The difference between spatially flat and asymptotically flat for a huge universe would be virtually impossible to distinguish by measuring the sum of angles in a triangle. Moreover, I don't see how spatially flat can have nothing to do with extent, since in applying Euclidean geometry we surely seem to be dealing with an infinitely extended plane. TIA.
On Thu, Nov 9, 2017 at 4:42 PM, Brent Meeker <[email protected]> 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 > > On 11/9/2017 3:10 PM, [email protected] 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]. > 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. > > > -- > You received this message because you are subscribed to a topic in the > Google Groups "Everything List" group. > To unsubscribe from this topic, visit https://groups.google.com/d/ > topic/everything-list/0XZFBcBdqYU/unsubscribe. > To unsubscribe from this group and all its topics, 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. > -- 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.
