Black holes - pools of gravity so powerful that even light can't escape them - remain some of the most mysterious objects in the universe. Yet, though black holes themselves are invisible, the matter around them is not. In fall 2014, Henric Krawczynski, professor of physics at Washington University in St. Louis, will use an instrument called X-Calibur to study two "beautifully bright" black holes visible from Earth's northern hemisphere. By measuring the polarization of X-rays emitted from material near the black holes, X-Calibur will help Krawczynski and his colleagues investigate questions that have perplexed scientists since Albert Einstein first proposed his Theory of General Relativity.
*Correction from the episode audio: X-Calibur will launch from New Mexico, not Arizona.