# If you were travailing the speed of light in a box and you turned a flashlight on would you see light ?

if you were travailing the speed of light in a box and you turned a flashlight on would you see the light on the box ahead of you?

Relevance

Wow, there's a lot of mis-understanding of the theory of relativity going on here. Sunken, ignore everything everyone has been saying about not being able to turn on a flashlight at the speed of light, because length has shortened or time has stopped or whatever. It's simply not true.

Why? Because speed is relative. You aren't moving at the speed of light relative to, say, the box you're in. From your frame of reference, you'll never notice any change in your mass and what-not, because you never move relative to yourself.

If you were to move at the speed of light relative to some object, from your frame of reference IT is the one whose time, length, and mass are changing. Not yours.

Now, on to your question. Yes, you would be able to see the light coming out of the flashlight, and you would measure its speed to be the speed of light. This makes sense, because you know if you're driving in a car and you throw a rock out at 20m/s, you will measure its speed to be 20m/s, no matter how fast the car is traveling relative to the ground.

Now comes the tricky part. If someone were watching you whiz by in your box, and they had X-ray vision and thus witnessed you switch on the flashlight, they would also measure the light to be moving at the speed of light. The explanation for this is a bit complicated, and rather than explain it here, I'm just going to suggest that you read up on special relativity. I'll give you a couple good links to get started with below.

• LeAnne
Lv 7

Here goes:

The speed of light is exactly the same for every observer - regardless of their speed.

Now for the fun part - at the speed of light, time slows to a stop. You would not be able to turn your flashlight on because that would take a certain amount of time - and you wouldn't have any time.

On a more realistic note - be aware that you will never travel at the speed of light - no mass or object ever will. As you approach the speed of light, both time and distance shorten in the direction of travel, and mass increases - to the extent that at the speed of light, your mass would be infinite, distance would be zero and time would stop! Obviously, this cannot happen in reality.

The theory of relativity states that time stops when an object is at the speed of light. However it also states that you couldn't approach the speed of light without the mass of the flashlight crushing you and the box being crushed.

• Anonymous

NO! That's exactly why it is not possible to travel at the speed of light. Time stops. There is a famous thought experiment where you build a clock out of two mirrors with light bouncing back and fourth between them. The faster you go the longer the light has to travel and the clock slows. When you are travelling at the speed of light the light can no longer bounce up and down between the mirrors without going faster than the speed of light.

It is exactly questions like that which caused Einstein to formulate his theories of relativity. According to his theories, no material object can ever travel at the speed of light. It it did, then the math says time would stop and distance would shrink to zero. To a stationary observer you are frozen like a statue and not turning on your light. To you, you never are aware of your travel. You simply appear at your destination without ever experiencing the trip. It would be like teleporting. For you, the time passes infinitely fast, or you get where you are going in 0 time. So you can turn on the light before you leave or after you get there, but not during the trip. And if it is on during the trip, you don't have time to observe it.

yes thats einstien's theory of relativity even though you are going the speed of light relative to a stationary object every other object going the speed of light is still going the speed of light relative to you

think about it like you are in a car going 35 mph and another car next to you is going 36 mph relative to you the car is pulling ahead at 1mph in fact if you couldnt feel the friction force of the ground and the force of the car and couldnt see any stationary objects you would be able to say that the other car was moving at 1mph and you were stationary even though you are both moving

this does not apply to light no matter how fast you go light still moves away form you at the speed of light

the theory of relativity says yes... the light released from a flashlight being held by someone moving at the speed of light would react the same as a missile launched from a moving jet.lets say that the jet is point a, the target is point b. and that some one standing on the ground exactly under the jet at time of release is point c... the missile fly at 1000 miles per hour,the plane is traveling at 500 miles per hour, from point c the missile is traveling at 1000 miles per hour as viewed from the person on the ground. to the pilot the missile is moving at 500 miles per hr.the same would apply to the flashlight question, altho the person is traveling at the same speed as would the light from the flashlight,the speed of light would be relative to his position and to him it would seem as the light was operating in a normal manner, to a stationary observer, he would not see the light from the flash light because both the person and the light would be traveling at the same speed as seen from his position

I do not believe it is physically possible to travel at the speed of light. Einstein's theory of relativity predicts that your mass would increase as you approach that speed, preventing you from ever attaining it.

Assuming the box is moving at a constant velocity, you would not feel any movement, and the light would shine on the box like normal.

• Anonymous