Abstract
Following a line of research that I have developed for several years, I argue that the best strategy for understanding quantum gravity is to build a picture of the physical world where the notion of time plays no role at all. I summarize here this point of view, explaining why I think that in a fundamental description of nature we must “forget time”, and how this can be done in the classical and in the quantum theory. The idea is to develop a formalism that treats dependent and independent variables on the same footing. In short, I propose to interpret mechanics as a theory of relations between variables, rather than the theory of the evolution of variables in time.
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Ashtekar, A.: Gravity and the quantum. New J. Phys. 7, 198 (2005)
Rovelli, C.: Time in quantum gravity: an hypothesis. Phys. Rev. D 43, 442 (1991)
Rovelli, C.: Quantum mechanics without time: a model. Phys. Rev. D 42, 2638 (1991)
Rovelli, C.: Quantum evolving constants. Phys. Rev. D 44, 1339 (1991)
Rovelli, C.: What is observable in classical and quantum gravity? Class. Quantum Gravity 8, 297 (1991)
Rovelli, C.: Quantum reference systems. Class. Quantum Gravity 8, 317 (1991)
Rovelli, C.: Is there incompatibility between the ways time is treated in general relativity and in standard quantum mechanics? In: Ashtekar, A., Stachel, J. (eds.) Conceptual Problems of Quantum Gravity. Birkhauser, New York (1991)
Rovelli, C.: Analysis of the different meaning of the concept of time in different physical theories. Nuovo Cimento 110B, 81 (1995)
Rovelli, C.: Partial observables. Phys. Rev. A 65, 124013 (2002). gr-qc/0110035
Rovelli, C.: A note on the foundation of relativistic mechanics. I: Relativistic observables and relativistic states. In: The Proceedings of the 15th SIGRAV Conference on General Relativity and Gravitational Physics, Rome, September (2002). gr-qc/0111037 (to appear)
Rovelli, C.: A note on the foundation of relativistic mechanics. II: Covariant Hamiltonian general relativity. gr-qc/0202079 (2002)
Rovelli, C.: Covariant Hamiltonian formalism for field theory: symplectic structure and Hamilton-Jacobi equation on the space G. In: The Proceedings of the Conference DICE 2002, Piombino, September 2002. Lect. Notes Phys., vol. 633, pp. 36–62. Springer, Berlin (2003)
Reisenberger, M., Rovelli, C.: Spacetime states and covariant quantum theory. Phys. Rev. D 65, 124013 (2002). gr-qc/0111016
Marolf, D., Rovelli, C.: Relativistic quantum measurement. Phys. Rev. D 66, 023510 (2002). gr-qc/0203056
Rovelli, C.: Quantum Gravity. Cambridge University Press, Cambridge (2004)
Dittrich, B.: Partial and complete observables for canonical general relativity. Class. Quantum Gravity 23, 6155–6184 (2006)
Dittrich, B., Tambornino, J.: A perturbative approach to Dirac observables and their space-time algebra. Class. Quantum Gravity 24, 757–784 (2007)
Rovelli, C., Smolin, L.: Phys. Rev. Lett. 61, 1155 (1988)
Rovelli, C., Smolin, L.: Nucl. Phys. B 331, 80 (1990)
Ashtekar, A., Rovelli, C., Smolin, L.: Phys. Rev. Lett. 69, 237 (1992)
Iwasaki, J., Rovelli, C.: Int. J. Mod. Phys. D 1, 533 (1993)
Rovelli, C., Smolin, L.: Nucl. Phys. B 442, 593–619 (1995)
Perez, A.: Nucl. Phys. B 599, 427–434 (2001)
Crane, L., Perez, A., Rovelli, C.: Phys. Rev. Lett. 87, 181301 (2001)
Crane, L., Perez, A., Rovelli, C.: arXiv:gr-qc/0104057 (2001)
Engle, J., Livine, E., Pereira, R., Rovelli, C.: Nucl. Phys. B 799, 136 (2008)
Engle, J., Pereira, R., Rovelli, C.: Nucl. Phys. B 798, 251 (2008)
Engle, J., Pereira, R., Rovelli, C.: Phys. Rev. Lett. 99, 161301 (2007)
Freidel, L., Krasnov, K.: Class. Quantum Gravity 25, 125018 (2008)
Baez, J.C.: Spin foam models. Class. Quantum Gravity 15, 1827 (1998)
Arnold, V.I.: Matematičeskie metody klassičeskoj mechaniki. Mir, Moscow (1979). See in particular Chapter IX, Section C
Souriau, J.M.: Structure des systemes dynamics. Dunod, Paris (1969)
Lagrange, J.L.: Mémoires de la première classe des sciences mathematiques et physiques. Institute de France, Paris (1808)
Rovelli, C.: Statistical mechanics of gravity and thermodynamical origin of time. Class. Quantum Gravity 10, 1549 (1993)
Rovelli, C.: The statistical state of the universe. Class. Quantum Gravity 10, 1567 (1993)
Connes, A., Rovelli, C.: Von Neumann algebra automorphisms and time versus thermodynamics relation in general covariant quantum theories. Class. Quantum Gravity 11, 2899 (1994)
Martinetti, P., Rovelli, C.: Diamonds’s temperature: Unruh effect for bounded trajectories and thermal time hypothesis. Class. Quantum Gravity 4919–4932 (2003)
Rovelli, C., Smerlak, M.: Thermal time and the Tolman-Ehrenfest effect: temperature as the ‘speed of time’. Class. Quantum Gravity 28, 075007 (2011)
Hartle, J.: Spacetime quantum mechanics and the quantum mechanics of spacetime. In: Julia, B., Zinn-Justin, J. (eds.) Proceedings on the 1992 Les Houches School, Gravitation and Quantisation, p. 285. Elsevier Science, Paris (1995)
Halliwell, J.: The Wheeler-deWitt equation and the path integral in minisuperspace quantum cosmology. In: Ashtekar, A., Stachel, J. (eds.) Conceptual Problems of Quantum Gravity. Birkhauser, New York (1991)
Halliwell, J.: The interpretation of quantum cosmology and the problem of time. In: Proceedings of Stephen Hawking’s 60th Birthday Conference (2002). gr-qc/0208018 (to appear)
Smolin, L.: The present moment in quantum cosmology: challenges to the arguments for the elimination of time. In: Durie, R. (ed.) Time and the Instant. Clinamen Press, Manchester (2000)
Ismael, J.: The Situated Self. Oxford University Press, London (2006)
Ismael, J.: Temporal experience. In: Oxford Handbook on Time (2011) (to appear)
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Rovelli, C. “Forget time”. Found Phys 41, 1475–1490 (2011). https://doi.org/10.1007/s10701-011-9561-4
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DOI: https://doi.org/10.1007/s10701-011-9561-4