Physicists tweak quantum force, reducing barrier to ti...( GAINESVILLE Fla. Cymbals don't clas...)

GAINESVILLE, Fla. Cymbals don't clash of their own accord in our world, anyway.

But the quantum world is bizarrely different. Two metal plates, placed almost infinitesimally close together, spontaneously attract each other.

What seems like magic is known as the Casimir force, and it has been well-documented in experiments. The cause goes to the heart of quantum physics: Seemingly empty space is not actually empty but contains virtual particles associated with fluctuating electromagnetic fields. These particles push the plates from both the inside and the outside. However, only virtual particles of shorter wavelengths in the quantum world, particles exist simultaneously as waves can fit into the space between the plates, so that the outward pressure is slightly smaller than the inward pressure. The result is the plates are forced together.

Now, University of Florida physicists have found they can reduce the Casimir force by altering the surface of the plates. The discovery could prove useful as tiny "microelectromechanical" systems so-called MEMS devices that are already used in a wide array of consumer products become so small they are affected by quantum forces.

"We are not talking about an immediate application," says Ho Bun Chan, an assistant professor of physics and the first author of a paper on the findings that appears today in the online edition of the journal Physical Review Letters.

"We are talking about, if the devices continue to be smaller and smaller, as the trend of miniaturization occurs, then the quantum effects could come into play."

More specifically, the finding could one day help reduce what MEMS engineers call "stiction" when two very small, very close objects tend to stick together.

Although stiction has many causes including, for example, the presence of water molecules that tend to clump together the Casimir force can contribute. Such quantum effects could pro
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