Dom found a really good foundation document for the understanding of Van der Waals attraction, chemical bonding, etc. Atomic attraction or, more properly, Atomic Covalent Bonding is what the physics people state is the reason that these extremely flat, steel, surfaces with millions of atoms in such extremely close proximity to each other, bond so quickly and with such power. Iron/steel has another reason to bond with like materials in close proximity. The iron atom has 26 electrons total and two in the outer of four energy layers. Materials with even numbers of electrons orbiting in the outer layer are far more likely to form covalence shells by combining equal numbers of electrons with adjacent atoms.
For non-scientists like Mike and I, the concept of these surfaces 'growing' together is more easily visualized and is very close to what actually happens according to the information I have read about this subject. The Physics people say that the longer these materials are in close proximity, the stronger the bond gets. Do the two gage blocks eventually become one? We don't know. Maybe.
Good grief Gary, you have a very good memory or was it that you had an unforgettable instructor?
Boom J., You are incorrigible! Yoda would say, "Quite an explanation, it was."
Tracy and Mike