if my car went faster than the speed of light, and i turned on the headlights, what would happen?

First of your car can't go faster than the speed of light. If your car were going faster than the speed of light, the laws of physics would not apply (since the car is breaking them), so there is no way to accurately predict what would happen.

That said, if you were going really close to the speed of light relative to some observer (keep in mind that velocity is relative, so it could just as easily be you standing still and the observer moving at near the speed of light), you would see the headlights behave perfectly normally, but he would see you almost catching up to them. So if we imagine that you could go faster than the speed of light it would follow that everything would seem normal to you, but the observer would see you pass the front of the beam of light emitted by the headlights (actually he would see you in front of the light because he can only see the light when it reaches his eyes, and basically you would get there first, but it's the same idea).

***Response to Cecil***

Anyone with the audacity to assert that they *know* what would happen based on the laws of physics is mistaken. Because the car CANNOT travel faster than the speed of light, and therefore the laws of physics DO NOT APPLY! Any attempts to address this question are purely speculative, and an explaination based on science is no more likely to be correct than one based on Gene Roddenberry's imagination. Anyone who attempts to apply Einstein's theory of relatively or any other scientific law or theory to this senario and present it as the absolute truth clearly has no understanding of the theories they are attempting to apply, and is, so to speak, the one "without a clue."

***Response to Boomer***

Apparently I need to defend my answers yet again. Nothing can travel faster than the speed of light. There are no exceptions, and that's not a "belief," it's a fact. Thus the car defies the laws of physics, and consequently its interactions with the physical world are unpredictable. Meaning we cannot predict them, and thus cannot know what would happen. And anyone who thinks that light and urine behave in the same manner is in no position to be calling others "ignorant morons."

***Response to Cecil's Response***

Firstly, if you're going to assert that your answer is correct based on the extend of your education, I strongly recommend the use of proper grammar. As for the car and the light, if you had actually read my answer you may have noticed it is based on the assumption that the speed of light is constant. For the person in the car, everything is perfectly normal. He would see the light moving in front of him at 3 x 10^8 m/s and the observer (relative to whom we are measuring the speed of the car) would appear to be moving away from him faster than 3 x 10^8 m/s second, lets say 4 x 10^8 m/s. The observer would also see the light moving 3 x 10^8 m/s, but he would see the car moving in the same direction at 4 x 10^8 m/s, so to the observer it would appear that the car reaches any given point before any of the light it had previously emmitted. Also, I'm not sure what the doppler effect has to do with any of this, but it occurs because the wavelength of the sound waves decreases because the object creating the wave moves either closer to or farther away from the previous peak before creating the next one, not because the speed of the sound waves change. This occurs with light as well, and can been observed as red shift and blue shift. When this occurs, the speed of the light does not change but the wavelenght of the light is altered by the motion of its source.

***Comment on Tjtindal's Response to Cecil***

Star Trek is science fiction, but the entire concept of faster-than-light travel is pure fiction. Nothing can move faster than the speed of light because mass increases with velocity and becomes infinite at 3 x 10^8 m/s. Because F=ma the force need to increase the velocity of an object traveling at the speed of light would also become infinite. It is not possible to apply infinite force to an object so an object cannot exceed the speed of light. Anything based on an object moving faster than the speed of light is fiction. Although the Star Trek version is no more fictional than any other explaination (as explained above), it's not really fair to say it is based on fact.

As in Star Trek: The Next Generation and beyond, some of the interior lights on the Enterprise are on already when they go faster than the speed of light. Since light emits at the speed of light, if you went faster than light speed, (which is 186,000 miles per second,) the lights on the ship (or car) would fall back and create a trail effect that would never catch up to the original object unless it slowed down to sub-light speed or stopped entirely. That's why in the opening title sequence of ST:TNG, you see the Enterprise take off at warp and a split second later, the lights and warp nacelles trail behind trying to catch up.

--And to Cecil below, who seems to know everything, Star Trek's basic technology is based in fact, they just built on it to make the show. Oh, and excellent job with the lightsabre comment. Wrong series entirely. Like the "dweeb" comment though! Real original!

The headlights would not help you see--they would be on, but the light would not travel forward to light your path. You could only drive the speed of light in the daytime. I heard Toyota is working on a hybrid engine that can go the speed of light, but they are trying to deal with that very problem with the headlights.

To make it simple think of peeing in the wind. The pee is going slower then the wind so it comes back at you. So if you turned on the headlights, the light would come back at you and go behind you.

Owh and any a**hole that says that someone can't say we know what's gonna happen is an ignorant moran because all of physics is based off of theories and there are always exceptions to theories so they aren't even perfect even though we believe in them.

Because you are also traveling at the speed of light, from your point of view, the light would be "trapped" in the headlight, and wouldn't come out.

well you can't go faster than the speed of light, but i assume the headlights will travel away from you at the speed of light... it's all relative

if in theroy you car could go faster than your headlights ur head lights would be your tail lights and noone would be able to know ur coming but at that speed head lights would do no good as you would not beable to see to navigate

well if you waited until you reached that speed you would turn into energy and would be unable to turn on the headlights.

You simply would not be able to tell you turned on the lights, because you would be moving so fast the light would not be visible.

I agree that'd you'd be pinned to your seat unable to move, to reach the headlights.