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Magnetic Field Fluctuations

  1. Jun 10, 2008 #1
    I have heard many claims about many things over the years, but this on interested me very much, and I'd like to know if there is truth behind it. According to this documentary I watched, the Earth's magnetic fields have reversed many times in the past. Apparently, some beleive we are about due for another switch, and the Bermuda Triangle is an effect of this slow, radical process. Could this be true?
  2. jcsd
  3. Jun 11, 2008 #2


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    That's 100% true. If we look at the remnant magnetism in igneous rocks, we can see that they are polarised in the direction of the magnetic field at the time they formed. If we look at areas near ocean ridges, we can see alternating bands of N & S polarised rock where new crust has formed in different magnetic fields.

    I've heard this too. A weakening of the field and a magnetic anomaly in the south atlantic may point to the fact that it has already begun. I don't know how certain people are about this. Any switch will be very slow (thousands of years) and won't be the drastic and dangerous event the apocalypse junkies and 2012 nuts believe.

    No. As far as I know no magnetic anomalies have been observed in the triangle. Sounds like someone just made that up to make the topic sound more interesting. I won't go in to the issue of whether there's anything unusual about the triangle though.
  4. Jun 11, 2008 #3
    Excuse me if im wrong but wouldnt studying magnetism by the ocean not be a good palce to study. I remember an experiment in Chemistry class that we actually changed polarization and magnetism with water and heat(i believe)

    Again excuse me if im wrong, but magnetic fields can move through water cant they? And hasn't it been a known fact that the entire magnetic field throughout the world is slowly diminishing?
  5. Jun 11, 2008 #4
    "Again excuse me if im wrong, but magnetic fields can move through water cant they?"

    Well, to my knowledge, magnetic fields pass through just about anything, including water, but how is that relevant? After all, these areas studied are formed of igneous rock. As the igneous rock cools, the iron grains in the molten rock alligns with the Earth's magnetic field. Once fully cool, these metal bits won't turn around. So, if at the time of eruption the field is varied just a little, it would show up in our studies.

    "I remember an experiment in Chemistry class that we actually changed polarization and magnetism with water and heat(i believe)"
    Number one, i don't believe water is magnetic, but i suppose that is possible.
    Number two, These rock formations were formed long before humans heated up the planet, therefor the changes would be completly natural.

    "And hasn't it been a known fact that the entire magnetic field throughout the world is slowly diminishing?"
    Well, the diminishing magnetic field could be a sign of this switch. After all, you have to slow to a stop before you can turn change to reverse.
    Last edited: Jun 11, 2008
  6. Jun 11, 2008 #5
    Simple. The magnetic field was attracted or repelled by something much more powerful than the small particles itself. You dont have to stop to turn around if your on a globe though. They could rotate themselves around instead of stopping.

    And u flawed ur logic with the igneous rock show.

    can someone show me proof that the magnetic fields have switched before?
  7. Jun 11, 2008 #6
    ya, read my edited post one up from yours.
  8. Jun 11, 2008 #7
  9. Jun 12, 2008 #8
    Not only can reversal of the magnetic field be found using iron grains in igneous but you may also track the position of the north pole. Why even stop with igneous rocks. Paintings with iron grains can be used for these same purposes.
  10. Jun 12, 2008 #9
    The polarization of the igneous rock on both sides of the mid-atlantic ridge. Although just cause the field is diminishing now does not suggest a flip (it, of course, don't rule it out) but if you look at the magnetic field over time you'll find it varies quite a bit. And I think bother the OP and JCrules should probably read up on basic E&M. Magnetic fields aren't 'attracted' or 'repelled' by anything, they're a mathematical construct which characterizes the interactions between moving charges.
  11. Jun 12, 2008 #10


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    I'm not sure exactly how you mean, but I don't know what's wrong with studying seafloor rocks. The magnetic components in the rock become 'frozen' in to position at quite a high temperature. once the rock has formed, in normal circumstances it won't be subject to those kinds of temperatures again until it reaches a subduction zone.

    I think so, yes, but don't forget we've measured only a very small part of what is likely to be a long term trend. Concluding that it would continue until it disappears would be like watching the tide go down for an hour and deciding the oceans will be dry within a year.
  12. Jun 14, 2008 #11
    The Bermuda triangle and other disaster areas at sea have been explained, at least in principle years ago.An american geologist (can't remember his name) said that methane hydrates in the mud under the sea at certain places around the world can be suddenly released by landslides/earthquakes.It bubbles to the surface and is highly explosive so aircraft passing through it would ignite the gas with disastrous consequences.The sea becomes less dense because of the bubbles and ships sink quickly.A ship's captain was on television saying he had seen one such huge bubble event close to his ship so he knows it happens.Also frothy water has a magnetic field and this could be what throws compasses off course.
    Around the world where there are large deposits of methane hydrate on the sea floor there are more ship disasters than normal too.
    Last edited: Jun 14, 2008
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