Classical Physics and Hamiltonian Quantum Mechanics as Relics of the Big Bang

TL;DR

This paper explores how classical physics and Hamiltonian quantum mechanics emerge as approximate features from the fundamental quantum description of the universe, emphasizing their origin after the Planck time.

Contribution

It proposes that classical and Hamiltonian quantum mechanics are emergent phenomena resulting from the universe's quantum state and dynamics, not fundamental aspects.

Findings

Classical physics emerges after the Planck time.

Hamiltonian quantum mechanics is an approximate feature.

The universe's quantum state influences emergent classical behavior.

Abstract

In a fundamental formulation of the quantum mechanics of a closed system such as the universe as a whole, three forms of information are needed to make predictions for the probabilities of alternative time histories of the closed system . These are the action functional of the elementary particles, the quantum istate of the universe, and the description of our specific history. We discuss the origin of the "quasiclassical realm" of familiar experience and Hamiltonian quantum mechanics with its preferred time in such a formulation of quantum cosmology. It is argued that these features of the universe are not general properties of quantum theory, but rather approximate features that are emergent after the Planck time as a consequence of theories of the closed system's quantum state and dynamics.