In current thinking about the Big Bang, the baryogenesis phase involves CP/CPT symmetry violation. There is an excess (says Wikipedia) of perhaps 1 in $10^{10}$ baryons over antibaryons, the majority annihilate and some matter is left over.

That's all fine so far except - the energy output (gamma rays?) of annihilating something like $2 × 10^{10}$ times as much baryonic matter/antimatter as remained in the universe after baryogenesis, sounds like it should have lit up the early universe. But the models seem to skip over this, and the next thing we hear is the classic mass-energy distribution of around 63% dark energy, 23% dark matter, 4% baryonic matter.

Where did the vast production of high energy photon pairs (I guess?) from the annihilation phase, end up? What happens to them, in this model, at and after annihilation? Thinking of background neutrino/background microwave from other singular large-scale "creation-of-afterglow" Big Bang events, where are they now?

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    $\begingroup$ Most of the energy went to producing more baryons and anti-baryons, which also annihilated with a few extra baryons left over. This process continued until it petered out when there were few anti-baryons left to annihilate. $\endgroup$
    – antlersoft
    Jan 6, 2021 at 17:10
  • $\begingroup$ Baryon-antibaryon annihilation happened at around 20 microseconds, well before BB nucleosynthesis started. See en.wikipedia.org/wiki/Hadron_epoch (& en.wikipedia.org/wiki/Lepton_epoch for the lepton-antilepton annihilation). $\endgroup$
    – PM 2Ring
    Jan 6, 2021 at 21:29
  • $\begingroup$ I have always thought that CMB (Cosmic Microwave Background) is the product? $\endgroup$
    – Leos Ondra
    Jan 7, 2021 at 16:45
  • $\begingroup$ No. CMB comes from recombination/decoupling, around 377k years, $\endgroup$
    – Stilez
    Jan 7, 2021 at 20:37


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