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Earth's Magnetic Field

  1. May 30, 2010 #1
    I am very curious about the planet's weakening magnetic field. From what I understand, it's leading up to a pole shift that will occur in the next 500-1000 years.

    During this time, there will be a period where the field is drastically weakened; this period goes on for quite some time, correct?

    So my question: what exactly occurs during a pole shift? As far as I know, there will be Auroras everywhere, multiple poles in bizarre locations, radioactive storms, and EMP. Is this correct?
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  3. May 30, 2010 #2


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    Welcome to PF!

    Hi lukifell! Welcome to PF! :smile:

    No, more like 20,000 - 1,000,000 years … see http://en.wikipedia.org/wiki/Earth's_magnetic_field#Magnetic_field_reversals"

    and http://en.wikipedia.org/wiki/Geomagnetic_reversal#History"
    Last edited by a moderator: Apr 25, 2017
  4. May 31, 2010 #3


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    Since modern humans have never observed a geomagnetic reversal, we can't be too sure about what the precise impact may be on electronics and our electrical grid. However, we do know that our ancestors (homo erectus) survived numerous reversals. There are also no wide spread die offs of life during the thousands of reversals that have occurred over the history of the earth. This may be because the solar wind induces a magnetic field that shields the earths surface from energetic cosmic particles even in the absence of the Earth's normal magnetic field.

    So, the actual impact of a reversal may be gradual, minimal and insignificant to most people.
  5. Jun 1, 2010 #4
    With all due respect, Tiny-tim, I think you answered a different question than was asked. Lukifell wasn't asking about the frequency of reversals, he/she asked what would happen during a reversal. Also magnetic reversals aren't predictable, so your 20,000 to 1,000,000 year estimate is merely a wild guess - consider the 40,000,000 year Cretaceous Long Normal or the 70,000 year Kaena (keeping in mind that the last reversal was 780,000 years ago). Lukifell is perhaps referring to the fact that the geomagnetic field intensity has decreased 10% over the last 150 years with the magnetic dipole loosing ground to higher order polar components. Some, not all, consider this to be a sign that a reversal is impending. There is some evidence that suggests that while the time between reversals is large, a reversal itself can happen in a geological instant. This would include magnetic field changes of 6 degrees/day frozen into lava flows at Steens Mountain, Oregon.
  6. Jun 1, 2010 #5


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    Yes, scientists think we might see a flip in the next thousand years, but it's a pole reversal.

    You might be interested in the South Atlantic Anomaly, a large area where the earth's magnetic field has dipped drastically.

    Last edited: Aug 28, 2011
  7. Jun 2, 2010 #6
    As I understand the process there will be many smaller poles for a period of time before the actual "switch" takes place. the danger to this is that a large solar fragment could devistate the earth during that period without the strong magnetic field to protect us.
  8. Jun 2, 2010 #7


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    Not true.

    This risk is equivalent to that which people living
    within the arctic circle currently face.

    Many people will probably not even notice a problem.
  9. Jun 9, 2010 #8

    Thanks for the responses, definitely interesting.

    I wasn't aware of the anomaly. Wow. Thanks for the link. The article I read on Nova talked about worldwide auroras, multiple poles in weird places like Africa, and other stuff. I'll see if I can dredge up a link. But yeah, there hasn't been a drop-off of life before, but the dinosaurs didn't use computers.

    If there were some sort of worldwide electromagnetic disturbance, planes would fall out of the sky and all you'd know is what your neighbor told you. It'd be back to the dark ages, right? According to the events of the storm in 1859, the telegraph literally caught on fire, operators were electrocuted, and in some places, the telegraph was perfectly fine and work without being connected to a battery.
  10. Jun 9, 2010 #9


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    Those are pole shifts, not to be confused with pole reversals. I'll look up a link.

    This gives you the differnce in a nutshell, and easy to see the difference.


    And here is a great NOVA segment on pole reversal.

    Last edited by a moderator: Apr 25, 2017
  11. Jun 10, 2010 #10
    The most damage would be to the power grid in the big cities and the generators that put the power into the grid.
    That could take years to recover from because new generators would have to be built.
    If the power companies had enough warning they could shut down and the damage might be minimal but I doubt that all the power companies would shut down even if they had days notice. Most would probably decide to "ride it out" and deal with the aftermath.
    Yep! just like the dark ages. People would have to learn to read again. :)
  12. Aug 23, 2010 #11
    A couple of questions:
    1) Do you think the earths magnetic field effected the size of life forms in the past in relation to its strength?
    2)Do you think the earths magnetic field effected the general lifespan of life on our planet(this is just a thought, when thinking about the tales of ancient biblical life)?
  13. Aug 23, 2010 #12


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    There is no evidence that I know of that would support this.
    No, the last reversal was over 700,000 years ago.
  14. Oct 16, 2010 #13
    I think MichaelDieu is referring to the biblical references of Noah and many others stated to have existed for several hundred years or so, and whether or not the magnetic field itself was different back then and affected the lifespan of 'ancient biblical life'.

    If this telegraph worked without a battery connected to it, whether or not the magnetic field was stronger or weaker epoc's ago it would have affected the biology of all lifeforms in one way or another because it would be affecting any form of electromagnetism from molecules to DNA and RNA to cells, bacteria and organisms.

    The Magnetic field is percieved by the force it exerts on moving electric charges (countless moving electric charges are needed to support a single cell, let alone a whole organism).
    The magnetic field to any observer is specified by a direction and a magnitude;

    "Viewed from above the magnetic north pole (geographic south), ions circulate clockwise, electrons counterclockwise, producing a net circulating clockwise current, known (from its shape) as the ring current. No voltage is needed—the current arises naturally from the motion of the ions and electrons in the magnetic field."

    Some animals tell direction through their biology by the magnetic field, so lifeforms have evolved with it's help (ex. shark's Ampullae of Lorenzini electroreceptors).
    "Ocean currents moving in the magnetic field of the Earth also generate electric fields that sharks can use for orientation and possibly navigation."
    How an organism may be affected by the electromagnetic field of the Earth, or any changes in it is also a question of the biology and chemistry of thier design. A magnetic pole shift may affect the neurochemistry of the shark.
    Last edited: Oct 16, 2010
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