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2

Its been a while since I studied relativity, so I wont attempt the math, but I remember covering a similar situation at university. From what I remember, the issue is the reference frame you are considering it from. When you say they are moving in opposite directions, that is from a specific reference frame, the earth. In that frame, the separation between ...


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You've assumed the law to add velocities is the same in special relativity as it is in Gallilean kinematics. This is wrong (as the paradox you've reached shows). Its possible to derive a way to "add" velocities which is compatible with relativity. Your version is: \begin{equation} s=v_1 - v_2 \end{equation} The correct version is: \begin{equation} s= ...


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A force is defined as a change in momentum over time. In the Newtonian limit, this means a mass times an acceleration. But when dealing with things like photons, the formal definition is applied. Photons have no mass, only momentum. Therefore, if a force is applied to them, their momentum can be changed. This can happen in two important ways, a force can ...


1

This question is a little naive but interesting. A common mistake is to confound speed of information and effective bandwidth. ie : my network documentation tells me that a flow of ( unzipped ) information travels at "speed of light" * k , with k between 0.3 and 0.6. After a new software release, using high compression , I see that I can send my ...


3

In a rotating reference frame, the coordinate velocity of an object can exceed $c$. However, this doesn't mean that they're moving "faster than light". If we were to look at the light-cones at these distant locations, we would see that the four-velocities of these objects are still confined within the light-cones at those locations. To put this another ...


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When Miguel Alcubierre proposed a "warp drive" solution resolving the prohibition in Einstein’s special relativity on traveling faster than light the problem turns out to be that anybody in the path of the incoming space ship gets fried. That’s the conclusion of a group of University of Sydney physics students who have re-examined the maths of the ...


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So as we from the outside of the black hole observe matter approach the event horizon, we will see time slow for the falling matter. Conversely, an observer falling into a black hole would see external events speed up (possibly, not sure about light travelling from external objects). At the event horizon objects will appear stationary for us, frozen in ...


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For instance, take a rigid pole of several AU in length. [...] The person on the opposite end should receive the pushes and pulls instantaneously as no particle is making the full journey. As other answers have pointed out, you can't have perfect rigidity, and the signal would propagate at the speed of sound in the material. If tap a steel rod with a ...


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Technically no, because if something went faster than c it would be classified as a Tachyon. If they did however, they would only be a Tachyon by definition, physically they would still be Photons.



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