Linked Questions
28 questions linked to/from GR. Einstein's 1911 Paper: On the Influence of Gravitation on the Propagation of Light
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What is the speed of light at the photon sphere? [duplicate]
At the photon sphere (where photon exhibit circular orbit around a black hole), the radius is given by $r={\frac {3}{2}}r_{\rm {s}}$, and the angular velocity is $({\frac {d\phi }{dt})^{2}=\frac {c^{2}...
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Is there variation in the speed of light? [duplicate]
I read recently that there may be (very slight) variations in the speed of light due to the nature of spacetime itself, I had the idea that this may be due to the photon having mass, but that's ...
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Speed of light in gravitational field [duplicate]
Why has the speed of light in a gravitational field always the same value $c$ when measured locally?
More precise: When you are far away from any masses, that means when the spacetime is flat, and ...
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Gravitational Time Dilation and Speed of Light [duplicate]
From what I'm understanding, the Speed of Light is roughly 186k MPS NO MATTER WHAT!
Then say if a bean of light shoot pass near a Black Hole (Outside the Event Horizon of course) 1k lightyear away to ...
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Is the light escaping from a massive star held back a bit by the pull of gravity, or by the warping of spacetime near it? [duplicate]
In The Universe in a Nutshell chapter 4, Hawking explains the warping of spacetime according to general relativity.
Near a massive but ordinary star, spacetime is warped such that the light emitted ...
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If a black hole bends light what does to a beam that arrives at a zero degree angle directly towards the singularity? [duplicate]
We can only speculate what is going on but does the black hole singularity make the light arrive faster than it would in space not affected by gravity?
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Can I change the speed of light in vacuum? [duplicate]
General theory of relativity proved that gravity does attract light ( photons ), what if I project a beam of light radially towards a black holes will it increases it's speed or not?
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What is the connection between special and general relativity?
What is the connection between special and general relativity? As I understand general relativity does not need the assumption on speed of light constant.
It is about the relation between mass and ...
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Why is the speed of light said to be constant when we know it slows down in a medium? [duplicate]
If we ask someone what the speed of light is, they will say that it is constant and its value is $3\times 10^{8}\ \mathrm{m/s}$.
But if we recall refraction of light, we say that when the light ...
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Speed of light in general relativity [duplicate]
My question has a few parts concerning the speed of light in general relativity.
Firstly, time changes in response to gravity and speed. Therefore, as gravity effects time in an area of space, should ...
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Can a photon that is emitted from a denser part of the universe to a less dense part appear redshifted?
Galaxy one is located in a dense area of the universe and galaxy two is located in a less dense part of the universe. Would galaxy one appear red-shifted to galaxy two? Is the mass density at our ...
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Is speed of gravitational waves constant? [duplicate]
Is the speed of gravitational waves constant in all inertial frames? If so, why isn't this included as one of the postulates of special relativity?
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Wrong statements in Special Relativity [closed]
In my lecture notes on General Relativity, I have the following statements that are said to be wrong in Special Relativity:
Every physical observer measures a speed of light equal to $c$.
Every ...
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Does the speed of light change? [duplicate]
I know that there is a similar questions, but I think mine is a bit different. I wonder if with the expansion of the universe the speed of light changes. It seems that the speed of light is very ...
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Is there a difference between what Schwarzschild vs Gullstrand-Painleve predict for c?
When we set the interval(ds) for a given coordinate(i.e. Schwarzschild coordinates) to 0 to calculate for the velocity of light in a gravitational field, we can arrive at an equation such as the one ...