The ability to work-out the Casimir force between arbitrarily-shaped objects could be one step closer thanks to work done by physicists in the US. The team used an atomic force microscope to measure the force between two gold-coated spheres. This is unlike most experiments today, which are limited to measuring the Casimir force between a flat surface and a sphere.
The research could lead to a better understanding of the Casimir force in complicated geometries – something that would be very useful to those trying to create more robust and versatile microelectromechanical systems (MEMS).
Physicist - Hendrik - Casimir - Mirrors - Plates
In 1948, the Dutch physicist Hendrik Casimir predicted, counter-intuitively, that two uncharged, parallel mirrors, or “plates”, should attract one another very slightly when in a vacuum. He reasoned that the virtual photons, which quantum mechanics says continually flit into and out of existence within the vacuum, would exert radiation pressure on both sides of each plate. But because the plates create what amounts to an optical cavity, only electromagnetic waves with certain well-defined frequencies could exist between them. The radiation pressure would therefore be greater on the outside, so pushing the plates inwards.
Casimir’s prediction has since been confirmed in the lab many times over. However, most experiments do not involve parallel plates because the effect is extremely sensitive to changes in distance. Therefore, any minute misalignment between plates would affect the results. Instead, most experiments measure the attraction between a single, long plate and a sphere. In this configuration, there is no need to worry about alignment because the shortest distance between the two objects will remain the same no matter how the sphere rotates.
Casimir - Equation - Case - Plates - Outcome
Because Casimir’s equation describes the case of two parallel plates, predicting the outcome of plate-sphere experiments relies on approximating a curved surface by a series of very small parallel plates and that the total...
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