Now here is some science...

**Philip Regent of Hospitallers** · October 26, 2012, 07:43 PM

If car should go at the speed of light (which of course never will be achieved) and then driver decides to turn headlights on...does still light beam will appear ahead of the moving car??

**Nutsack** · October 26, 2012, 09:42 PM

I believe the time it would take for you to turn on the light is infinite. Because I heard from someone that at the speed of light time actually stops.

**Morkonan** · October 26, 2012, 10:31 PM

Originally Posted by Philip Regent of Hospitallers

If car should go at the speed of light (which of course never will be achieved) and then driver decides to turn headlights on...does still light beam will appear ahead of the moving car??

Yes, it does. Light always moves at a constant speed in a vacuum. However, the view may not be what you expect.

(Also, you can't move at the speed of light. But, it's OK to phrase the question.)

Here's your answer, in detail, minus the maths - UCR.edu - Headlights

Originally Posted by Nutsack

I believe the time it would take for you to turn on the light is infinite. Because I heard from someone that at the speed of light time actually stops.

No. Time doesn't stop for you traveling inside the car. To observers on the outside, it might appear that you move ever-so-slowly up to a point where you stopped moving, if they could see you. But, for you, you wouldn't notice any change in time. However, once you stopped, the difference due to time-dilation would be obvious - More time would have passed than you personally experienced.

**Plyco678** · October 27, 2012, 01:15 AM

To dispel any wishful thinking (sorry) it isn't possible for us to travel at the speed of light. Travelling at the speed of light is therefore incomprehensible, and there isn't much we can do to describe what it would look like. This, therefore, is as good an explanation as any: http://www.youtube.com/watch?v=iFKvgo7q6lw But I guess the succinct answer, from my limited knowledge of physics, is yes. The light would shine and you would see it like normal, because the speed of light is a constant. However, it wouldn't have any outreaching effect on your hypothetical road, because you would be moving at the same speed.

**~~removeduser_4536284751384~~** · October 28, 2012, 07:34 PM

You could reach 99.999..% the speed of light. To you in the car, the lights would appear to function as normal; i.e. the light would move away from you at light speed. However, to an pedestrian you may pass, the light would move away from you at (speed of light) - (your speed), i.e. some miniscule fraction of the speed of light. In other words, the light would also go past the pedestrian at the speed of light, and you would folow the light at very close to its speed.

This is counterintuitive because if you were to drive at say 25 mph and throw a ball forwards out of the car at 30 mph, You would see the ball move at 30 mph relative to you and an onlooker would see the ball travel at 55 mph relative to her. With light, you both see it travel at the same speed even if you are moving at different speeds and even in different directions.

Let's say in a second scenario the ball behaved like light and always travelled at the speed of ball, 30 mph. If you drove 25 mph and threw it from your car, it would travel away from you at 30 mph. To the bystander, the ball would travel past at 30 mph and you would follow at 25 mph, and she would percieved much less of a gap between you than you would.

**Elfdude** · October 30, 2012, 03:08 AM

This gets into quantum mechanics and relativistic perspectives. Essentially the light appears in two different places depending on how it's detected. I.E. if you used a detector outside of a train traveling light speed it would see the train traveling at light speed and see the light traveling at light speed, no greater. From inside the train however you would see light traveling at the normal speed of light because of your frame of reference. This is because space warps because energy is mass and to hit the speed limit you need a lot of it. So while both observations are correct it is not because light is actually in two places going at different speeds but rather because space itself has warped to maintain the speed limit. We don't know that this really is the speed limit but it fits to a very high degree of accuracy and to really test it would require quite a bit more technology than we currently have.

Space and time are interconnected and both will dilate depending on relativity to prevent one from breaking the speed limit classically anyways.

Originally Posted by Plyco678

To dispel any wishful thinking (sorry) it isn't possible for us to travel at the speed of light. Travelling at the speed of light is therefore incomprehensible, and there isn't much we can do to describe what it would look like. This, therefore, is as good an explanation as any: http://www.youtube.com/watch?v=iFKvgo7q6lw But I guess the succinct answer, from my limited knowledge of physics, is yes. The light would shine and you would see it like normal, because the speed of light is a constant. However, it wouldn't have any outreaching effect on your hypothetical road, because you would be moving at the same speed.

This is only true in classical mechanics if light was purely a wave but it has wave and particle like properties. Not to mention even if it was classical mechanics we can still alter the distance and effectively break the speed of light by bending two points of space together.

**Wulfburk** · October 30, 2012, 08:35 PM

But why cant you reach the speed of light? I never understood this, i know light is the fastest ... thing, but is there really a "law" that says you cant go faster than it or people say that just because they never saw something going faster?

**Morkonan** · October 30, 2012, 10:04 PM

Originally Posted by Wulfburk

But why cant you reach the speed of light? I never understood this, i know light is the fastest ... thing, but is there really a "law" that says you cant go faster than it or people say that just because they never saw something going faster?

As your velocity increases, so does the energy required to accelerate.

See this: https://en.wikipedia.org/wiki/Mass_i...ial_relativity

Note this equation:

In that equation, calculate any mass you wish in which the velocity is at the speed of light. So, replace "v" with the speed of light, 299,792,458 mps. For simplicity's sake, we'll just substitute "c", which represents the speed of light.

Now, in the denominator of that equation, you would have 1-c^2/c^2 if the current velocity was the speed of light, yes? Then, that portion of the equation would equate to "0." But, according to the equation, you must now divide by zero, right? And, what happens then?

Just as importantly, as your velocity increases towards equaling the speed of light, the energy necessary to accelerate rises towards infinity, just as the mass would increase as well.

**Wulfburk** · October 31, 2012, 10:17 AM

Oh alright, i didnt knew about that, you just explained to me what all those stupid tv shows coudnt! Thanks mate!

**PointOfViewGun** · November 04, 2012, 11:49 AM

Originally Posted by Philip Regent of Hospitallers

If car should go at the speed of light (which of course never will be achieved) and then driver decides to turn headlights on...does still light beam will appear ahead of the moving car??

You wouldn't be able to see the car till the very moment it passed by you. The light beam would be a cross sectional area that you would have the chance to see at only a single moment in time.

**fkizz** · November 06, 2012, 06:16 PM

Depends if you have anything in front of you. The light bounces back to the car if it colides with an opaque object. What you would exactly see I do not know, but interesting question.