Reanalysis of Old Eötvös Data Suggests 5th Force…To Some

Newton's gravitational constant has been with us for three centuries. Yet despite our long and intimate acquaintance, we know this fundamental constant of nature to little better than a part per thousand. Astronomical data are of scant use, because they always involve G multiplied by the mass of the Earth or some celestial body, and our knowledge of the mean density of such bodies is even more uncertain. Our best knowledge of G comes from modern variants of the classic Cavendish experiment, measuring the horizontal force between test bodies at distances up to a few meters in the laboratory.