Lepton epoch

In physical cosmology, the lepton epoch was the period in the evolution of the early universe in which the leptons dominated the mass of the universe. It started roughly 1 second after the Big Bang, after the majority of hadrons and anti-hadrons annihilated each other at the end of the hadron epoch. During the lepton epoch the temperature of the universe was still high enough to create lepton/anti-lepton pairs, so leptons and anti-leptons were in thermal equilibrium. Approximately 10 seconds after the Big Bang the temperature of the universe had fallen to the point where lepton/anti-lepton pairs were no longer created.[1] Most leptons and anti-leptons were then eliminated in annihilation reactions, leaving a small residue of leptons. The mass of the universe was then dominated by photons as it entered the following photon epoch.[2][3]

See also

References

  1. "Thermal history of the Universe and early growth of density fluctuations" (PDF). Guinevere Kauffmann. Max Planck Institute for Astrophysics. Retrieved 2016-01-06.
  2. "First few minutes". Eric Chaisson. Havard Smithsonian Center for Astrophysics. Retrieved 2016-01-06.
  3. "Timeline of the Big Bang". The physics of the Universe. Retrieved 2016-01-06.


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