When you lift a paper clip off a table with a small magnet, you're accomplishing a remarkable feat: the tiny magnet is overcoming the gravitational pull from the entire Earth. Why does gravity seem so weak compared to electromagnetism and the other fundamental forces of nature? This vast discrepancy in scale—how a small magnet can beat out a whole planet—is related to what physicists call the hierarchy problem. Cliff Cheung—who joined Caltech this fall as an assistant professor of theoretical physics—is fascinated by this "very deep puzzle" (which may be solved through supersymmetry, a class of theories in which every fundamental particle has a partner particle, as well as by dark matter, the mysterious stuff that accounts for nearly a quarter of the universe). Recently, Cheung—who also plays guitar and piano, sings, and writes music—answered a few questions about coming to Caltech and his passion for physics.