Nonlinearity in Quantum Theory and Closed Timelike Curves

TL;DR

This paper explores how closed timelike curves induce nonlinear evolution of quantum states, leading initially pure states to become mixed, and discusses the implications for quantum theory's statistical interpretation.

Contribution

It demonstrates that closed timelike curves cause nonlinear evolution of quantum states, challenging the standard linear framework and raising questions about the statistical interpretation.

Findings

Pure states evolve into mixed states in the presence of closed timelike curves

Nonlinearity arises naturally in the density matrix approach with CTCs

Implications for CPT invariance and quantum statistical interpretation

Abstract

We examine consequences of the density matrix approach to quantum theory in the context of a model spacetime containing closed timelike curves and find that in general, an initially pure state will evolve in a nonlinear way to a mixed quantum state. CPT invariance and the implications of this nonlinearity for the statistical interpretation of quantum theory are discussed.