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 Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...The Space and Astronomy Agora Re: Don't Miss-correct You Didn't Understand Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response ToPosted by Zephram Cochrane/">Zephram Cochrane on February 11, 2000 19:28:16 UTC

: re - It is because the laws of physics are frame covariant and the Lorenz speed is finite. is a bit off.

Its not off at all. Don't miss-correct statements that you didn't understand.

: First - It is because the laws of physics are frame covariant (which is correct) means, in case you're unfamiliar with the language of relativity, that the laws of physics (usually expressed mathematically) are independent of the frame of the observer.

I know exactly what it means, and what you just said is exactly what I meant by it.

: Second - and the Lorenz speed is finite - I would phrase "the speed of light is locally invariant" (i.e. independent of the frame of reference).

I said it the way I did for a reason. As far as this question is concerned it doesn't really matter that light moves at the Lorenz invariant speed c. This is merely convenient for experimental purposes. What is relevant to the question is that the Lorenz speed c is finite. I was responding to the question in its general context which really boils down to "why must we use the equations of the Lorenz group and why can't we use the special case of Gallelean transformations?" The answer is exactly my response. Lorenz group transformations are the only 3d+1 transformations that leave the laws of physics frame covariant in space-time with Cartesian geometry. If the Lorenz speed c were infinite they would reduce to Gallelean. It is because the Lorenz speed c is finite that we have all the length contractions and time dilations of special relativity. : : Time dilation is always present with space shortening, why?

: This isn't true. One can have a non-Euclidean space in which there is no time dilatation.

This is always true in special relativity. This was obviously a special relativity question. If you'd take the question and answer in this context you'd have nothing to complain about.

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