On Sunday, August 2, 2020 at 1:55:15 PM UTC-6, Lawrence Crowell wrote: > > I looked at the precession question, wrote it in WORD and then posted it > in the wrong thread. A big line of anti-virus defense is working off-line. > I do a lot of work locally and pop on and off the internet. I try to never > leave my machines on-line with an open port for anyone or any bot to enter > to cause mischief. > > With this the question is odd. How something moves in free and flat space > and spacetime is just determined by its initial conditions. > > LC >
If one starts with SR and zero curvature of spacetime, and places a test particle in that spacetime spatially at rest, how will spacetime tell matter how to move if spacetime isn't curved? AG > > > > > On Sunday, August 2, 2020 at 9:05:57 AM UTC-5 [email protected] wrote: > >> >> >> 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/999d6fa8-8583-4919-a453-24f35d870f8ao%40googlegroups.com.
