Karl Gebhardt's research focuses on two main areas: black holes and dark energy. His work on black holes has helped build the case that a class of medium-mass black holes exists in between the stellar-mass black holes that result when massive stars explode as supernovae and the supermassive black holes that lie at the hearts of galaxies. Karl is also one of the architects of HETDEX, the $34-million Hobby-Eberly Telescope Dark Energy Experiment. This McDonald Observatory project seeks to understand dark energy, that enigmatic force causing the universe's expansion to speed up. Dark energy has been called the most important puzzle in all of science today. Karl received his Ph.D. in Physics and Astronomy from Rutgers University.