A Thermal Timeline Through a Bounce: When Each Epoch Occurs, Twice

In a bounce cosmology every thermal epoch of the early universe occurs twice, once during contraction and once during expansion. This paper tabulates the standard epochs with their temperatures and their times from the bounce in the symmetric approximation: the electroweak crossover at 100 GeV occurs 2.34e-11 seconds from the bounce, the QCD transition at 0.15 GeV at 1.37e-05 seconds, neutrino decoupling at 1 MeV at 7.37e-01 seconds, nucleosynthesis at 0.07 MeV at 1.50e+02 seconds, and recombination at 0.26 eV at 1.95e+13 seconds. The doubled timeline matters for baryogenesis because mechanisms keyed to a temperature window get two opportunities, separated by the bounce, but only the second opportunity is safe from later hot eras. The table also fixes the windows in which washout, sphaleron conversion and freeze-out must be scheduled in any bounce baryogenesis model. Computed from stated assumptions, not measured.