what if i travelled at light speed and pointed a flashlight forward?

Question

would the light travel at twice the speed of light? if i pointed it backwards would the light appear to stand still to an observer?

Answer 1

you would see where you are going? :)

Answer 2

There is a different law in relativity of how to combine relative velocities - you can't just add them.
If an somebody flies by you with a speed V1, and throws a ball ahead with a speed V2, the correct way to claculate the speed of the ball with respect to you would be V = (V1+V2)/(1 + V1V2/c^2).
Note, that when V1 and V2 are small, then V1V2/c^2 is almost 0, and can be ignored, so, you have the usual formula V=V1+V2 in that case.
But if one or both of speeds are high, then you can't ignore the denominator anymore. For example, if both speeds (or even any one of them) are "c", then (surprise...) their sum is "c" too.
The beam from your light will be moving as the speed of light with respect to you, as well as to any other inertial observer, regardless of which speed you are passing that observer with.
If you point your light backwards, the '+' sings in the formula change to '-' (because the speeds are now in opposite directions):
V = (V1-V2)/(1-V1V2/c^2).
You can see, that, again, as long as any of the speeds is c, the result is c too.

Answer 3

Imagine this: There is a car in front of you going 50 miles an hour. There is another car to your front/right, at a shorter distance away, going 25 miles an hour. If they both turn their headlights on in that scenario, which light hits you first?

The anwer is the car with the shortest distance to you b/c the speed of light is ALWAYS constant. What would happen if it werent? The beam of light coming from the car further would hit first b/c its velocity would be c + 50, while the other would have been c + 20. So, lets say you all come to a stop sign and the one heading at you is turning left and reaches the stop sign right before you (and we are assuming his light is faster than the other guys, so he is the first of all of us to the sign), then he would have to right of way. But, in reality, what would happen, is that he wouldn't be there at all. We see things because of refelcted light. If light isn't constant, the guy who's light is going c +50 would reach me first, even though he may not actually reach me first. So, if it weren't constant, he would appear to get there first, but in all reality, the other car might be the first there and we may sit there waiting for a car that isn't there yet.

Answer 4

This was the original thought experiment which led to Einstein's insight that space-time is relative. Your fram of reference would have the light travelling away from you at the speed of light. But your time would also come to a stop. Your time would always equal zero while moving at the speed of light. Since time is the deminsion where effects follow cause you would not be able to do anything.

The speed of light is the ABSOLUTE speed limit. Unlike our common experience with matter and sound velocities any light viewed anywhere from any frame of refence is the same as long as it is travelling in a vacuum.

Answer 5

you will possibly see the flashlight as you often might. in simple terms considering the fact which you're traveling on the cost of light would not recommend you're traveling with the gentle from the flashlight. in case you have been in a motor vehicle and have been going the right comparable speed as yet another motor vehicle next to you, might you nonetheless see it? of course you will possibly. an identical theory applies to gentle speed.

Answer 6

If you travel at the speed of light, then for you time stops. To you, it seems as if you can go anywhere in the whole universe in zero time. In fact it would seem as if you were in every place in the universe at the same time. In addition, distance in the direction you are moving shrinks to zero. To you, distance, or space itself, would cease to exist. So you don't have time to turn on the flashlight before you have traveled infinite distance. To the stationary observer, you are frozen, unmoving and not turning on your light. If you turned the light on at a slower speed, then you see the beam leaving you at the speed of light and the stationary person sees you following the light you are shining, with that light pulling ahead of you at less than the speed of light, but you don't see it that way. You see it pulling ahead of you at the speed of light no matter how fast or in what direction you are going. Space and time are altered for each observer, depending on the observer's speed, so that they all see the same speed for all light beams.

Answer 7

You would technically have the light move at twice the speed of light, which is theoretically impossible, because light can only move at the speed of light, because however fast light moves, that's the speed of light. Kind of a paradox, I guess. If you think of it in a really weird way, you might go throught the light. Cool.

Answer 8

Hi,

Light would travel at the same speed as you and the torch.

If you pointed it back wards it would would have no velocity in effect however you would be traveling away at the speed of light and it would look like normal light i.e. pointing a torch away from you when you aren't moving.

Jon

Answer 9

No, light wouldnt trivel twice the speed of light, thats part of the principle of relativity. c is a constant no matter what the speed of the observer is.

Answer 10

No, that's one of the key tenants of relativity. To you, it would still seem to travel away from you at the speed of flight. And also to an observer. But you would be travelling slower in time, relative to them.

Answer 11

U KIDDING... IF U TRVEL WITH THE SPEED OF LIGHT, ur body acquires so much energy that due 2 (nucleur) FUSION ur body shallcontract to a pt mass...{if ur mass>4.09543(kg)}
moreover, wen ur v=c, the light travels with ur speed, hence 4 u there would b complete darkness & for us... u would become a source of energy equal to 90000000000 (j), if ur mass=1(kg)