Two metal plates placed extremely close together in a vacuum will spontaneously attract each other due to quantum energy fluctuations.

The Casimir Effect was first predicted by Dutch physicist Hendrik Casimir in 1948 while he was researching colloidal solutions at Philips Research Laboratories. It is a fundamental consequence of quantum field theory, which states that the vacuum is not truly empty but is instead filled with virtual particles and fluctuating electromagnetic fields. These fluctuations exist at all possible wavelengths in open space.When two conductive plates are placed parallel to each other at distances typically less than a micrometer, they create a cavity. This physical boundary limits the number of virtual photons that can pop into existence between the plates because only certain resonant wavelengths can fit. Outside the plates, the entire spectrum of vacuum fluctuations remains present, creating a higher energy density on the exterior surfaces.The resulting imbalance in radiation pressure creates a measurable attractive force that pushes the plates together. It was not until 1997 that Steve Lamoreaux at the University of Washington provided the first definitive experimental verification of the force using a torsion pendulum. His measurements matched Casimir's original mathematical predictions within a 5% margin of error.This effect is a major hurdle in the field of Microelectromechanical Systems (MEMS). Because the force becomes significantly stronger as the distance between components decreases, it often leads to 'stiction,' where tiny gears or levers become permanently stuck together. Researchers at institutions like NASA and DARPA continue to study the Casimir Effect to develop anti-adhesive coatings for nanotechnology.