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Mountains and Gravity [pdf]

nature.com

16 points by omarchowdhury 5 years ago · 13 comments

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imglorp 5 years ago

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 5 years ago

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 5 years ago

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

    • dfischer 5 years ago

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

      • anvandare 5 years ago

        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

        • Gravityloss 5 years ago

          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.

        • dfischer 5 years ago

          Makes sense. Is it enough pressure to power a rudimentary digital computation without needing another source of power? Hmm.

  • scott31 5 years ago

    Yeah it makes even less sense than EmDrive

    • dfischer 5 years ago

      Why if you could take the time to share your understanding and help enlighten me?

  • omarchowdhuryOP 5 years ago

    Crazy would be not to try.

    • dfischer 5 years ago

      A try I shall do! I’ve had some interesting ideas with it but I feel stupid and or silly reasoning about it. For the sake of experimentation and fun I’ll definitely play around soon.

082349872349872 5 years ago

now we've even measured to https://en.wikipedia.org/wiki/Geoid#Anomalies

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