On Monday, December 24, 2018 at 4:47:02 AM UTC, Bruce wrote: > > On Mon, Dec 24, 2018 at 3:33 PM <[email protected] <javascript:>> wrote: > >> On Monday, December 24, 2018 at 4:22:24 AM UTC, [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 * >>> >> >> *Bruce says the universe is always flat if k=1. How can it be everywhere >> flat if there's a region which is infinitely tiny; hence not flat in the >> visible region? How are we to imagine this? TIA, AG * >> > > That's a bit confused. k=0 corresponds to a universe that is everywhere > flat (in space, but not necessarily in the time dimension - i.e., it might > be expanding. Our current visible universe originated in a small (tiny) > region of the total structure, which might be infinite in extent, but flat > everywhere, even in our tiny region. >
*Not to split hairs, but how can the tiny visible region also be flat and infinite in extent, if its age is finite? I can imagine the visible region to be asymptotically (but not mathematically) flat, and therefore finite in extent. AG * > > Bruce > -- 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.
