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Philosophy of Science pp 23–41Cite as

Quantum Gravity: A Dogma of Unification?

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Part of the book series: European Studies in Philosophy of Science ((ESPS,volume 9))

Abstract

The quest for a theory of quantum gravity is usually understood to be driven by philosophical assumptions external to physics proper. It is suspected that specifically approaches in the context of particle physics are rather based on metaphysical premises than experimental data or physical arguments. I disagree. In this paper, I argue that the quest for a theory of quantum gravity sets an important example of physics’ internal unificatory practice. It is exactly Weinberg’s and others’ particle physics stance that reveals the issue of quantum gravity as a genuine physical problem arising within the framework of quantum field theory.

I thank Andreas Bartels, Cord Friebe, Stefan Heidl, Niels Linnemann, James Read, Matthias Rolffs, Thorsten Schimannek, and Christian Wüthrich for helpful discussions and remarks. Furthermore, I thank the anonymous referee for pressing me to clarify some paragraphs, especially in the opening sections.

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Notes

  1. 1.

    I do not distinguish between ‘theory’ and ‘model (of a theory)’ here. More accurately, one would refer to the SM as a ‘model (of QFT)’.

  2. 2.

    Furthermore, actually suggestions are put forward for how theory assessment without experimental data could work (Dawid 2013)—a very interesting, but also highly controversial project (cf. Rovelli 2016).

  3. 3.

    Note that in light of the hole argument, the focus has shifted to the metric alone.

  4. 4.

    Note that Carroll’s definition of the SEP is not very precise. Read et al. (2017) carefully distinguish and discuss four versions of the SEP.

  5. 5.

    While Newtonian physics was unable to provide an explanation for why the equivalence principle should hold, the geometrical picture of GR provides an explanation in terms of an elimination (of gravitational potential and gravitational mass). As we will see in a moment, it is also possible to give a reductive account.

  6. 6.

    Here, ‘low energy’ means low energy with respect to the so-called Planck energy. Even the highest presently available energy scales in physics can safely be considered ‘low’ in that sense.

  7. 7.

    Of course, quantum field theory can be thought to be, first and foremost, a theory of fields. The corresponding particles are then derivative of the fields in the sense that they are excitations of the fields. Nevertheless, as the term particle physics stresses, we can also perceive it as a theory of particles. However, by talking about particles instead of fields I do not mean to have claimed anything substantial about the nature of QFT.

  8. 8.

    Here, the charge of a particle is defined as its coupling constant for emission of soft photons (Weinberg 1965b, B989).

  9. 9.

    That means that we demand the polarization vector to transform as 𝜖 μ (p) → ( Λ𝜖) μ (p) + α( Λp) μ .

  10. 10.

    Here we used a slight simplification, but for example Nicolis (2011) carefully proves that the gravitational coupling constants, κ i , are indeed forced to be universal.

  11. 11.

    Still, given that Read et al. (2017) argue that minimal coupling may violate certain versions of the SEP, there definitely remains more to be said. Ultimately, all claims involving the SEP here are in need of further clarification.

  12. 12.

    According to Maudlin (2011), there is another, very general conflict between SR and QM due to Bell’s theorem. Note, however, that this is an entirely different issue closely connected to the debate on the interpretation of QM—a debate which physicists might be safe to ignore as long as the theory is empirically adequate. The high energy conflict mentioned here is not of that kind: While QFT is empirically adequate, consistent and highly predictive at low energies, it becomes non-predictive at high energies.

References

  • Arkani-Hamed, N. 2010a. The Future of Fundamental Physics. Space-Time Is Doomed; What Replaces It?, Messenger Lecture Series at Cornell University. Lecture.

    Google Scholar 

  • Arkani-Hamed, N. 2010b. Robustness of GR. Attempts to Modify Gravity. Part I. Prospects in Theoretical Physics Program. Cornell University. Lecture.

    Google Scholar 

  • Arkani-Hamed, N. 2012. The Future of Fundamental Physics. Dædalus 141(3): 53–66.

    Google Scholar 

  • Arkani-Hamed, N. 2013. Philosophy of Fundamental Physics. Andrew D. White Professors-at-Large Program. Cornell University. Lecture.

    Google Scholar 

  • Belot, G. 2011. Background-Independence. General Relativity and Gravitation 43(10): 2865–2884. arXiv:grqc/1106.0920.

    Google Scholar 

  • Brown, H. 2005. Physical Relativity: Spacetime Structure from a Dynamical Perspective. Oxford: Oxford University Press.

    Book  Google Scholar 

  • Brown, H.R., and O. Pooley 2001. The Origins of the Spacetime Metric: Bell’s ‘Lorentzian pedagogy’ and Its Significance in General Relativity. In Physics Meets Philosophy at the Planck Scale, ed. C. Callender and N. Huggett, 256–272. Cambridge: Cambridge University Press.

    Chapter  Google Scholar 

  • Brown, H.R., and O. Pooley 2006. Minkowski Space-Time: A Glorious Non-entity. In The Ontology of Spacetime, Volume 1 of Philosophy and Foundations of Physics, ed. D. Dieks, 67–89. Amsterdam: Elsevier.

    Google Scholar 

  • Brown, H.R., and J. Read 2016. Clarifying Possible Misconceptions in the Foundations of General Relativity. American Journal of Physics 84: 327.

    Article  Google Scholar 

  • Carlip, S. 2008. Is Quantum Gravity Necessary? Classical and Quantum Gravity 25: 154010.

    Article  Google Scholar 

  • Carroll, S. 2004. Spacetime and Geometry. An Introduction to General Relativity. San Francisco: Addison Wesley.

    Google Scholar 

  • Dawid, R. 2013. String Theory and the Scientific Method. Cambridge: Cambridge University Press.

    Book  Google Scholar 

  • Donoghue, J. 1994. General Relativity as an Effective Field Theory. The Leading Quantum Corrections. Physical Review D 59: 3874–3888.

    Article  Google Scholar 

  • Donoghue, J. 2014. General Relativity as an Effective Field Theory. PSI Summer School ‘More than Higgs – Effective Theories for Particle Physics’. Zuoz. Lecture. blogs.umass.edu/donoghue/files/2009/06/Zuoz-3.pdf.

  • Eppley, K., and E. Hannah 1977. The Necessity of Quantizing the Gravitational Field. Foundations of Physics 7: 51–68.

    Article  Google Scholar 

  • Feynman, R., F.B. Morinigo, W.G. Wagner, and B. Hatfield 1995. Feynman Lectures on Gravitation. Reading, Massachusetts: Addison-Wesley.

    Google Scholar 

  • Huggett, N., and C. Callender 2001a. Introduction. In Physics Meets Philosophy at the Planck Scale. Contemporary Theories in Quantum Gravity, ed. N. Huggett and C. Callender, 1–33. Cambridge: Cambridge University Press.

    Google Scholar 

  • Huggett, N., and C. Callender 2001b. Why Quantize Gravity (Or Any Other Field for that Matter)? Philosophy of Science 68(Proceedings): S382–S394.

    Google Scholar 

  • Kiefer, C. 2006. Quantum Gravity: General Introduction and Recent Developments. Annals of Physics 15(1–2): 129–148.

    Article  Google Scholar 

  • Kiefer, C. 2007. Quantum Gravity. Oxford: Oxford University Press.

    Book  Google Scholar 

  • Lehmkuhl, D. 2008. Is Spacetime a Gravitational Field? In Philosophy and Foundations of Physics, Volume 4: The Ontology of Spacetime, Vol. II, ed. D. Dieks and M. Redei, 83–110. Amsterdam: Elsevier.

    Google Scholar 

  • Lehmkuhl, D. 2014. Why Einstein Did Not Believe that General Relativity Geometrizes Gravity. Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 46(Part B): 316–326.

    Google Scholar 

  • Mattingly, J. 2005. Is Quantum Gravity Necessary? In The Universe of General Relativity, ed. A.J. Kox and J. Eisenstaedt, 327–338. Basel: Birkhäuser. Talk at the 5th International Conference on the History and Foundations of General Relativity in 1999.

    Google Scholar 

  • Mattingly, J. 2006. Why Eppley and Hannah’s Thought Experiment Fails. Physical Review D 73: 064025.

    Article  Google Scholar 

  • Maudlin, T. 1996. On the Unification of Physics. The Journal of Philosophy 93(3): 129–144.

    Article  Google Scholar 

  • Maudlin, T. 2011. Quantum Non-locality and Relativity. Chichester: Wiley-Blackwell.

    Book  Google Scholar 

  • Nicolis, A. 2011. General Relativity from Lorentz Invariance. Lecture notes. phys.columbia.edu/~nicolis/GR_from_LI_2.pdf.

  • Read, J. 2016. Background Independence in Classical and Quantum Gravity. B.Phil. Thesis, University of Oxford.

    Google Scholar 

  • Read, J., H.R. Brown, and D. Lehmkuhl 2017. Two Miracles of General Relativity. Manuscript in Preparation.

    Google Scholar 

  • Redhead, M. 1999. Quantum Field Theory and the Philosopher. In Conceptual Foundations of Quantum Field Theory, ed. T.Y. Cao, 34–40. Cambridge: Cambridge University Press.

    Google Scholar 

  • Rickles, D., and S. French 2006. Quantum Gravity Meets Structuralism: Interweaving Relations in the Foundations of Physics. In The Structural Foundations of Quantum Gravity, ed. D. Rickles, S. French, and J. Saatsi, 1–39. Oxford: Oxford University Press.

    Chapter  Google Scholar 

  • Rovelli, C. 2016. The dangers of non-empirical confirmation. arXiv:1609.01966.

    Google Scholar 

  • Wald, R.M. 1984. General Relativity. Chicago: The University of Chicago Press.

    Book  Google Scholar 

  • Weinberg, S. 1964a. Derivation of Gauge Invariance and the Equivalence Principle from Lorentz Invariance of the S-Matrix. Physics Letters 9(4): 357–359.

    Article  Google Scholar 

  • Weinberg, S. 1964b. Photons and Gravitons in S-Matrix Theory: Derivation of Charge Conservation and Equality of Gravitational and Inertial Mass. Physics Review 135(4B): B1049–B1056.

    Article  Google Scholar 

  • Weinberg, S. 1965a. Infrared Photons and Gravitons. Physics Review 140(2B): B516–B524.

    Article  Google Scholar 

  • Weinberg, S. 1965b. Photons and Gravitons in Perturbation Theory: Derivation of Maxwell’s and Einstein’s Equations. Physics Review 138(4B): B988–B1002.

    Article  Google Scholar 

  • Weinberg, S. 1972. Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity. New York: Wiley.

    Google Scholar 

  • Weinberg, S. 1995. The Quantum Theory of Fields. Volume I: Foundations. Cambridge: Cambridge University Press.

    Book  Google Scholar 

  • Weinberg, S. 1999. What Is Quantum Field Theory, and What Did We Think It Is? In Conceptual Foundations of Quantum Field Theory, ed. T. Y. Cao, 241–251. Cambridge: Cambridge University Press.

    Google Scholar 

  • Wilczek, F. 2002. Scaling Mount Planck III: Is That All There Is? Physics Today 55: 10–11.

    Article  Google Scholar 

  • Wüthrich, C. 2005. To Quantize or Not to Quantize. Fact and Folklore in Quantum Gravity. Philosophy of Science 72: 777–788.

    Article  Google Scholar 

  • Wüthrich, C. 2006. Approaching the Planck Scale from a Generally Relativistic Point of View: A Philosophical Appraisal of Loop Quantum Gravity. Ph.D Thesis, University of Pittsburgh.

    Google Scholar 

  • Wüthrich, C. 2012. In Search of Lost Spacetime: Philosophical Issues Arising in Quantum Gravity. In La philosophie de la physique: d’aujourd’hui à demain, ed. S. Le Bihan. Paris: Vuibert. arXiv:1207.1489v1.

    Google Scholar 

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Authors and Affiliations

  1. Institute for Philosophy, University of Bonn, Am Hof 1, 53113, Bonn, Germany

    Kian Salimkhani

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  1. Kian Salimkhani
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Correspondence to Kian Salimkhani .

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Editors and Affiliations

  1. Düsseldorf Center for Logic and Philosophy of Science, Heinrich Heine University Düsseldorf, Düsseldorf, Germany

    Alexander Christian

  2. Düsseldorf Center for Logic and Philosophy of Science, Heinrich Heine University Düsseldorf, Düsseldorf, Germany

    David Hommen

  3. Düsseldorf Center for Logic and Philosophy of Science, Heinrich Heine University Düsseldorf, Düsseldorf, Germany

    Nina Retzlaff

  4. Düsseldorf Center for Logic and Philosophy of Science, Heinrich Heine University Düsseldorf, Düsseldorf, Germany

    Gerhard Schurz

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Salimkhani, K. (2018). Quantum Gravity: A Dogma of Unification?. In: Christian, A., Hommen, D., Retzlaff, N., Schurz, G. (eds) Philosophy of Science. European Studies in Philosophy of Science, vol 9. Springer, Cham. https://doi.org/10.1007/978-3-319-72577-2_2

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