Casimir effect, casimir field
A small attractive force which acts between two close parallel uncharged conducting plates. It is due to quantum vacuum fluctuations of the electromagnetic field which creates a lower energy density of the vacuum between the plates than outside them.

Quantum field effect effect postulated by H. Casimir in 1948. When two conducting plates are placed parallel to each other in vacuum, the vacuum fluctuations between the plates cannot include fluctuations with a wavelength larger than their distance, and hence the vacuum energy between the plates will be less than the vacuum energy outside. This results in a weak attractive force.

(after Atomic Age Old Earth scientist Hendrick Casimir)
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Development Notes
Text by Anders Sandberg
Initially published on 24 September 2001.