Brian Swingle’s first passion was condensed-matter physics. As a graduate student, he performed calculations to uncover and understand new quantum phases of matter, such as topological insulators and spin liquids. But then Swingle signed up for a string theory class. There he realized that the condensed-matter tools he was developing could be used to answer questions in quantum gravity, the theory that could reconcile Einstein’s general theory of relativity with quantum mechanics. Read his interview with Physics magazine's Matteo Rini.