Which Species Turns Around First? Threshold Crossing Order in a Cooling, Contracting Mixture of Neutrinos, Electrons and Nucleons

The crossing order is by mass, lightest first. The neutrino component crosses at an equivalent radiation temperature of 1.642e+13 K, the electron component at 3.712e+16 K, and the neutron component at 1.592e+18 K. Between the neutrino and electron crossings the density grows by a factor of 2.612e+13 while the scale factor shrinks by a factor of 0.000; between the electron and neutron crossings the density grows by 3.381e+06 with a scale-factor ratio of 0.023. The staging is therefore extremely uneven: the first crossing happens at a density so far below the last that, in a radiation-dominated contraction, the universe spends the overwhelming majority of its contracting history with only its lightest component in the torsion-softened regime. The study is a computation from stated assumptions, performed by the accompanying script; it is simulated, not measured.