Physics is filled with mysteries – and, believe it or not, gravity remains one of them. We rely on gravity to explain things large and small. But at a fundamental level, we still don’t fully understand it. At the heart of the challenge: a rift between general relativity and quantum mechanics – two spectacularly successful theories that won’t play nicely together. In this video, we go inside the labs where scientists are investigating gravity with innovative and ingenious experiments, such as cooling metal bars to near absolute zero, suspending microscopic gold beads, and searching for signs that gravity might be quantum.