Quote:
Originally Posted by HypothesisTesting
[Snip!] But they would then have had to use elliptical orbits in this geocentric or hybrid universe, and that violates the original ancient Greek idea of "perfect" circular motion. Even Copernicus didn't dare to violate that principle.
The ancient Greeks did not merely think that earth was center of universe, but combined this with a bunch of philosophical nonsense also, such as the notion that all celestial motions were "perfect": perfect circles and made of "perfect" substances like a ghost. It would have been unthinkable to them to use ellipses for orbits , which is why Ptolemy tried to salvage geocentrism with "equants" "deferents" "epicycles" "eccentrics" and weird stuff like that with perfect circles, just to make the theory accord with measurement. But after Tycho/Kepler, perfect circles just couldn't do it any more. [Snip!]
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I generally agree with what you say, but I would like to point out that the Greeks did study conic sections, Appolonius has a work on conics attributed to him (I don't know if any of it still survives, however), and I think that if their observations and data analysis techniques had been good enough to show elliptic motion they would have been delighted to throw out the circles even if they still kept the Earth at the center.
Of course this had to wait for the accurate observations of Brahe and the computing prodigies of Kepler for this to happen. I think the fact that the orbits were shown to be elliptical and conic sections were known and much studied from the time of ancient Greece on helped gain almost immediate acceptance of Kepler's ideas. If the planetary orbits had been some kind of difficult to construct quartic ovals or something, would acceptance have been as quick?