On Wednesday, February 20, 2019 at 12:30:01 AM UTC-7, Philip Thrift wrote: > > > > On Wednesday, February 20, 2019 at 1:06:25 AM UTC-6, [email protected] > wrote: >> >> >> >> On Tuesday, February 19, 2019 at 8:16:51 PM UTC-7, Brent wrote: >>> >>> >>> >>> On 2/19/2019 5:10 PM, [email protected] wrote: >>> >>> >>> *What you wrote makes no sense. It fails to explain why motion occurs in >>> the absence of force. AG * >>> >>> >>> So did Newton: "A body in motion will remain in motion." >>> >> >> *Right, but Newton "explained" why a body at "rest" can start moving, via >> the application of "force". What does "rest" mean in GR and what causes >> "motion" from that pov? Incidentally, when I posed the question of why >> space and time must be fused in relativity. I didn't know the answer. I >> came to a partial explanation by posing the question. AG* >> >>> >>> > > Physics doesn't really explain anything. It only creates expressions in > different mathematical dialects that we interpret. >
*Right. That's why I put the quotes around *explained*. AG * > > > https://www.newyorker.com/science/elements/a-different-kind-of-theory-of-everything > > > > In 1964, during a lecture at Cornell University, the physicist Richard > Feynman articulated a profound mystery about the physical world. He told > his listeners to imagine two objects, each gravitationally attracted to the > other. How, he asked, should we predict their movements? Feynman identified > three approaches, each invoking a different belief about the world. The > first approach used Newton’s law of gravity, according to which the objects > exert a pull on each other. The second imagined a gravitational field > extending through space, which the objects distort. The third applied the > principle of least action, which holds that each object moves by following > the path that takes the least energy in the least time. All three > approaches produced the same, correct prediction. They were three equally > useful descriptions of how gravity works. > *Except that it's wrong to put Newton's gravity theory on the same level as Einstein's. Also, I think we can dispense with the Principle of Least Action and just use the geodesic hypothesis as a postulate of GR. We could say that God preferred a unique path, the extremal, rather than having to choose among an uncountable set of paths for each path between distinct events in the manifold. AG* > > “One of the amazing characteristics of nature is this variety of > interpretational schemes,” Feynman said. ... “If you modify the laws much, > you find you can only write them in fewer ways,” Feynman said. “I always > found that mysterious, and I do not know the reason why it is that the > correct laws of physics are expressible in such a tremendous variety of > ways. They seem to be able to get through several wickets at the same time.” > > ... > > - pt > -- 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.
