Classical and quantum effective theories

TL;DR

This paper extends classical mechanics' action principle using the Closed Time Path scheme from quantum field theory to better handle initial conditions and dissipative forces, highlighting similarities between classical and quantum cases.

Contribution

It introduces a generalized action principle inspired by CTP, connecting classical dissipative forces with quantum entanglement, and discusses their relation to traditional effective theories.

Findings

Effective interactions describe classical dissipative forces.

Classical and quantum cases share underlying similarities.

Brief discussion on relation to traditional effective theories.

Abstract

A generalization of the action principle of classical mechanics, motivated by the Closed Time Path (CTP) scheme of quantum field theory, is presented to deal with initial condition problems and dissipative forces. The similarities of the classical and the quantum cases are underlined. In particular, effective interactions which describe classical dissipative forces represent the system-environment entanglement. The relation between the traditional effective theories and their CTP extension is briefly discussed and few qualitative examples are mentioned.