In 1948 a Dutch theoretical physicist named Hendrik Casimir predicted that two uncharged plates, when placed very close to each other in a vacuum, would have a tiny attractive force. Ten years later, his theory was validated by Marcus Spaarnay. Scientists eventually explained that the “Casimir” effect—as the phenomenon was called—was caused by quantum vacuum fluctuations, or what they termed “zero point fluctuations.”
The “Casimir effect” is caused by the electromagnetic field within the plates. Even in the most controlled conditions, there are millions of minute virtual electromagnetic particles and anti-particles. These are “vacuum energy” (which seems like an oxymoron, but only proves that there can never be a total vacuum). These particles interact with the other. However, when two plates are put close together, there are less particles between them. The difference in energy density in that gap, and in the space around the objects, leads to a “negative pressure.” This pulls the plates toward each other.
The vacuum energy density is directly proportional to the distance between the plates. As the plates become closer, the energy density decreases. Steve K. Lamoreaux, Umar Mohideen and Anushree Roy were able to arrive at a precise measurement for this: “the zero-point energy of the Fourier modes of the electromagnetic field between the plates.”
Though the Casimir Effect has yet to be tapped for practical applications, scientists believe that it can eventually be used to generate energy or to develop micromechanical or nanomechanical robotic devices. Research continues, though a real breakthrough may only come about once science develops the tools and depends its understanding of physics.