On Thursday, November 9, 2017 at 4:42:45 PM UTC-7, Brent wrote: > > Cosmologist think the universe is spatially flat. That just means > triangles have interior angles summing to 180deg. It doesn't have anything > to do with extent. But the universe is not flat in spacetime; it's > expanding and at an increasing rate. > > Brent >
I don't understand how a flat universe has nothing to do with extent. I don't understand the distinction; spatially flat (and therefore presumably infinite in extent?), but not flat in spacetime. Also, when it was discovered that the expansion is accelerating, did the solutions of the field equations which allowed tunneling from a vacuum and presumably automatically came with a positive CC (indicating expansion), also automatically come with a spatially flat (and presumably infinite in extent) geometry? Hard to grasp how a universe emerging from a vacuum could start out spatially flat and therefore IMO infinite in extent. TIA. > > On 11/9/2017 3:10 PM, [email protected] <javascript:> wrote: > > IIUC, the difference is huge. In the former case, the universe is open, > spatially infinite with infinite mass (assuming a nonzero mass distribution > on large scale everywhere), whereas the latter is closed, finite in spatial > extent and mass. But I notice that most cosmologists claim the universe is > *flat*, as in mathematically flat. Are they just speaking loosely and > really mean the universe is ASYMPTOTICALLY flat? I find it contradictory > for a universe which is finite in age, to be truly mathematically FLAT. TIA. > -- > 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] <javascript:>. > To post to this group, send email to [email protected] > <javascript:>. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > > -- 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.
