The attractive force between two uncharged, parallel conducting plates held a small distance apart in vacuum, predicted by Hendrik Casimir in 1948 and measured to about one percent by Steve Lamoreaux in 1997 and by Umar Mohideen and Anushree Roy in 1998.
Several of the 37 DIRDs in PURSUE Release 06 turn on it: one reports that an experiment with hydrogen switchable mirrors found the Casimir force did not noticeably decrease, one calls a Casimir-cavity force quite feeble but ripe for further exploration, and two forecast a laboratory demonstration of the dynamical Casimir effect before 2012.
What it demonstrates
That the vacuum is not empty in the relevant sense: the plates exclude some electromagnetic modes from the gap and not from outside it, and the imbalance produces a measurable pressure. It is the single cleanest laboratory demonstration that Zero-Point Energy is a real feature of the vacuum rather than an accounting artefact, which is why every book on this shelf reaches for it.
What it does not demonstrate
That the energy is extractable. The force is conservative: the plates do work coming together and the same work must be done to separate them, so there is no cycle. Nothing in the effect scales to a propulsion system or a power source, and the gap between the measured picoNewtons and the terawatt figures in the propulsion literature is the whole of the problem. The site’s Casimir bench computes the real force and prices the rhetoric against it; The Hunt for Zero Point takes its title from the vacuum and Imminent routes the bubble theory through it.
Connections
Zero-Point Energy · The Hunt for Zero Point · Nick Cook · Imminent · Hal Puthoff · Engineering the Vacuum · Polarisable Vacuum · Exotic Matter · Alcubierre Warp Drive · DIRDs