Reply #10: Very hypothetical, but... [View All]

This is something of a guess since we don't have any models in which a material object (i.e. one made of matter) can travel even at the speed of light, much less faster. However, if you were traveling faster than the speed of light you would be outrunning any light trying to reach you, so you should see nothing outside your ship.

If we suspend our cosmological model and pretend that you *could* travel faster than light, the light inside your ship would be traveling at the speed of light in your frame of reference, and everything would seem completely normal to the occupants of the ship. A lot of people have a hard time understanding this even for plain old relativity--but in your own rest frame, that is the frame in which *you* are not moving, everything looks to you as it would here on earth, regardless of your speed. Relativity only comes into play when you ask what an external observer would measure. There's a relativistic formula for the addition of velocities. However, that formula becomes imaginary if the speed is greater than that of light. That is, it is imaginary in the mathematical sense, i.e. a multiple of the square root of -1. Imaginary numbers are, in fact, relevant to the "real world" but I don't think anybody's worked out how an imaginary net velocity would be perceived by an observer.

Tachyons are hypothetical particles that *always* travel at faster than the speed of light--in fact they *can't* slow down to or below light speed (c). There's a fairly well developed theory of tachyons although I don't know whether they have a good quantum mechanics for them. But they can't be causally connected to our normal, slower-than-light universe. So you can't see them whether they exist or not :-)