Gravity gets measured to greater certainty

Despite more than 200 years of experiments, the best laboratory determinations of the force of gravity have yielded no better than a ballpark figure. Adding to the haziness, metrologists have scarcely probed the force's strength at distances of 1 millimeter or less. There, gravity may vary drastically from Newton's law, possibly signaling the presence of unseen extra dimensions, some theories suggest (SN: 2/19/00, p. 122: Hunting for Higher Dimensions).

Penetrating the fog, researchers in Seattle now report preliminary results from two separate gravity experiments. One set of findings offers the most precise value thus far for the