High energy nuclear physics; relativistic heavy ion collisions; ATLAS/LHC collaboration. Studying the Earliest Moments of the Universe with the World’s Biggest Collider! My focus is on high energy nuclear physics, in particular relativistic heavy ion collisions measured with the ATLAS experiment at the Large Hadron Collider. Relativistic heavy ion collisions are thought to produce a quark-gluon plasma; a state of matter in which the smallest constituents of matter are deconfined. We seek to study these collisions, and there by learn about fundamental properties of nature.