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Science. 1998 Dec 18;282(5397):2230-4.

A free-fall determination of the newtonian constant of gravity

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J. P. Schwarz and J. E. Faller, JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440, USA. D. S. Robertson, National Geodetic Survey, NOS, NOAA, and CIRES, University of Colorado, Bould.


Recent determinations of the Newtonian constant of gravity have produced values that differ by nearly 40 times their individual error estimates (more than 0.5%). In an attempt to help resolve this situation, an experiment that uses the gravity field of a one-half metric ton source mass to perturb the trajectory of a free-falling mass and laser interferometry to track the falling object was performed. This experiment does not suspend the test mass from a support system. It is therefore free of many systematic errors associated with supports. The measured value was G = (6.6873 +/- 0. 0094) x 10(-11) m3 kg-1 sec-2.

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