# Question about speed of light?

1. Jul 18, 2011

### tutondrius

question about speed of light??!?!?

speed off light is a constant, so if theoretically we travel in empty space in a theoretical car on a theoretical road (no drag) with the speed of light and we turn on the head lights of the car, what would happen? The light form the head lights will stay on one place or it is going to move forward, faster then me, also faster than itself????

p.s. sorry for the bad English

2. Jul 18, 2011

### Staff: Mentor

Re: question about speed of light??!?!?

Forget about a car traveling at the speed of light--that can't happen. Instead, say the car traveled at 0.99c with respect to the road, where c = the speed of light. If you turn on the lights, the observer in the car will see the light move at speed c with respect to the car. An observer on the road will also see the light move at speed c with respect to the road.

3. Jul 18, 2011

### tutondrius

Re: question about speed of light??!?!?

ok let me change the question. Only theoretically if a light source is travailing 100% the speed of light. What is happening with the light in the direction it is travailing. And please explain it like you would to a moron.

4. Jul 18, 2011

### Staff: Mentor

Re: question about speed of light??!?!?

I assume you want a factual answer based on accepted physics? If so, the premise of the question is impossible, as things such as light sources cannot travel at the speed of light.

5. Jul 18, 2011

### xts

Re: question about speed of light??!?!?

Even theoretically light source cannot travel at 100% of the speed of light.

6. Jul 18, 2011

### tutondrius

Re: question about speed of light??!?!?

ok 10x very much. :D