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Hi, just a hypothetical question. If a Rocket was to take off from the earth and reach the speed of light instantaneously (I know it can't in reality), and it had a camera facing back towards the earth. Would there be any motion shown on the receiver, or would it appear the Rocket was standing still? Regards,
Question Date: 2005-01-19
Answer 1:

Lets make the problem a bit simpler-- suppose we take off in a rocket which rapidly approaches the speed of light. From the rocket's point of view, the view back to Earth is drastically red-shifted and events on earth appear to be moving rather slowly. (Unfortunately in the rocket --you'd be unable to notice since you'd be a plasma coating the 'floor').

As your rocket continues to accelerate, the red shift increases, and the motions continue to slow down. (These are the same effects after all, photons emitted on the earth in rapid succession arrive at the rocket after traversing longer distances due to the motion of the rocket).

From the earth, the picture is much the same-- extreme red shift and motions on the rocket appear to be happening very slowly. However, the rocket is still moving away from the earth at nearly the speed of light (it does not appear to be stopped, standing on the earth).

From the rocket camera, the rocket is not moving, but the earth is receding at nearly the speed of light. Unfortunately, at the speed of light, the red-shift is infinite -- so you no longer get any information from the camera to the rear. The camera to the front, on the other hand records all the future time in the universe (at least until the rocket is destroyed) and compresses it to a single event for your viewing inside. Physicist's don't like to talk about infinite energies, densities etc. as physics has no data on which to make experiments -- so 'speed of light' travel of massive objects is strictly extrapolation, and likely involves effects and physics that are not currently known,if, indeed the concept makes any sense at all.

Answer 2:

Everything would appear to be standing still. If you were watching the hands of a clock, the hands would be frozen at a certain time and not move despite the fact that your clock on your ship would continue ticking away like normal, as far as you are concerned. Time would APPARENTLY stop on Earth from your perspective!

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