On Thursday, January 23, 2020 at 4:03:24 AM UTC-7, Lawrence Crowell wrote: > > On Wednesday, January 22, 2020 at 2:46:35 PM UTC-6, John Clark wrote: >> >> On Wed, Jan 22, 2020 at 3:34 PM Lawrence Crowell < >> [email protected]> wrote: >> >> > For an accelerated expansion of the sphere there is a cosmological >>> horizon that one can't cross. in other words, the sphere will keep >>> expanding faster than you can ever go. Think of the scene in the movie >>> "*The >>> Shining*" with Jack Nicholson where the hotel hallway telescoped away >>> faster than he could run. >>> >> >> OK. But in that case in what sense could it be said that such a universe >> is "closed"? It seems to me if the expansion is accelerating I'll never get >> back to where I started no matter how far I go even if it's spherically >> curved as you say. >> >> John K Clark >> >> > I would say the spatial surface is topologically closed, but not causally > closed. >
*As I just posted, this is correct, but can you give a precise mathematical meaning to "topologically closed"? TIA, AG * > > LC > >> >> >> >> >>> >>> -- 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 on the web visit https://groups.google.com/d/msgid/everything-list/c947302a-9e7a-42f9-87a9-1fedcb5929c1%40googlegroups.com.
