Condensed Matter Physics and the Nature of Spacetime
Background: In the philosophy of spacetime literature not much attention has been given to concepts of spacetime arising from condensed matter physics. These are based on analogies between spacetime and a quantum liquid that have arisen from effective field theoretical approaches to highly correlated many-body quantum systems. Such approaches have suggested to some authors that spacetime can be modeled by a quantum liquid with its contents (matter and force fields) being given by effective field theories (EFT's, hereafter) that describe the low-energy excitations of this liquid. While directly relevant to ongoing discussions concerning the ontological status of spacetime, this programme also has many consequences that philosophers of physics in general should be interested in. It suggests, for instance, a particular approach to quantum gravity (e.g., Smolin 2003), as well as an "anti-Grand Unified Theory", anti-reductionalist attitude towards the nature of symmetries and EFT's in quantum field theory (e.g., Zhang 2004, Volovik 2003, Laughlin and Pines 2000, Froggatt and Nielsen 1991). While some discussion of these topics has appeared in the philosophical and historical literature (e.g., Cat 1999), the gory theoretical details have not been made explicit. Moreover, while the topic of EFT's in the philosophy of quantum field theory literature has also been given some attention (e.g., Castellini 2002, Hartmann 2001, Huggett and Weingard 1997, Cao and Schweber 1993), surprisingly little has been said about how EFT's arise in condensed matter systems. Examples of simple (2+1)-dimensional EFT's in condensed matter systems include (see, e.g., Zhang 2004):
Cao, T. Y. and S. Schweber (1993) 'The Conceptual Foundations and the Philosophical Aspects of Renormalization Theory', Synthese 97, pp. 33-108.
Castellani, E. (2002) 'Reductionism, Emergence, and Effective Field Theories', Studies in History and Philosophy of Modern Physics 33, pp. 251-267.
Cat, J. (1999) 'The Physicists' Debates on Unification in Physics at the End of the 20th Century', Historical Studies in the Physical and Biological Sciences 28, pp. 253-300.
Froggatt, C. D. and H. B. Nielsen (1991) Origin of Symmetries, World Scientific: Singapore.
Hartmann, S. (2001) 'Effective Field Theories, Reductionism and Scientific Explanation', Studies in History and Philosophy of Modern Physics 32, pp. 267-304.
Huggett, N. and R. Weingard (1995) 'The Renormalization Group and Effective Field Theories', Synthese 102, pp. 171-194.
Laughlin, R. B. (2003) 'Emergent Relativity', gr-qc/0302028.
Laughlin, R. B. and D. Pines (2000) 'The Theory of Everything', Proceedings of the National Academy of Sciences 97, pp. 28-31.
Novello, M., M. Visser, and G. Volovik (2002) Artificial Black Holes, World Scientific: Singapore.
Smolin, L. (2003) 'How Far Are We From the Quantum Theory of Gravity?', hep-th/0303185.
Sparling, G. A. J. (2002) 'Twistor Theory and the Four-Dimensional Quantum Hall Effect of Zhang and Hu', cond-mat/0211679.
Unruh, W. G. (1981) 'Experimental Black-Hole Evaporation?', Physical Review Letters 46, pp. 1351-1353.
Visser, M. (1998) 'Acoustic Black Holes: Horizons, Erogspheres and Hawking Radiation', Classical and Quantum Gravity 15, pp. 1767-1791.
Vollhardt, D. and P. Wölfle (2000) 'Superfluid Helium 3: Link Between Condensed Matter Physics and Particle Physics', Acta Physica Polonica B 31, pp. 2837-2856. Available online as cond-mat/0012052.
Volovik, G. (2003) The Universe in a Helium Droplet, Oxford University Press: Oxford.
Zhang, S. -C. (2004) 'To See a World in a Grain of Sand', in Science and Ultimate Reality: Quantum Theory, Cosmology and Complexity, J. D. Barrow, P. C. W. Davies, C. L. Harper (eds.), Cambridge University Press: Cambridge, pp. 667-690. Available online as hep-th/0210162.