2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/14207Indirect but significative evidence (from fusion research data, and from the known 4He abundance) relevant to primordial nucleosynthesis is examined. It is shown that this evidence supports a change in cosmic equation of state at decoupling, compatible with Einstein's cosmological equations, from ROm T^4 aprox. cte (ROm=ROr) prior to decoupling (t<taf), to ROmT^3 aprox. cte after (t>taf), being taf the atom formation time. Implications at the baryon threshold time (temperature) and beyond are discussed.4 pages, RevTex; minor correctionsAstrophysicstext