Relational Quantum Mechanics

TL;DR

Relational Quantum Mechanics argues that the discomfort with quantum theory stems from assuming an observer-independent state. It reframes quantum states as relations between systems and introduces information as the fundamental physical content, operationalized through yes/no questions and correlations. By positing two information-theoretic postulates (with a third needed for full derivation), the paper sketches how the Hilbert-space formalism and unitary dynamics emerge from relational principles, while rejecting absolute states. The approach provides a unifying lens that accommodates major interpretations as perspectival facets of a fundamentally relational theory, clarifying the meaning of measurement without invoking universal data. Overall, it proposes that physics describes relational information among systems, not an observer-free description of an objective reality.

Abstract

I suggest that the common unease with taking quantum mechanics as a fundamental description of nature (the "measurement problem") could derive from the use of an incorrect notion, as the unease with the Lorentz transformations before Einstein derived from the notion of observer-independent time. I suggest that this incorrect notion is the notion of observer-independent state of a system (or observer-independent values of physical quantities). I reformulate the problem of the "interpretation of quantum mechanics" as the problem of deriving the formalism from a few simple physical postulates. I consider a reformulation of quantum mechanics in terms of information theory. All systems are assumed to be equivalent, there is no observer-observed distinction, and the theory describes only the information that systems have about each other; nevertheless, the theory is complete.