NIST’s 10‑Year Experiment Yields New Value for Gravitational Constant, Confirms Long‑Standing Discrepancy

After a decade of meticulous work, the National Institute of Standards and Technology (NIST) released a new measurement of the universal gravitational constant, G, from an experiment that had been sealed for ten years. The value differs unexpectedly from the most precise result obtained by another leading laboratory, widening the gap that has persisted for 225 years. Although the numerical difference is tiny—on the order of parts per million—it is significant for a constant that underpins all of gravitation theory. The finding deepens the mystery surrounding G and suggests that either subtle experimental errors remain unaccounted for or that the physics community may need to consider new theoretical explanations. The result will prompt additional independent measurements and a re‑examination of systematic uncertainties in G determinations.