Advertisement

Niels Bohr, objectivity, and the irreversibility of measurements

  • Ulrich J. MohrhoffEmail author
Regular Paper
  • 8 Downloads

Abstract

The only acceptable reason why measurements are irreversible and outcomes definite is the intrinsic definiteness and irreversibility of human sensory experience. While QBists deserve credit for their spirited defense of this position, Niels Bohr urged it nearly a century ago, albeit in such elliptic ways that the core of his message has been lost or distorted beyond recognition. Then as now, the objectivity of empirical science was called into question. It was defended by Bohr along the lines of Kant’s (then) revolutionary theory of science, according to which the possibility of empirical science hinges on the possibility of thinking of experiences as experiences of a system of interacting, re-identifiable objects. What Bohr added to Kant’s theory was his insight that empirical knowledge was not necessarily limited to what is directly accessible to the senses, and that, therefore, it does not have to be solely a knowledge of objects of sensible intuition. It can also be a knowledge of phenomena that are not objects of sensible intuition but instead are constituted by experimental contexts, which are objects of sensible intuition. Bohr’s grounding of objectivity (or the objectivity consistent with quantum mechanics), however, is weaker than Kant’s (or the objectivity consistent with Newtonian physics). This conclusion is based on an examination of Bohr’s intentions in appealing to irreversible amplification effects or the sufficient size and weight of the measurement apparatus.

Keywords

Bohr Experience Irreversibility Kant Measurement Objectivity QBism 

Notes

References

  1. 1.
    Caves, C.M., Fuchs, C.A., Schack, R.: Quantum probabilities as Bayesian probabilities. Phys. Rev. A 65, 022305 (2002)MathSciNetCrossRefGoogle Scholar
  2. 2.
    Mermin, N.D.: Why QBism is not the Copenhagen interpretation and what John Bell might have thought of it. In: Bertlmann, R., Zeilinger, A. (eds.) Quantum [Un]Speakables II: 50 Years of Bell’s Theorem, pp. 83–93. Springer, Berlin (2017)CrossRefGoogle Scholar
  3. 3.
    Van Fraassen, B.C.: The problem of measurement in quantum mechanics. In: Lahti, P., Mittelstaedt, P. (eds.) Symposium on the Foundations of Modern Physics, pp. 497–503. World Scientific, Singapore (1990)Google Scholar
  4. 4.
    Bohr, N.: In: Rosenfeld, L. (general editor) Niels Bohr: Collected Works (13 Volumes). Elsevier, Amsterdam, Netherlands (1972–2008) Google Scholar
  5. 5.
    Mohrhoff, U.: “B” is for Bohr, to appear in the combined proceedings of the workshops on meaning and structure of quantum mechanics at Buenos Aires (2016 and 2019), arXiv:1905.07118 [quant-ph]
  6. 6.
    Mohrhoff, U.: Bohr, QBism, and beyond, to appear in the proceedings of the 2019 Copenhagen Interpretation and Beyond Conference at Chapman University, Los Angeles, honoring Henry P. Stapp, arXiv:1907.11405 [quant-ph]
  7. 7.
    Fuchs, C.A., Mermin, N.D., Schack, R.: An introduction to QBism with an application to the locality of quantum mechanics. Am. J. Phys. 82(8), 749–754 (2014)CrossRefGoogle Scholar
  8. 8.
    Hooker, C.A.: The nature of quantum mechanical reality: Einstein versus Bohr. In: Colodny, R.G. (ed.) Paradigms and Paradoxes: The Philosophical Challenge of the Quantum Domain, pp. 67–302. University of Pittsburgh Press, Pittsburgh (1972)Google Scholar
  9. 9.
    Schrödinger, E.: The principle of objectivation. In: What is Life? With: Mind and Matter and Autobiographical Sketches, Chapter 3, pp. 117–127. Cambridge University Press, Cambridge (1992) Google Scholar
  10. 10.
    Von Weizsäcker, C.F.: The unity of physics as a philosophical problem. In: Drieschner, M. (ed.) Carl Friedrich von Weizsäcker: Major Texts in Physics, pp. 67–71. Springer, Heidelberg (2014)Google Scholar
  11. 11.
    D’Espagnat, B.: A physicist’s approach to Kant. In: Bitbol, M., Kerszberg, P., Petitot, J. (eds.) Constituting Objectivity: Transcendental Perspectives on Modern Physics, pp. 481–490. Springer, Berlin (2009)CrossRefGoogle Scholar
  12. 12.
    Schrödinger, E.: Nature and the Greeks, and Science and Humanism, p. 162. Canto Classics, Cambridge (2014)CrossRefGoogle Scholar
  13. 13.
    Mermin, N.D.: What’s wrong with those epochs. Phys. Today 43(11), 9–11 (1990)CrossRefGoogle Scholar
  14. 14.
    Bohr, N.: Can quantum-mechanical description of physical reality be considered complete? Phys. Rev. 48, 696–702 (1935)CrossRefGoogle Scholar
  15. 15.
    Chevalley, C.: Why do we find Bohr obscure? In: Greenberger, D., Reiter, W.L., Zeilinger, A. (eds.) Epistemological and Experimental Perspectives on Quantum Physics, pp. 59–73. Kluwer, Dordrecht (1999)CrossRefGoogle Scholar
  16. 16.
    Kant, I.: Critique of Pure Reason, transl. and ed. P. Guyer, A.W. Wood, pp. 115. Cambridge University Press, Cambridge (1998) Google Scholar
  17. 17.
    Bohr, N.: Discussion with Einstein on the epistemological problems in atomic physics. In: Schilpp, P.A. (ed.) Albert Einstein: Philosopher-Scientist, pp. 201–241. MFJ Books, New York (1949)Google Scholar
  18. 18.
    Ulfbeck, O., Bohr, A.: Genuine Fortuitousness. Where did that click come from? Found. Phys. 31(5), 757–774 (2001)MathSciNetCrossRefGoogle Scholar
  19. 19.
    Mermin, N.D.: What’s bad about this habit. Phys. Today 62(5), 8–9 (2009)CrossRefGoogle Scholar
  20. 20.
    Bell, J.S.: Against “measurement”. Physics World, pp. 33–40 (August 1990) Google Scholar
  21. 21.
    Falkenburg, B.: Particle Metaphysics: A Critical Account of Subatomic Reality, pp. 205–206. Springer, Berlin (2007)Google Scholar
  22. 22.
    Von Weizsäcker, C.F.: The Structure of Physics, p. 25. Springer, Berlin (2006)Google Scholar

Copyright information

© Chapman University 2019

Authors and Affiliations

  1. 1.Sri Aurobindo International Centre of EducationPondicherryIndia

Personalised recommendations