Variations in Gravity

The Variations in Gravity are the supposed variations to gravity due to either the gravity gradient of the earth or due to the presence of masses such as hills or celestial bodies. A number of tests have been conducted in search of these variations.

It has been found that in experiments on medium, long, and 'celestial' ranges, "gravity" does not deviate from the Universality of Free Fall or the Equivalence Principle. Nor can external gravity sources be felt. Gravity appears to behave as if the earth is accelerating upwards, that there is no gravity gradient, and there are no other gravitating sources around us.

Celestial Variations in G
The Equivalence Principle Torsion Balance tests are incredibly reliable precision machines which are used to measure the Equivalence Principal to increasing sensitivity. Experimenters have redesigned the Equivalence Principle's Torsion Balance tests to try and detect the gravity variations caused by the sun, moon, and the tidal forces. It was found that the gravitational influence of the sun, moon, or the tidal forces could not be measured as manifest of the attraction of the bodies in the experiments. Variations to "gravity" did not appear.

Princeton Experiment
From 'The Pendulum Paradigm: Variations on a Theme and the Measure of Heaven and Earth', by Professor Martin Beech, we read the following on p.176:



Essentially, the experiment is summarized as follows:

The masses were not attracted to the sun in the experiment, to an accuracy of one part in one hundred billion.

Moscow State University Experiment
The experiment was repeated and improved by researchers at Moscow State University. The title of the paper states the conclusion:

Verification of the Equivalence of Inertial and Gravitational Mass V. B. Branginsky and V. I. Panov Full Text Link (Archive)

Repetitions
Additional experiments of this class are described (Archive). The two experiments experiment in this list is the Princeton and Moscow State experiments above:

The Eöt-Wash experiments were repeated by others:

https://plato.stanford.edu/entries/physics-experiment/app4.html (Archive)

Universality of Free Fall
The Newtonian gravitational constant: recent measurements and related studies By George T Gillies

https://iopscience.iop.org/article/10.1088/0034-4885/60/2/001/pdf

p.200

'''5. Searches for variations in G 5.1. Spatial dependence of G'''

p.202

It should be noted that 500 meters is 1640.42 feet, and about as high as the Shanghai World Financial Center, a skyscraper in China.

Eöt-Wash Hill Experiments
From No Easy Answers: Science and the Pursuit of Knowledge by Allan Franklin, on p.70 we read a summary of the Eöt-Wash hillside experiments with the rotating torsion balance:

Study Link

An Eöt-Wash presentation explains (Archive) that the influence of an external source mass on these type of experiments would be a violation of the Equivalence Principle (EP).



One will notice from the graphic above that any horizontal pulling phenomenon would violate Equivalence Principle which states that gravity operates exactly like a rocket ship accelerating upwards at 1G with no other gravitating bodies around.

Short Range Variations in G
On shorter ranges, such as with the Cavendish Experiment, it has been seen that the attraction is not consistent, which might suggest that there are other effects at that range creating or modifying those results. See the Cavendish Experiment.