Strange fluid acts like a solid and liquid at the same time

Physicists have used high-speed cameras to see a drop of an odd fluid both solidify and keep flowing when it falls and hits the ground

By Karmela Padavic-Callaghan

When drops of some unusual fluids hit the ground fast enough, the bottoms solidify and bounce while the tops stay liquid and spill over. Researchers have now taken the first high-speed images of this process.

A complex fluid is an unusual type of fluid whose viscosity changes when put under pressure. For example, ketchup is a complex fluid that becomes less viscous when you press on the sides of its container, while a mixture of cornstarch and water turns fully solid when compressed. However, the exact details of how such changes happen aren’t fully understood, so Michelle Driscoll at …