Princeton Engineering

Under a microscope, a tiny droplet slides between two fine hairs like a roller coaster on a set of rails until — poof — it suddenly spreads along them, a droplet no more. That instant of change, like the popping of a soap bubble, comes so suddenly that it seems almost magical. But describing it, and mapping out how droplets stretch into tiny columns, is key to understanding how liquids affect fibrous materials, from air filters to human hair. That knowledge could allow scientists