On 3/8/2018 4:24 AM, agrayson2...@gmail.com wrote:
On Wednesday, March 7, 2018 at 11:04:09 PM UTC-5, Brent wrote: On 3/7/2018 5:39 AM, agrays...@gmail.com <javascript:> wrote:*Thanks for your time and effort, but I don't think you understand my* *question. Suppose a test particle is restrained spatially, say in * *the Sun's gravitational field. When released, it starts to move (toward * *the Sun). How does GR explain this motion? By the advance of time? AG*Time was advancing all along. Your restraint was a force causing the particle to follow a non-geodesic path through space-time. When you released it, it then followed the "straightest path possible", i.e. a geodesic. BrentSo time is the "culprit". What has this resumption of spatial motion (along a geodesic in spacetime) have to do with conservation of momentum, if at all ? TIA, AG
It's not a "resumption" of motion; it's just tilting the direction of motion from being along your coordinate time line (which you think of as 'not moving') to being along the geodesic (which you think of as 'falling'). The 4-momentum of the system, including whatever device you were using to keep the particle from falling is conserved.
Didn't you say you had read Epstein? Brent -- 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 post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
