Work in quantum gravity suggests that spacetime is not fundamental. Rather, spacetime emerges from an underlying, non-spatiotemporal reality. After clarifying the type of emergence at issue, I argue that standard conceptions of emergence available in metaphysics won’t work for the emergence of spacetime. I go on to consider spacetime functionalism as a way to make sense of spacetime emergence. I argue that a functionalist approach to spacetime modelled on mental state functionalism is not a viable alternative to the standard conception of emergence in metaphysics. I go on to consider an alternative: ‘partial’ functionalism, whereby certain aspects of spacetime are functionalised, rather than spacetime as a whole.
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Causation is usually thought to be a relation between events, which are individuated by their spatiotemporal locations. Baron and Miller (2014), Tallant (2018) argue that causation without time is possible. However, the resulting notion of causation may not be sufficient for observation [see Braddon-Mitchell and Miller (2019)].
A number of philosophers suggest that there is a non-causal, mathematical style of explanation that plays a substantive role in scientific explanation. Gravitational explanations and geometric explanations are often cited as examples, see Colyvan (2001, pp. 50–52).
It may be false for strong emergence, see Barnes (2012).
One might argue that some approaches cannot be understood in compositional terms, such as Hu’s (1999) account of emergent gravity, and so we shouldn’t try to capture quantum gravity inside this framework. However, note that Hu appears to characterise his own emergent gravity program in compositional terms (of course we would need to look at the details):
Something assumed to be ‘elementary’ at a lower energy or with a coarser resolution at one time will later be found to be a composite at a higher energy or under a finer resolution... Constructing the macroscopic structure and dynamics from known microscopic constituents is often easier, such as getting hydrodynamics from molecular dynamics. Going the other way, i.e., deducing molecular features from hydrodynamics, is more difficult. For spacetime structures, the former is the task of emergent gravity, the latter is the goal of quantum gravity. (Hu 2009, p. 3)
Moreover, even if the compositional approach is a non-starter for Hu’s view, the causal sets approach and loop quantum gravity appear to posit physical entities at high energy scales that could potentially compose entities at low energies.
I am grateful to an anonymous referee for raising this issue.
Braddon-Mitchell and Miller (2006, pp. 224–225) also argue that the concept of a part breaks down when STP is falsified.
Le Bihan (2017) makes this suggestion.
One option that has been suggested to me by a referee for this journal is to look more carefully at Causal Set Theory. Like LQG, Causal Set Theory, lacks fundamental spacetime (see Huggett and Wüthrich 2013). Nonetheless, the basic elements of Causal Set Theory do seem to be isomorphic to a part-whole structure of some kind. I lack the space to consider this option here, but I agree broadly that causal set theory provides a more natural basis for developing a notion of parthood* and a mereological conception of spacetime emergence.
Ney (2015) briefly argues against the use of spacetime functionalism as the basis for emergence. The argument I will present goes beyond the cursory remarks that Ney makes, but is broadly similar in spirit.
I am grateful to two anonymous referees for pressing me on this issue.
Anderson, E. (2012). Problem of time in quantum gravity. Annalen der Physik, 524, 757–786.
Bain, J. (2013). The emergence of spacetime in condensed matter approaches to quantum gravity. Studies in History and Philosophy of Modern Physics, 44, 338–345.
Barbour, J. (1999). The End of Time. Oxford: Oxford University Press.
Barnes, E. (2012). Emergence and fundamentality. Mind, 121, 873–901.
Baron, S., & Miller, K. (2014). Causation in a timeless world. Synthese, 191, 2867–2886.
Barrett, J. A. (1999). The quantum mechanics of minds and worlds. New York: Oxford University Press.
Bilson-Thompson, S., Hackett, J., & Kauffman, L. (2009). Particle topology, braids and braided belts. Journal of Mathematical Physscs, 50, 113505.
Bilson-Thompson, S., Hackett, J., Kauffman, L., & Wan, Y. (2012). Emergent braided matter of quantum geometry. SIGMA, 8, 14–47.
Bilson-Thompson, S. O. (2005). A topological model of composite preons. https://arxiv.org/abs/hep-ph/0503213.
Bilson-Thompson, S. O., Markopolou, F., & Smolin, L. (2007). Quantum gravity and the standard model. Classical and Quantum Gravity, 24, 3975.
Braddon-Mitchell, D., & Miller, K. (2006). The physics of extended simples. Analysis, 66, 222–226.
Braddon-Mitchell, D., & Miller, K. (2019). Quantum gravity, timelessness and the contents of thought. Philosophical Studies, 179(7), 1807–1829.
Butterfield, J., & Isham, C. (1999). On the emergence of time in quantum gravity. In The arguments of time (pp. 111–168). Oxford: Oxford University Press.
Colyvan, M. (2001). The indispensability of mathematics. Oxford: Oxford University Press.
Crowther, K. (2016). Effective spacetime: Understanding emergence in effective field theory and quantum gravity. Heidelberg: Springer.
Crowther, K. (2018). Inter-theory relations in quantum gravity: Correspondence, reduction, and emergence. Studies in History and Philosophy of Modern Physics, 63, 74–85.
de Haan, J. (2006). How emergence arises. Ecological Complexity, 3, 293–301.
Feinberg, T. E. (2001). Why the mind is not a radically emergent feature of the brain. Journal of Consciousness Studies, 8, 123–145.
Gilmore, C. (2018). Location and mereology. In E. N. Zalta (Ed.) Stanford encyclopedia of philosophy. https://plato.stanford.edu/archives/fall2018/entries/location-mereology/. Accessed 1 June 2019.
Healey, R. (2002). Can physics coherently deny the reality of time? In C. Callender (Ed.), Time, Reality & Experience (pp. 293–316). Cambridge: Cambridge University Press.
Hu, B.-L. (1999). Stochastic gravity. International Journal of Theoretical Physics, 38(11), 2987–3037.
Hu, B.-L. (2009). Emergent/quantum gravity: Macro/micro structures of spacetime. Journal of Physics: Conference Series, 174, 1–16.
Huggett, N., & Wüthrich, C. (2013). Emergent spacetime and empirical (in)coherence. Studies in History and Philosophy of Modern Physics, 44, 276–285.
Humphreys, P. (1997). How properties emerge. Philosophy of Science, 64, 1–17.
Kim, J. (1999). Making sense of emergence. Philosophical Studies, 95, 3–36.
Knox, E. (2017). Physical relativity from a functionalist perspective. Studies in History and Philosophy of Modern Physics. https://doi.org/10.1016/j.shpsb.2017.09.008.
Kuchar, K. V. (1992). Canonical quantum gravity. In R. J. Gleiser, C. N. Kozameh & O. M. Moreschi (Eds.), General relativity and gravitation 1992: Proceedings of the 13th international conference on general relativity and gravitation (pp. 119–150). Bristol: Institute of Physics Publishing.
Lam, V., & Esfeld, M. (2013). A dilemma for the emergence of spacetime in canonical quantum gravity. Studies in History and Philosophy of Modern Physics, 44, 286–293.
Lam, V., & Wüthrich, C. (2018). Spacetime is as spacetime does. Studies in History and Philosophy of Modern Physics, 64, 39–51.
Le Bihan, B. (2017). Priority monism beyond spacetime. Metaphysica. https://doi.org/10.1515/mp-2018-0005.
Markosian, N. (2014). A spatial approach to mereology. In S. Kleinshmidt (Ed.), Mereology and Location. Oxford: Oxford University Press.
Maudlin, T. (2007). Completeness, supervenience and ontology. Journal of Physics A: Mathematical and Theoretical, 40, 3151–3171.
Ney, A. (2015). Fundamental physical ontologies and the constraint of empirical coherence: A defense of wave function realism. Synthese, 192, 3105–3124.
Oriti, D. (2014). Disappearance and emergence of space and time in quantum gravity. Studies in History and Philosophy of Modern Physics, 46, 186–199.
Parsons, J. (2007). Theories of location. In Oxford studies in metaphysics (Vol. 3, pp. 201–232). Oxford University Press.
Paul, L. A. (2002). Logical parts. Noûs, 36, 578–596.
Paul, L. A. (2012). Building the world from its fundamental constituents. Philosophical Studies, 158, 221–256.
Reuger, A. (2000). Physical emergence, diachronic and synchronic. Synthese, 124, 297–322.
Rovelli, C. (2004). Quantum gravity. Cambridge: Cambridge University Press.
Sider, T. (2007). Parthood. Philosophical Review, 116, 51–91.
Tallant, J. (2018). Causation in a timeless world? Inquiry. https://doi.org/10.1080/0020174X.2018.1446051.
Van Cleve, J. (1990). Mind-dust or magic? Pansychism versus emergence. Philosophical Perspectives, 4, 215–226.
Van Gulick, R. (2001). Reduction, emergence and other recent options on the mind/body problem: A philosophic overview. Journal of Consciousness Studies, 8, 1–34.
Wilson, J. (2016). Metaphysical emergence: Weak and strong. In T. Bigaj & C. Wüthrich (Eds.), Metaphysics in contemporary physics (pp. 345–402). Leiden: Brill.
Wüthrich, C. (forthcoming). The emergence of space and time. In S. Gibb, R. F. Hendry & T. Lancaster (Eds.), Routledge handbook of emergence. Routledge.
I am grateful to two anonymous referees for their immensely helpful feedback on the paper. Earlier versions of this paper were presented at the CPT/FraMEPhys Workshop on Time and Explanation held at the University of Milan and the First International Workshop on Time held at Osaka City University. I am grateful to audiences at both workshops for their feedback on the paper, and am especially grateful to Alastair Wilson for hosting the Milan workshop and Takeshi Sakon for hosting the Osaka workshop. Work on this paper was funded by an Australian Research Council Discovery Early Career Researcher Award DE180100414 and a Discovery Project DP180100105.
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Baron, S. The curious case of spacetime emergence. Philos Stud 177, 2207–2226 (2020). https://doi.org/10.1007/s11098-019-01306-z