The Casimir effect, a curious consequence of quantum theory, may yet have practical applications

It seems that these recent studies on the Casimir effect would help reduce the coefficient of friction, which would lead in turn to less fuel being needed for locomotion. The following lines aroused my interest: "That is because only particles with a wavelength smaller than the gap between the plates could appear in that gap, whereas particles of any wavelength could appear on the other sides of the plates. There would thus be more particles pushing in than pushing out, and the plates would clash together like a pair of tiny cymbals." This looks for me a lot like diffraction, except that in the classical diffraction experiments the separation that deflects a wavefront does not move. It has a specific distance that doesn't change. I wonder how the separation moves in this case. The text above tries to explain it, but some uncertainty remains: are the particles creating a pressure difference inside the plates that attracts them together? The first difficulty with this explanation would be that the particles exist in a vacuum already...