Re: Magnetic field energy loss

From: Donald Nield (
Date: Tue Sep 30 2003 - 18:12:25 EDT

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    George Murphy wrote:

    > Thanks for the references. I suspect that one reason why Barnes & other YECs
    > became so smitten with the idea that the decay of the earth's field proved YEC was not
    > any observational data but the simple theoretical result that the decay time for a B
    > field initially frozen in a highly conducting sphere with dimensions on the order of the
    > earth's core is a few thousand years. Of course whether such an elementary model
    > represents the real earth very well is another matter!
    > Shalom,
    > George

    Could George please check the estimate of the decay time? My back-of-the-envelope
    calculation based on data in H. K. Moffat, "Magnetic Field Generation in Electrically
    Conducting Fluids", CUP, 1978 (core radius 3500 km, magnetic diffusvity 2.6 m^2 /s) yielded
    a time of the order of 10^5 years, which is a bit too long to be useful for the YECs.

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