Causality and the Interpretation of Quantum Mechanics

TL;DR

This paper proposes a quantum field theory-based framework that resolves conflicts between causality, non-locality, and measurement in quantum mechanics, supporting a complete and relativistically compatible interpretation.

Contribution

It introduces a novel approach using reduced density matrices to ensure local evolution and offers an interpretation that aligns quantum mechanics with relativity without additional assumptions.

Findings

Reduced density matrices cannot evolve superluminally

The framework harmonizes causality, non-locality, and measurement

Supports a complete, relativistically compatible interpretation

Abstract

From the ancient Einstein-Podolsky-Rosen paradox to the recent Sorkin-type impossible measurements problem, the contradictions between relativistic causality, quantum non-locality, and quantum measurement have persisted. Based on quantum field theory, our work provides a framework that harmoniously integrates these three aspects. This framework consists of causality expressed by reduced density matrices and an interpretation of quantum mechanics that considers quantum mechanics to be complete. Specifically, we use reduced density matrices to represent the local information of the quantum state and show that the reduced density matrices cannot evolve superluminally. Unlike recent approaches that address causality by introducing new operators to represent detectors, our perspective is that everything--including detectors, the environment, and even humans--is made up of the same fundamental fields. This viewpoint leads us to question the validity of the Schrodinger's cat paradox and motivates us to propose an interpretation of quantum mechanics that requires no extra assumptions and remains fully compatible with relativity.