Casimir Effect
An attractive physical force acting between two uncharged parallel conductive plates in vacuum, arising from quantum vacuum fluctuations.
Governing formula
F / A = - (π² ℏ c) / (240 d⁴)
SI unit
N/m² (Pressure)
In depth
Conducting plates impose boundary conditions that restrict allowable virtual photon electromagnetic modes between plates compared to open space outside, creating a net inward quantum radiation pressure.
Examples in the real world
Causing stiction and unwanted adhesion in micro-electromechanical systems (MEMS) at nanometer gaps.