Viscosity due to the long mean free paths of electron neutrinos in the primordial fireball just before e-νₑ scattering stops at 10¹⁰^∘{}K reduces any homogeneous anisotropy in the expansion of the universe to a level which does not effect the expansion rate significantly thereafter.
No takes yet. Share an insight, caveat, or question.
Charles W. Misner (1967) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: