bill@utastro.UUCP (William H. Jefferys) (11/18/84)
Larry Bickford has provided a laundry list of alleged evidence that the Earth is much younger than Science says it is. Several people have responded to his claims. The fact is that *not one* of the things Larry cites is valid evidence of the age of the Earth. Rather than to refute each one (although I could do so) I have decided to concentrate on one of the Creationist's favorite examples. This one is thought by Creationists to be one of their better examples, judging by the frequency with which it is cited and the heavy emphasis they place on it. It is my feeling that a thorough expose of the flimsy basis on which it rests would be instructive. > Decay of Earth's Magnetic Field - Result of research by Thomas Barnes > during his tenure as Physics Professor at UTEP. Published in _Origin and > Destiny of Earth's Magnetic Field_, 1973. Barnes notes the measured > values over the last 150 years and models according to uniformitarian > principles. Briefly, Barnes took approximately 150 years of data on the Earth's dipole magnetic field and extrapolated it backwards to about 10000 years Before Present (B.P.). He stated that the field 10,000 years ago would, on this calculation, have been as strong as that of a magnetic star, and stated (correctly) that this was absurd. However, there are four fatal flaws in his analysis. In the first place, Barnes studied only the *dipole* component of the Earth's magnetic field, In fact, the very same data that Barnes used show that the *nondipole* component of the field *increased* during the same period of time, almost exactly cancelling the decrease in the dipole field that Barnes calculated (D. Brent Dalrymple, U. S. Geological Survey, Menlo Park CA, in *Reviews of 31 Creationist Books*). This alone is sufficient to destroy the basis of his work. The second failure of Barnes' study was the idea that one can take data from a short period of time and simply extrapolate it backwards to obtain a reliable estimate at a time remotely removed from the data. Anyone competent in analyzing scientific data knows that extrapolations are good only for a relatively short period of time, if at all, and that the further away from the actual data one goes, the less reliable it becomes. Barnes extrapolated 150 years' worth of data back 10,000 years! In real life, one would be surprised if extrapolation of these data more than a few hundred years back were accurate. Barnes' third failure of Barnes' study was the mathematical model he chose. He decided to fit the data to an exponential. The data fit a straight line just as well (see Figure 1 of Stephen G. Brush's article in *Scientists Confront Creationism*), but a straight line would have given a much older age for the Earth than the 10,000 years that Barnes, because of his Biblical literalism, wishes to promote. The fourth failure of Barnes' study was his failure to consider any other evidence than the 150 years worth of data from geomagnetic observatories that he used. There exists, in paleomagnetic data, a long record of the Earth's magnetic dipole strength (extending backwards for millions of years). The data are in agreement with the observatory data Barnes used over their common intersection, but they differ drastically from Barnes' extrapolation when one goes further back in time. Below I give a plot which will make clear how badly Barnes' extrapolation fits the actual record. 32+ X | 30+ X | 28+ X | 26+ X <--Barnes' extrapolation | 24+ X | 22+ X | 20+ X | 18+ X | 16+ X | 14+ X | o o 12+ X o o | o o <--Paleomagnetic data o 10+ X o | o o o 8/ o | 6+ o o | o 4+ o | 2+ | 0+-------+-------+-------+-------+-------+-------+-------+-------+-------+ 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 AGE (Years Before Present) The vertical axis gives the strength of the Earth's dipole field (in units of 10^25 gauss cm^3). The paleomagnetic data are plotted with the symbol "o" (after Cox, 1975, *Plate Tectonics and Geomagnetic Reversals*). The short diagonal line on the extreme left represents the run of data which Barnes relied upon. The "X"s show Barnes' exponential extrapolation of this short run of data back about 3000 years (Barnes obtained a doubling time of about 1400 years). At 7000 years B.P., Barnes' extrapolation would be at +250 on the chart instead of the +6 indicated by the directly measured paleomagnetic data. The foolishness of Barnes' exponential extrapolation of the short run of geomagnetic observatory data is painfully evident from this comparison with the paleomagnetic data. It is not clear from Barnes' work whether he is merely ignorant of proper data analysis techniques, of the meaning of the data he used, and of the existence of other data that conclusively refute his thesis, or whether he is guilty of the much more serious crime (to a scientist) of dishonesty. Whichever is the case, it is clear that Barnes' work has absolutely no validity whatsoever. The sad thing is that Creationists point proudly to Barnes' work as an example of good "Creation Science". Indeed, most Creationist work falls well below even the abysmally low standards set by Barnes' research. Serious scientists are used to a far higher *minimum* standard of excellence than that represented by Barnes' work. Is it any wonder that they dismiss Creationist weitings as so much claptrap? Is it any wonder that they consider Creationism to be nothing but pseudoscientific nonsense? -- "When evolution is outlawed, only outlaws will evolve" Bill Jefferys 8-% Astronomy Dept, University of Texas, Austin TX 78712 (USnail) {allegra,ihnp4}!{ut-sally,noao}!utastro!bill (uucp) bill%utastro.UTEXAS@ut-sally.ARPA (ARPANET)