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I Foucault pendulum and a round globe

  1. Nov 30, 2017 #1
    Imagine we are all cavemen without satellite technology and just discovered the Foucault pendulum! As we know the angle of presession depends on the latitude. This can be used to prove that the earth is rotating, right? Now by putting several Foucault pendula around the Earth, at equidistant longitude and latitude, can we prove that the Earth is a sphere as well?
  2. jcsd
  3. Nov 30, 2017 #2


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    You could exclude a lot of potential shapes, and by assuming certain smoothness between your sample positions narrow it down to a sphere.
  4. Nov 30, 2017 #3
    cool. then all pendula must be installed at the same altitude to guarantee smoothness. :smile:
  5. Nov 30, 2017 #4


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    It's not about the altitude, but how densely they are spaced.

    Also, since pendulums are based on gravity, you have to assume some model of gravity, which by itself might already imply an equipotential surface, without even the need for swinging pendulums.
    Last edited: Nov 30, 2017
  6. Nov 30, 2017 #5


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    Wouldn't it be much easier for them to just glance at the sky and notice how the position of the North Star varies with latitude?
    (Flaw: The North Star moves, it was not north in all periods of history.)
  7. Nov 30, 2017 #6


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    If it was (very) cloudy all over the Earth, it would be harder to arrive at an initial Geocentric model Universe but the Fuocault pendulums would definitely indicate rotation. No one would every have moved to a Heliocentric model, I reckon ('till Radio came along).
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