BUT. Thousands of measurements spanning all the continents over many decades document changes in the pull over local scales. These are correlated with the observed properties of subsurface media (rocks, sediments, ice, water) in exploration settings, or with sun-moon positions, as you alluded to. Collectively, the local variations of the pull measured from all these gravimeters point to spatial and temporal variations in that pull. This collection of measurements and supporting ground truthing data is the evidence that gravity is the force exerting the pull, rather than a uniform upward acceleration.
Are you sure that the weight in a seismometer/gravimeter device isn't returning to its zero state in the raw readings of these gravity signals?
Look at the first graph in black called "SG Raw Gravity" here, from a superconducting gravimeter:
https://www.researchgate.net/figure/Raw-gravity-black-contains-all-signals-Residual-gravity-with-the-step-function-blue_fig2_264122117The first graph in black, labled "Raw Gravity" seems to be returning to a zero state. If the mass in the superconducting gravimeter device (suspended by magnetism) was being pulled upwards or downwards - and stayed that way - we should see something more like the step functions and residual graphs, constantly rising or lowering, rather than something that looks like a seismograph that returns to its zero state.
Here is a live reading from a gravimeter in Sweden:
http://holt.oso.chalmers.se/hgs/SCG/monitor-plot.htmlThe Observed Gravity (middle black) shows that there is a bunch of noise, labeled with a 'Typical noise level' range, and the thinner yellow line is the gravity signal.
So it looks like:
- There is a bunch of noise which dwarfs the gravity signal.
- The signal in the raw results returns to a zero or common state and the signal does not stay suspended or suppressed, except in step sizing algorithms and filters
The Sweden Gravimeter site also has a 24 hour gravity plot:
http://holt.oso.chalmers.se/hgs/SCG/daily-residual-plots.htmlWhen gravity gets stronger, the yellow gravity signal grows thicker.
The black is presumably still the noise like in the previous graph.
It gets vertically thicker because the earth is moving more violently up and down, like in a vertical component seismometer.
Of course, this 'violent' movement is very small.
It is telling that we have to look into noise to get the gravity signal. If the gravity signal is dwarfed by noise then the gravity signal could be a component of whatever else is causing that noise, such as seismic activity, which would explain why
those gravity anomaly maps on the gravimetery page are all associated with seismic zones.