(November 19, 2021 at 6:17 pm)HappySkeptic Wrote: Macroscopic reality forms when single states get so entangled with the environment that their Hamiltonian becomes diagonal or "classical", or when many random events (owing to the law of probabilities) create what we think of as classical laws (F=ma, thermodynamics, etc.).
In other words, the Correspondence Principle:
Wikipedia -- Correspondence principle