If you are holding a mirror in front of you and run at the speed of light, will the mirror turn black?

You would never get there.

No, the mirror would only turn black in the case that there was no light in front of you to shine on the mirror.

I don’t know how to run at the speed of light. Once I figure that one out, I’ll let you know, if I can, though at that point, it might be hard to do.

now, how does one even figure something like that out?

If you are holding a mirror and run at the speed of sound and the mirror cracks will you have seven years bad luck???

What I you were running with scissors at the speed of sound?

No, the mirror will not turn black. light still travels at the speed of light (the constant c) relative to you so there won’t be any change to the image you see in the mirror. This does not mean light is going faster than c, specifically 2c in this case (because you are going c as well) though it may seem like that is what I just said. To the observer standing still, the light still goes at c for them as well, and this results in time dilation.

what if you had a car and went at the speed of light and you turned on the head lamps?

classic question. but I have to correct the asker’s question and your question… one of the assumptions before we can answer such questions about relativity is we assume nothing can go the speed of light except light, and also that nothing, not even light, can go faster than the speed of light. therefore, the question we can ask is “what if you have a car going .9999c and you turned on the head lights”
(c = speed of light)

to the driver, the light is coming out of the headlights and away from the car at the speed of light relative to him. however, to the pedestrian ( a female), the light comes out of the head lamps at the speed of light relative to her and is only going just barely faster than the car. Remember, nothing can go faster than the speed of light. again, this seems contradictory, and that the light is going two different speeds, depending on your frame of reference. its called relativity for a reason… things are relative to where your standing and how fast your going.

Theoretically, one could travel faster than the speed of light, but not if the light is traveling in a vacuum.

well yes, because light goes slower than c if it is not in a vacuum. so you wouldnt be going faster than c, just faster than the light around you.

Well, not me. My let knee has been bothering me.

i think you will see yourself…