Intermolecular and Surface Forces, 3rd Edition

1 Historical Perspective

1.1 The Four Forces of Nature

It is now well-established that there are four distinct forces in nature. Two of these are the strong and weak interactions that act between neutrons, protons, electrons, and other elementary particles. These two forces have a very short range of action, less than 10⁻⁵ nm, and belong to the domain of nuclear and high-energy physics. The other two forces are the electromagnetic and gravitational interactions that act between atoms and molecules (as well as between elementary particles). These forces are effective over a much larger range of distances, from subatomic to practically infinite distances, and are consequently the forces that govern the behavior of everyday things (Figure 1.1 ...