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Old 22-09-2011, 12:50 PM
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pmrid (Peter)
Ageing badly.

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Quote:
Originally Posted by renormalised View Post
Light can only travel at c, whatever c is in the medium within which the light is traveling. Be it a vacuum or a bowl of jelly.

The answer to your question is still no....c is a constant. To change the equations to get 2c, you would have to change the constancy of the speed of light, which you can't do. As I mentioned before, your example doesn't produce a "2c" result, whether that's "seems" or "relative" to anything you or the other object is doing.
OK. I'm struggling here.
Photon A and I both leave our respective destinations at the same time, heading towards one-another. At the point of departure we are, say, 5 light years apart. Our relative starting positions.

After 1 year, I have travelled a light year towards the source of photon A. In the same year, Photon A has travelled a light year in my direction.
At the end of year 1, we are therefore 3 light years apart, not 5. To my observing eye, hasn't the distance between us reduced at the rate of 2 light years/year?

Peter
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