Hey, Was reading how the CMB is ~2.75 Kelvin, while the Neutrino BG is ~2 Kelvin. Clearly this means that neutrino transparency occured before photon transparency did in the early evolution of the universe. My question is why? Does is have anything to do with neutron-to-proton decay? I'm guessing (probably incorrectly) that after neutrons and protons cooled sufficiently to bind in nuclei, the neutron was now stable and therefore stopped decaying into protons (as free neutrons do) + electrons + electron antineutrinos. And it was these antineutrinos that ceased to be produced, which gave normal neutrinos free reign in the universe without fear of being annihilated by their antineutrino counterparts. So then neutrino transparency was achieved and the neutrinos were free to redshift to today's cool 2 degrees Kelvin? I wonder if this makes sense. Help appreciated, thanks.