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Suppose I was sitting in the glassed in nose of a spaceship trsvelling at the speed of light, and turned on a flashlight?

What would be the forward speed of the light coming from the flashlight?

This is fun (if mind-bending) stuff, so let me play a little.

Your spaceship cannot be moving at the speed of light, just really close to it. So try this:

Your spaceship is moving at 0.999c and you shine a flashlight forward. Two questions: (1) What speed do you see the light traveling away from you? (2) What speed does someone you fly past see (a) you moving, (b) the light moving relative to that someone, and (c) the light from the flashlight moving away from you?

Answers: (1) You see the light moving away from you at the speed of light. (2a) The person sees you moving at near the speed of light. (2b) The person sees the light from the flashlight moving at the speed of light relative to themselves. (2c) The person sees the light form the flashlight moving away from you at the speed of light, too!

What, makes no sense? How can that be? Without getting into the messy math, time and space distort in ways that make ALL of that happen. Again, as posted up thread, these effects occur at lower speeds, too, and in fact had to be accounted for to make GPS work.

Suppose I was sitting in the glassed in nose of a spaceship trsvelling at the speed of light, and turned on a flashlight?

Flashlights aren't allowed on faster than speed of light spaceships.......

As a side note, auto manufacturers have refused to build faster than light automobiles due to the fact that the TASA would never approve the headlights on those vehicles if they didn't exceed the speed of light. That's a conundrum........

That is akin to the old question we used to argue when I was a kid:

"A fly is on the back glass of a station wagon that is traveling at 70 m.p.h. The fly takes flight and moves forward from the back glass to the dashboard of the station wagon. At what rate of speed is the fly travelling? Is it exceeding 70 m.p.h.? Or, is it traveling at 2 m.p.h. in its enclosed environment?"

My answer was always "2 m.p.h. in its enclosed environment." Keep in mind, though, that if someone standing on the roadside was able to actually see the fly moving from the back glass to the dashboard the observer would be seeing a fly moving at 72 m.p.h. It depends upon whether you are inside or outside of the station wagon as to what speed you would be observing the fly travelling. To me the enclosed environment for the fly is comparable to the enclosed environment for the light from your flashlight in that the light particle/wave function is not moving against the forces found in the area surrounding the exterior of the spacecraft in which you are moving. The light from your flashlight would still be traveling away the you at 299,792,458 meters / second. If someone were in a stationary position (in a pressurized environment since we are in space) and was able to observe you passing by in your spacecraft when you turned on your flashlight, technically they would be seeing the light from your flashlight at 2 x 299,792,458 meters / second. Unfortunately, the doubling of the speed would be imperceptable for us...

Just my 2 cents...