On Saturday, January 25, 2020 at 5:49:36 PM UTC-7, Brent wrote: > > > > On 1/25/2020 4:32 PM, Lawrence Crowell wrote: > > > > On Saturday, January 25, 2020 at 6:23:54 AM UTC-6, John Clark wrote: >> >> On Fri, Jan 24, 2020 at 5:21 PM Bruce Kellett <[email protected]> wrote: >> >> >> And I've heard a bunch of bad analogies but I still haven't heard a >>>> direct answer to my question: >>>> What is the difference between a "finite" universe that is expanding >>>> and accelerating forever and an infinite universe that is expanding and >>>> accelerating forever? >>>> >>> >> >> *> If you don't understand Brent's answer in terms of the range of values >>> in coordinate maps, then you will never understand the difference.* >>> >> >> Then I guess I'll never understand the difference. >> >> >>> > A finite universe has a finite range of coordinate values. >>> >> >> NOPE! Brent specifically said "*I'm assuming a continuum spacetime. So >> even a 1cm interval takes an infinite number of labels*". Thus even if >> the universe is not expanding at all and even if it's only 1cm across a >> infinite number of labels with a infinite rage of coordinate values >> printed on them would be needed. >> > > Nope. Space and spacetime are an epiphenomenology. They are mental > perceptual models that result from large N-entanglements of quantum states. > There are no infinite sets of points and labels, that would in fact be > uncountably infinite. These things only exist in our mathematical > representations or axiomatic systems. Now, what information we can get > about space from the IR domain of energy at extreme distances, such as with > burstars etc,, is the representation of what we call space being smooth > fits the data. This does not mean that fundamentally there is an actual > smooth continuum of space. > > > I don't disagree, but you're getting further and further from saying what > it means for spacetime to be finite versus infinite. Since it's our > mathematical model, that should have a simple mathematical answer. > > Brent >
I've answered JC's question above. The answer has nothing to do with coordinate systems. JC wants to know how to distinguish a finite spherical universe from an infinite flat universe (finite or infinite in VOLUME) and he thinks if he can't directly MEASURE non-observational regions, which both have, he can't distinguish the cases. The difference is this: every observer in a spherical universe can calculate its radius if he knows the rate of expansion and how long it has persisted for, which is not the case for observers in a flat space which presumably has an infinite past (for otherwise it would have what is impossible, an edge). 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/255682c7-e776-48c3-88c6-4a3b11999be5%40googlegroups.com.
