In a classic image of high-speed photography, a drop of milk landing on a surface explodes into an ornate crown with beads of fluid leaping from its rim. Now, a study of other splashes finds that the air in which such bursts unfold is a previously overlooked actor in that performance.
"I don't think anyone ever thought poor little old air could do anything to the splash," says physicist Sidney R. Nagel, who led the investigation. Yet he, Lei Xu, and Wendy W. Zhang, all of the University of Chicago, have discovered that even modestly reducing the air pressure completely quells the rococo exuberance of crashing drops.
"Flabbergasting," comments Detlef Lohse