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Flat Earth Theory / Re: Gravity - measurement and applications
« on: September 09, 2020, 07:46:24 PM »
Tom, thanks for providing the link to the wiki. It was an interesting read. My questions stemmed from that, and I will try to rephrase.
My issue is that the gravimeter readings of local changes in relative pull, as the wiki puts it, are supported by the subsequent drilling of boreholes and measurement of the properties from the subsurface materials. In mining camp settings, there are hundreds of boreholes drilled to provide the necessary ground-truthing.
I would argue that the wiki article misrepresents the density differences that are interpreted from the changing reading on gravimeters. It's really the total amount of mass beneath the meter (the relative densities of subsurface materials just influence the total mass because denser materials have more mass per unit volume).
The other issue is the seismometer-gravimeter comparison. The wiki article seems to argue that the fact that the two are variations of the same setup invalidates either of them. That's just not true because both are devices that measure acceleration. Why would they need to be different? The fact that they differ in precision and frequency is a function of the nature of the acceleration they are developed to measure at-large amplitude high frequency seismic waves vs. Low amplitude low frequency gravitational variations.
The wiki article does no seem to provide any explanation as to why the relative pull measured by a gravimeter would change over small areas, nor why temporal changes in gravitational strength are observed across large areas.
If you could provide further clarification to those last points that would be great!
Cheers
Edit, these variations are often in the interior portions of tectonic plates and far from mountains or other features
My issue is that the gravimeter readings of local changes in relative pull, as the wiki puts it, are supported by the subsequent drilling of boreholes and measurement of the properties from the subsurface materials. In mining camp settings, there are hundreds of boreholes drilled to provide the necessary ground-truthing.
I would argue that the wiki article misrepresents the density differences that are interpreted from the changing reading on gravimeters. It's really the total amount of mass beneath the meter (the relative densities of subsurface materials just influence the total mass because denser materials have more mass per unit volume).
The other issue is the seismometer-gravimeter comparison. The wiki article seems to argue that the fact that the two are variations of the same setup invalidates either of them. That's just not true because both are devices that measure acceleration. Why would they need to be different? The fact that they differ in precision and frequency is a function of the nature of the acceleration they are developed to measure at-large amplitude high frequency seismic waves vs. Low amplitude low frequency gravitational variations.
The wiki article does no seem to provide any explanation as to why the relative pull measured by a gravimeter would change over small areas, nor why temporal changes in gravitational strength are observed across large areas.
If you could provide further clarification to those last points that would be great!
Cheers
Edit, these variations are often in the interior portions of tectonic plates and far from mountains or other features