The Equipartition Field at the Maximum Temperature of a Bounce, and What Its Absence Means

A bounce replaces the infinite temperature of a singular beginning with a maximum temperature fixed by its maximum density. For the torsion-bound density of 9.72e57 kg per cubic metre, radiation equipartition gives a maximum temperature of 3.28e+22 kelvin, corresponding to a thermal energy of 2.82e+09 gigaelectronvolts, a factor 2.31e-10 below the Planck temperature. A magnetic field in equipartition with that radiation would, after adiabatic dilution, measure 3.24e+03 nanogauss today, about seven hundred times the microwave-background limit. The observed universe therefore did not pass through a bounce in magnetic equipartition: the field at the hottest moment carried at most about two millionths of the energy, and an exactly equipartitioned fraction of 1e-6 would give 3.24e+00 nanogauss, close to the limit. That shortfall is itself information: whatever generated the primordial field operated far below thermal equipartition even at the most extreme moment of cosmic history, or its product was subsequently degraded. Computed from stated assumptions, not measured.