Abstract
To judge by what we have seen so far, it does indeed seem that nature can produce nonlocal correlations. But scientists won’t usually let go of a theory or a concept as easily as that. Whenever an experiment delivers strange results, they question not only the theory, but also the experiment. Is it reproducible? Has it been interpreted correctly? In our case, the experiment has been repeated many times and on every continent with all kinds of variants. However, we shall nevertheless see that it is extremely difficult to be sure that all possible alternative interpretations have indeed been ruled out, even though the scientific community is today quite convinced that nature is effectively nonlocal.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Notes
- 1.
In principle, the fact that a photon is lost is not particularly serious, provided we know that before asking it any questions, i.e., before pushing the joystick to the left or right. Otherwise, the photon might decide to lose itself somehow whenever it finds the question unsuitable.
- 2.
M.A. Rowe, et al.: Experimental violation of Bell’s inequalities with efficient detection, 149, 791–794 (2001); D.N. Matsukevich, et al.: Bell inequality violation with two remote atomic qubits, Phys. Rev. Lett. 100, 150404 (2008). Recently experiments with photons have also been realized: M. Giustina, A. Mech, S. Ramelow, B. Wittmann, J. Kofler, J. Beyer, A. Lita, B. Calkins, T. Gerrits, S.W. Nam, R. Ursin, A. Zeilinger: Bell violation using entangled photons without the fair-sampling assumption, Nature 497, 227 (2013); B.G. Christensen, K.T. McCusker, J.B. Altepeter, B. Calkins, T. Gerrits, A.E. Lita, A. Miller, L.K. Shalm, Y. Zhang, S.W. Nam, N. Brunner, C.C.W. Lim, N. Gisin, P.G. Kwiat: Detection-loophole-free test of quantum nonlocality, and applications, Phys. Rev. Lett. 111, 130406 (2013).
- 3.
Those who feel worried about relativity theory may find it useful to note the following point: if a light signal cannot connect two events in one inertial reference frame, then it will not be able to in any other such frame, so this is a frame-independent concept.
- 4.
Aspect, A., Dalibard, J., Roger, G.: Experimental test of Bell’s inequalities using time-varying analyzers, Phys. Rev. Lett. 49, 91–94 (1982).
- 5.
Weihs, G. Jenneswein, T., Simon, C., Weinfurter, H., Zeilinger, A.: Violation of Bell’s inequality under strict Einstein locality conditions, Phys. Rev. Lett. 81, 5039 (1998).
- 6.
Tittel, W., Brendel, J., Zbinden, H., Gisin, N.: Violation of Bell inequalities by photons more than 10 km apart, art. cit.; Tittel, W., Brendel, J., Gisin, N., Zbinden, H.: Long-distance Bell-type tests using energy–time entangled photons, Phys. Rev. A 59, 4150 (1999).
- 7.
Gisin, N., Zbinden, H.: Bell inequality and the locality loophole. Active versus passive switches, Phys. Lett. A 264, 103–107 (1999).
- 8.
P.C.W. Davies, J.R. Brown (Eds): The Ghost in the Atom, Cambridge University Press (1986), pp. 48–50.
- 9.
Lineweaver, C., et al.: The dipole observed in the COBE DMR 4 year data, Astrophys. J. 38, 470 (1996), http://pdg.lbl.gov
- 10.
Salart Subils, D., Baas, A., Branciard, C., Gisin, N., Zbinden, H.: Testing the speed of “spooky action at a distance”, Nature 454, 861–864 (2008).
- 11.
Cocciaro, B., Faetti, S., Fronzoni, L.: A lower bound for the velocity of quantum communications in the preferred frame, Phys. Lett. A 375, 379–384 (2011).
- 12.
Bohm, D.: A suggested interpretation of the quantum theory in terms of ‘hidden’ variables, Phys. Rev. 85, 2 (1952).
- 13.
To avoid having communication without transmission, the Bohm model assumes that certain variables are forever inaccessible to us. But intrinsically and forever inaccessible variables aren’t physical. Interestingly Bohm himself wrote: “It is quite possible that quantum nonlocal connections might be propagated, not at infinite speeds, but at speeds very much greater than that of light. In this case, we could expect observable deviations from the predictions of current quantum theory (e.g., by means of a kind of extension of the Aspect-type experiment)”, see D. Bohm and B.J. Hiley, The Undivided Universe, Routledge, London and NY 1993 (p. 347 of the paperback edition).
- 14.
Scarani, V., Gisin, N.: Superluminal hidden communication as the underlying mechanism for quantum correlations. Constraining models, Brazilian Journal of Physics 35, 328–332 (2005); Bancal, J.D., Pironio, S., Acin, A., Liang, Y.C., Scarani, V., Gisin, N.: Quantum nonlocality based on finite-speed causal influences leads to superluminal signaling, Nature Physics 8, 867 (2012).
- 15.
Suarez, A., Scarani, V.: Does entanglement depend on the timing of the impacts at the beam-splitters?, Phys. Lett. A 232, 9 (1997).
- 16.
This experiment was financed by the Fondation Marcel et Monique Odier de Psycho-Physique. After doing a degree in physics and a doctorate in mathematics, Marcel Odier represents the fifth generation in his family’s private bank.
- 17.
Stefanov, A., Zbinden, H., Gisin, N., Suarez, A.: Quantum correlation with moving beamsplitters in relativistic configuration, Pramana (Journal of Physics) 53, 1–8 (1999); Gisin, N., Scarani, V., Tittel, W., Zbinden, H.: Quantum nonlocality: From EPR-Bell tests towards experiments with moving observers, Annalen der Physik 9, 831–842 (2000).
- 18.
When Suarez learnt of our result, he immediately came to Geneva and observed that the student had set up the experiment the wrong way round: the mirrors were moving toward one another rather than moving apart! And none of us had noticed. We were not proud of ourselves! The experiment was corrected and repeated, but the result was the same.
- 19.
Moreover, such a huge conspiracy would require extreme fine tuning in order for Alice and Bob’s apparently free choices to be correlated in just the right way to ‘win’ at Bell’s game.
- 20.
Laplace, P.-S.: Essai philosophique sur les probabilités, Bachelier (1814).
- 21.
For some physicists, realism implies determinism. But we have seen that nonlocality implies irreducible randomness. We must therefore find some concept of realism that lives alongside true randomness.
- 22.
In this context, it is interesting to note that the first publication on quantum cryptography was refused by all the physics journals! For this reason, it appeared in the proceedings of a computing conference held in India. This may seem rather surprising to an outsider, but all experienced physicists know that it is difficult to publish a particularly original idea. One must get past the barrier of skepticism within the community, a barrier that serves as an essential filter, removing ideas that are incompatible with well-established facts.
- 23.
Gisin, N.: Non-realism: Deep thought or a soft option?, Foundations of Physics 42, 80–85 (2012).
- 24.
Franson, J.D.: Bell’s theorem and delayed determinism, Phys. Rev. D 31, 2529–2532 (1985).
- 25.
Penrose, R.: On gravity’s role in quantum state reduction, General Relativity and Gravitation 28, 581–600 (1996); Diosi, L.: A universal master equation for the gravitational violation of the quantum mechanics, Phys. Lett. A 120, 377 (1987); Adler, S.: Comments on proposed gravitational modifications of Schrödinger dynamics and their experimental implications, J. Phys. A 40, 755–763 (2007).
- 26.
Salart, D., Baas, A., Van Houwelingen, J.A.W., Gisin, N., Zbinden, H.: Spacelike separation in a Bell test assuming gravitationally induced collapses, Phys. Rev. Lett. 100, 220404 (2008).
- 27.
Of course, one can cheat here. One can always adjoin nonlocal hidden variables to the quantum theory which determine the whole future. These parameters could simply be the future! They are necessarily nonlocal and hidden from our present day view. Quite frankly, that does not look very interesting to me. Once again, it’s more a play on words than anything else.
- 28.
Followers of the multiverse idea claim that their theory is local, but it is not really clear in what sense it would be so. When Alice pushes her joystick, her box and the whole of its environment is supposed to divide into two superposed branches, each one as real as the other. Likewise for Bob. When Alice and Bob’s environments meet, they entangle in just the right way to honour the rules of Bell’s game in each branch. This is supposed to be an account of the dynamics described by Schrödinger’s equation, but does it really do anything more than assign some somewhat vague words to a beautiful equation? Does it constitute an explanation? And above all, is it really a local explanation?
- 29.
For a theory including both quantum and classical variables (for example, measurement results), this can be formulated by requiring that it must be possible for the evolution of the quantum variables to be conditioned by the classical variables (the experimenter must be able to activate or otherwise a potential as a consequence of previous measurement results). L. Diósi: Classical–quantum coexistence. A ‘free will’ test, J.Phys.Conf.ser. 361, 012028 (2012); arXiv:1202.2472
- 30.
Gisin, N.: L'épidémie du multivers. In: Le plus grand des hasards. Surprises quantiques, ed. by Dars, J.-F., Papillaut, A., Belin (2010).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Copyright information
© 2014 Springer International Publishing Switzerland
About this chapter
Cite this chapter
Gisin, N. (2014). Is Nature Really Nonlocal?. In: Quantum Chance. Copernicus, Cham. https://doi.org/10.1007/978-3-319-05473-5_9
Download citation
DOI: https://doi.org/10.1007/978-3-319-05473-5_9
Published:
Publisher Name: Copernicus, Cham
Print ISBN: 978-3-319-05472-8
Online ISBN: 978-3-319-05473-5
eBook Packages: Physics and AstronomyPhysics and Astronomy (R0)