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Effect of the 1999 solar eclipse on atomic clocks


Solar eclipses have been reported to have a strange influence on the behaviour of atomic clocks1 and pendulums2,3, which has been attributed to some unknown feature of gravity4. Here we correct this idea after being unable to detect any anomalous changes in the relative rates of three types of atomic clock, based on the ground-state hyperfine transitions of hydrogen, rubidium and caesium, during the solar eclipse of 11 August 1999 over central Europe.

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Figure 1: Time differences in four atomic clocks during the solar eclipse.


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Udem, T., Reichert, J., Holzwarth, R. et al. Effect of the 1999 solar eclipse on atomic clocks. Nature 402, 749–750 (1999).

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