Constant of nature; the fundamental Newton’s law of gravity and thus a measure for the natural strength of gravity. Analogously, in Einstein’s equations in the general theory of relativity, it occurs as the proportionality factor determining how strongly mass, energy and similar properties of matter distort space and time. In formulae, it is usually written as G. The best current value for G is
G = 6.674 30(15)·10-11m³kg-1s-2.
Compared with other fundamental constants, G is known only to a comparatively low accuracy.