On Mon, Jul 21, 2025 at 4:51 PM Brent Meeker <[email protected]> wrote:
> >> *>> The gravitational potential energy of a sphere of particles of matter >> like sand is always negative, this is true in Newtonian Physics and remains >> true in General Relativity, so the gravitational potential energy of a >> sphere of particles of mass-energy M and radius R is PE= (-G*M^2)/R where >> G is the gravitational constant. It’s important to note that this is >> negative energy, so the larger R gets the closer the potential energy gets >> to zero, and if it was at infinity it would be precisely zero. **If the >> sphere expands and is made of sand, which is normal matter, then M stays >> the same but R increases, so the gravitational potential energy becomes >> less negative and more positive, and that means it's uphill; It would take >> an external expenditure of work to do that, so if you let the sphere go to >> rest it would fall inward as you'd expect.* > > > *> But if the total energy, gravitational potential plus sand kinetic, is > zero* > *That would be true only if you assume** that empty space contains energy and is the source of the acceleration of the universe, and while that's not a crazy assumption to make it's far from a proven fact. * > * > then the sphere will expand forever but with a rate asymptotically > approaching zero.* > *If empty space contains energy then the universe will not only expand forever it will accelerate forever, BUT the rate of acceleration will be constant, there would be no jerk, so there would be no Big Rip. But if a scalar field like Quintessence is the source of Dark Energy then a Big Rip would be possible, in fact a whole lot of different things would be possible. * *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* 667 > -- 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 view this discussion visit https://groups.google.com/d/msgid/everything-list/CAJPayv3u6m%2BrJrGfQUP6NSvfPAbdRn2PARbAiZN6d7%3DwWv6E%2BA%40mail.gmail.com.
