Muthukrishnan, Siddharth (2025) Many Worlds as Anti-Conspiracy Theory: Locally and causally explaining a quantum world without finetuning. [Preprint]

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Abstract

Why are quantum correlations so puzzling? A standard answer is that they seem to require either nonlocal influences or conspiratorial coincidences. This suggests that by embracing nonlocal influences we can avoid conspiratorial fine-tuning. But that’s not entirely true. Recent work, leveraging the framework of graphical causal models, shows that even with nonlocal influences, a kind of fine-tuning is needed to recover quantum correlations. This fine-tuning arises because the world has to be just so as to disable the use of nonlocal influences to signal, as required by the no-signaling theorem. This places an extra burden on theories that posit nonlocal influences, such as Bohmian mechanics, of explaining why such influences are inaccessible to causal control. I argue that Everettian Quantum Mechanics suffers no such burden. Not only does it not posit nonlocal influences, it operates outside the causal models framework that was presupposed in raising the fine-tuning worry. Specifically, it represents subsystems with density matrices instead of random variables. This allows it to sidestep all the results (including EPR and Bell) that put quantum correlations in tension with causal models. However, this doesn’t mean one must abandon causal reasoning altogether in a quantum world. After all, quantum systems can clearly stand in causal relations. When decoherence is rampant and there’s no controlled entanglement, Everettian Quantum Mechanics licenses our continued use of standard causal models. When controlled entanglement is present---such as in Bell-type experiments---we can employ recently proposed quantum causal models that are consistent with Everettian Quantum Mechanics. We never need invoke any kind of nonlocal influence or any kind of fine-tuning.

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Item Type:	Preprint
Creators:	Creators Email ORCID Muthukrishnan, Siddharth siddharth@pitt.edu 0000-0002-3335-7810
Additional Information:	To appear in the collection "Everett and Locality", editor: Alyssa Ney, forthcoming with Oxford University Press.
Keywords:	quantum mechanics, Everett interpretation, causal models, non-locality, fine-tuning
Subjects:	General Issues > Causation Specific Sciences > Computation/Information > Quantum General Issues > Explanation Specific Sciences > Physics > Quantum Mechanics
Depositing User:	Dr. Siddharth Muthukrishnan
Date Deposited:	26 Jul 2025 13:08
Last Modified:	26 Jul 2025 13:08
Item ID:	25958
Subjects:	General Issues > Causation Specific Sciences > Computation/Information > Quantum General Issues > Explanation Specific Sciences > Physics > Quantum Mechanics
Date:	30 April 2025
URI:	https://philsci-archive.pitt.edu/id/eprint/25958

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• Many Worlds as Anti-Conspiracy Theory: Locally and causally explaining a quantum world without finetuning. (deposited 05 Nov 2024 12:59)
  • Many Worlds as Anti-Conspiracy Theory: Locally and causally explaining a quantum world without finetuning. (deposited 26 Jul 2025 13:08) [Currently Displayed]

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