Abstract
In seeking an answer to the question of what it means for a theory to be fundamental, it is enlightening to ask why the current best theories of physics are not generally believed to be fundamental. This reveals a set of conditions that a theory of physics must satisfy in order to be considered fundamental. Physics aspires to describe ever deeper levels of reality, which may be without end. Ultimately, at any stage we may not be able to tell whether we’ve reached rock bottom, or even if there is a base level—nevertheless, I draft a checklist to help us identify when to stop digging, in the case where we may have reached a candidate for a final theory. Given that the list is—according to (current) mainstream belief in high-energy physics—complete, and each criterion well-motivated, I argue that a physical theory that satisfies all the criteria can be assumed to be fundamental in the absence of evidence to the contrary.
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.
While this discussion reflects the beliefs of contemporary high-energy physics, I must register my own scepticism regarding such a “reductionist” picture, and refer to the substantial literature on emergence in science. Particularly, I have doubts about the basis of these “in principle” claims, and their meaningfulness.
- 2.
There is another common, yet distinct notion of relative fundamentality in physics that is level-independent, and associated with more general theories, rather than higher-energy theories. I do not discuss this conception here. As we shall see, however, equating “more fundamental” with “shorter-distance”, is problematic because the very idea of distance may cease to be applicable at some point, and yet we may have reasons to expect there to be another, presumably more fundamental, theory beyond that point—i.e., beyond the domain of space and time—which could then not be called a “shorter-distance” theory!
- 3.
Indeed, as I discuss below, QFT is not considered a fundamental framework, and so it is expected that a fundamental theory will not be a QFT.
- 4.
This arbitrarily large vacuum energy may, in fact, be interpreted as an artifact of a non-fundamental formalism (Sect. 3.1).
- 5.
- 6.
Physicists usually distinguish between a fundamental theory and a final theory, arguing that although QCD is not a final theory, its UV completeness means that it is a fundamental theory. On this reasoning, Newtonian mechanics would also be considered a fundamental, though not final, theory. I argue below Sect. 4 that this reasoning is not consistent with the rest of the conditions on a fundamental theory.
- 7.
Neglecting the possibility of the UV silence scenario, Footnote 5. Also, I take a “theory without distance” (as in Footnote 2) to be UV complete, in the sense that it does not break down at any short distance scale.
- 8.
As we shall see, this problem was solved by considering QFT as EFT.
- 9.
In the case of QED, this is due to the presence of a Landau pole divergence.
- 10.
- 11.
Thus, I argue that a fundamental theory should be single, contra the typical distinction drawn between a fundamental and final theory, according to which only the latter need be single (Footnote 6).
- 12.
Note that there may be overlap in lower-energy, less-fundamental descriptions.
- 13.
Arguments for this appear in [20].
References
Georgi, H.: Effective-field theory. Ann. Rev. Nucl. Part. Sci. 43, 209–252 (1993)
Anderson, P.W.: More is different. Science 177, 393–396 (1972)
Cao, T.Y., Schweber, S.S.: The conceptual foundations and the philosophical aspects of renormalization theory. Synthese 97(1), 33–108 (1993)
Castellani, E.: Reductionism, emergence, and effective field theories. Stud. Hist. Philos. Mod. Phys. 33(2), 251–267 (2002)
Crowther, K.: Effective Spacetime: Understanding Emergence in Effective Field Theory and Quantum Gravity. Springer, Heidelberg (2016)
Huggett, N., Weingard, R.: The renormalisation group and effective field theories. Synthese 102(1), 171–194 (1995)
Crowther, K., Linnemann, N.: Renormalizability, fundamentality and a final theory: the role of UV completion in the search for quantum gravity. Br. J. Philos. Sci. axx052 (2017)
Giudice, G.F.: Naturally speaking: the naturalness criterion and physics at the LHC. In: Kane, G., Pierce, A. (eds.) Perspectives on LHC Physics. World Scientific, Singapore (2008)
Wells, J.D.: The utility of naturalness, and how its application to quantum electrodynamics envisages the standard model and Higgs boson. Stud. Hist. Philos. Mod. Phys. 49, 102–108 (2015)
Williams, P.: Naturalness, the autonomy of scales, and the 125 GeV Higgs. Stud. Hist. Philos. Sci. Part B Stud. Hist. Philos. Mod. Phys. 51, 82–96 (2015)
Hossenfelder, S.: Screams for explanation: finetuning and naturalness in the foundations of physics (2018). arXiv:1801.02176v2
Franklin, A.: Whence the effectiveness of effective field theories? Br. J. Philos. Sci. axy050 (2018)
Maudlin, T.: On the unification of physics. J. Philos. 93(3), 129–144 (1996)
Belot, G.: Background-independence. Gen. Relativ. Gravit. 43(10), 2865–2884 (2011)
Smolin, L.: The case for background independence. In: Rickles, D., French, S., Saatsi, J. (eds.) The Structural Foundations of Quantum Gravity, pp. 196–239. Oxford University Press, Oxford (2006)
Albert, D.: Quantum Mechanics and Experience. Harvard University Press, Cambridge (1992)
Omnès, R.: Understanding Quantum Mechanics. Princeton University Press, Princeton (1999)
Saunders, S., Barrett, J., Kent, A., Wallace, D. (eds.): Many Worlds? Everett. Quantum Theory Reality. Oxford University Press, Oxford (2010)
Weinberg, S.: Newtonianism, reductionism and the art of congressional testimony. Nature 330, 433–437 (1987)
Dawid, R.: String Theory and the Scientific Method. Cambridge University Press, Cambridge (2013)
Castellani, E., Rickles, D. (eds.): Special Issue on Dualities in Physics. Stud. Hist. Philos. Mod. Phys. 59, 1–142 (2017)
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2019 Springer Nature Switzerland AG
About this chapter
Cite this chapter
Crowther, K. (2019). When Do We Stop Digging? Conditions on a Fundamental Theory of Physics. In: Aguirre, A., Foster, B., Merali, Z. (eds) What is Fundamental?. The Frontiers Collection. Springer, Cham. https://doi.org/10.1007/978-3-030-11301-8_13
Download citation
DOI: https://doi.org/10.1007/978-3-030-11301-8_13
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-11300-1
Online ISBN: 978-3-030-11301-8
eBook Packages: Physics and AstronomyPhysics and Astronomy (R0)