
Mountains and Gravity [pdf] - omarchowdhury
https://www.nature.com/articles/1691079a0.pdf
======
imglorp
Fascinating subject.

I feel someone should make a long-form, James Burke Connections style piece on
how mountain gravity was measured and how it fits in with history.

The label on the tin might say, "While surveying the Allegheny mountains in
1772, surveyors encountered a systematic error they could not explain, and
took a side track into the developing theory of gravitation to resolve it." It
ties together Newton, Cavendish, Mason and Dixon, the Royal Society, mountains
on two continents, the mass of the Earth, and the fields of astronomy,
geology, physics, and surveying.

------
dfischer
Is it completely crazy to potentially harvest energy from gravity through the
force of pressure on crystals sitting in between a mountain generating
piezoelectricity and perhaps doing some form of computation or cymatics with
it?

~~~
FreeFull
A constant pressure isn't enough to produce power. You'd need a changing
pressure.

~~~
dfischer
At what rate? Is there enough geological movement to induce a change of
pressure? What type of gradient/size/rate is needed here?

~~~
anvandare
Thankfully, we already have a source of constantly changing pressure: the
Moon! (Well, the Earth's rotation)

Since the Earth rotates around its own axis, you're oscillating closer to and
further from the Moon every 24 hours. When you're "facing" the Moon, it's
puling you up (from the Earth). When you're away from the moon (on the
opposite end of the Earth) it's pulling you down (toward the Earth).

This (along with other factors) causes tides. And tides are already used to
generate power.[1] Including using the piezo-electric effect (not sure how
with what efficiency, though).

[1]
[https://en.wikipedia.org/wiki/Tidal_power](https://en.wikipedia.org/wiki/Tidal_power)

~~~
Gravityloss
Interesting idea.

You could carve a few cubic kilometers of rock. Raise it when the moon is at
zenith. Lower it when the moon is on the other side of earth.

There was this idea to use a carved rock cylinder for pumped water energy
storage (have the water under the cylinder).

You could even combine these.

Of course, in reality the difference in gravity is so tiny, the round trip
efficiency is too low, killing the idea.

------
082349872349872
now we've even measured to
[https://en.wikipedia.org/wiki/Geoid#Anomalies](https://en.wikipedia.org/wiki/Geoid#Anomalies)

