MindBlast
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Will the world end in 2012? Maybe. Who knows?
But sometime, someday the earth's polarity will shift, and at that point it would be over.
Nope. A magnetic polarity change is not the end of the world. Take my point of view as a geophysicist for a second. First of all, the most compelling evidence is in old rocks where the magnetic polarity has been locked in. The Earth's magnetic field has flipped over MULTIPLE times in the past. Earth is still here.
What happens when a magnetic dynamo switches polarities? Well, the total amplitude of the field decreases slowly until it reaches zero, and once it hits zero, the polarity reverses and the field is almost instantly at full strength in the other direction.
The Earth's magnetic field is an infinite sum of multipoles. In other words, adding up the dipole moment, the quadrupole moment, the octopole moment, and so on for infinitely many multipoles adds up to 1 (where 1 is the the total magnetic field, I've normalized it so that it doesn't matter what the actual numbers are). As the Earth's total magnetic field intensity decreases, the dipole part of the field gets weaker. As the dipole gets weaker, we start to see and experience the quadrupole and octopole parts more and more.
Look at this map of the total magnetic field intensity of the Earth. You can CLEARLY see the magnetic field starting to approximate a quadrupole. It won't be long (geologically speaking) before it starts to resemble and octopole.


I think what he meant is that it'll all be over for life on Earth, not the actual planet itself.
