On Monday, August 3, 2020 at 8:55:17 AM UTC-6, Alan Grayson wrote: > > > > On Sunday, August 2, 2020 at 5:00:22 PM UTC-6, Alan Grayson wrote: >> >> >> >> 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 >> > > I think in this situation the direction of motion is ambiguous. AG >
No. It doesn't spatially move, but it moves in space-time since the observer's clock continues to advance. 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/66c5bf45-f1ef-4104-92f5-611a9af14cb1o%40googlegroups.com.
