Measurements of Newton's gravitational constant and the length of day
Abstract
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 \text{yr} , an amplitude of (1.619 +/ 0.103) × 10^{14} \text{m}^{3} \text{kg}^{1} \text{s}^{2} , and meanvalue 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 innercore 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 Earthbased experiments measure G. In this case, there might be correlations with terrestrialmagneticfield measurements.
 Publication:

EPL (Europhysics Letters)
 Pub Date:
 April 2015
 DOI:
 10.1209/02955075/110/10002
 arXiv:
 arXiv:1504.06604
 Bibcode:
 2015EL....11010002A
 Keywords:

 General Relativity and Quantum Cosmology
 EPrint:
 6 pages, 4 figures, 1 table, added appendix in response to arXiv:1505.01774 [grqc]