On Friday, March 9, 2018 at 8:59:09 PM UTC-5, Brent wrote: > > > > On 3/9/2018 5:28 PM, [email protected] <javascript:> wrote: > > > > On Friday, March 9, 2018 at 12:51:29 PM UTC-5, Lawrence Crowell wrote: >> >> On Friday, March 9, 2018 at 9:44:30 AM UTC-6, [email protected] wrote: >>> >>> >>> >>> On Friday, March 9, 2018 at 12:10:13 AM UTC-5, Brent wrote: >>>> >>>> >>>> >>>> On 3/8/2018 8:40 PM, [email protected] wrote: >>>> >>>> >>>> >>>> ... >>>> >>>> *This I find troubling. We have two fundamental physical phenomenon, >>>> gravity and EM, and they seem to have no intrinsic relationship between >>>> each other. AG * >>>> >>>> >>>> They have more relationship than they did when Maxwell discovered EM. >>>> It was purely a field on a fixed background. So you've been troubled >>>> since >>>> 1862. >>>> >>>> Under GR the EM field is a source of gravity and hence warps spacetime; >>>> and warped spacetime deflects EM waves. >>>> >>>> Brent >>>> >>> >>> *Good perspective on the situation. OTOH, for Newton movement is caused >>> by an attractive force, whereas for Einstein it's caused by the advancement >>> of time. So, IMO, the mystery of movement in a gravity field persists. AG* >>> >>> >> >> I am not exactly sure why you are stuck on the idea that the advance of >> time causes motion. >> > > > *Because in the absence of a force causing non-geodesic motion, the > increase in time results in a change in spatial position since in the > equations of motion, spatial coordinates are not independent variables; > they depend on time IIUC. AG* > > > You seem to have a confused concept of "cause". To say time causes motion > is like saying being different places at different times causes motion. > > Brent >
*I didn't intend "cause" to be taken so literally. I just meant that if time changes, and it does so for no apparent reason, the equations of motion imply or result in different positions in space; thus, the advancement of time necessarily yields different positions in space and can be understood as the "cause" of motion. 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
