No Geodynamos in 2D

Ideas about how a world with more than three spatial dimensions would work - what laws of physics would be needed, how things would be built, how people would do things and so on.

No Geodynamos in 2D

Postby PatrickPowers » Sun Jan 24, 2016 5:23 am

According to David Stevenson of Cal Tech, there are no geodynamos in 2D. The third dimension is necessary to break symmetry. No magnetic fields for 2D planets.

https://www.youtube.com/watch?v=F488kOmhu9Q
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Re: No Geodynamos in 2D

Postby PatrickPowers » Sun Jan 24, 2016 12:57 pm

On second thought I think Stevenson was speaking loosely. Convective cooling is possible in 2D. That and rotation could be all that is necessary. Besides, geodynamos are favored in bodies with a very large radius. 2D planets would have extremely large radii.
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Re: No Geodynamos in 2D

Postby PatrickPowers » Tue Dec 11, 2018 1:03 pm

Looking at this three years later, there certainly isn't a Coriolis effect in 2D. So no geodynamos.
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Re: No Geodynamos in 2D

Postby mr_e_man » Tue Dec 11, 2018 10:44 pm

There is Coriolis in 2D! It's always perpendicular to the direction of motion; so if something were moving along the rotating planet's surface, it would feel like more or less gravity. If something were rising or falling, it would be deflected sideways.
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Re: No Geodynamos in 2D

Postby PatrickPowers » Tue Dec 11, 2018 11:35 pm

mr_e_man wrote:There is Coriolis in 2D! It's always perpendicular to the direction of motion; so if something were moving along the rotating planet's surface, it would feel like more or less gravity. If something were rising or falling, it would be deflected sideways.


No, that's the Eotvos effect. You are correct in that they are essentially the same thing, but in physics the Coriolis effect is a lot more important so the Eotvos effect is excluded as an unnecessary complication. The Eotvos effect doesn't create a geodynamo. There are no geodynamos near the equator, where the Eotvos effect is at its maximum and the Coriolis at minimum. The plumes of magma rise and fall, but they don't rotate, so no geodynamo.

What sort of magnetic field would a planet with a Clifford rotation have? It could be quite weak. There would be plenty of Coriolis effect everywhere, but each such would be cancelled by an equal and opposite antipodal potential geodynamo. Also the radius of a 4D planet could be a lot less, which is unfavorable for geodynamos.
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