On the pre-nucleosynthesis cosmological period

Physics, as known from our local, around--earth experience, meets some of its applicability limits at the time just preceding the period of primeval nucleosynthesis. Attention is focussed here on the effects of the nucleon size. Radiation--belonging nucleons are found to produce an extremely high pressure at kT of the order of some tens or hundreds of MeV. Quark deconfinement at higher energies would not change the results.