2015/04/01 by J. D. Anderson, John D. Anderson, Gerald Schubert +3 · 1 citation
Decision Sciences · Earth and Planetary Sciences · Physics and Astronomy · #Geophysics and Gravity Measurements #Scientific Measurement and Uncertainty Evaluation #Scientific Research and Discoveries #gr-qc
paper · pdf · doi:10.1209/0295-5075/110/10002
published as EPL 110 (2015) 10002 · 6 pages, 4 figures, 1 table, added appendix in response to arXiv:1505.01774 [gr-qc]
openalex publication_date 2015/04/01 · arxiv created 2015/05/22 · arxiv updated 2015/05/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
About a dozen measurements of Newton's gravitational constant, G, since 1962 have yielded values that differ by far more than their reported random plus systematic errors. We find that these values for G are oscillatory in nature, with a period of P = 5.899 ± 0.062 yr, an amplitude of (1.619 ± 0.103) × 10-14 m3 kg-1 s-2, and mean-value crossings in 1994 and 1997. However, we do not suggest that G is actually varying by this much, this quickly, but instead that something in the measurement process varies. Of other recently reported results, to the best of our knowledge, the only measurement with the same period and phase is the Length of Day (LOD - defined as a frequency measurement such that a positive increase in LOD values means slower Earth rotation rates and therefore longer days). The aforementioned period is also about half of a solar activity cycle, but the correlation is far less convincing. The 5.9 year periodic signal in LOD has previously been interpreted as due to fluid core motions and inner-core coupling. We report the G/LOD correlation, whose statistical significance is 0.99764 assuming no difference in phase, without claiming to have any satisfactory explanation for it. Least unlikely, perhaps, are currents in the Earth's fluid core that change both its moment of inertia (affecting LOD) and the circumstances in which the Earth-based experiments measure G. In this case, there might be correlations with terrestrial-magnetic-field measurements.