Icarus
I must disagree with your answer to Sky Yachts question. Yes, the person standing in front of the car will see the light being emmitted from the headlights but only at the same time as he is hit by the car because the car is travelling at the same speed as the light.
You say that the driver does not see the light emmitted from his own headlights. This is a false statement. It is a cosequence of Einstiens special theory that the speed of light measured by any observer whether moving or stationary will be the same (c is absolute as TR3 kindly points out). You infer however that in relation to himself, the driver measures the speed of the light emitted from his headlights as zero.
This result contradicts our elementary notion of relative velocities, and it may not appear to agree with common sense. But common sense is intuition based on everyday experience, and this does not usually include measurements of the speed of light.
Incidentally this answers the question posed by the original post. Nothing can travel faster than the speed of light. Suppose a spacecraft is travelling at the speed of light relative to an observer on the earth. If the spacecraft now turns on a headlight the principle of invariance of c asserts that the earth observer measures the headlight beam to be also moving at c. Thus this observer measures the beam and spaceship to be always at the same point in space. Our invarience principle also asserts that the beam moves at c relative to the spaceship, so they cannot be at the same point in space. This contradictory result can only be avoided if it is impossible for the spaceship to move at c.
[ 29 July 2001: Message edited by: Harry999 ]