Complex sentence: When an observer measures a system decoherence occurs and a form of natural selection (einselection) eliminates interferance; and stable states remain known as "pointer states" that have the classical appearance of a well-defined position.
Split into simpler sentences: When an observer measures a system decoherence occurs and a form of natural selection (einselection) eliminates interferance. Stable states remain known as "pointer states" that have the classical appearance of a well-defined position.