From: George Murphy (gmurphy@raex.com)
Date: Tue Mar 18 2003 - 15:01:12 EST
gordon brown wrote:
>
> Many years ago I heard a talk by Jack Eddy in which he gave results on the
> strength of the earth's magnetic field based on measurements made in tree
> rings. I don't know the science behind it. It may be based on quantities
> of certain isotopes. The conclusion was that the earth's magnetic field
> had a relative maximum at a certain date in the past. (I believe it was
> either 500 or 1500 A.D.) You ought to be able to find Eddy's paper in the
> literature somewhere.
If one assumes that the earth's field is simply frozen into a core with finite
conductivity then it's easy to do a back of the envelope calculation & get exponential
decay with a characteristic time of a few thousand years, & it's simple enough to fit a
semi-log plot to a few data points. But this makes sense only if one has reason to
believe that such a model is adequate to explain geomagnetic data & it isn't.
But in a more fundamental way the whole enterprise is just silly because
paleomagnetic data extends back millions of years. Beyond that, we're now getting
detailed information - e.g., from the current Wilkinson Microwave Anisotropy Probe
(WMAP) - about the condition of the universe ~13 _billion_ years ago. The whole YEC
enterprise is just sad. It's not just that a lot of ignorant people buy into it, but
that there are some who have real ability for science who have been misled into wasting
their talents on a completely futile enterprise.
BTW, is Jack Eddy the discoverer of Eddy currents? (:))
Shalom,
George
George L. Murphy
gmurphy@raex.com
http://web.raex.com/~gmurphy/
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