On Wed, Feb 5, 2014 at 7:38 PM, meekerdb <[email protected]> wrote:
> On 2/5/2014 9:31 AM, Jesse Mazer wrote: > > --question 1 dealt with the question of how YOU would define p-time > simultaneity in a cosmological model where there's no way to slice the 4D > spacetime into a series of 3D surfaces such that the density of matter is > perfectly uniform on each slice (and that uniform can be characterized by > the parameter Omega), unlike in the simple FLRW model where matter is > assumed to be distributed in this perfectly uniform way. > > > I don't see that perfect uniformity is necessary. We have calculated our > epoch relative to the CMB as 13.8By. I assume any other scientific species > in the universe could do the same and so say whether they were 'at the same > time' as measured by expansion of the cosmos. I don't see how the > existence of galaxies and galaxy clusters precludes this kind of > measurement. > Using the CMB may give an approximate answer, but would you argue it could distinguish between different simultaneity definitions that agree approximately when averaged over large scales, but disagree somewhat about the details of simultaneity in highly curved regions? For example, could the CMB be used to define a unique definition of simultaneity in the neighborhood of a black hole (where coordinate systems like Schwarzschild coordinates and Eddington-Finkelstein coordinates and Kruskal-Szekeres coordinates give very different definitions of simultaneity)? Edgar isn't just claiming some approximate pragmatic truth about simultaneity, he's claiming an absolute and exact truth about simultaneity in all circumstances, I was asking if he thinks this truth can be empirically determined to arbitrary precision even in principle, and if so what empirical observations would be used. Jesse > > 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 http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/groups/opt_out. > -- 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 http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
