What is decoherence?” and “Why do worlds split?
) Decoherence occurs when irreversible macro-level events take place and the macrostate description of an object admits no single description. (A macrostate, in brief, is the description of an object in terms of accessible external characteristics.) The advantage of linking the definition of worlds and the splitting process with thermodynamics is the splitting process becomes irreversible and only permits forward-time-branching, following the increase with entropy.
