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Earth-based clocks test general relativity

Optical clocks held at slightly different heights provide a stringent test of general relativity comparable to space experiments and open new opportunities for clock-based geophysical sensing.

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Fig. 1: Illustration of how in the future relativistic geodesy might be done with clocks.


  1. Walsh, D., Carswell, R. & Weymann, R. Nature 279, 381–384 (1979).

    ADS  Article  Google Scholar 

  2. Clemence, G. M. Rev. Mod. Phys. 19, 361–364 (1947).

    ADS  Article  Google Scholar 

  3. Takamoto, M. et al. Nat. Photon. (2020).

    Article  Google Scholar 

  4. Pound, R. V. & Snider, J. L. Phys. Rev. 140, B788–B803 (1965).

    ADS  Article  Google Scholar 

  5. Delva, P. et al. Phys. Rev. Lett. 121, 231101 (2018).

    ADS  Article  Google Scholar 

  6. Herrmann, S. et al. Phys. Rev. Lett. 121, 231102 (2018).

    ADS  Article  Google Scholar 

  7. Katori, H., Takamoto, M., Pal’chikov, V. G. & Ovsiannikov, V. D. Phys. Rev. Lett. 91, 173005 (2003).

    ADS  Article  Google Scholar 

  8. Origlia, S. et al. Phys. Rev. 98, 053443 (2018).

    Article  Google Scholar 

  9. Koller, S. B. et al. Phys. Rev. Lett. 118, 073601 (2017).

    ADS  Article  Google Scholar 

  10. Grotti, J. et al. Nat. Phys. 14, 437–441 (2018).

    Article  Google Scholar 

  11. Vermeer, M. Reports of the Finnish Geospatial Research Institute 83 (National Land Survey of Finland, 1983).

  12. Bjerhammar, A. Bull. Geod. 59, 207–220 (1985).

    Article  Google Scholar 

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Correspondence to Kai Bongs.

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Bongs, K., Singh, Y. Earth-based clocks test general relativity. Nat. Photonics 14, 408–409 (2020).

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