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 > >> >> >> >> On Sunday, August 2, 2020 at 9:05:57 AM UTC-5 agrays...@gmail.com 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 agrays...@gmail.com >>>> 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/dddfe57e-d619-446b-949a-90d2b23e4576o%40googlegroups.com.
