I am fascinated by the "inner space/outer space" connections that link the science at the smallest and largest scales. My research focusses on the highest-energy sites in nature--the big bang, exploding stars (supernovae), and high-energy particles in space (cosmic rays)--where nuclear physics and elementary particle physics play a central role. Understanding these processes and their interplay allows us to trace the history of matter over cosmic time. Turning the problem around, I use these high-energy phenomena as particle accelerators to probe fundamental physics in ways inaccessible to terrestrial experiment.