On Saturday, March 10, 2018 at 10:54:50 PM UTC-5, Brent wrote: > > > > On 3/10/2018 7:32 PM, [email protected] <javascript:> wrote: > > > > On Saturday, March 10, 2018 at 10:09:45 PM UTC-5, Brent wrote: >> >> >> >> On 3/10/2018 5:04 PM, [email protected] wrote: >> >> >> >> On Sunday, March 4, 2018 at 11:35:24 PM UTC-5, [email protected] >> wrote: >>> >>> I don't think so. I think its equations of motion mix time and space, so >>> if time increases, spatial position must change. That is, the assumption >>> that time increases, produces changes in spatial position. CMIIAW. AG >>> >> >> Here's a related question; if you assume a 4d spacetime manifold, how >> does one imagine the shortest path between two points, aka a geodesic path, >> using the Lorentzian metric? AG >> >> >> In the Lorentz metric a geodesic is the longest path between two >> time-like events. >> >> Brent >> > > Right; we've discussed this in the past. But if that's true, why choose > motion along a geodesic in spacetime for a model of gravity > > > He didn't "choose" it, it's implicit in the motion being force-free. As > Russell pointed out it's implied by conservation of energy-momentum. > > Brent >
Where exactly is it argued that conservation of energy-momentum implies motion along a geodesic in the absence of external forces? TIA, AG > > if it's the LONGEST path between two time-like events. Wasn't Einstein > motivated by the fact that a geodesic along a sphere using the Euclidean > metric for path length, is the SHORTEST distance between two points on a > sphere? 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] <javascript:>. > To post to this group, send email to [email protected] > <javascript:>. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > > -- 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.
