- Hadron epoch
In
physical cosmology , the hadron epoch was the period in the evolution of the early universe during which the mass of the Universe was dominated byhadron s. It started approximately 10-6 seconds after theBig Bang , when the temperature of the universe had fallen sufficiently to allow thequark s from the precedingquark epoch to bind together into hadrons. Initially the temperature was high enough to allow the creation of hadron/anti-hadron pairs, which kept matter and anti-matter inthermal equilibrium . However, as the temperature of the universe continued to fall, hadron/anti-hadron pairs were no longer produced. Most of the hadrons and anti-hadrons were then eliminated inannihilation reactions, leaving a small residue of hadrons. The elimination of anti-hadrons was completed by one second after the Big Bang, when the followinglepton epoch began.References
*cite book | last = Allday | first = Jonathan | title = Quarks, Leptons and the Big Bang | publisher = Second Edition | date = 2002 | id = ISBN 978-0750308069
* [http://ic030059.ithaca.edu/~britt/ph175/Stars29.pdf "Physics 175: Stars and Galazies - The Big Bang, Matter and Energy"] ;Ithaca College , New York
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