Foundations of Physics

, Volume 49, Issue 12, pp 1404–1414 | Cite as

Comment on “The Notion of Locality in Relational Quantum Mechanics”

  • Jacques PienaarEmail author
Letter to the Editor


A recent paper (Martin-Dussaud et al. in Found Phys 49:96, 2019) has given a lucid treatment of Bell’s notion of local causality within the framework of the relational interpretation of quantum mechanics. However, the authors went on to conclude that the quantum violation of Bell’s notion of local causality is no more surprising than a common cause. Here, I argue that this conclusion is unwarranted by the authors’ own analysis. On the contrary, within the framework outlined by the authors, I argue that far from saving the notion of ‘locality’ from the grip of Bell’s theorem, the authors have deprived it of a meaningful definition.



I thank G. Barreto Lemos for helpful feedback on an earlier draft. This work was supported in part by the John E. Fetzer Memorial Trust.


  1. 1.
    Martin-Dussaud, P., Rovelli, C., Zalamea, F.: The notion of locality in relational quantum mechanics. Found. Phys. 49, 96 (2019)ADSMathSciNetCrossRefGoogle Scholar
  2. 2.
    Rovelli, C.: Relational quantum mechanics. Int. J. Theor. Phys. 35, 1637 (1996)MathSciNetCrossRefGoogle Scholar
  3. 3.
    Wiseman, H.M., Cavalcanti, E.G.: Causarum Investigatio and the Two Bell’s Theorems of John Bell. In: Bertlmann, R., Zeilinger, A. (eds.) Quantum [Un]Speakables II: Half a Century of Bell’s Theorem, pp. 119–142. Springer, Cham (2017)CrossRefGoogle Scholar
  4. 4.
    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. 17, 033002 (2015)ADSCrossRefGoogle Scholar
  5. 5.
    Pienaar, J., Brukner, Caslav: A graph-separation theorem for quantum causal models. New J. Phys. 17, 073020 (2015)ADSCrossRefGoogle Scholar
  6. 6.
    Costa, F., Shrapnel, S.: Quantum causal modelling. New J. Phys. 18, 063032 (2016)ADSCrossRefGoogle Scholar
  7. 7.
    Allen, J.-M.A., Barrett, J., Horsman, D.C., Lee, C.M., Spekkens, R.W.: Quantum common causes and quantum causal models. Phys. Rev. X 7, 031021 (2017)Google Scholar
  8. 8.
    Barrett, J., Lorenz, R., Oreshkov, O.: Quantum causal models. (2019). eprint arXiv:1906.10726
  9. 9.
    Henson, J., Lal, R., Pusey, M.F.: Theory-independent limits on correlations from generalized Bayesian networ. New J. Phys. 16, 113043 (2014)ADSCrossRefGoogle Scholar
  10. 10.
    Guérin, P.A., Brukner, C.: Observer-dependent locality of quantum events. New J. Phys. 20, 103031 (2018)CrossRefGoogle Scholar
  11. 11.
    Pienaar, J.L.: Quantum causal models via QBism. (2018). preprint: arXiv:1806.00895
  12. 12.
    Oreshkov, O., Cerf, N.: Operational formulation of time reversal in quantum theory. Nat. Phys. 11, 853 (2015)CrossRefGoogle Scholar
  13. 13.
    Price, H.: Time’s arrow & Archimedes’ point: new directions for the physics of time. New directions for the physics of time, Oxford Paperbacks: Philosophy. Oxford University Press (1997)Google Scholar
  14. 14.
    Argaman, N.: A lenient causal arrow of time? Entropy 20, 294 (2018). ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.International Institute of Physics, Universidade Federal do Rio Grande do Norte, Campus UniversitarioNatalBrazil
  2. 2.Department of PhysicsUniversity of Massachusetts BostonBostonUSA

Personalised recommendations