speed of light

[bswwood]

So if I am traveling in a dark tunnel at the speed of light and turn on my flashlight, will I be able to find my way?

[mathematic]

If you travel at the speed of light (which you can't) anything is possible.

[mooeypoo]

That's an interesting question. Moving *at* the speed of light makes things impossible, but let's say moving very very close to it. 99.99% the speed of light.

 

I can't say I'm an expert on Relativity, so this will be my thought-experiment guesstimate; I'm hoping one of the more knowledgeable physicists will chip in here.

 

The speed of light is the same regardless of your reference frame. So, even though you're moving, the light beam travels from your flashlight and to the surroundings at the speed of light, which means it will hit the wall and bounce back as if you were standing there, and so yes.. you should be able to see your surroundings.

 

You will see a very weird surroundings, though, because on those speeds you also need to take into account length contraction (and time dilation, but that would be less of a visible effect).

 

This will only "work", even in theory only, if you are LESS than the speed of light. If you insist on going at the speed of light, this entire thought experiment fails since you - as an object with mass - simply cannot. In order to go at the speed of light, you must be massless. It makes no sense to wonder *at* the speed of light.

 

~mooey

[bswwood]

Of coruse an object with mass cant travel at the speed of light but if it were able to and it turned on the flashlight would the light from the flashlight be traveling at c from the lens of the flashlight giving you c squared?

[mooeypoo]

Of coruse an object with mass cant travel at the speed of light but if it were able to and it turned on the flashlight would the light from the flashlight be traveling at c from the lens of the flashlight giving you c squared?

 

The thought experiment of "if it traveled the speed of light" breaks down. There's no answer for that.

 

The closest answer we can consider is for a situation where you travel as close as possible to the speed of light. There is no reference frame AT the speed of light.

 

If you were very very close to the speed of light and turned on a flashlight, the speed of the beam will be c relative to you, and c relative to the tunnel wall you're in. It's always c, regardless of your frame.

[ajb]

Heuristically one can use the velocity addition formula

 

[math]s = \frac{v+u}{1+ \frac{vu}{c^{2}}}[/math],

 

setting [math]v=u=c[/math]. Doing so you get [math]s= c[/math].

 

I warn though, as mooeypoo has said, a physical flashlight cannot travel at the speed of light.

[hawksmere]

No matter where you are or what speed you travel at light will always recedes away at 299,783,458 metres per second. SPL is a constant of nature irrespective of the motion or the observer.