# Disentangling the Quantum World

^{1}

^{2}

^{*}

^{†}

## Abstract

**:**

## 1. Strange Connections

## 2. The Parisian Zigzag

For me it is so reasonable to assume that the photons in those experiments carry with them programs [i.e., “hidden instructions”], which have been correlated in advance, telling them how to behave. This is so rational that I think that when Einstein saw that, and the others refused to see it, he was the rational man. The other people, although history has justified them, were burying their heads in the sand … So for me, it is a pity that Einstein’s idea doesn’t work. The reasonable thing just doesn’t work.— J. S. Bell [6]

## 3. Alice Through the Looking Glass

#### 3.1. Polarizing Cubes

#### 3.2. Into the Mirror

#### 3.3. The One-Photon Experiment

#### 3.4. Backing out of the Mirror

#### 3.5. Too Good to Be True?

- If Alice can control τ over on Bob’s side of the experiment, why can’t she send a signal to him? It is well-known that QM does not allow signaling in the kind of experiment depicted in Figure 1, and we might therefore suspect that this zigzag connection would be incompatible with standard QM. (Typical causal channels can be used to signal, after all.)
- Why is Alice allowed to influence τ, when Bob seems to do no such thing? (Discrimination against experimenters on the right!)
- Isn’t the zigzag model just another version of the discredited “superdeterminist” proposal?

## 4. Causation without Signaling

#### 4.1. Can Ecila Signal?

#### 4.2. No Signaling, with Mirrors

#### 4.3. Generalized No-Signaling?

## 5. What about Bob?

## 6. Isn’t This Just “Superdeterminism”?

A respectable class of theories, including contemporary quantum theory as it is practiced, have “free” “external” variables in addition to those internal to and conditioned by the theory. These variables … provide a point of leverage for “free willed experimenters”, if reference to such hypothetical metaphysical entities is permitted. I am inclined to pay particular attention to theories of this kind, which seem to me most simply related to our everyday way of looking at the world.— J. S. Bell [22]

## 7. Entanglement without Spooks

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## References

- Schrödinger, E. Discussion of probability relations between separated systems. Math. Proc. Camb. Philos. Soc.
**1935**, 31, 555–563. [Google Scholar] [CrossRef] - 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] - Albert, D.Z.; Galchen, R. A quantum threat to special relativity. Sci. Am.
**2009**, 300, 32–39. [Google Scholar] [CrossRef] [PubMed] - Trimmer, J.D. The Present Situation in Quantum Mechanics: A Translation of Schrödinger’s “Cat Paradox” Paper. Proc. Am. Philos. Soc.
**1980**, 124, 323–338. [Google Scholar] - Costa de Beauregard, O. Méchanique quantique. C. R. Math. Acad. Sci.
**1953**, 236, 1632–1634. (In French) [Google Scholar] - Bernstein, J. Quantum Profiles; Princeton University Press: Princeton, NJ, USA, 1991; p. 84. [Google Scholar]
- Cramer, J.G. Generalized Absorber Theory and the Einstein-Podolsky-Rosen Paradox. Phys. Rev. D
**1980**, 22, 362–376. [Google Scholar] [CrossRef] - Pegg, D.T. Objective reality, causality and the aspect experiment. Phys. Lett. A
**1980**, 78, 233–234. [Google Scholar] [CrossRef] - Pegg, D.T. Time-symmetric electrodynamics and the Kocher-Commins experiment. Eur. J. Phys.
**1982**, 3, 44–49. [Google Scholar] [CrossRef] - Price, H. Time’s Arrow and Archimedes’ Point; Oxford University Press: Oxford, UK, 1996. [Google Scholar]
- Wood, C.J.; Spekkens, R.W. The lesson of causal discovery algorithms for quantum correlations: Causal explanations of Bell-inequality violations require fine-tuning. New J. Phys.
**2015**, 17, 033002. [Google Scholar] [CrossRef] - Almada, D.; Ch’ng, K.; Kintner, S.; Morrison, B.; Wharton, K.B. Are Retrocausal Accounts of Entanglement Unnaturally Fine-Tuned? 2015; arXiv:1510.03706. [Google Scholar]
- Wharton, K.B.; Koch, D. Unit quaternions and the Bloch sphere. J. Phys. A
**2015**, 48, 235302. [Google Scholar] [CrossRef] - Evans, P.W. Quantum Causal Models, Faithfulness and Retrocausality. 2015; arXiv:1506.08925. [Google Scholar]
- Aharonov, Y.; Vaidman, L. The Two-State Vector Formalism: An Updated Review. In Time in Quantum Mechanics; Springer: Heidelberg/Berlin, Germany, 2008; pp. 399–447. [Google Scholar]
- Wharton, K. Quantum States as Ordinary Information. Information
**2014**, 5, 190–208. [Google Scholar] [CrossRef] - Pusey, M. Time-symmetric ontologies for quantum theory. In Presented at Free Will and Retrocausality in the Quantum World, Trinity College, Cambridge, UK, 3 July 2014; Available online: http://bit.ly/Pusey2014 (accessed on 9 November 2015).
- Price, H. Does time-symmetry imply retrocausality? How the quantum world says “maybe”. Stud. Hist. Philos. Sci. B Stud. Hist. Philos. Mod. Phys.
**2012**, 43, 75–83. [Google Scholar] [CrossRef] - Pusey, M.F.; Barrett, J.; Rudolph, T. On the reality of the quantum state. Nat. Phys.
**2012**, 8, 475–478. [Google Scholar] [CrossRef] - Wiseman, H. From Einstein’s theorem to Bell’s theorem: A history of quantum non-locality. Contemp. Phys.
**2006**, 47, 79–88. [Google Scholar] [CrossRef] - Maudlin, T. What Bell Did. J. Phys. A
**2014**, 47, 424010. [Google Scholar] [CrossRef] - Bell, J.S. Speakable and Unspeakable in Quantum Mechanics, 2nd ed.; Cambridge University Press: Cambridge, UK, 2004; p. 101. [Google Scholar]
- Woodward, J. Making Things Happen: A Theory of Causal Explanation; Oxford University Press: Oxford, UK, 2003. [Google Scholar]
- Pearl, J. Causality: Models, Reasoning, and Inference; Cambridge University Press: Cambridge, UK, 2000. [Google Scholar]
- Menzies, P.; Price, H. Causation as a secondary quality. Br. J. Philos. Sci.
**1993**, 44, 187–203. [Google Scholar] [CrossRef] - Price, H. Agency and probabilistic causality. Br. J. Philos. Sci.
**1991**, 42, 157–176. [Google Scholar] [CrossRef] - Price, H.; Weslake, B. The time-asymmetry of causation. In The Oxford Handbook of Causation; Beebee, H., Hitchcock, C., Menzies, P., Eds.; Oxford University Press: Oxford, UK, 2010; p. 414. [Google Scholar]
- Price, H. Toy models for retrocausality. Stud. Hist. Philos. Sci. B Stud. Hist. Philos. Mod. Phys.
**2008**, 39, 752–761. [Google Scholar] [CrossRef] - Dummett, M. Can an Effect Precede Its Cause? Aristot. Soc. Proc. Supp. Vols.
**1954**, 28, 27–62. [Google Scholar] - Price, H.; Wharton, K. A Live Alternative to Quantum Spooks. 2015; arXiv:1510.06712. [Google Scholar]

© 2015 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Price, H.; Wharton, K.
Disentangling the Quantum World. *Entropy* **2015**, *17*, 7752-7767.
https://doi.org/10.3390/e17117752

**AMA Style**

Price H, Wharton K.
Disentangling the Quantum World. *Entropy*. 2015; 17(11):7752-7767.
https://doi.org/10.3390/e17117752

**Chicago/Turabian Style**

Price, Huw, and Ken Wharton.
2015. "Disentangling the Quantum World" *Entropy* 17, no. 11: 7752-7767.
https://doi.org/10.3390/e17117752