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Gravity Probe B
<i>Originally posted by Jim</i>
<br />You seem to be saying the standard view now is that the speed of light is not the speed of gravity and the standard model accepts this as a fact now. Do you know when this view was adopted by the standard model? I need a time line for my simple minded understanding of these things.
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Jim
i have no idea,to be honest.
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- tvanflandern
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<br />You seem to be saying the standard view now is that the speed of light is not the speed of gravity and the standard model accepts this as a fact now. Do you know when this view was adopted by the standard model? I need a time line for my simple minded understanding of these things.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Except for the confusion that has arisen in the last 30 years about gravitational waves, it was always the case that gravity (meaning gravitational force) had to propagate FTL or not at all. Laplace showed in 1820 that the speed of gravitational force had to be no less than 10 million c. We now know it must be at least 20 billion c. GR was always aware that the speed of gravitational force could not be as slow as c.
But to maintain consistency with SR's constraint that nothing real can propagate faster than c, GR started claiming that gravity <i>is not a force that propagates</i>, but instead is a curvature of spacetime. This was the basis of "geometric GR" (gravity is just geometry). Only recently (2002) has it been argued that the geometric interpretation is not physically viable, and that gravity must be a classical force to remain consistent with the causality principle and with the prohibition against creating new momentum for target bodies from nothing.
So getting these concepts straight is still a work in progress, with many people still at each different location along the learning curve. -|Tom|-
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- tvanflandern
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<br />Why doesn't the media wait until scientific results have been sufficiently critized? After all, the media has a moral obligation to report news with a minimum of subjectivism.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">It's a question of whether news media should be allowed to cover scientific meetings. Kopeikin announced at an American Astronomocal Society meeting where he gave an oral presentation. All such papers are preliminary, and are given to get feedback from peers before they go to a journal and peer review. Many oral papers never see the ink of print. But is the answer to ban media from covering the meetings?
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Has the general public been misled by Kopeikin's results? (it surely looks that way)<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, but most people who know much about the issue know the outcome. I don't think the damage done will be lasting. -|Tom|-
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- tvanflandern
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<br />no "magic wand" here!![]<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">One person's science is another person's magic. []
I still have no idea what gravity is from your rough description. What exactly makes Earth follow a curved path centered on the Sun instead of any other path?
But more to the point, in the laboratory as well as in the solar system, the main gravitational force exerted by a body is independent of its own spin. Orbital speeds are a function of distance from primary, but not at all of the spin of the primary. So associating your still (to me) magical mechanism with spin is yet another magical (i.e., non-sequitur) step.
I understand the psychology of becoming convinced by one's own theory. It happens to everyone. But unless you can say something a whole lot clearer than the quoted message, I'd caution you to be much more self-critical. A good theoretician falsifies his/her own models without having to wait for feedback. -|Tom|-
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