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Does Gravity Cause Heat Flow to the Center of the Earth?

  1. Aug 16, 2015 #1
    Here is a review article identifying some causes for the high temperature in the central volume of the Earth. http://www.scientificamerican.com/article/why-is-the-earths-core-so/

    Inside all massive astronomical bodies like the Earth, collisions of atoms occur in a gravitational field. Because of gravity, atoms moving toward the center of mass of the Earth would have greater velocities associated with them than atoms moving away from the center of mass.

    Within the Earth, are atomic collisions toward the Earth's center of mass more energetic than those for atoms moving away from its center of mass? Would that factor tend to cause heat flow toward the center of mass?
  2. jcsd
  3. Aug 16, 2015 #2


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  4. Aug 17, 2015 #3
    I don't think so. Gravity in a liquid is offset by hydrostatic pressure.
    That is why you are near weightless under water.
    In a liquid atoms or molecules do not collide.
    For that you need a gas, where in the constituent particles are ballistic.
  5. Aug 18, 2015 #4

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    No. That would violate the second law of thermodynamics.

    That said, the Earth's core does generate heat. There might be some radioactive material in the Earth's core. Most geophysicists don't think there would be very much, but there might be some. The reason is the chemistry of the sidereophiles in the Earth's core and the lithophiles in the mantle and crust.

    Two larger sources of heat are a result of the Earth's growing inner core. Freezing is an exothermic reaction; it releases latent heat. Finally, gravitation does play a role in generating heat in the Earth's core. There is a marked density discontinuity at the inner core / outer core boundary. The inner core is more dense than is the outer core. This means that gravitational potential energy is being released as heat as the inner core grows.
  6. Aug 18, 2015 #5
    Heat flows in the opposite direction, its hotter deep down due to gravitation and probably a little radioactivity. You don't see volcanoes spewing out ice.
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