Scientists seal a ten-year measurement of the gravitational constant G and find it still does not match existing measurements. Gravity still does not make sense.

[Finley_19]

A physicist who spent a decade measuring the gravitational constant G with a sealed-envelope prediction published the result on May 18th and found the mystery deepened rather than resolved. G, the constant that describes how strongly masses attract each other, has been measured hundreds of times since Cavendish in 1798 and the measurements disagree with each other in ways that no other fundamental constant does. The precision of individual measurements has improved dramatically while the spread between different experiments has not narrowed.

The gravitational constant is the least precisely known fundamental constant in physics, despite gravity being the first force to be mathematically described. The ongoing disagreement between measurement teams suggests either unidentified systematic errors in experimental setups or something genuinely unknown about gravity at the laboratory scale.

Space & Time News

https://www.sciencedaily.com/news/space_time/

[Callum28]

The gravitational constant being the worst measured fundamental constant despite being the first one we understood is one of physics' great ironies. We have been trying for over 200 years and the measurements still disagree

[TheGreatMoney]

The sealed envelope methodology is unusually rigorous for a metrological result. Committing to a prediction before opening the comparison data eliminates post-hoc adjustment of the analysis

[RayOfLight32]

G is the only fundamental constant that cannot be traced to atomic physics standards. The kilogram, the metre, and the second are now all defined through quantum phenomena. G sits outside that framework

[IronFist38]

The spread between G measurements from different laboratories is not narrowing as precision improves. That pattern strongly suggests systematic errors that each team cannot identify in their own setup

[Raven]

Every measurement of G uses torsion balance variants descended from Cavendish's original experiment. The possibility that the experimental geometry itself has systematic issues has never been ruled out

[ScarletDaemon]

If the disagreement is not systematic error then it implies something about gravity at the sub-millimetre scales these experiments probe. There are theoretical reasons to expect modifications at that scale from extra dimensions

[QubitZero13]

A constant that disagrees between experiments is not actually a constant in any useful sense. The practical implications are limited because the disagreement is at the part per thousand level, but philosophically it is uncomfortable

[Owen84]

The dark matter gravitational wave paper from the same week and the Schrodinger's clock result and this all point at the same fundamental question. We do not understand gravity at the edges of its domain

[Badger27]

The measurement problem with G is that gravity is so weak relative to other forces that you need very large masses or very precise instruments to measure it. Both create systematic uncertainty