That's not what shashank asked... he asked what if the train was moving faster than the speed of light... and then turned on it's headlight, what would the observer standing on the ground see...
Interesting question...
there's a theory that if you're travelling faster than the speed of light, and turned on your headlights, observers will still see your headlights travel at the speed of light.
What's more interesting is that you will see time move backwards
so you will see yourself starting to move backwards (away from the observer) instead of forwards (towards him).
The observer will see your headlights (and your train)
after you have already passed him, but still, at the speed of light, not faster. This is because C is constant, and we cannot see things moving faster than the speed of light in real-time, we will only see them later (when the light they emit catches up to the point they just passed while moving at a speed faster than light).
Of course, all this is just one theory, because others suggest that in order to attain a speed faster than light, you have to have infinite power to accelerate, and you will become infinite mass.
This is why we currently assume that greater than C speeds are impossible, because if you are travelling at C-1 m/s, time is already almost at a standstill. So in order to accelerate that 1 m/s faster, you have to apply infinite power of acceleration to move any faster.
Raaabo
