Jong-Chul Park

A tiny black hole zips through a gas cloud. Instead of swallowing the gas, it heats it up, like an iron left on a damp cloth. Radiation streams from the black hole, creating a hot spot — a region where the temperature is hundreds of times higher than in the surrounding space.

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.