On Formalisms and Interpretations

Abstract

One of the reasons for the heated debates around the interpretations of quantum theory is a simple confusion between the notions of formalism versus interpretation. In this note, we make a clear distinction between them and show that there are actually two inequivalent quantum formalisms, namely the relative-state formalism and the standard formalism with the Born and measurement-update rules. We further propose a different probability rule for the relative-state formalism and discuss how Wigner's-friend-type experiments could show the inequivalence with the standard formalism. The feasibility in principle of such experiments, however, remains an open question.

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• Quantum Circuits Architecture
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• Physics without Determinism: Alternative Interpretations of Classical Physics
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• QBism and Relational Quantum Mechanics compared
• Generalized probability rules from a timeless formulation of Wigner's friend scenarios
• Physics and Metaphysics of Wigner's Friends: Even performed pre-measurements have no results
• Inadequacy of Modal Logic in Quantum Settings
• A "thoughtful" Local Friendliness no-go theorem: a prospective experiment with new assumptions to suit
• A possibilistic no-go theorem on the Wigner's friend paradox
• Decoherence framework for Wigner's friend experiments
• Testing quantum theory with thought experiments
• Indeterminism, causality and information: Has physics ever been deterministic?
• Quantum erasing the memory of Wigner's friend
• Particle mixing and the emergence of classicality: A spontaneous-collapse-model view
• Real or Not Real that is the question
• Wigner's friend's memory and the no-signaling principle
• Unitary Interactions Do Not Yield Outcomes: Attempting to Model "Wigner's Friend"
• Wigner's Isolated Friend
• Classical information and collapse in Wigner's friend setups
• The Completeness of Quantum Mechanics and the Determinateness and Consistency of Intersubjective Experience: Wigner's Friend and Delayed Choice
• Wigner's friend scenarios: on what to condition and how to verify the predictions
• The Measurement Problem Is the "Measurement" Problem
• No master (key) No (measurement) problem
• Quantum Mechanics: Statistical Balance Prompts Caution in Assessing Conceptual Implications