Newton's gravitational constant has eluded scientists for centuries

During a presentation at the American Physical Society meeting in April 2022, he gave the impression that he was about to open the envelope to read a number that would indicate the outcome of his most recent efforts to pursue a lifelong passion.

The gravitational constant of Newton was a goal for Schlamminger of the National Institute of Standards and Technology in Gaithersburg, Maryland. In his NIST experiment, the hidden number in the envelope served as a form of code—an intentional and deliberate inaccuracy introduced to obfuscate the measurement as it developed. The number was only known by one individual. And Schlamminger was not that individual.

He couldn't know the results of the experiment without access to it. To guard against bias in the experiment, including unconscious bias that can afflict even the greatest experimenters, Schlamminger had imposed the secrecy on himself. Extra care was taken to protect the integrity of an experiment that could assist in resolving enigmatic inconsistencies in measurements of the constant G that have developed over the past few years.

The gravitational force between any two objects with mass is expressed as G, also known as "big G" (to distinguish it from "g," which depends on G and is the particular case of the acceleration of gravity near the surface of the Earth). It establishes the trajectories of planets and galaxies and explains the gravitational attraction.

It's also quite challenging to measure. Recent G measurements are concerning despite two centuries of increased precision. Several laboratories across the globe have produced figures that diverge (SN Online: 4/30/15). The dispersed values can indicate issues with the measurement methods used by different parties, or they might point to something more interesting.

Speake claims that there is a "haunting elephant in the room" that raises the possibility that there is something going on that we are unaware of. It might be the biggest discovery since Newton if the measurements are accurate.

Schlamminger's revelation was planned to be virtual, similar to many other scientific presentations during the time of COVID-19. It's likely that I wasn't the only physicist or scientific journalist squinting at a screen.

The envelope needed to be torn open at this point. However, the video stream ceased. The big unveiling was no longer happening. The measurements included some strange disparities that made it impossible to believe the results. Schlamminger returned to the lab to attempt one of the most difficult observations in physics once more, but the envelope remained sealed for at least another year.

Next time will be speaking of: 

What is Newton’s gravitational constant?

Recent measurements of big G don’t agree

Why do we care about the precision of big G?

Other approaches to measuring big G

The original G test

The original torsion balance design (pictured), created more than 200 years ago by Henry Cavendish, provides the foundation for many of the G tests used today. Cavendish suspended two tiny lead spheres from a wire at either side of a long pole. Larger lead spheres were placed close by (inset). The force of attraction between the smaller and larger lead spheres was seen in the way the hanging rod twisted on its wire. An ongoing experiment at NIST employs copper cylinders rather than lead spheres.

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