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(Vikram, hope you don't mind me reiterating the obvious)
As I understand the matter, we are speaking of the extreme: the question did not regard "approaching the speed of light" but "at the speed of light." As Vikram pointed out, time *is* zero (not *essentially* zero). When you speak of relativistic time, perception implies some movement of time (however slowly). If time stops, perception stops.
For example, if you were traveling very very fast, one second for the traveler (t) might be equivalent to a million million years to the stationary observer (t0); the traveler would not be able to *perceive* this slowing of time (i.e. time would be relative for him). However, *at* the speed of light, time has stopped for the traveler (t). He will *never* perceive the event to occur, nor will the stationary observer ever observe an event (unless the traveler should eventually slow to sub-light speed).
The flaw is in the question (apart from the obvious mass issues): one will/can never turn his headlights on while traveling at the speed of light.
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C# or Bb wrote: However, *at* the speed of light, time has stopped for the traveler (t).
Why?
Why is there a sudden change in rules for the traveller that at 99.999999999999999999999999999999999999999999999999999999999% the speed of light it is all nice and relative and time is chugging along fine for him but at 100% the speed of light he suddenly has no time?
I am just curious 
regards,
Paul Watson
Ireland
Feed Henry!
eh, stop bugging me about it, give it a couple of days, see what happens.
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Paul,
We could distill the question down to: "how long does it take... if time equals zero." This is an unmeasurable event.
My off-the-cuff analogy would be of a person walking in a straight line from point A to point B. If he had speed (i.e. *anything* above 0), he *must* reach point B eventually (although the time it would take would be a function of his speed). This is a measurable event. If the person had a speed of 0 (i.e. never left point A), how long would it take him to reach point B? This is an unmeasurable event.
The nuance can be subtle, but it is one of the unique characteristics of 0 that sets it apart from the set of all Real numbers -- and when using mathematics to describe a principle, we must be prepared to accept the answers we get. A mathematical example of the difference between "close to" and "at" is the following function:
f(x) == x/x, x = 0
The answer is strictly undefined at 0. However, using our rudimentary calculus, we can represent this as:
lim(x/x), x -> 0: 3/3 == 1, 2/2 == 1, 1/1 == 1, .5/.5 == 1,... Therefore, we can say the "limit" (i.e. near but not at 0) of the above function is 1.
Remember that we are speaking theoretically, so *any* percentage below the speed of light will create a measurable event.
Warmest regards.
I always get lost half-way to clever.
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You would never actually turn your headlights on. Attaining the speed of light is impossible, since the closer you come to it, the slower time will pass for you - relative to the rest of the universe. So, you would get closer and closer to the speed of light, without actually reaching it. The passage of time would slow down, even though you wouldn't notice it. It would seem to you that you were just about to reach light speed, but you would be forever waiting to turn your headlights on - since time would travel slower and slower, as you go faster and faster.
http://www.goamazing.com/content.asp?id=2203[^]
In 1971, scientists used atomic clocks and jets to test out Einstein's Theory of Relativity. Atomic clocks are so accurate they can measure time in billionths of a second. One atomic clock was set on the ground and another was sent around the world on a jet travelling at 966 km per hour. At the start both clocks showed the same time, but at the end of the experiement the clock on the jet was behind by a few billionths of a second. A few billionths of a second isn't much, but then the speed of the jet was a very long way short of light-speed!
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There go my people. I must find out where they are going so I can lead them.
- Alexander Ledru-Rollin
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Even more interesting than the above test, GPS uses relativistic calculations to make sure that the correct flight time is calculuated from the satellite to your hand held.
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The only possible answer is, we don't know.
So many people embrace theory as fact. Since no one in this group has ever traveled at the speed of light(including me), we only have Einstein's theory which talks of infinite mass and in contrast, recent experiments that suggest particles in an atomic accelerator move faster than the speed of light by bumping them together at near light speeds.
If you move out of Einsteinian theory, into theories by more modern scientists such as Steven Hawkins, other ways of thinking suggest that faster than light travel is possible. If it is possible, then why is it not possible to project a photon from a speed of light body, which would then be moving faster than the object, or faster then other light.
Also, if it is possible to go faster than light, but light can't be emmitted at these speeds, then the photons would be trapped and it would be dark in "front" of you.
As of right now, I hold that we don't have any solid emperical evidence to support either position, only theory to support both, clock experiments not withstanding.
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You will never get your hand to the headlight button because time has stopped for you.
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The (formula for) mass increase has been verified experimentally on elementary particles going more the 99.999% of the speed of light in empty space. I agree that this is not 100%, but to my knowledge there is nothing to suggest that this formula will break down at some point. Experiments that allegedly prove the existence of signals "things" (signals) going faster than light actually describe the effects of entanglement in quantum mechanics. This issue was already raised by Einstein in the 1930's and it was already shown then that entanglement does *not* imply that there is anything moving faster than light to produce the effect.
It is worth pointing out that it is a misconception that time will come to a standstill. It does not! At least not for the person doing the travelling. For example when a person falls into a black hole (a similar situation) that person will seem be frozen in time before reaching the edge (event horizon) of the black hole *to an outside observer*. The person him/herself *will* experience going over the edge and hardly notice it, unless he/she is ripped to pieces before that of course. For any person travelling at high speed and/or accelerations the experienced time will always be as normal. It is the relative observation by somebody else that is affected only, that is why they call it relativity.
Anyway, since you can't drive at the speed of light the question is meaningless. Close to the speed of light you would see the objects in front of you rotated towards you (e.g. you could see the far side of a house or tree that would otherwise be invisible). The Lorentz/Fitzgerald contraction would be measurable but unobservable because you would really see the combined effect of this contraction and an optical illusion because of travelling so fast.
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Alex Fekken wrote: Close to the speed of light you would see the objects in front of you rotated towards you (e.g. you could see the far side of a house or tree that would otherwise be invisible).
How?  I understand objects become more two-dimensional as they travel faster, but how on earth would you be able to see the far side of things?
Cheers,
Vikram.
I don't know and you don't either.
Militant Agnostic
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Because the light emitted from your imaginary headlights doesn't know that it already going at the speed of light. In its own little world, it is going 0 klicks until it is emitted - and then it seems to be going C away from its point of origin -- in its own relatavistic frame of reference.
ergo "relativity", not "absolutivity"
This is Einstein's whole point.
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Have a look at this site:
http://www.anu.edu.au/Physics/Searle/Obsolete/Raytracer.html
and its download page:
http://www.anu.edu.au/Physics/Searle/Obsolete/Download.html
From the latter page:
"The camera moves with constant proper acceleration along a highway in a world where c = 1 m/s. Note that objects behind the camera appear to be still in front of it and to rotate as we move past them."
So it is really an illusion caused by the fact that it takes so "long" for the light emitted or reflected by the objects that you see to reach your eyes.
Alex
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The wall that you are heading straight into. Ahhhhhhhhhhhhhhhh!! 
Regards,
1tg46
Check out 3D Game Development with Dark Basic Professional [^]programming.
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All heady theories aside, if the speed of light is fixed and that's the speed you're going, light cannot go any faster than you can. Simple logic says you won’t see anything in ahead of you.
For argument’s sake, let’s take out the speed of light conundrum and use the speed of something else.
If I’m driving down a dark road at the speed of Grandpa’s Rascal and I suddenly push the Rascal, Grandpa and all, out of the car, will Grandpa hit the wall first? 
OK, so what's the speed of DARK?
Ozma
Time flies when you don't know what you're doing.
-- modified at 21:12 Tuesday 9th May, 2006
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Ozma6 wrote: Grandpa’s Rascal
Cool car 
regards,
Paul Watson
Ireland
Feed Henry!
eh, stop bugging me about it, give it a couple of days, see what happens.
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I have to thank Antonio for submitting this question. To date this trivia question has created the most buzz 
According to his professor, ”No, you wouldn't see anything because you and your car would be pure energy.”
Jordon
News Editor/Publisher
The Code Project Insider
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I'd like to email his prof and ask what the heck the answer means. I thought the question was baffling but the answer is far worse 
regards,
Paul Watson
Ireland
Feed Henry!
eh, stop bugging me about it, give it a couple of days, see what happens.
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If you can't dazzle 'em with your brilliance, baffle 'em with your bullshit.
You may be right
I may be crazy
-- Billy Joel --
Within you lies the power for good - Use it!
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ur prof is right, i guess, my revision guide tells me that objects with mass can actually never reaches the speed of light, therefore u and ur car have to be energy to fulfill this statement
-- modified at 14:39 Wednesday 10th May, 2006
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Remember E=mc^2, i.e. the equivalence of mass and energy?
What the professor probably means is that you would not have any *rest* mass, which in turn means that you would not be able to travel slower than the speed of speed, and therefore it wouldn't be you behind the wheel because you do have rest mass, and therefore would not be able to reach the speed of light.
I hope this closes the gap between (some of) the answers and shows their consistency.
Alex
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The Physics Part of the IB (or rather my revision guide) teaches me that it is impossible for an object with mass to reach the speed of light, since when the object aproaches the speed of light, its mass would have infinite values.
But over looking that u would see nothing because the speed of light is the same for every observer (in any frame of reverence), so the light rays/waves would actually never leave the bulb.
I wrote my exam on that (Literary today).
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Arctic King, Saladin and Tom Thumb are which types of vegetable?
Jordon
News Editor/Publisher
The Code Project Insider
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Arctic King is a type of lettuce, so that's my guess.
Tom Bryan
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Then we can move on to the headlights part... 