On Monday, December 24, 2018 at 10:42:10 PM UTC, Brent wrote: > > > > On 12/24/2018 1:04 PM, [email protected] <javascript:> 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* > > > Why don't you look at his web tutorial. He does not conclude the > *visible* universe might be infinite. >
*From the statement above, due to poor use of language, it seems he concludes the visible universe might be infinite. I didn't see that corrected anywhere in his tutorial, but I didn't read it in its entirety. AG* > > Brent > -- 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.
