Re: A89: What's Wrong?
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Re: A89: What's Wrong?
The speed of light is the same for all observers, no matter their frame of reference (relative velocity).
Here's an example. c = speed of light (which can vary, but is about 3 x 10^8 m/s in a vacuum)
You have two observers, A and B. A is stationary, B is moving 3 x10^7 m/s (approx 1/10 speed of light) away from A.
A beam of light is moving in the same direction. According to classical physics, B should measure a lower value for c than A would, but this doesn't happen. All observers measure the same value for c. That's where "Relativity" comes from, not the fact that light has a fixed speed, but that all observers will measure the same speed for a light ray, no matter their relative motion/velocity/whatever. That's where all the time discrpency comes in =).
Conceiveably, there could be a medium in which light could be slowed to 1 m/s (or even slower), although I don't think that anything exists like that in nature.
(Note that these descriptions are for non-accelerating frames of reference. That's were general relativity comes in, and I really don't want to butcher it (come on, it took Einstein over 10 years from his original paper on special relativity to figure this crap out, and tensor algebra is evil math I just really don't want to learn =) Also, don't hold any of what I said as 100% correct, it's been a while since I've read on it, though I think I'm mostly correct. Read a book on it. A physicist will give a much better description of physics than anybody on a calc programming mail list =)
Mike
I'm still confused. Was my earlier statement right or wrong? I said that the
speed of light varies depending on what it is passing through, but the speed
of some particular beam (or photon, or whatever) of light appears to move at
the same speed regardless of the speed of the observer. Is that roughly what
relativity says? A lot of people seem to think that it says light *always*
goes the same speed, but I'm almost sure this is wrong.
-Kevin
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