On Sunday, August 2, 2020 at 5:30:36 AM UTC-6, Lawrence Crowell wrote: > > The periapsis or perihelion advance of Mercury is largely a result of > classical perturbation theory in classical mechanics. About 10% of the > perihelion advance could not be accounted for by perturbation methods in > classical mechanics. > > This has to be admired in some ways. Finding the ephemeris of Mercury is > tough, for the planet makes brief appearances near the sun in mornings and > evenings. Finding an orbital path from its course across the sky is not > easy. The second issue is that perturbation methods in classical mechanics > are difficult. These were developed arduously in the 19th century and Le > Verrier worked on this to find the planet Neptune from the perturbed motion > of Uranus in 1848. These methods were worked on through the 19th century. > The later work of von Zeipel and Poincare were used to compute the > periapsis advance of Mercury, but there was this persistent 43arc-sec/year > that resisted these efforts. > > It was general relativity that predicted this anomaly in ways that are far > simpler than the classical perturbation methods. This post-diction of GR > was an initial success in the theory, followed up shortly by the Eddington > expedition that found the optical effects of GR in a solar eclipse in 1919. > > LC >
I appreciate your grasp of the history, but you haven't answered my question and don't seem aware of what it is (plus you posted your reply on the wrong thread). AG > > On Sunday, August 2, 2020 at 3:49:28 AM UTC-5 [email protected] wrote: > >> >> >> On Saturday, August 1, 2020 at 10:35:09 PM UTC-6, Alan Grayson wrote: >>> >>> In flat space, which is tantamount to assuming the absence of gravity, >>> and non-zero curvature, a body placed at spatial coordinates x,y,z, will >>> move because t increments. But if there is zero curvature, in which >>> direction will it move? That is, how is the direction of motion determined? >>> TIA, AG >>> >> >> CORRECTION; above, I meant to write, " ... which is tantamount to >> assuming the absence of gravity and ZERO curvature, ... " AG >> > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/48781f39-ebf5-44e1-9d43-606db21e42c2o%40googlegroups.com.
