On Tuesday, December 25, 2018 at 7:05:10 AM UTC, Jason wrote: > > > > On Tue, Dec 25, 2018 at 1:53 AM <agrays...@gmail.com <javascript:>> wrote: > >> >> >> On Tuesday, December 25, 2018 at 5:57:35 AM UTC, Jason wrote: >>> >>> >>> >>> On Mon, Dec 24, 2018 at 11:27 PM <agrays...@gmail.com> wrote: >>> >>>> >>>> >>>> On Tuesday, December 25, 2018 at 2:13:46 AM UTC, agrays...@gmail.com >>>> wrote: >>>>> >>>>> >>>>> >>>>> On Tuesday, December 25, 2018 at 12:35:24 AM UTC, Jason wrote: >>>>>> >>>>>> >>>>>> >>>>>> On Mon, Dec 24, 2018 at 6:28 PM <agrays...@gmail.com> wrote: >>>>>> >>>>>>> >>>>>>> >>>>>>> On Monday, December 24, 2018 at 9:47:52 PM UTC, Jason wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Mon, Dec 24, 2018 at 4:04 PM <agrays...@gmail.com> wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Monday, December 24, 2018 at 8:25:11 PM UTC, >>>>>>>>> agrays...@gmail.com wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Monday, December 24, 2018 at 6:40:03 AM UTC, Brent wrote: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On 12/23/2018 8:22 PM, agrays...@gmail.com wrote: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On Monday, December 24, 2018 at 3:50:33 AM UTC, Brent wrote: >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On 12/23/2018 4:47 PM, agrays...@gmail.com 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
