On Sunday, January 19, 2020 at 11:52:18 AM UTC-7, Brent wrote: > > > > On 1/18/2020 11:58 PM, Alan Grayson wrote: > > > > On Sunday, January 19, 2020 at 12:18:54 AM UTC-7, Brent wrote: >> >> >> >> On 1/18/2020 10:56 PM, Alan Grayson wrote: >> >> I don't claim anything except that GR has solutions for a cosmos in which >>> space is flat and, in that solution, space is infinite and empirically it >>> appears that space is flat. >>> >> >> *Measurements don't establish it's flat, as I previously argued. And, as >> you previously stated, the sign of k, the parameter in GR intimately >> associated with curvature, is folded into the initial conditions. But since >> the initial conditions are really unknown, or are speculative, you can >> assume initial conditions which satisfy your bias, in this case FLAT. AG * >> >> >> No. It's not an assumption. Empirically the universe appears flat, which >> (assuming the FLRW model) implies it was always flat. It is not a >> question of assuming an initial condition, it is inferring the initial >> condition from present measurements of k. >> > > *This seems to modify what you wrote a few day ago. In any event, > "empirically" means "measurement", and one cannot measure the curvature as > exactly zero, which is what you need to empirically establish flatness. The > measurements are very close to zero, but not zero. AG* > > > When you measure something and it is so close to zero as to be > indistinguishable from zero, then taking it to be zero is not an assumption. > > Brent >
*But it could be HUGELY spherical and seem to be zero! The cases could be indistinguishable. What I want to know is this; when you solve using the FLRW model, does it give exactly zero for the curvature? TIA, AG * -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/0bfce24d-35c4-4450-8079-661bfa0dace2%40googlegroups.com.
