After a decade of careful work, scientists at NIST have announced a new measurement of the universal gravitational constant, G. The result, published in a new report, does not match another leading measurement of the same fundamental quantity. The difference is extremely small, but for a constant that underpins our understanding of gravity, even tiny discrepancies matter.
The finding adds fresh fuel to a puzzle that has persisted for 225 years. Physicists have long struggled to pin down G with high precision because gravity is so weak compared with other fundamental forces. The new NIST value, produced with an experiment designed to reduce uncertainty, instead introduces more tension rather than resolving it.
Because this article is based on a single source, there is no independent source to compare or corroborate the details. The report notes only that the discrepancy is unexpected and that it deepens the longstanding mystery. No explanation is offered in the source for why the two measurements differ.