  Ultra-relativistic heavy ion collisions produce a high-temperature,
thermalized system that may mimic the conditions present shortly after the big
bang. This writeup will given an overview of early results from the
Relativistic Heavy Ion Collider (RHIC), and discuss what we have learned about
hot, strongly interacting nuclear systems. The thermal and chemical composition
of the system will be discussed, along with observables that are sensitive to
the early evolution of the system. I will also discuss the implications of the
RHIC results for cosmic ray air showers.
