By: David Rice To: Mark Fox Re: Magnetic Fields cc: J.J. Hitt DR+gt; Mark claimed that the

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By: David Rice To: Mark Fox Re: Magnetic Fields cc: J.J. Hitt DR> Mark claimed that the Earth's magnetic field is DR> "decaying," when in fact it is not. MF> 1835...8.558 x 102 amps per meter MF> 1945...8.065 x 102 amps per meter MF> 1965...8.017 x 102 amps per meter MF> Measuring by a consistent rate, the magnetic rate it is MF> declining at a half life rate of 830-1400 years (26 nanoteslars MF> per year)-- half life every 830 (Magstat)-1400 years (Barnes). <*Laughing!*> That's from the Creationist Thomas Barnes in his "magnetic field decay" idea, as published in the Institute for Creation Research cult's Technical Monograph called _The Origin and Destiny of the Earth's Magnetic Field_. Barnes's assumptions are rather. . . how shall it be put. . . "unique." You present these numbers as if they were factual, but that is not even close to the truth. Barnes's data rests on the following falsified assumptions: 1) Exponential extrapolation is justified far beyond his data (x50) 2) A uniform decay of a process known to not change in a uniform manner 3) An out-of-favor model for the source of the earth's magnetic field 4) There is no force that "drives" the field (i.e., no energy input) 5) The non-dipole component of the field can be ignored 6) A better straight-line fit to the data can be ignored You are encouraged to read (Dalrymple, 1983) or (Dalrymple, 1986, pp. 54-57). References: Dalrymple, G. Brent, 1983, "Can the Earth be Dated from Decay of Its Magnetic Field?", Journal of Geological Education, 1983, Vol. 31, pp. 124-133. Dalrymple, G. Brent, 1986, "USGS Open-File Report 86-110: Radiometric Dating, Geologic Time, and the Age of the Earth: A Reply to ``Scientific Creationism''", U.S. Geological Survey, 76 pp. The latter paper (Dalrymple, 1986) is an excellent introduction to radiometric dating and Creationist criticisms thereof. It is available from the Government Printing Office for $14. It's trivial to shoot Barnes's propositions full of holes, but it is even better to try to test them by measuring the strength of the Earth's magnetic field back beyond Barnes's limited data. This can be done by measuring the remnant magnetism in lava flows and archaeological objects (e.g., clay pots). If Barnes were correct, then the data would confirm his exponential extrapolation. However, THE DATA REFUTES BARNES. The diagram I've seen appears originally in (Chapman, 1980) and is reproduced in (Dalrymple, 1983) and (Dalrymple, 1986, Figure 15). It shows a decreasing trend over the last 2500 years (or so), preceeded by an increasing (on average) trend that covers 2000 years. The data indicates that the strength of the magnetic field from about 8,000 years ago to about 4,000 years ago was slightly less than its present strength. (Barnes's "model" predicts that the strength of the field would have been approximately 20 TO 50 TIMES its present value, during that same interval.) There is no support from the measurement of remnant magnetism for a continuous field decay, linear or exponential. This is not too surprising, as there is ample evidence that the entire field has reversed itself several times through history -- meaning that any unidirectional extrapolation would be senseless. References: Champion, D. E., "Holocene geomagnetic secular variation in the earth's magnetic field in the western United States: Implications for the global geomagnetic field", Ph.D. Thesis, California Institute of Technology, 1980. Dalrymple, G. Brent, 1983. See Section (I). Dalrymple, G. Brent, 1986. See Section (I). -.- 666 - number of the beast. 700 Club - church of the beast.


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