Sphere in Oblique Air-Jet, 1967

Hans Haacke's sculpture Sphere in Oblique Air-Jet, presents the viewer with precisely what its title indicates: a buoyant balloon that stably hovers in space. The sculpture accomplishes this feat through what is known as Bernoulli's principle, according to which a stream of air - or fluid - has lower pressure than stationary air - or fluid. On a practical level, this means that moving air can create aerodynamic lift.

source: ekac.org/levitation

Damian Hirst, Beach Ball, 1997
courtesy Larry Gagosian, New York.