We now have the most precise estimates for the strength of gravity yet.
Two experiments measuring the tiny gravitational attraction between objects in a lab have measured Newton’s gravitational constant, or Big G, with an uncertainty of only about 0.00116 percent. Until now, the smallest margin of uncertainty for any G measurement has been 0.00137 percent.
The new set of G values, reported in the Aug. 30 Nature, is not the final word on G. The two values disagree slightly, and they don’t explain why previous G-measuring experiments have produced such a wide spread of estimates (SN Online: 4/30/15). Still, researchers may be able to use the new values, along with other estimates of G, to discover why measurements for this key fundamental constant are so finicky — and perhaps pin down the strength of gravity once and for all.