Overview
- NIST published a decade-long replication in Metrologia that measured the gravitational constant G as 6.67387 × 10^-11 m^3 kg^-1 s^-2.
- The team rebuilt a BIPM-style torsion balance with eight weights on two turntables and also used an electrical torque method as an independent cross-check.
- Researchers ran the setup with copper and then sapphire masses and got nearly the same result, which rules out material-dependent bias.
- The measured value comes in lower than the earlier BIPM result and the CODATA recommendation, and it does not close the long-standing spread among top experiments.
- The work tightens control of tiny forces and improves instruments and software, which could help future tests reach closer agreement as other gravity-based measurements gain precision.