Casimir force

The Casimir force is the force produced by the Casimir effect.

When two mirrors are facing each other in a vacuum, fluctuations in the vacuum exert a "radiation pressure" on them. The two mirrors are thus mutually attracted to each other by what is called the Casimir force. This is the force F that is proportional to A/d⁴, where A is the surface area of the mirrors and d the distance between them.