The gravitational constant is fundamental quantity of the universe. The gravitational constant, G, was the first great universal constant of physics (the others subsequently being the speed of light and Planck's constant) and modern physicists still argue its importance and relationships to cosmology. Regardless, almost all the major theoretical frameworks dictate that the value for the gravitational constant (G) is in some regard related to the large-scale structure of the cosmos. Ironically, despite centuries of research, the gravitational constant, G, is—by a substantial margin—the least understood, most difficult to determine, and least precisely known fundamental constant value. The quest for "G" provides a continuing challenge to the experimental ingenuity of physicists, and often spurs new generations of physicists to recapture the inventiveness and delicacy of measurement first embodied in the elegant experiments conducted by English physicist Henry Cavendish (1731–1810).

The Cavendish constant "G" must not...