Imagine a physical object that can float and move freely in the air, unconstrained by gravity. ZeroN is a new interaction element that can be levitated and moved freely by computer in the mid-air space to represent 3D information. Users are invited to place and move the ZeroN just as they can place objects on surfaces. They can place the sun above physical models to cast digital shadows, place a planet that will start revolving based on programmed conditions, or play 3D tangible pong. To realize such a space of zero-gravity, we developed a magnetic and mechanical control system and an optical tracking system.