From Wikipedia on quantum decoherence: "Let us choose an expansion where the resulting basis elements interact with the environment in an element-specific way. Such elements will—with overwhelming probability—be rapidly separated from each other by their natural unitary time evolution along their own independent paths. After a very short interaction, there is almost no chance of any further interference" I never understood that part. Why do the elements separate rapidly from each other? Why don't they continue to interfere with each other and the environment in an ever more complex pattern? Is there any simple mathematical (or other kind of) reason for that?