Borehole Measurement of the Newtonian Gravitational Constant

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Science  21 Aug 1987:
Vol. 237, Issue 4817, pp. 881-883
DOI: 10.1126/science.237.4817.881


It has been reported that the geophysically determined Newtonian gravitational constant is consistently larger than the laboratory value by 1 to 2% on the basis of gravity measurements in Australian mines. This discrepancy may have strong implications for the physics of gravitation. To test whether similar results can be observed in a different geological environment, gravity measurements in a Michigan borehole have been examined. Although these results cannot be taken as conclusive, owing to the large uncertainties involved in mass determination on a geophysical scale, these measurements are generally consistent with those of the Australian experiment.