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“The tennis racket theorem or intermediate axis theorem, is a kinetic phenomenon of classical mechanics which describes the movement of a rigid body with three distinct principal moments of inertia. It has also dubbed the Dzhanibekov effect, after Soviet cosmonaut Vladimir Dzhanibekov, who noticed one of the theorem's logical consequences whilst in space in 1985. Formally the effect had been known for at least 150 years, having been described by Louis Poinsot in 1834.” - wiki

Would this affect the crust, or is it too spherical and spinning on its primary axis to flip? If not the crust, could it flip the core if it is shaped so that it is rotating on its intermediate axis? Or is the core too close to spherical and rotating around its primary access to cause the core to flip?

I am asking regarding the flipping of the magnetic poles and in regards to the “Noah Myth” in the Bible about a “great flood.”

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2 Answers 2

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As you note, Earth is spherical (and already spinning on an axis). So, the three moments of inertia required for the Dzhanibekov Effect are not very distinct. Without some massive additional force suddenly being applied to Earth, it's not going to happen. The Dzhanibekov Effect does apply to some of our neighbours like asteroids and Pluto's moon Nix, for example.

With regard to magnetic pole flipping, geological records suggest this happens with some regularity and since it's a reversible process, it can also come close to happening but then revert. A threat occasioned by pole flipping would be strong solar radiation caused by puncturing of Earth's temporarily weakened magnetic field** by solar flares. Floods, not particularly expected.

You might the link below interesting. In contrast to your question it examines how abrupt sea change levels cause magnetic reversal.

https://www.osti.gov/servlets/purl/1004148

** the weakened protective magnetic field would allow for holes to be made in the ozone layer.

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  • $\begingroup$ I’m aware of pole flipping and its effects. I was more interested in what would cause it. Since the core seems to be less spherical, I wondered if the Dzhanibekov Effect would be more possible with the core. $\endgroup$
    – Digcoal
    Commented Mar 24 at 19:03
  • $\begingroup$ Consider that the Dzanibekov Effect was first noticeably observed in a wingnut: the object possesses a hollow core, the centre of gravity being significantly shifted along the axis of rotation in comparison to Earth which has a spheroidal solid iron core. The dynamics between the crust-mantle (taking them as one here) molten outer core and solid inner core are complex but there are other factors not mentioned in the answer making the Earth's rotation stable: 1) speed of rotation 2) gravitational stabilisation by the Sun and Moon. We're nowhere near tumbling in space like a wingnut is. $\endgroup$
    – Wookie
    Commented Mar 24 at 21:26
  • $\begingroup$ From the article you posted: “Changes in the moment of inertia of the earth, brought about by the redistribution of ocean water from the tropics to ice at high latitudes, couple energy from the spin of the earth into convection in the liquid core.” so we are back to the Dzhanibekov Effect possibly being back in play due to the Earth’s oceans creating an off center moment if inertia. $\endgroup$
    – Digcoal
    Commented Jun 18 at 12:16
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    $\begingroup$ Yes, that is part of the abstract and the paper more substantially deals with massive incoming bolides applying the additional force necessary for effectual ocean water displacement as referred to in the first paragraph of the answer. $\endgroup$
    – Wookie
    Commented Jun 18 at 15:06
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The weight distribution of earth is not very symmetric at all, especially when taking the polar ice caps and the core mantle into account. There are 2 huge mantle blobs known as Large Low-Velocity Provinces (LLVP). They are located at:

  • 1st blob is located beneath the Pacific Ocean.
  • 2nd blob is located under the African continent.
  • Both are twice the size of our moon.

Therefore it is highly likely that earth has flipped several times due to this instability. There are several Youtube videos on explaining this in detail. In addition there are many anthropological and archeological indications that that has happened many times in earths history. (I'm not going to list any of those references here,as they are readily available in large quantities a google search away.

enter image description here

It should also be clear that the inner core rotates (mostly) separately from the outer core and mantle ([2]). In addition it has been recently discovered that the inner core rotation have slowed down ([3]). Because of the fluidity and dynamics in rotation period of inner,vs surface, modelling a flip would be both very difficult and likely yield inaccurate results in terms of time-frame/duration of such an event.

However, both ancient texts and geological features seem to indicate that the surface effects of such a flip could happen in a very short period of 1-5 days, with catastrophic and/or near-extinction level type of global floods and tsunamis. The oceans would be relatively sloshing around to adjust to crustal movements.

enter image description here

Reference:

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  • $\begingroup$ Would you say that the core is irregularly shaped enough for it to flip at fairly regular intervals causing the magnetic poles to flip with them? I imagine that the crust is regularly shaped enough ti not experience a flip, but your sources suggest the core may be able to. Such flipping would mostly likely cause geological variations as well, I would think. $\endgroup$
    – Digcoal
    Commented Jun 17 at 19:09
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    $\begingroup$ @Digcoal Added update to my answer. Yes, it would happen again, but the time interval would not be completely regular as the entire mass system is continuously evolving, with some mantle/crust viscosity dependency on solar and intergalactic magnetic fields. Many (but unverified) geologic studies seem to indicate a time interval of ~12,000 years. $\endgroup$
    – not2qubit
    Commented Jun 18 at 9:21
  • $\begingroup$ The second word should probably be “weight,” and in your last paragraph “near-distinction” is probably supposed to be “near-extinction.” Other than that, thank you for your answer and update. $\endgroup$
    – Digcoal
    Commented Jun 18 at 12:11
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    $\begingroup$ @Digcoal Thanks, fixed. Not sure why my spell checker doesn't work under SE edit. $\endgroup$
    – not2qubit
    Commented Jun 18 at 12:19
  • $\begingroup$ No worries. Cheers 🍻 $\endgroup$
    – Digcoal
    Commented Jun 19 at 14:59

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