On Wednesday, January 22, 2020 at 8:54:37 PM UTC-7, Brent wrote: > > > > On 1/22/2020 6:38 PM, Alan Grayson wrote: > > > > On Wednesday, January 22, 2020 at 1:34:00 PM UTC-7, Lawrence Crowell > wrote: >> >> On Wednesday, January 22, 2020 at 11:33:04 AM UTC-6, John Clark wrote: >>> >>> On Wed, Jan 22, 2020 at 12:06 PM Lawrence Crowell < >>> [email protected]> wrote: >>> >>> > *It is then possible to have an expanding accelerated cosmos that is >>>> spherically closed.* >>> >>> >>> So if I keep going I will eventually return to where I started even >>> though everything is constantly getting more distant from me and is doing >>> so at an accelerating rate? >>> >>> John K Clark >>> >> >> 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. >> >> LC >> > > I don't think it depends on acceleration. As long as the universe expands, > even at a constant rate, at some distance, the distance between, say, an > Earth observer, and some terminal point along a line of sight, will exceed > 300,000 km (the distance light travels in one second) and points beyond > that will keep increasing the increment every second, creating a > cosmological horizon that light cannot cross. > > > That's not quite right. Light can cross it just fine. But a photon > crossing it toward us, can never reach us. This is how the Hubble boundary > differs from a black hole event horizon. > > Brent >
Good point. TY. AG > > This is because the creation of the horizon is purely a geometric effect > of the expansion, and the rate of expansion is irrelevant. 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] <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/928bfcb1-8892-4858-a5d3-c2e6297c0256%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/928bfcb1-8892-4858-a5d3-c2e6297c0256%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- 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/585f0db2-6319-43f0-8e59-07a4745d4e5e%40googlegroups.com.
