Researchers finally observe the repulsive Casimir force

[bananas]

http://www.medgadget.com/archives/2009/01/mysterious_force_to_help_build_future_nanomachines.html

Wednesday, January 7, 2009
Mysterious Force to Help Build Future Nanomachines

Harvard University researchers have finally observed the repulsive Casimir force, a quantum phenomenon that was predicted back in the 1940's. The force comes into effect only when two particles locate themselves very close to each other, provided a few other parameters are true (see Wikipedia entry: Casimir effect). Now with new knowledge of how to use the force (no pun intended), scientists should be able to build more complicated nano devices.

From Harvard:

“Repulsive Casimir forces are of great interest since they can be used in new ultra-sensitive force and torque sensors to levitate an object immersed in a fluid at nanometric distances above a surface,” said Federico Capasso, Robert L. Wallace Professor of Applied Physics at Harvard's School of Engineering and Applied Sciences (SEAS), who led the study. “Further, these objects are free to rotate or translate relative to each other with minimal static friction because their surfaces never come into direct contact.”

<snip>

The discovery builds on previous work related to the Casimir force, which was theorized by Hendrick Casimir in 1948 as both attractive and repulsive, pulling materials together under some circumstances and pushing them apart under others.

Until now, however, researchers have only been able to measure the attractive Casimir force, which, in some cases, has created headaches for nano-engineers because it can cause the components of tiny devices to stick together. Discovery of the repulsive version of the Casimir force can potentially help researchers overcome this problem.

<snip>

[provis99]

1. only as a force of nature could Casimir be both attractive and repulsive

[elleng]

2. 'Repulsive' not meaning 'disgusting!'

but like 'opposites attract' etc!