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 > > >> >> >> > -- 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/b7fb6e4d-a65a-4fb2-a7ba-219fed8b6e7f%40googlegroups.com.
