From: gordon brown (gbrown@euclid.colorado.edu)
Date: Tue Mar 18 2003 - 12:06:31 EST
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.
Gordon Brown
Department of Mathematics
University of Colorado
Boulder, CO 80309-0395
On Tue, 18 Mar 2003, allenroy wrote:
> I let a friend of mine read some anonymous comments on Barnes and his
> magnetic data that was made here not long ago. He (anonymously) makes
> the following comments. (following the **** marks)
> Allen Roy
> ----------------------------------------
>
> >Barnes took the data from c1835 which shows that aspect of the
> magnetic field has been declining. However Barnes left out the first
> reading from c1831 which was lower than the second of c1835. It was in
> the data he cited so i presume he ignored as it was inconvenient.
> Naughty Boy!! So he was wrong (Ken Ham would prefer to say Fraudulent)
> to do this . <
>
> ****Let's examine the reference where Barne's obtained the data from.
>
> McDonald, Keith L. and Robert H. Gunst. 1967. An analysis of the earth's
> magnetic field from 1835 to 1965. ESSA Technical ReportIER 4 6 -IES 1,
> U.S. Government Printing Office, Washington, D. C.
>
> ---. 1968. Recent trends in the earth's magnetic field. Journal of
> Geophysical Research 73:2057-2067. This is a summary of their ESSA
> report of 1967.
>
> *****Note the title, " . . earth's magnetic field from 1835 to 1965". It
> is the secular guys who chose this time period, starting from 1835. They
> are the ones who pointed out that the data shows that the earth's field
> had decayed 8% over that time period.. Barnes did nothing wrong or
> fraudulent in the least, he simply used the same data and provided an
> exponential fit as predicted by the Lamb theory of free induction decay.
>
> Why would one take data from 1835 onward and neglect all kinds of data
> from prior to that time? Because it was in 1833 and 1839 that Karl Gauss
> began systematizing the analysis and measurement of earth's magnetic
> field, Gauss' first recorded data of the total strength of the earth's
> magnetic moment was in 1835. (see references to Gauss in Humphreys paper
> cited below)
>
> There were all kinds of data from magnetic dip needles prior to Gauss,
> in fact, going clear back to 1600, but there was nothing systematic
> until Gauss published his analysis of data using what are now called
> spherical harmonics, to separate out the earth's dipole and non-dipole
> field components. By the way, the earlier data with dip needles also
> shows the same marked decay of the magnetic field with time, although
> the slope is slightly different than some of the most recent data. It
> makes no sense to only include the one data point in 1831, if one is
> going to go back prior to Gauss. What is your citation for the value you
> claim was neglected by Barnes?
>
> The data prior to Gauss shows a large decay, at least as far back as
> 1600, as figure 2.11, p. 56, in Merrill, McElhinny, and McFadden's book
> "The Magnetic Field of the Earth", (Academic Press, 1996) clearly shows.
> In fact, as McElhinny et al discuss on p. 55-57, several secular authors
> have analyzed the data since 1835 and they quote a number of about 5%
> per century since then, for the decrease of the earth's dipole field. So
> there is no question about the observed decrease in the dipole component
> of the earth's magnetic field. It is very large. Therefore the notion
> that the earth's magnetic dipole field has decayed strongly is only
> established further by examining all the earlier, directly measured data.
>
> All this and much more is discussed in detail and references provided in
> Russ Humphreys excellent recent CRSQ paper. I recommend you read it so
> that you will know what Humphreys really says.
>
> A copy of Russ Humphreys recent CRSQ article can be found on the CRS web
> site here,
>
> http://www.creationresearch.org/crsq/articles/39/39_1/GeoMag.htm
>
> You can also get a PDF version, if you prefer, at the same location at
> the top of the page.
>
>
> K.W.
>
> PS. Your research may need to go a little beyond Talk.Origins to find
> reality.
>
> ----------------
> Allen Roy
>
> "I have been shown that, without Bible history, geology can prove nothing. Relics found
> in the earth do give evidence of a state of things differing in many respects from the
> present. But the time of their existence, and how long a period these things have been in
> the earth, are only to be understood by Bible history. It may be innocent to conjecture
> beyond Bible history, if our suppositions do not contradict the facts found in the sacred
> Scriptures. But when men leave the word of God in regard to the history of creation, and
> seek to account for God's creative works upon natural principles, they are upon a
> boundless ocean of uncertainty. Just how God accomplished the work of creation in six
> literal days, he has never revealed to mortals. His creative works are just as
> incomprehensible as his existence." Ellen Gould Harmon White, 1864
>
>
>
>
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