# Speed of light - yey.

In a vacuum, one torch facing East, one facing West. Both are switched on at exactly the same time. The light hits opposite walls of the vacuum at exactly the same time. At what speed were the photons moving away from each other before they hit the walls?

And a quote:

I'm so fast that last night I turned off the light switch in my hotel room and was in bed before the room was dark.

09:34 Tue 30th Nov 2010

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 speed of light - don't judge things on the everyday experience of seeing moving objects because the speeds of such things are so small compared to the speed of light that you will never be aware of relativistic effects. 09:38 Tue 30th Nov 2010 From the perspective of the photon they have no concept of velocity since time does not pass for anything that travels at the speed of light. Being everywhere they have ever been and everywhere they ever will be are simultaneous events for the photon. The rest of us will always see them at traveling at the speed of light no matter what. 11:44 Tue 30th Nov 2010 Question Author Yes, they were traveling at the speed of light, but at what speed were the moving away from each other? 11:58 Tue 30th Nov 2010 -- answer removed -- They were not moving away from each other at all since no time was passing for them. They were both moving away from you at the speed of light. 12:41 Tue 30th Nov 2010 ED why was my answer removed? "c" is the recognised symbol for the speed of light that's all I said? 12:53 Tue 30th Nov 2010 I can see what you are trying to get at here. You are saying that the speed the photons are moving away from each other is twice the speed of light right? But that's OK, that's their speed RELATIVE to each other, but neither of them individually is moving at a speed greater than the speed of light. This doesn't contradict the Theory of Relativity. 13:22 Tue 30th Nov 2010 No matter what frame of reference the speed of light is the limit. High speed motion changes the observation of distance, time, mass and energy. Only momentum is independent of frame of reference. In fact at the speed of light direction changes in such a way that things cannot move away from each other. The entire Universe appears to be in front of the object in the direction of the travel. Relative to each other the photons would appear as stationary. The key to understand the speed of light is the realisation that there is only one speed in the Universe. Everything is traveling at that speed. "Stationary" objects are traveling at the speed of light in the direction of Time. SpaceTime is a four dimensional Cartesian space. Using any speed to travel through Space slows down the passing of time. This is why photons stand still in time. 08:38 Wed 01st Dec 2010 " From the perspective of the photon they have no concept of velocity since time does not pass for anything that travels at the speed of light. Being everywhere they have ever been and everywhere they ever will be are simultaneous events for the photon. " I've had nights like that. 08:45 Wed 01st Dec 2010 R1G: What do you expect. You used the "c" word. 10:10 Wed 01st Dec 2010 What if the batteries in one torch became flat. Would the light slow down, stop immediately or carry on and hit the wall before the batteries lost all power? If you replaced the batteries at the speed of light and switched it on, would this second beam of light catch up with the first? Sorry, this snow has gone to my head. 10:15 Wed 01st Dec 2010 twice the speed of light is the obvious answer but i suspect its wrong.. 10:27 Wed 01st Dec 2010 Look here: http://en.wikipedia.o...n-light#FTL_phenomena This is what I referred to for my earlier post. 11:09 Wed 01st Dec 2010 Forgive my limited knowledge but, Are you considering 'approach speed' as in two cars travelling in opposite directions eg. 70mph x 70mph = 140mph? I think I'm correct in saying 'light' is a constant no matter what relevance it remains at 186.000mps? Please correct me if that's a wrong statement. 18:33 Mon 06th Dec 2010 -- answer removed --

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