Yue-Lin Sming Tsai

No one has ever seen dark matter, but every galaxy feels its pull. Usually, it's pictured as a sea of identical, silent particles. The new work paints a livelier picture: two kinds of particles, heavy and light, constantly exchanging between them.

Conventional dark matter detectors are like a soccer goalkeeper waiting for a powerful shot while the ball barely rolls. The invisible particles filling our galaxy often move too slowly to be noticed by sensitive sensors.

A galaxy is like a cosmic highway where stars, like cars, race along circular orbits. Their speed is set by the invisible "cargo" of mass enclosed within the orbit: the more massive the central region, the faster the stars at the periphery.