light means proper time is zero, ...
- 1,261
0
votes
2
answers
62
views
Can Shapiro Time Delay cause light in a vacuum to go faster than c as viewed from a remote reference frame?
I know within any reference frame the speed of light is fixed. But it has been shown that light does appear to slow down when passing massive objects as viewed from a remote reference frame per https:/...
- 319
0
votes
1
answer
39
views
Does local gravity change when approaching the speed of light? (Relativistic mass) [duplicate]
Let's say we'd transform earth into a giant space ship and had some planetary drive that can accelerate it without burning any kind of fuel (so the amount of matter on earth stays the same - we'd ...
6
votes
2
answers
532
views
Does kinetic energy of an object curve spacetime? [duplicate]
Based on general relativity mass and energy distribution curves spacetime. Thus, if an object with 1kg rest mass moves with constant speed and has a speed very close to speed of light, then it has an ...
- 947
1
vote
2
answers
277
views
Time and speed of light in Relativity
Time running slower near a massive object, but the speed of light does not really change near a massive object, according to Relativity - it just curves. Is not time directly related to the speed of ...
- 103
4
votes
3
answers
759
views
Constant speed of light violates accelerating expansion of universe?
My question regards the following:
One of the most fundamental principles of Einstein's GR is that all free bodies move through spacetime with constant velocity $c=1$.
However, in 1998 Hubble showed ...
- 201
-2
votes
3
answers
189
views
Is the speed of light the limit or just everything moves at this speed?
When I was a little kid, I was fascinated by the fact that we are not able to surpass the speed of light. I imagined a giant spaceship trying to catch a light beam like superman tries to catch flash.
...
- 117
0
votes
1
answer
59
views
Does light travel same distance in same time not depending of the path orientation regarding Earth's surface?
Does light travel the same distance at the same time regardless of the path orientation? The light in the proximity of a gravitational source can bend its trajectory and frame-dragging can cause the ...
- 2,255
2
votes
3
answers
167
views
Is there an exact constant value for the speed of light in a vacuum distorted by a gravitational wave?
In a vacuum, construct a cylinder of photons arranged as follows:
A 'measuring apparatus' computes the speed of light as 299,792,458 m/s.
However, suppose the vacuum is distorted by a gravitational ...
- 173
2
votes
1
answer
59
views
What is observed by Astronauts traveling from M at just under $c$, but proper distance increases at greater than $c$ due to spacetime expansion?
A rocket is traveling at a reasonable speed directly away from planet M at a large distance D. M is shaped like a coin and to the astronaut looking through a telescope directly out the back of the ...
- 143
2
votes
3
answers
444
views
Why does $ds^2=0$ for a light signal's worldline in general relativity?
I know that in special relativity, the invariant interval $ds^2$ for a light signal's worldline is $$ds^2=\eta_{\mu\nu}dx^\mu dx^\nu=0$$ where the flat metric $\eta_{\mu\nu}=\text{diag}(-1,1,1,1)$.
...
- 4,235
0
votes
2
answers
605
views
At what speed does mass warp spacetime?
It is well understood that Einstein’s General Theory of Relativity explains how gravitational effects appear to occur instantaneously at a distance. Mass warps spacetime and so objects simply follow ...
- 9