On Sunday, January 26, 2020 at 5:28:42 AM UTC-7, Lawrence Crowell wrote: > > On Sunday, January 26, 2020 at 1:57:51 AM UTC-6, Alan Grayson wrote: >> >> >> >> On Sunday, January 26, 2020 at 12:50:42 AM UTC-7, Lawrence Crowell wrote: >>> >>> On Sunday, January 26, 2020 at 1:20:53 AM UTC-6, Philip Thrift wrote: >>>> >>>> >>>> >>>> On Saturday, January 25, 2020 at 10:47:55 PM UTC-6, Brent wrote: >>>>> >>>>> >>>>> >>>>> On 1/25/2020 6:10 PM, Lawrence Crowell wrote: >>>>> >>>>> >>>>> >>>>> On Saturday, January 25, 2020 at 6:49:36 PM UTC-6, 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 >>>>>> >>>>> >>>>> There seems to be some sort of issue with the idea of continuum or >>>>> space having an infinite number of points. I see this as a modern day >>>>> version of asking how many angels can dance on a pin. >>>>> >>>>> >>>>> I have no issue with it. But it doesn't mean that a spherical >>>>> spacetime is infinite. The infinity of metric distance in a Riemannian >>>>> space is not the same as the infinite cardinality of point in a real >>>>> interval. >>>>> >>>>> Brent >>>>> >>>> >>>> >>>> >>>> If the Universe is truly infinite, if you travel outwards from Earth, >>>> eventually you will reach a place where there's a duplicate cubic meter of >>>> space. The further you go, the more duplicates you'll find. >>>> >>>> Ooh, big deal, you think. One hydrogen pile looks the same as the next >>>> to me. Except, you hydromattecist, you'll pass through places where the >>>> configuration of particles will begin to appear familiar, and if you >>>> proceed long enough you'll find larger and larger identical regions of >>>> space, and eventually you'll find an identical you. And finding a copy of >>>> yourself is just the start of the bananas crazy things you can do in an >>>> infinite Universe. >>>> >>>> In fact, hopefully you'll absorb the powers of an immortal version of >>>> you, because if you keep going you'll find an infinite number of yous. >>>> You'll eventually find entire duplicate observable universes with more >>>> yous >>>> also collecting other yous. And at least one of them is going to have a >>>> beard. >>>> >>>> So, what's out there? Possibly an infinite number of duplicate >>>> observable universes. We don't even need multiverses to find them. These >>>> are duplicate universes inside of our own infinite universe. That's what >>>> you can get when you can travel in one direction and never, ever stop. >>>> >>>> Whether the Universe is finite or infinite is an important question, >>>> and either outcome is mindblenderingly fun. So far, astronomers have no >>>> idea what the answer is, but they're working towards it and maybe someday >>>> they'll be able to tell us. >>>> >>>> https://phys.org/news/2015-03-universe-finite-infinite.html >>>> >>>> @philipthrift >>>> >>> >>> This is the case for a spatial surface that is infinite, but distance is >>> using the idea of Poincare recurrence around 10^{10^{100}} light years >>> away. This is far beyond the cosmological horizon and you could never get >>> there no matter how long or extremely you try to accelerate outwards. With >>> the spherical universe much the same also holds, but where getting around a >>> spatial sphere with an enormous radius of curvature is impossible because >>> it will always expand faster than you can travel. With the flat spacetime >>> the existence of repeated versions of this local world means there is some >>> covering space that is a torus or maybe the Poincare dodecahedral space. I >>> tend to think this covering space is some form of quasi-crystal. For all we >>> know we are in a cosmos with that sort of space. >>> >>> LC >>> >> >> I don't see any basis for assuming infinite repetitions in an infinite >> universe. It's sort-of like the claim that every thing that can happen, >> must happen. What's your take? AG >> > > > These repetitions are an aspect of what is called the level I multiverse. > It is just the world beyond the horizon that if infinite is by statistical > necessity going to reproduce local regions. > > LC >
*This is consistent with my intuitions; namely, that we live in a finite universe, approximately hyper-spherical, with no repetitions. 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/89ef2eab-725c-4cd8-aaf1-5abdba024b68%40googlegroups.com.
