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 by hadrons.
It started approximately 10−6 seconds after
the Big Bang, when the temperature of the
universe had fallen sufficiently to allow
the quarks from the preceding quark epoch
to bind together into hadrons.
Initially the temperature was high enough
to allow the formation of hadron/anti-hadron
pairs, which kept matter and anti-matter in
thermal 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 in annihilation reactions,
leaving a small residue of hadrons.
The elimination of anti-hadrons was completed
by one second after the Big Bang, when the
following lepton epoch began.
== See also ==
Timeline of the Big Bang
Chronology of the universe
Big Bang
