On Tuesday, December 25, 2018 at 7:05:10 AM UTC, Jason wrote: > > > > On Tue, Dec 25, 2018 at 1:53 AM <[email protected] <javascript:>> wrote: > >> >> >> On Tuesday, December 25, 2018 at 5:57:35 AM UTC, Jason wrote: >>> >>> >>> >>> On Mon, Dec 24, 2018 at 11:27 PM <[email protected]> wrote: >>> >>>> >>>> >>>> On Tuesday, December 25, 2018 at 2:13:46 AM UTC, [email protected] >>>> wrote: >>>>> >>>>> >>>>> >>>>> On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Mon, Dec 24, 2018 at 6:28 PM <[email protected]> wrote: >>>>>> >>>>>>> >>>>>>> >>>>>>> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Mon, Dec 24, 2018 at 4:04 PM <[email protected]> wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Monday, December 24, 2018 at 8:25:11 PM UTC, >>>>>>>>> [email protected] wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On 12/23/2018 8:22 PM, [email protected] wrote: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On 12/23/2018 4:47 PM, [email protected] wrote: >>>>>>>>>>>> >>>>>>>>>>>> *If by "flat", you mean mathematically flat, like a plane >>>>>>>>>>>> extending infinitely in all directions, as opposed to >>>>>>>>>>>> asymptotically flat >>>>>>>>>>>> like a huge and expanding sphere, you have to reconcile an >>>>>>>>>>>> infinitesimally >>>>>>>>>>>> tiny universe at the time of the BB, and simultaneously an >>>>>>>>>>>> infinitely large >>>>>>>>>>>> universe extending infinitely in all directions. AG* >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> All that's "infinitesimally tiny" is the visible universe. You >>>>>>>>>>>> must know that the Friedmann equation just defines the dynamics of >>>>>>>>>>>> a scale >>>>>>>>>>>> factor, not a size. >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> *Are you claiming the visible universe at the BB was >>>>>>>>>>> infinitesimally tiny, but the non visible part was infinitely large >>>>>>>>>>> (mathematically flat), or huge (asymptotically flat)? AG * >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Right. Although we can't be sure whether it is actually flat or >>>>>>>>>>> just very big. >>>>>>>>>>> >>>>>>>>>>> Brent >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> *OK. Agreed. We seemed to disagree on this in the past, but maybe >>>>>>>>>> we miscommunicated. AG* >>>>>>>>>> >>>>>>>>> >>>>>>>>> Here's what Ned Wright wrote. >>>>>>>>> >>>>>>>>> Is the Universe really infinite or just really big? >>>>>>>>> >>>>>>>>> We have observations that say that the radius of curvature of the >>>>>>>>> Universe is bigger than 70 billion light years. But the observations >>>>>>>>> allow >>>>>>>>> for either a positive or negative curvature, and this range includes >>>>>>>>> the >>>>>>>>> flat Universe with infinite radius of curvature. The negatively >>>>>>>>> curved >>>>>>>>> space is also infinite in volume even though it is curved. So we know >>>>>>>>> empirically that the volume of the Universe is more than 20 times >>>>>>>>> bigger >>>>>>>>> than volume of the observable Universe. Since we can only look at >>>>>>>>> small >>>>>>>>> piece of an object that has a large radius of curvature, it looks >>>>>>>>> flat. The >>>>>>>>> simplest mathematical model for computing the observed properties of >>>>>>>>> the >>>>>>>>> Universe is then flat Euclidean space. This model is infinite, but >>>>>>>>> what we >>>>>>>>> know about the Universe is that it is really big >>>>>>>>> <http://www.astro.ucla.edu/~wright/HGTTG.html>. >>>>>>>>> >>>>>>>>> >>>>>>>>> <http://www.astro.ucla.edu/~wright/cosmology_faq.html#top> >>>>>>>>> >>>>>>>>> *It is misleading. He's referring to the VISIBLE universe and >>>>>>>>> concludes it might be infinite in spatial extent. Impossible due to >>>>>>>>> its >>>>>>>>> finite age. I wrote him about this, but never received a reply. AG* >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>> It's only impossible if you believe the believe the big bang >>>>>>>> occurred only at a point, rather than everywhere. >>>>>>>> >>>>>>>> Consider that every point in space sees everything else around it >>>>>>>> flying away from it, such that if you rewound time, everything would >>>>>>>> return >>>>>>>> to a single point centered at that location. But this is true for >>>>>>>> every >>>>>>>> point in space, so the implication is that the BigBang didn't happen >>>>>>>> at one >>>>>>>> particular location long in the past, but at every point, including >>>>>>>> the >>>>>>>> period at the end of this sentence. >>>>>>>> >>>>>>> >>>>>>> *You seem inclined to extreme hypotheses for which there is no data. >>>>>>> AG * >>>>>>> >>>>>>>> >>>>>>>> >>>>>> This is the default "standard" model used used by cosmologists, it's >>>>>> called the concordance model, or the Lambda-CDM model. There is >>>>>> significant >>>>>> data for it. >>>>>> >>>>> >>>>> *I don't believe it. AG * >>>>> >>>> >>>> *I mean I don't believe your interpretation of the Concordance model. >>>> AG * >>>> >>>>> >>>>> >>> http://www.universeadventure.org/big_bang/expand-balance.htm >>> >> >> *When the movie is played in reverse, all points converge to a single >> point. This is for the observable universe, which is finite in spatial >> extent. It can't be infinite if the expansion has been proceeding for >> finite time. Outside the observable region, it could be spatially infinite >> or just very large. AG* >> >>> >> > Other points in space belong to different observable universes >
*And you have evidence for that? You're way OFF the reservation! Now you're claiming the galaxies we observe are in different observable universes. AG* (they can see different parts of the universe than you or I can see). If > you rewind thing, everything comes to a point (centered on them). Space > isn't expanding into something else, it is just plain expanding. > *I know. The volume of space is increasing. The observable universe is not expanding into a pre-existing space, like an explosion, but space is being created in the course of the expansion. AG* Something that is already infinite can still expand e.g. Hilbert's Hotel > <https://en.wikipedia.org/wiki/Hilbert%27s_paradox_of_the_Grand_Hotel>. > *The observable universe is finite, extending out to about 50 BLY's. If you imagine being in a different location, the observable universe is the same size due to homogeneity and isotropy. Since all points converge to a single point, we could say the BB originated from every point in the observable universe. AG * > > Anyway, you don't have to take "my interpretation" for it. See: > https://www.cfa.harvard.edu/seuforum/faq.htm > > Did the Universe expand from a point? If so, doesn't the universe have to > have an edge? > No. The Big Bang was not an explosion IN space. It was a process that > involved ALL of space. This misconception causes more confusion than any > other in cosmology. Unfortunately, many students, teachers, and > scientists(!) mistakenly picture the "Big Bang" as an explosion that took > place at some location in space, hurtling matter outward. > > In reality, ALL of space was filled with energy right from the beginning. > There was no center to the expansion, and no magical point from which > matter hurtled outward. The confusion arises in part because of the amazing > conclusion that the OBSERVABLE portion of the universe was once packed into > an incredibly tiny volume. But that primordial pellet of matter and energy > was NOT surrounded by empty space... it was surrounded by more matter and > energy (which today is beyond the region we can observe.) In fact, if the > whole universe is infinitely large now, then it was always infinite, > including during the Big Bang as well. > > To put it another way, the current evidence indicates only that the early > universe - the WHOLE universe - was extremely DENSE - but not necessarily > extremely small. Thus the Big Bang took place everywhere in space, not at a > particular point in space. > ^ back to top <https://www.cfa.harvard.edu/seuforum/faq.htm#top> > > > Jason > -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
