On Monday, March 16, 2015 at 7:40:24 AM UTC-4, Jonathan Thornburg [remove -animal to reply] wrote:

The standard big bang model requires that the mass distribution in the
universe should become more and more anisotropic over time. We have good
evidence from CMBR observations that the universe was isotropic to within
a few parts per million at the CMBR-last-scattering time (redshift
somewhere around 1100 or so if I recall correctly).


If I remember correctly, the Planck results at some point generated
talk of an inherent "directionality" to the observable portion of the
cosmos. If deeper and more sensitive observations turned up a dipole
anisotropy that was not due to our relative motion, but rather due to
the distribution of matter, would that require a qualitatively
different model for the global expansion?

[Mod. note: reformatted -- mjh]