Decoherence
Definition
Decoherence is the process where a quantum system’s contact with its surroundings wipes out the interference between the parts of its superposition. After that, it behaves classically.
On this site
The physical reason the Atom rung can use classical mechanics for most of the universe most of the time.
Role in the model
Decoherence is why the Atom rung can use classical physics for most of the universe most of the time. Macroscopic objects stop acting quantum-mechanically because their surroundings keep interacting with them. It’s the physics that makes a cheap simulation defensible.
Related
14 short pages, one per thinker, each with its matching dial. See also the reading list.