Quark-Gluon Plasma: The Stuff of the Early Universe

In its earliest, densest stages our Universe was an inhospitable place, filled with relativistic gases of every known particle. At temperatures above a trillion degrees Kelvin -- roughly the first microsecond after the Big Bang -- the Universe was dominated by the hadronic/QCD sector, and the properties of strongly interacting matter in this regime are now being studied experimentally using ultra-relativistic collisions between nuclei. In this talk we will review the basic framework used to describe the early thermal Universe, and discuss how recent results in nuclear physics may have a bearing on the Universe's evolution in its earliest history.