Over 50 years ago, Hendrik Casimir, a Dutch theoretical physicist, determined that two parallel mirrors would attract each other when placed in a vacuum. The energy of virtual particles that flit into and out of existence generates this enigmatic force, as explained by quantum theory.
Now, Norio Inui, a researcher at the University of Hyogo located in Japan, has hypothesized that in specific circumstances, an ultrathin plate can be levitated when the direction of the Casimir force is reversed. Inui’s prediction and computations have been reported in Journal of Applied Physics, a journal of the American Institute of Physics.
Identical plates are pushed together by the Casimir force. However, the direction of the Casimir force can be reversed when one of the plates’ material properties and geometry are changed. Inui estimated that an yttrium iron garnet (YIG) plate having a thickness of 1 nm could float half a micrometer on top of a gold plate. He discovered that the thinner the YIG plate, the higher the repulsive force. This means the plate weight and the amount of the force required to levitate it reduce in tandem with its thickness.
At present, the existence of the levitating plates is only a theoretical fact. Inui’s next step is to perform an experimental testing of numerous key assumptions in his calculations. If further studies prove successful, then possible applications may include levitation of gyroscopes in MEMS and prevention of sticking together of different components in nanomachines.