QUANTUM FIELDS. “Intermolecular forces are pervasive in nature and give rise to various phenomena including surface wetting, adhesive forces in biology, and the Casimir effect, which causes two charge-neutral, metal objects in vacuum to attract each other. These interactions are the result of quantum fluctuations of electromagnetic waves and the boundary conditions imposed by the interacting materials.”
https://www.nature.com/articles/s41586-018-0777-8