- Quark epoch
In
physical cosmology the quark epoch was the period in the evolution of the early universe when thefundamental interaction s ofgravitation ,electromagnetism , thestrong interaction and theweak interaction had taken their present forms, but the temperature of the universe was still too high to allowquark s to bind together to formhadron s. The quark epoch began approximately 10-12 seconds after theBig Bang , when the precedingelectroweak epoch ended as theelectroweak interaction separated into the weak interaction and electromagnetism. During the quark epoch the universe was filled with a dense, hotquark-gluon plasma , containing quarks, leptons and their antiparticles. Collisions between particles were too energetic to allow quarks to combine intomeson s orbaryon s. The quark epoch ended when the universe was about 10-6 seconds old, when the average energy of particle interactions had fallen below thebinding energy of hadrons. The following period, when quarks became confined within hadrons, is known as thehadron epoch .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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