Levitation (from Latin levitas "lightness") is the process by which an object is suspended against gravity, in a stable position, without physical contact.
It is also a conjuring trick, appearingly raising a human being (or other object) without any physical aid. The illusion can be produced by clever mechanics, lighting arrangements and other means.
For levitation on Earth
, first, a force is required directed vertically upwards and equal to the gravitational force, second, for any small displacement of the levitating object, a returning force should appear to stabilize it. The stable levitation can be naturally achieved by, for example magnetic
or aerodynamic forces. With the former, it is essential that diamagnetic elements are used. In this case the returning force appears from the interaction with the screening currents
. For example, a superconducting
sample, which can be considered either as a perfect diamagnet or an ideally hard superconductor
, easily levitates an ambient external magnetic field. In very strong magnetic field, by means of diamagnetic levitation
even small live animals have been levitated.
By means of aerodynamic forces, the effect of levitation can also be achieved using the upthrust of air, with the levitating object having the same average density as air.
Scientists have discovered a way of levitating ultra small objects by manipulating the so-called Casimir force, which normally causes objects to stick together by quantum force. This practice however, is only possible for micro-objects.