> >* Newton "explained" *
Why did you put explained in quotation marks? If you can predict what something is going to do then you've explained it, the better the prediction the better the explanation. I don't know what else the word could possibly mean. And in science no explanation is perfect, but some are less wrong than others. *> why a body at "rest" can start moving, via the application of "force"* And Einstein explained that a body moving in a geodesic through 4D spacetime will take a path that is not a geodesic if a force is applied. The Earth is moving in a straight line (aka a geodesic) through curved spacetime; the reason Earth's orbit looks elliptical to us is due to map distortion, the same reason that in a flat map of the curved surface of the Earth Greenland looks larger than South America and is almost as large as Africa. Except that it's even worse, in one we're projecting the 2 D curved surface of the Earth into the flat 2D surface of the map, but with Einstein we're projecting a curved 4D volume into a flat 3D volume. *> What does "rest" mean in GR * In General Relativity moving in a geodesic is as close as you can get to the traditional idea of rest, but as long as time passes you're going to be moving through 4D spacetime. *> what causes "motion" from that pov?* Force, same as with Newton. John K Clark -- 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.
