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    Re: Historical Magnetic Variation/Declination
    From: Frank Reed CT
    Date: 2004 Jun 19, 16:26 EDT
    Jared S wrote:
    "If we lose the magnetic field, we'll lose our entire "shielding" and we'll be so badly zapped by all kinds of energy that the GPS will be the least of anyone's concerns.  With all the money you save not buying sextant stock, you can buy deep mine shafts. No magnetic
    field for any length of time would mean some serious problems for life as we know it."

    It's not quite that bad. Most of the radiation shielding comes from the atmosphere. When you fly in a plane at 35,000 feet (as I'll be doing tomorrow morning), you're exposed to radiation levels that are dozens of times higher than at sea level. Yet airline flight crews who spend long periods of time at these altitudes show no (or ambiguous) evidence of health effects.

    That said, sure, if the field strength drops for a few thousand years, cancer rates would probably increase measurably. Are we doomed? Well, there have been dozens of polarity reversals in the past fifty million years, and no major extinction events. So no. Probably not doomed. Sicker? Yes.

    And added:
    "No one really wants to spend the money on the basic science needed to look into this in real detail, it just isn't sexy enough, or urgent-seeming enough"

    Well, we do spend a lot of money on cancer treatment. Since that's the primary health effect, it probably makes sense at a public policy level to work on all forms of cancer instead of those specifically related to increased cosmic ray levels.

    And there's another problem besides lack of urgency. No one really has any great ideas on what to do! After centuries of study, we still only have computer simulations that *may* mimic features of the dynamics of the Earth's core (and they do show random fluctuations and polarity reversals, so they *seem* relevant at least). But we really don't know what's going on 4000 miles beneath our feet, and there doesn't seem to be any way to get around that basic ignorance.

    Frank R
    [ ] Mystic, Connecticut
    [X] Chicago, Illinois
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