Under the best of conditions, from how far away can an automobile's headlights be seen?
538925
Also depends on conditions where the watcher is.  In 1995 I was backpacking in the mountians of northern New Mexico and we could clearly see the headlights on the interstate over 15 miles away.  At the same location in 1982 we were able to see a handheld flashlight aimed down from the top of a mountain at over 3 miles distance.
483012
Because lights bother other motorists at night, (some can't be seen by others), but many complaints from other motorists about the novelty lights in vehicles...they say makes it hard to see  All but 6 states made them illegal to have in the car.  They also say that it is distracting for hte driver in the vehicle in which the lights are present.  Dont' really understand their point of view on that, but we can't make the laws, just abide by them
1029970
1.21 gigawatts\nYou have to outfit your car with a big pole and hook.
723110
Yes....all people see that under the right conditions.  It's easiest to see on a brutally hot day as you look out over a highway or something.
385496
Brighter colors are more visible to motorists, which makes drivers more aware of your presence and avoid hitting you.  Clothing with reflective areas is even better, as it reflects the light from vehicle headlights.
684422
I know EM can go up to 100,000x (maybe beyond?), and light can go up to 1000x.  I'm not sure what the limit on EM is, but i think it's less than 800,000x.  So #4 looks right.
1081001
Most race cars do not have headlights, but depending on the class and type of racing some do.
91916
a car trvelling in a straight line\na beam of light
30733
If you were traveling at the speed of light, whether or not your lights work would probably be the least of your concerns.\n\nIn reality, the laws of physics prevent any object from traveling faster than the speed of light.\n\nSomething that is perhaps just as interesting, however, is what happens as your vehicle APPROACHES the speed of light.  Take a look at some of the work done by Einstein to get a general idea on that.
1116675
Ha\n\nInteresting speculation \n\n1. The light will not change color no matter how fast you go. Only in your perception it will, so unless the law enforcement is traveling within your frame of reference you would be found guilty anyway.\n2. True, if you are moving towards the light its frequency will increase towards the blue and will appear green to you, but the acceleration would kill you.  \n3. If you could travel with speed of light why would you care about traffic lights?\n\nGood question anyway.
533149
The rods in the eye are so sensitive that it can react to one ten-billionth of a watt.\n\nThis is equivalent of a match struck on a clear, pitch dark night 50 miles (80 km) away. \n\nOf course, for someone to actually see that match, there would have to be impossibly ideal conditions; a total absence of other light sources and a perfectly clear atmosphere.
247428
that we can see?  The sun.
694238
You are probably 35 thousand feet too far away to see anything.\n\nMind you, you would probably still hear them, they are all noise these days.
158568
All these answers are wrong. Light moves from each source at a speed we'll call one. If you are traveling at the speed of light, then anything that leaves you at the speed og light will be traveling the same. Now while you will not see far with your headlights, they may well provide sufficeient view, as they are ahead, to give you sight enough to drive. But you shouldn't think about changing direction. Those sorts of speed are highly unstable and could rip your car apart
902581
The moment you hit the speed of light, time would stop for you, so it would be pretty hard (impossible) to turn the darn lights on!\n\nSaid another way, as you approach the speed of light, the outside observer sees you slowing down; when you hit the speed of light, it would take the observer an infinite amount of time to see any change in your state.\n\nNow, suppose you left your headlights on the whole way, what would everyone see?\n\nAs you approached the speed of light, the light is still reflecting off the objects around you, so the observer, and you, continue to see the reflected light. Once you hit light speed, however, the energy transfer required to turn heat into light wouldn't occur, so no one would see the photons. Of course, since you're traveling at the speed of light at that point, everyone would see you hit the object.\n\nOr this way... the light leaving your headlight changes it's frequency in proportion to the speed you're moving, once you hit light speed, the light would become matter! Of course, the wave packet that is light + your car wouldn't are too much, since time wouldn't exist for you anymore.\n\nHave a nice trip!
79821
Simple answer is NOTHING.  This is the explaination:  When you are traveling in a car at 70 MPH and there is a bug flying around in the car (say 0.5MPH), the bug is also traveling at 70 MPH ().5MPH can be ignored as bug is flying around in the car with null effect on the speed).  This is the part of theory of relativity.  Now let's see our car is traveling at the sped of light, when you turn the light on, the rays are traveling at the same spped and you see no effect of light (i.e. still dark-if driving at night).  If you just slow down at little (say 5%) then you will see light just ahead of the car and same applies as if you spped up the car slightly, it will be still dar and you may see back of the car lit (light left behind) for having lheadights in the front.
70554
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.\n\nThat 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).\n\n***Response to Cecil***\nAnyone 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."\n\n***Response to Boomer***\nApparently 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."\n\n***Response to Cecil's Response***\nFirstly, 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.\n\n***Comment on Tjtindal's Response to Cecil***\nStar 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 i