Abstract
One of the great challenges for 21st century physics is to quantize gravity and generate a theory that will unify gravity with the other three fundamental forces of nature. This paper takes the (heretical) point of view that gravity may be an inherently classical, i.e., nonquantum, phenomenon and investigates the experimental consequences of such a conjecture. At present there is no experimental evidence of the quantum nature of gravity and the likelihood of definitive tests in the future is not at all certain. If gravity is, indeed, a nonquantum phenomenon, then it is suggested that evidence will most likely appear at mesoscopic scales.
Similar content being viewed by others
References
Weyl, H.: Gravitation and electricity. Translated from Sitz. Preuss. Akad. Wissen. (1918) In: The Principle of Relativity, pp. 201–216 (1923). (Reprinted by Dover, New York (1952))
Kaluza, T.: Zum unitstaetsproblem in der physik. Sitz.ber. Preuss. Akad. Wiss., 966–972 (1921)
Eddington, A.: The Mathematical Theory of Relativity. Cambridge University Press, Cambridge (1923). Chap. 7
Green, M., Schwarz, J., Witten, E.: Superstring Theory. Cambridge University Press, Cambridge (1987)
Ashtekar, A., Rovelli, C.: Connections, loops and quantum general relativity. Class. Quantum Gravity 9, S3–S12 (1992)
Moller, C.: Les Theories Relativistes de la Gravitation. In: Lichnerowicz, A., Tonnelat, M.-A. (eds.) Colloques Internationaux CNRS, vol. 91. CNRS, Paris (1962)
Rosenfeld, L.: On quantization of fields. Nucl. Phys. 40, 353–356 (1963)
Carlip, S.: Is quantum gravity necessary? Class. Quantum Gravity 25, 154010 (2008)
Zurek, W.: Decoherence, einselection, and the quantum origins of the classical. Rev. Mod. Phys. 75, 715–775 (2003)
Hall, M., Reginatto, M.: Interacting classical and quantum ensembles. Phys. Rev. A 72, 062109 (2005)
Weinberg, S., Witten, E.: Limits on massless particles. Phys. Lett. B 96, 59–82 (1980)
Barceló, C., Visser, M., Liberati, S., Ahluwalia, D.: Einstein Gravity as an Emergent Phenomenon? Int. J. Mod. Phys. D 10, 799–806 (2001)
Dyson, F.: The world on a string, review of The Fabric of the Cosmos: Space, Time, and the Texture of Reality by Brian Greene. New York Rev. Books 51(8) (2004)
Rothman, T., Boughn, S.: Can gravitons be detected? Found. Phys. 36, 1801–1825 (2006)
Boughn, S., Rothman, T.: Aspects of graviton detection: graviton emission and absorption by atomic hydrogen. Class. Quantum Gravity 23, 5839–5852 (2006)
Smolin, L.: On the intrinsic entropy of the gravitational field. Gen. Relativ. Gravit. 17, 417–437 (1985)
Misner, C., Thorne, K., Wheeler, J.: Gravitation. Freeman, New York (1973). Chap. 37
Milgrom, M.: A modification of the Newtonian dynamics as a possible alternative to the hidden mass hypothesis. Astrophys. J. 270, 365–370 (1983)
Hackermuller, L., Uttenthaler, S., Hornberger, K., Reiger, E., Brezger, B., Zeilinger, A., Arndt, M.: Wave nature of biomolecules and fluorofullerenes. Phys. Rev. Lett. 91, 090408 (2003)
Lamine, B., Herve, R., Lambrecht, A., Reynaud, S.: Ultimate decoherence border for matter-wave interferometry. Phys. Rev. Lett. 96, 050405 (2006)
Penrose, R.: On gravity’s role in quantum state reduction. Gen. Relativ. Gravit. 8, 581–600 (1996)
Diosi, L.: Model for universal reduction of macroscopic quantum fluctuations. Phys. Rev. A 42, 1165–1174 (1989)
Ghirardi, G., Grassi, R., Rimini, A.: Continuous-spontaneous-reduction model involving gravity. Phys. Rev. A 42, 1057–1064 (1990)
Zurek, W.: Pointer basis of quantum apparatus: into what mixture does the wave packet collapse? Phys. Rev. D 24, 1516–1525 (1981)
Schlosshauer, M.: Decoherence, the measurement problem, and interpretations of quantum mechanics. Rev. Mod. Phys. 76, 1267–1305 (2005)
Joos, E.: In: Blanchard, P., Giulini, D., Joos, E., Kiefer, C., Stamatescu, I. (eds.) Decoherence: Theoretical, Experimental, and Conceptual Problems. In: Lecture Notes in Physics, No. 538, p. 14. Springer, New York (2000)
Page, D., Geilker, C.: Indirect evidence for quantum gravity. Phys. Rev. Lett. 47, 979–982 (1981)
Marshall, W., Simon, C., Penrose, R., Bouwneester, D.: Towards quantum superpositions of a mirror. Phys. Rev. Lett 91, 130401 (2003)
Armour, A., Blencowe, M., Schwab, K.: Entanglement and decoherence of a micromechanical resonator via coupling to a Cooper-pair box. Phys. Rev. Lett. 88, 148301 (2002)
Myatt, C., : Decoherence of quantum superpositions through coupling to engineered reservoirs. Nature 403, 269–273 (2000)
Hackermueller, L., Hornberger, K., Brezger, B., Zeilinger, A., Arndt, M.: Nature 427, 711–714 (2003)
Eppley, K., Hannah, E.: The necessity of quantizing the gravitational field. Found. Phys. 7, 51–68 (1977)
Terno, D.: Inconsistency of quantum-classical dynamics. Found. Phys. 36, 102–111 (2006)
Caro, J., Salcedo, L.: Impediments to mixing classical and quantum dynamics. Phys. Rev. A 60, 842–852 (1999)
Peres, A., Terno, D.: Hybrid classical-quantum dynamics. Phys. Rev. A 63, 022101 (2001)
Padmanabhan, T.: Is gravity an intrinsically quantum phenomenon? Mod. Phys. Lett. A 17, 1147–1158 (2002)
Mattingly, J.: Why Eppley and Hannah’s thought experiment fails. Phys. Rev. D 73, 064025 (2006)
Einstein, A., Podolsky, B., Rosen, N.: Can quantum-mechanical description of physical reality be considered complete? Phys. Rev. 47, 777–780 (1935)
Albers, M., Kiefer, C., Reginatto, M.: Measurement analysis and quantum gravity. Phys. Rev. D 73, 064051 (2008)
Schiff, L.: Quantum Mechanics, 3rd edn. McGraw-Hill, New York (1968). Chap. 11
Ford, L.: Gravitational radiation by quantum systems. Ann. Phys. 144, 238–248 (1982)
Pound, R., Rebka, G.: Apparent weight of photons. Phys. Rev. Lett. 4, 337–341 (1960)
Salzman, P., Carlip, S.: A possible experimental test of quantized gravity. arXiv:gr-qc/0606120 (2006)
van Wezel, J., Oosterkamp, T., Zaanen, J.: Towards an experimental test of gravity-induced quantum state reduction. Philos. Mag. 88, 1005–1026 (2008)
Stapp, H.: The Copenhagen interpretations. Am. J. Phys. 40, 1098–1116 (1972)
Bekenstein, J.: Black holes and entropy. Phys. Rev. D 7, 2333–2346 (1973)
Hawking, S.: Particle creation by black holes. Commun. Math. Phys. 43, 199–220 (1975)
Preskill, J.: Do black holes destroy information? arXiv:hep-th/9209058 (1992)
Hawking, S.: Information loss in black holes. Phys. Rev. D 72, 0840013 (2005)
Hayden, P., Preskill, J.: Black holes as mirrors: quantum information in random subsystems. J. High Energy Phys. 09, 120 (2007)
Bahcall, N., Ostriker, J., Perlmutter, S., Steinhardt, P.: The cosmic triangle: Revealing the state of the universe. Science 284, 1481–1488 (1999)
Kolb, E., Matarrese, S., Riotto, A.: On cosmic acceleration without dark energy. New J. Phys. 8, 322 (2006)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Boughn, S. Nonquantum Gravity. Found Phys 39, 331–351 (2009). https://doi.org/10.1007/s10701-009-9282-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10701-009-9282-0