Dark matter’s stubborn resistance to discovery has forced us to reevaluate what it may look like. If it is much lighter than we’ve assumed, there must be more of it around to make up the total mass required to hold galaxies together. Our challenge: the signals these lighter particles would leave in terrestrial detectors are smaller than any we’ve ever set out to measure. To answer that challenge, DM physicists are constructing the coldest, quietest, most sensitive particle detectors ever made.