What is Casimir force?

When two uncharged metals are kept micrometers away from each other in a vaccum. There is a quantum force betwen them (repulsion or attraction) depending upon the arrangement of the metals. The repulsion properties of casimir force can be used in levitationg micro objects. Casimir force is very significant in nanotechnology as this helps to reduce the friction between submicromillimeters parts. Since this force is created in vaccum It is also described as force from nothing.