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Originally Posted by Ken G
I wouldn't say they predict a coordinate change, but I think you mean that they predict the motion within any set coordinate system would be different.
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Though you're view is correct, I actually was trying to push the envelope a little, since I can't seem to open it.
I meant that regardless of what mapping system is thrown upon an orbital body, changing the coordinates in any fashion will not alter the fixed amount of mass. Yet the converse does, even though the invariance of physics is unchanged, of course.
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... but again the coordinates need not be slave to causation, they merely must respect the connection between the mass and the motion.
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Nicely said. Though inexorably linked, I still this connection as one way; a diode is in this circuit, or a horse is pulling the cart.
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Causation is indeed viewed as a principle of physics, but the question here is, shall we impose a connection between it and coordinatization, or may the two be viewed entirely independently (as in, "the Sun set"). That relativity works is trying to tell us something, but that cause-and-effect works is saying something too. Perhaps an open mind is the best course at this stage.
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Does a hollow mind count as open?
Although the coordinate view from the cart is just as valid as the coordinate view from the horse or the on-watcher, the erratic movement of the horse will cause coordinate changes.
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To me, the failure of geocentricity is not in how the motion gets described, it is in how we attribute that motion. If one merely states that one has chosen to center the coordinates on the Earth for no reason but personal preference or convenience, no fault can be laid. If one claims that this is somehow a special coordinate singled out by nature, rather than purely a choice by man, then one is not using the physical principles that have been demonstrated. But the same can be said about any coordinate system-- I think if one becomes adept at GR (I'm not), one finds that nature simply does not single out coordinates-- it's the same "crank" no matter what coordinates you use, sometimes the math is just easier.
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Agreed. I probably should not have used a capital G in Geocentricity, which attempts to represent the absolute center. For me, those that favor the Geocentric model don't appreciate what you've said, so I like the fact that the Earth jiggles as it rotates. Air mass movements, primarily, and other mass shifts cause the Earth to speed-up or slow down enough to be measurable (using quasar alignments, interestingly). For one to argue that the universe causes these changes, then they will find themselves in Sillyville trying to compare their causal arguments against a rotating Earth with its observable changes in air mass.
I'm plowing through the brush here, at y'all's expense, as I try to wrestle with how subjective I am willing to make the causal arguments. I sense an indifference intrinsic to GR on this kind of issue and it seems counter to how the scientific method has worked before in developing prior theories. GR seems beautiful but cold (ok, that's subjective.
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Indeed it is-- but which one is most elegant may vary from problem to problem, more so than from law to law.
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Yes, and geocentricity is a good example as it is the one used the most, I suspect. Yet, I go a little further than the view Geocentrists are wrong with the superior view, I say that it is inferior for the causal reason given above. Not inferior in its utility or mathematical equivalence, but inferior when it attempts to interface, as Len Moran stated, with reality. The broader universe, perhaps, is what I am trying to embrace and certain models are superior to others. I think the scientific method helps identify this in an objective way, though the final conclusions require some subjective view, too. This is some tricky stuff for me, as you can guess, as I am uncomfortable about allowing subjective views imposing on science, so I am trying to be sure this superiority idea is not beyond the purview of science.