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Question

you are traveling in a space ship at the speed , of light, and you turn on your headlights,, is the light visible in front of you or not.??. if not, is the light beam behind you ????

Answer 1

The trouble with that hypothetical is that it can't even be answered in theory. By General Relativity, as a body accelerated towards light speed, it becomes more massive. It can't reach light speed because to do so would mean making it infinitely massive, so no force could accelerate it to that speed.

If, however, they were travelling at almost the speed of light, then the beam would appear to them to be travelling ahead at light speed. To the observer, the beam would be travelling at light speed from the observer's point of view, in other words, it would be getting ahead of the spaceship slowly.

This shows one of the effects of relativity. The driver of the ship sees the light beam go 186,000 miles ahead of his ship in 1 second. To the observer, it takes many seconds to get 186,000 miles ahead of the ship, because the ship is travelling nearly as fast as the beam. In other words, the seconds are passing more slowly on the ship than they are to the stationary observer.

Answer 2

You on your ship would see the headlights shine in front of you just like normal. That is the simple, accepted answer. What makes the question so controversial is that other observers not traveling at the speed of light would see of you, your ship, and its headlights. In the end, in no case would the light of the headlights not be seen in front of the headlights.

And congratulations! This thought experiment is nearly exactly what Einstein considered as he wended his way to understanding the reality of time dilation. So keep on thinking!

Answer 3

Headlights on a space ship?
Bit like a screen door on a submarine isn't it?

Answer 4

Spaceships don't have headlights.

ETA: KBW3 - Are you absolutely sure of that? Because my husband laughed out loud when I read him the question.