Causality and a possible interpretation of quantum mechanics

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 focus on causality by introducing new operators to describe detectors, we consider that everything--including detectors, environments, and humans--is composed of the same fundamental fields, which prompts us to question the validity of the derivation of Schrodinger's cat paradox and leads us to propose an interpretation of quantum mechanics that does not require any additional assumptions and is compatible with relativity.