# Everett’s Interpretation and Convivial Solipsism

^{1}

^{2}

^{3}

## Abstract

**:**

## 1. Introduction

## 2. The Measurement Viewed as Something Happening in the Reality

- -
- Metaphysical Realism (MR) contends that there is an external reality independent of any observer or of the knowledge that any observer could have about it.
- -
- The thesis of Intelligibility of Reality (IR) says that independent reality is composed of entities that are in principle describable and understandable.
- -
- Epistemic Realism (ER) ascribes to science the role of describing and explaining intelligible reality and claims that our good theories give an adequate description of Reality that corresponds to the picture given by them.

_{2}after having been observed at a position x

_{1}but says nothing about the trajectory that the particle follows between x

_{1}and x

_{2}. In a certain sense, the Copenhagen interpretation gives up the goal to describe precisely microscopic reality. As Bohr [20] says:

“In our description of nature the purpose is not to disclose the real essence of phenomena but only to track down as far as possible relations between the multifold aspects of our experience.”

“The distinction between a realist interpretation of a quantum state that is psi-ontic and one that is psi-epistemic is only relevant to supporters of the first approach.”

- (1)
- Outcomes are unique for a given observer
- (2)
- The quantum state is epistemic (information, knowledge, beliefs)
- (3)
- Quantum theory is universal
- (4)
- Quantum theory is complete (i.e., it does not need to be supplemented by hidden variables)

## 3. Interpreting the Measurement of Entangled Systems

## 4. Everett Interpretation

“The “world” in my MWI [Many Worlds Interpretation] is not a physical entity. It is a term defined by us (sentient beings), which helps to connect our experience with the ontology of the theory, the universal wave function. My definition is: A world is the totality of macroscopic objects: stars, cities, people, grains of sand, etc., in a definite classically described state.”

_{1}+ x

_{2}]

_{1}and the other where the particle is in x

_{2}. However, this interpretation is only due to their inability to imagine that the world could really be such that this superposition describes a world no less legitimate than a world where the particle has a defined position. So let us take seriously the idea that the superposed wave function describes a unique world that is really in this state. The question is then to explain why we see a determinate value of the position. Convivial Solipsism explains that what our consciousness sees is limited to classical things even if the world itself is not classical (See below (Section 5) for what I mean by “classical” and why we can only see classical things). Convivial Solipsism makes a clear distinction between what the world is and what we see from it. In this case, the artificial split in as many worlds as there are possible results is eliminated because it is no more needed. This solves also the puzzling questions attached to Everett’s interpretation: When is the world supposed to split? Is it when a measurement is made? However, in this case, what is a measurement? Does that need the involvement of an observer? If not, is the world splitting every time there is an interaction between two systems? None of these questions has a clear answer, and the different supporters of Everett can even supply different answers.

“What is the probability of self-location in a particular world? I claim that it has to be postulated in addition to the postulate of unitary evolution of the universal wave function and a postulate of the correspondence between the three-dimensional wave function of an observer within a branch and the experience of the observer. The postulate is that the probability of self-location is proportional to the “measure of existence”, which is a counterpart of the Born rule of the collapse theories.”

“A believer in the MWI witnesses the same change, but it represents the superluminal change only in her world, not in the physical universe which includes all worlds together, the world with probability 0 and the world with probability 1. Thus, only the MWI avoids action at a distance in the physical universe.”

## 5. Convivial Solipsism (ConSol)

“We, as agents capable of experiencing only a single world, have an illusion of randomness”.

## 6. The Dissolution of the Problems

“The dissolution of this family of “paradoxes” is based on the remark that “Bob’s answer is created for Alice only when it enters her experience”. As long as one compares the outcomes and predictions of agents from some “God’s eye standpoint”, discrepancies between them can (artificially) occur. And as long as experimental outcomes are dealt with as intrinsically occurring macroscopic events, or macroscopic traces of former events, comparing them from “God’s eye standpoint” is a permanent temptation. However, if outcomes and predictions are compared in the only place where they can be at the end of the day, namely in the experience of a single agent at a single moment, any contradiction fades away, and even the need for mysterious actions (or passions) at a distance disappears. We can conclude from these remarks that, far from being the whim of some maverick physicists, the strict transcendental reduction to pure experience, the uncompromising adhesion to the first-person standpoint, is indispensable to make full sense of quantum mechanics by making its “paradoxes and mysteries” vanish at one stroke.”

## 7. Conclusions

## Funding

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

- d’Espagnat, B. Conceptual Foundations of Quantum Mechanics; W. A. Benjamin: New York, NY, USA, 1971. [Google Scholar]
- Einstein, A.; Podolsky, B.; Rosen, N. Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? Phys. Rev.
**1935**, 47, 777–780. [Google Scholar] [CrossRef][Green Version] - Bell, J.S. On the Einstein-Podolski-Rosen Paradox. Physics
**1964**, 1, 195–290. [Google Scholar] [CrossRef][Green Version] - Spekkens, R.W. In defense of the epistemic view of quantum states: A toy theory. Phys. Rev. A
**2007**, 75, 032110. [Google Scholar] [CrossRef][Green Version] - Bohm, D. A suggested interpretation of the quantum theory in terms of ‘hidden’ variables, I. Phys. Rev.
**1952**, 85, 166–179. [Google Scholar] [CrossRef] - Bohm, D. A suggested interpretation of the quantum theory in terms of ‘hidden’ variables, II. Phys. Rev.
**1952**, 85, 180–193. [Google Scholar] [CrossRef] - Ghirardi, G.C.; Rimini, A.; Weber, T. Unified dynamics for microscopic and macroscopic systems. Phys. Rev.
**1986**, D34, 470. [Google Scholar] [CrossRef] - Ghirardi, G.C. Collapse Theories. In The Stanford Encyclopedia of Philosophy; Stanford University: Stanford, CA, USA, 2011. [Google Scholar]
- Everett, H. On the Foundations of Quantum Mechanics. Ph.D. Thesis, Princeton University, Princeton, NJ, USA, 1957. [Google Scholar]
- Everett, H. Relative State Formulation of Quantum Mechanics. Rev. Mod. Phys.
**1957**, 29, 454–462. [Google Scholar] [CrossRef][Green Version] - DeWitt, B.S.; Graham, N. (Eds.) The Many-Worlds Interpretation of Quantum Mechanics; Princeton University Press: Princeton, NJ, USA, 1973. [Google Scholar]
- Zwirn, H. Les Limites de La Connaissance; Odile Jacob: Paris, France, 2000. [Google Scholar]
- Zwirn, H. The Measurement Problem: Decoherence and Convivial Solipsism. Found. Phys.
**2016**, 46, 635. [Google Scholar] [CrossRef][Green Version] - Zwirn, H. Delayed Choice, Complementarity, Entanglement and Measurement. Phys. Essays
**2017**, 30, 3. [Google Scholar] [CrossRef][Green Version] - Zwirn, H. Non Locality versus Modified Realism. Found. Phys.
**2020**, 50, 1–26. [Google Scholar] [CrossRef] - Zwirn, H. Is the Past Determined? Found. Phys.
**2021**, 51, 57. [Google Scholar] [CrossRef] - van Fraassen, B. The Scientific Image; Oxford University Press: Oxford, UK, 1980. [Google Scholar]
- Rescher, N. Scientific Realism, D; Reidel Publishing Company: Dordrecht, Holland, 1987. [Google Scholar]
- Dummett, M. Truth and other Enigmas. Philos. Q.
**1981**, 31, 47–67. [Google Scholar] - Bohr, N. Physique Atomique et Connaissance Humaine; Gauthier-Villars: Pairs, France, 1961. [Google Scholar]
- Bruckner, C. On the Quantum Measurement Problem. In Quantum [Un]Speakables II; Bertlmann, R., Zeilinger, A., Eds.; The Frontiers Collection; Springer: Berlin/Heidelberg, Germany, 2017. [Google Scholar]
- Alchourron, C.E.; Gardenfors, P.; Makinon, D. On the logic of theory change: Partial meet contraction and revision functions. J. Symb. Log.
**1985**, 50, 510–530. [Google Scholar] [CrossRef][Green Version] - Gardenfors, P. Knowledge in Flux; MIT Press: Cambridge, MA, USA, 1988. [Google Scholar]
- Katsuno, A.; Mendelzon, A. On the difference between updating a knowledge base and revising it. In Belief Revision; Gärdenfors, P., Ed.; Cambridge University Press: Cambridge, UK, 1992; pp. 183–203. [Google Scholar]
- Healey, R. Quantum Theory: A Pragmatist Approach. Br. J. Philos. Sci.
**2012**, 63, 729–771. [Google Scholar] [CrossRef][Green Version] - Healey, R. Quantum-Bayesian and pragmatist views of quantum theory. In The Stanford Encyclopedia of Philosophy; Zalta, E.N., Ed.; Metaphysics Research Lab, Stanford University: Stanford, CA, USA, 2016; Volume 34, Available online: https://plato.stanford.edu/archives/win2016/entries/quantum-bayesian/ (accessed on 2 February 2023).
- Healey, R. The Quantum Revolution in Philosophy; Oxford University Press: Oxford, UK, 2017. [Google Scholar]
- Fuchs, C.A. On participatory Realism. arXiv
**2016**, arXiv:1601.04360. [Google Scholar] - Zwirn, H. Is Qbism a Possible Solution to the Conceptual Problems of Quantum Mechanics? In The Oxford Handbook of the History of Quantum Interpretation; Freire, O., Ed.; Oxford University Press: Oxford, UK, 2022. [Google Scholar]
- Leifer, M.S. What Are Copenhagenish interpretations and Should They Be Perspectival? Talk Given at Wigner’s Friend Workshop, Boston. 2018. Available online: https://www.youtube.com/watch?v=C-C_K-gK6q4 (accessed on 23 January 2023).
- Bub, J.; Pitowsky, I. Two Dogmas about Quantum Mechanics, in Many Worlds? Everett, Quantum Theory,& Reality; Saunders, S., Barrett, J., Kent, A., Wallace, D., Eds.; Oxford University Press: Oxford, UK, 2010. [Google Scholar]
- Rovelli, C. Relational Quantum Mechanics. Int. J. Theor. Phys.
**1996**, 35, 1637–1678. [Google Scholar] [CrossRef] - Pienaar, J. QBism and Relational Quantum Mechanics compared. arXiv
**2012**, arXiv:2108.13977. [Google Scholar] [CrossRef] - Pienaar, J. A Quintet of Quandaries: Five No-Go Theorems for Relational Quantum Mechanics. Found. Phys.
**2021**, 51, 97. [Google Scholar] [CrossRef] - Vaidman, L. Why the Many-Worlds Interpretation? Quantum. Rep.
**2022**, 4, 264–271. [Google Scholar] [CrossRef] - Wallace, D. A Formal Proof of the Born Rule from Decision Theoretic Assumptions. In Many Worlds? Everett, Quantum Theory and Reality; Saunders, S., Barrett, J., Kent, A., Wallace, D., Eds.; Oxford University Press: Oxford, UK, 2010. [Google Scholar]
- Kent, A. One World versus Many: The Inadequacy of Everettian Accounts of Evolution, Probability, and Scientific Confirmation. In Many Worlds? Everett, Quantum Theory and Reality; Saunders, S., Barrett, J., Kent, A., Wallace, D., Eds.; Oxford University Press: Oxford, UK, 2010. [Google Scholar]
- Groisman, B.; Hallakoun, N.; Vaidman, L. The measure of existence of a quantum world and the sleeping beauty problem. Analysis
**2013**, 73, 695–706. [Google Scholar] [CrossRef][Green Version] - Wigner, E.P. Remark on the mind-body question. In The Scientist Speculates; Good, I.J., Ed.; Heinemann: London, UK, 1961. [Google Scholar]
- Frauchiger, D.; Renner, R. Quantum theory cannot consistently describe the use of itself. Nat. Commun.
**2018**, 9, 3711. [Google Scholar] [CrossRef] [PubMed][Green Version] - Bruckner, C. A no-go theorem for observer-independent facts. Entropy
**2018**, 20, 5. [Google Scholar] [CrossRef] [PubMed][Green Version] - Bitbol, M.; De la Tremblaye, L. Towards a Phenomenological Constitution of Quantum Mechanics: A QBist Approach. Mind Matter
**2022**, 20, 35–62. [Google Scholar]

Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |

© 2023 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Zwirn, H.
Everett’s Interpretation and Convivial Solipsism. *Quantum Rep.* **2023**, *5*, 267-281.
https://doi.org/10.3390/quantum5010018

**AMA Style**

Zwirn H.
Everett’s Interpretation and Convivial Solipsism. *Quantum Reports*. 2023; 5(1):267-281.
https://doi.org/10.3390/quantum5010018

**Chicago/Turabian Style**

Zwirn, Hervé.
2023. "Everett’s Interpretation and Convivial Solipsism" *Quantum Reports* 5, no. 1: 267-281.
https://doi.org/10.3390/quantum5010018