Liquid can levitate and boats can float upside down in this gravity-defying physics experiment. Researchers in Paris have been investigating the effect of vertical shaking, which can be used to suspend a layer of liquid in mid-air. They have discovered a peculiar phenomenon that allows lightweight objects to float on the bottom surface of this liquid, with a kind of reverse-buoyancy. This counter-intuitive behaviour is a result of the constant vibrations which changes the forces acting on the floating objects.