Linked Questions

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Velocity of massless particles in $\mathrm{AdS}_4$ space-time

In spherical coordinates in a $(1+3)$-dimensional space-time one has the $\mathrm{AdS}_4$ metric $$ds^{2}=-\left(1+k^{2}r^{2}\right)dt^{2}+\left(1+k^{2}r^{2}\right)^{-1}dr^{2}+r^{2}d\Omega ^{2}.$$ ...
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2answers
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Speed of light in a perfect vacuum

Lets' say that something is in a universe with a perfect vacuum, where nothing exists but that object. This universe has an infinite amount of space and time. Now that object emits a single photon. ...
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0answers
103 views

Can you outrun light in general relativity?

The top answer on this question explains that the speed of light can change with distance from an accelerated observer. Is there then in any meaningful sense a way to outrun light emitted from a ...
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1answer
54 views

Spatial variation in velocity of light or curved space-time?

In the case of spherical symmetry you can say that the velocity of light (in coordinate time) goes as: $v_{light}=c(1-\frac{2GM}{rc^2})$ in the radial direction and as: $v_{light}=c\sqrt{(1-\frac{...

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