On Thursday, April 18, 2019 at 9:20:36 PM UTC-6, [email protected] wrote: > > > > On Thursday, April 18, 2019 at 8:08:58 PM UTC-6, [email protected] > wrote: >> >> >> >> On Thursday, April 18, 2019 at 6:53:33 PM UTC-6, Brent wrote: >>> >>> Sorry, I don't remember what, if anything, I intended to text. >>> >>> I'm not expert on how Einstein arrived at his famous field equations. I >>> know that he insisted on them being tensor equations so that they would >>> have the same form in all coordinate systems. That may sound like a >>> mathematical technicality, but it is really to ensure that the things in >>> the equation, the tensors, could have a physical interpretation. He also >>> limited himself to second order differentials, probably as a matter of >>> simplicity. And he excluded torsion, but I don't know why. And of course >>> he knew it had to reproduce Newtonian gravity in the weak/slow limit. >>> >>> Brent >>> >> >> Here's a link which might help; >> >> https://arxiv.org/pdf/1608.05752.pdf >> >> AG >> > > I'm coming to the view that what I have been seeking these many years - > namely, a mathematical derivation of Einstein's field equations, somewhat > like a mathematical theorem -- doesn't exist. It's more a case of a set of > highly subtle physical intuitions about how the universe functions, which, > when cobbled together, result in the field equations. For this reason, most > alleged explanations of GR involve, at some point, essentially pulling the > field equations out of the proverbial hat. As with the Principle of > Relativity and the Least Action Principle, the latter say applied to > asserting geodesic motion for freely falling bodies, they're not provable > as "true", but assuming them "false" would be a dead-end for physics and > would, as well, make our lives miserable. AG >
One possible exception to the above is the Einstein-Hilbert Principle of Least Action, from which, it is alleges, Einstein's field equations can be derived. https://en.wikipedia.org/wiki/Einstein%E2%80%93Hilbert_action But what it is, and how it would work, is above my pay grade. Maybe someone here can shed some light on this topic. 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.
