  Initially produced quark-gluon matter at RHIC and LHC does not have a
temperature. A quark-gluon plasma has a high temperature. From this quark-gluon
matter to the quark-gluon plasma is the early thermalization or the rapid
creation of temperature. Elastic three-parton scattering plays a key role in
the process. The temperature originates from the two-parton scattering, the
three-parton scattering, the four-parton scattering and so forth in quark-gluon
matter.
