With the aid of a strong magnetic field, mice have been made to levitate for hours at NASA's Jet Propulsion Laboratory (JPL) in
Pasadena, California. The floating rodents could provide a valuable insight into how astronauts are affected by extended spells in zero gravity.
Strawberries and frogs have previously been levitated using the same method. It works because a strong magnetic field distorts the movement of electrons in water molecules, which in turn produces a magnetic field that opposes the one applied. The net result is a repulsive effect which, if suitably oriented and strong enough, can overcome the pull of gravity.
Yuanming Liu and colleagues at JPL in Pasadena, California, used a purpose-built levitation device containing a coil of wire, or solenoid, cooled to a few degrees above absolute zero so that it became superconducting. Running a current through the solenoid creates a magnetic field of 17 teslas, about 300,000 times that of the Earth.
The magnetic field varies along the length of the coil. A water-containing object placed at the base of the coil develops an opposing magnetic field that generates a force twice that of Earth's gravity at the bottom, Earth-like gravity in the middle, and zero gravity at the top. Liu's system can levitate water-based objects for hours or even days at a time.
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