An Elementary Proof That Everett's Quantum Multiverse Is Nonlocal: Bell-Locality and Branch-Symmetry in the Many-Worlds Interpretation

Abstract

Everett's many-worlds or multiverse theory is an attempt to find an alternative to the standard Copenhagen interpretation of quantum mechanics. Everett's theory is often claimed to be local in the Bell sense. Here, we show that this is not the case and debunk the contradictions by analyzing in detail the Greenberger--Horne--Zeilinger (GHZ) nonlocality theorem. We discuss and compare different notions of locality often mixed in the Everettian literature and try to explain the nature of the confusion. We conclude with a discussion of probability and statistics in the many-worlds theory and stress that the strong symmetry existing between branches in the theory prohibits the definition of probability and that the theory cannot recover statistics. The only way out from this contradiction is to modify the theory by adding hidden variables à la Bohm and, as a consequence, the new theory is explicitly Bell-nonlocal.

References in corpus (7)

• What Bell Did
• Quantum non-locality - It ain't necessarily so...
• Quantum Mechanics as Classical Physics
• All entangled states display some hidden nonlocality
• Should the wave-function be a part of the quantum ontological state?
• Pilot-Wave Theory without Nonlocality
• Collapse of the many-worlds interpretation: Why Everett's theory is typically wrong