Congrats to @philipy who was declared winner of today’s Answer of the Day.

He Answered the question.
“A man is driving a car at the speed of light, he turns on the headlights, what happens?”

According to our present understanding of physics, objects that have mass cannot be accelerated up to the actual speed of light.

Therefore, if a car were to be travelling at the speed of light, it is for sure that the theory of relativity is wrong in some respect, and since that is the only scientific basis we have for answering your question, all bets are off!

Now the car could be accelerated up close to the speed of light, without quite getting there. In that case, using the headlights works as normal.

However if you plan to drive at close to the speed of light, I advise you to do it in deep space. Doing it on a road would have unfortunate consequences because of friction, if nothing else. Also it would be illegal. :)

Physics
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