Entropy of the Relic Neutrino Background Carried Through a Bounce

The neutrino entropy is comparable to, and slightly below, the photon entropy today, and adiabatic transport preserves the ratio through the bounce. If re-coupling occurred at the bounce temperature the background would be reprocessed rather than preserved, which would erase the decoupling signature; the preservation result therefore doubles as a statement about which bounce temperatures are compatible with an intact relic background. The computation is performed from stated assumptions in a density-limited bounce, in which the neutron-branch limit density sets a maximum density, a finite bounce temperature, and a minimum horizon size. Headline values from the deposited calculation are: T_nu_K = 1.95; n_nu_per_m3 = 3.36e+08; S_nu_kB = 3.78e+89; T_bounce_K = 3.28e+22; Tnu_over_Tbounce = 5.93e-23. The study is simulated and computed, not measured, and its conclusions are stated at the precision the stated assumptions support.