Floating under a levitating liquid

Abstract

When placed upside down a liquid surface is known to destabilize above a certain size. However, vertical shaking can have a dynamical stabilizing effect. These oscillations can also make air bubbles sink in the liquid when created below a given depth. Here, we use these effects to levitate large volumes of liquid above an air layer. The loaded air layer acts as a spring-mass oscillator which resonantly amplifies the shaking amplitude of the bath. We achieve stabilization of half a liter of liquid with up to 20 cm width. We further show that the dynamic stabilization creates a symmetric Archimedes' principle on the lower interface as if gravity was inverted. Hence, immersed bodies can float upside down under the levitated liquid.