Published in Physics World, 1 Aug 2013
A vacuum is abuzz with quantum fluctuations of particles that constantly pop into and out of existence. The particles are deemed “virtual” because they can only exist by borrowing energy from the vacuum for a fleeting period dictated by the uncertainty principle, but their effects are very real. In 1948 the Dutch physicist Hendrik Casimir predicted that the jostling of virtual particles would generate an imbalanced force on two parallel mirrors held in a vacuum. Since a virtual photon can appear only in regions that are large enough to contain its wavelength, the density of photons between the mirrors will be less than that than on the outside. As a result, Casimir showed, the mirrors will be drawn closer together.
It took 50 years to observe this subtle effect. Since then researchers have begun to recognize it as a potential nuisance for microelectromechanical systems (MEMS), such as pressure sensors and accelerometers. As manufacturing scales shrink from hundreds of microns down to the nanoscale, there is a concern that the Casimir force will generate friction between MEMS components. Yet physicists have also started to wonder whether this force from nothing could be turned into a force for good. “There is no reason why not,” says George Palasantzas at the University of Groningen in the Netherlands. […]
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