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Four Principles for Quantum Gravity

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Gravity and the Quantum

Part of the book series: Fundamental Theories of Physics ((FTPH,volume 187))

Abstract

Four principles are proposed to underlie the quantum theory of gravity. We show that these suffice to recover the Einstein equations. We also suggest that MOND results from a modification of the classical equivalence principle, due to quantum gravity effects.

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Notes

  1. 1.

    The notion of causal sets was introduced by [7]. Causal sets built out of intrinsic structures was developed by [11,12,13].

  2. 2.

    A different proposal for relative locality is in [18].

  3. 3.

    This does not yet address the need for dark matter on scales of clusters and large scale structure. It is possible that these are explained by dark matter while MOND explains the galaxy rotation curves.

  4. 4.

    The notion of causal sets was introduced by [7]. Causal sets built out of intrinsic structures was developed by [11,12,13].

  5. 5.

    This idea is developed in relational quantum theory [23,24,25] and relative locality [14, 15].

  6. 6.

    Related ideas have been suggested previously in [49].

  7. 7.

    The idea that dark energy might be the result of non-locality in loop quantum gravity, or disordered locality [51], was suggested in [52]. The extension of this to dark matter and MOND was studied in an unpublished draft [53].

  8. 8.

    A related argument was proposed in [54].

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Acknowledgements

I would like to thank Andrzej Banburski, Jacob Barnett, Linqing Chen, Marina Cortes, Bianca Dittrich, Laurent Freidel, Henriques Gomes, Andrew Liddle, Stacy McGaugh, Mordehai Milgrom, Krishnamohan Parattu, Percy Paul and Vasudev Shyam for very helpful discussions and encouragement. I am also indebted to Stacy McGaugh for permission to reproduce Fig. 1 and its caption from [21].

This research was supported in part by Perimeter Institute for Theoretical Physics. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Research and Innovation. This research was also partly supported by grants from NSERC, FQ** and the John Templeton Foundation.

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    Lee Smolin

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  1. Department of Physical Sciences, IISER Mohali, Mohali, Punjab, India

    Jasjeet Singh Bagla

  2. Ryussi Technologies Pvt. Ltd., Pune, India

    Sunu Engineer

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Smolin, L. (2017). Four Principles for Quantum Gravity. In: Bagla, J., Engineer, S. (eds) Gravity and the Quantum. Fundamental Theories of Physics, vol 187. Springer, Cham. https://doi.org/10.1007/978-3-319-51700-1_26

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