Young Ju Ko

Dark matter doesn't emit or reflect light, but its presence is revealed through gravitational effects. To catch even a single particle, physicists build detectors that are like very quiet rooms: inside lie crystals that flash when a particle hits them. But the flash is faint, and if light is lost along the way, the signal can be missed.

No one has ever seen dark matter, but it should pass through detectors like wind through leaves. Sometimes, very rarely, a dark matter particle bumps into an atomic nucleus, and then the detector must catch that jolt. The trouble is that light dark matter particles can hardly move heavy nuclei: it's like trying to knock down a bowling pin by throwing a feather at it.