In its simplest form, the Casimir effect is an attractive interaction between two uncharged and perfectly conducting plates held a short distance apart—usually less than a micron. Classically, the only attractive force acting between such plates should be gravity. But that’s vanishingly small for microscale objects. In 1948 theorist Hendrik Casimir predicted the existence of the now eponymous force on the scale of a few hundred piconewtons when the plates are held 100 nm apart.1 Seen experimentally many times,2–7 the force is a nanoscale phenomenon that arises from quantum fluctuations of the electromagnetic vacuum. For a short survey of the first 60 years of research on the Casimir effect, see the article by Steve Lamoreaux, Physics Today, February 2007, page 40.
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