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Re: Luminosity

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Posted by Lancer/">Lancer on April 22, 1999 20:26:12 UTC

: Just clarifying my thoughts on the speed of light, : Is it true that indeed if you are traveling at the : speed of light (in relation to the earth), and : measure a particle of light moving in the same : direction (also in relation to the earth), you : will still measure it at 186,000mi/s?

: Any words you might have on the absolute speed of : light you have would be appreciated.

: -Adam

That is correct Adam. Relativistic theory does not follow the rules of Newtonian physics cleanly. That is the rules that deal with relative velocities (that we may take as common sense) for example, "If a car is moving away from us at 50 mph and we are traveling at 40 mph then the relative speed of the receding car to us is 90 mph", is not applicable to relativity. Conceptually, the reasons for this lie in a factor that most physics texts would call "gamma" that increases as you approach relativistic speeds. When gamma gets too large (at one tenth the speed of light or greater), Newtonian physics falls apart. The reason why Newtonian physics works in everyday life is because going 50, 90 or even 1000 mph have small gammas, there the Newtonian laws would still apply. When velocities become really big say at .1c (about 1860 miles/sec!!!) gamma becomes significant and then you would need to use Einstein's laws of relativity to be able to solve for the speed that you see from the other object. At any rate, the absolute speed from EVERY and ANY reference frame that any observer sees light traveling would always be 186,000 miles/sec no matter what. Light is the absolute speed of the universe

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