Formation of Nucleons100 Ás after the Big Bang
During the first few seconds after the Big Bang the universe was composed of:
- Nucleons (protons and neutrons). Any nuclei formed at this point would not have survived long in this high-temperature environment.
- Leptons (electrons, neutrinos, and photons)
During this phase baryons, anti-baryons, and photons were in equilibrium and their abundances were nearly equal.
The ratio NB / Ng observed today is 10-9.
This ratio represents the fractional discrepancy between matter and antimatter during this phase:
- For every one billion anti-baryons there were one billion and one baryons.