Radiation Catastrophe

Abstract

IN the big-bang cosmologies the universe initially consists of almost equal quantities of matter and antimatter. This is true even in the cold models¹ if the temperature of the primordial fireball is limited to the “hadronic boiling-point” of Hagedorn's theory². From the present densities of matter and radiation it is possible to estimate the difference in the quantities of matter and antimatter in the early universe^3–5. If n_γ is the number of photons per unit volume of the 3 K background radiation and b₀ is the observed average number of nucleons per unit volume, it is found that Also, if b⁺ and b⁻ are the baryon and antibaryon densities, b = b⁺+b⁻ is the total baryon density, and Δb = b⁺−b⁻¹ is the baryon number (or baryon charge) density, then in the very early universe one finds The baryon charge asymmetry Δb/b may be either uniform or space varying. As the universe expands, the baryon and antibaryon populations annihilate and eventually Δb/b→±1. This annihilation is almost complete by the time the universe is 10⁻³ s old and the temperature has dropped below T_π = m_πc²/k ≃10¹² K, where m_π is the pion mass. The energy initially in the form of hadrons is inherited by the leptons and photons.