What happens when a train traveling at the speed of light turns on its headlights?

Question

What happens when a train traveling at the speed of light turns on its headlights? If they illuminate anything, then wouldnt the light coming from then be going faster than the speed of light? Is it even possible for the train to go that fast in the first place?
Thoughtful answers only, please.

Answer 1

So much for getting "thoughtful" answers. Everyone here seems to think it's news that you can't travel at the speed of light. HOWEVER, I'm certain that the poser would, had she known the lack of intellectual power out there, have said "IF IT WERE POSSIBLE TO TRAVEL AT THE SPEED OF LIGHT", etc. Idiots.

To answer the question, if you are traveling at the speed of light (C) and you turn on your headlights, you get an effect somewhat similar to spitting into the wind.

Answer 2

Yes, there is a possibility of a train to travel at the speed of light but, that train has not yet been engineered. Hypothetically speaking, if a train was travelling faster than the speed of light on a dark night and the headlights were turned on, the railroad track would still be dark, just as if the lights were off because by the time light reaches a certain point in front of the train, the train will have already passed that point because it is travelling faster than light.

Answer 3

First up the train could not travel at light speed because it's a massive body (it has mass). It's mass would increase toward infinity the faster it goes. Secondly light speed is a constant irrespective of the motion of the observer so, therefore the train's headlight would make no difference and an observer standing still would measure the speed of light at the same speed as an observer on the train. This is what accounts for time dilation at relativistic speeds.

Jules, Australia.

Answer 4

Light always travels at the speed of light relatively to anything, even if that thing travels at the speed of light. This is the fundamental property of light. If you want to calculate how it will illuminate something else, use Lorentz transformation formulas. Mankind has no knowledge of how to make a train travel exactly at the speed of light, however, to achieve this, the train must be traveling at the speed of light at time of its creation. There is no way to speed up an existing train to light speed, although it may be possible to get a speed very close to light speed

Answer 5

It's abso-fu*k'n-lutely amazing how so many people (many of whom even claim English as their native language) don't seem to understand what the words "Thoughtful answers only, please" actually mean ☺

To answer the last part of your question first; No, it's not possible for anything which has mass to be accelerated to the speed of light (as far as we know ☺)

But if a train (or anything else) were traveling very close to the speed of light and turned on their headlights, to an observer on the train, they'd see the light from the headlights travelling away from them at the speed of light.

To really understand all of this (absolute velocity, reference frames, time/mass/length dilation, etc.) you simply have to take about a one year long class on Special Relativity.


Doug

Answer 6

well maybe the headlights would show because the headlights would be traveling relative to the train. good question though. even einstien once asked if i were traveling the speed of light and had a mirror then would i be able to see myself in it. meaning that the light would have to travel faster than him. and he had a hard time finding an answer,but, the faster somethin travels toward the speed of light the more time slows down. so the light would be relative to you. but once you reach the speed of light time would stop. so, who knows>?

Answer 7

You could not get a train to travel at the speed of light.

Answer 8

The train would travel right along with the light, at the same pace.
Not really possible for "light speed" travel, since the mass of the train would approach the infinite and it would fall into its own gravitational singularity. But to an objective observer, the light would glow along with the rest of the train.

Answer 9

Of course it is not possible for a train to travel close to the speed of light, but we can do a mental exercise so lets suppose it is. The speed of light is absolute, so for the train driver, he will see the beam of light traveling at the "speed of light" in front of him.
What changes, is the perception of time between the driver and the observers outside the train. So for everybody, that beam of light is traveling at the same speed,the speed of light.

Answer 10

A train cannot go as fast as the speed of light.