That is similar to how Feynman explained it in his Lectures: “The reason for this unexpected behavior is that when the atoms in contact are all of the same kin

That is similar to how Feynman explained it in his Lectures: “The reason for this unexpected behavior is that when the atoms in contact are all of the same kind, there is no way for the atoms to ‘know’ that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin surface layers of contaminants in between, the atoms ‘know’ when they are not on the same part.”