Four notes on van der waals forces: Induction effect, nonadditivity, attraction between a cone and a flat plate (asperities), history

The derivation of the induction or Debye—Falkenhagen effect has been carried out in the past both for a purely classical system and for a system in the quantum limit. In both cases the same equation was the result. An explanation of this fact is given in terms of statistical thermodynamics. The London interaction between two chains of four coupled oscillators is discussed. There is a nonadditivity effect, which amounts to ±10%. The role of asperities on flat surfaces is discussed with respect to the attraction between two flat plates. It is shown that this role is significant when the linear dimensions of these asperities are 10–20% or more of the interplate distance. The results of the three first notes are discussed in a separate section on nonadditivity and adhesion. Attention is drawn to the fact that Newton was really the first to discuss a “London” type of force-distance law and that he arrived at correct results regarding the attraction between macroscopic bodies.