# Car as fast as the speed of light

1. Dec 21, 2008

### mildpiranha

What would happen if you drove a car as fast as the speed of light and then switched on the headlights

2. Dec 21, 2008

### Staff: Mentor

"[URL [Broken] am driving my car at the speed of light and I turn on my headlights. What do I see?
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Last edited by a moderator: May 3, 2017
3. Dec 21, 2008

### Dmitry67

Last edited by a moderator: Sep 25, 2014
4. Dec 21, 2008

### HallsofIvy

Because you cannot have a car moving at the speed of light, you are asking a question that basically says "Assuming relativity does not hold, what would relativity say happens"- it just doesn't make sense.

You can ask, "suppose I am in a car traveling (relative to some frame of reference) 99.9% the speed of light, what would I see?" You would see, of course, light traveling away from you at the speed of light and, if it reflected from some object, coming back to you at the speed of light, exactly as you would moving at any speed below that of light.