EPFL researchers have discovered that a droplet of liquid can bounce for several minutes—and perhaps indefinitely—over a vibrating solid surface. The seemingly simple observation has big implications for physics and chemistry.
If you’ve ever added liquid to a hot frying pan, maybe you noticed how the droplets bubbled up and skittered across the sizzling surface, rather than immediately flattening and wetting. This happens because the pan’s heat starts boiling the undersides of the droplets, producing vapor that acts as an insulating cushion on which they can—momentarily—dance.
Previously, scientists have produced a room-temperature version of this phenomenon—known as the Leidenfrost effect—by replacing the hot surface with a rapidly vibrating liquid bath. In these experiments, the vibrations produced a thin film of air on which the liquid droplets could bounce and hover perpetually.