Originally Posted by Clown Boy
7. The Earth's Magnetic Field:
The Earth's magnetic field is decaying at the rate of about 5 % every 100 years. This means that about 1450 years ago it was twice as strong as it is today, and 2900 years ago it was four times as strong. Therefore, assuming that the rate of decay has been constant for the recent past, then only 10,000 years ago the earth's magnetic field would have been 128 times as strong as it is today: so strong that the amount of heat produced would have prevented life as we know it from existing on the earth. 23,24,25,26 In other words, it seems likely that the Earth's magnetic field is, in fact, quite young, suggesting that the earth itself is young also.
The fact that the earth's magnetic field is decaying is well documented. For example, a recent NOVA Special on this subject brought this out very clearly. In fact, at present rates of decay, the earth may not even have a magnetic field 1000 years from now. And although, the NOVA special strongly suggested that this may simply mean the earth is getting ready for another reversal, such may not be the case, as Dr. Humphreys work suggests. A brief portion of Dr. Humphreys findings are quoted below.
"Shortly after that I published a review of the evidence for past polarity reversals, reaffirming their reality (Humphreys, 1988). Then I developed my dynamic-decay theory further, showing that rapid (meters per second) motions of the core fluid would indeed cause rapid reversals of the field’s polarity (Humphreys, 1990). I cited newly discovered evidence for rapid reversals (Coe and Prévot, 1989), evidence in thin lava flows confirming my 1986 prediction. Since then, even more such evidence has become known (Coe, Prévot, and Camps, 1995).
The reversal mechanism of my theory would dissipate magnetic energy, not sustain it or add to it, so each reversal cycle would have a lower peak than the previous one. In the same paper (Humphreys, 1990, p. 137), I discussed the non-dipole part of the field today, pointing out that the slow (millimeter per second) motions of the fluid today could increase the intensity of some of the non-dipole parts of the field. However, I concluded by saying the total energy of the field would still decrease.
Despite these creationist answers, skeptics today still use Dalrymple’s old arguments to dismiss geomagnetic evidence. Much of that is probably due to ignorance of our responses, but some skeptics are still relying on the non-dipole part of the field. They hope that an energy gain in the non-dipole part will compensate for the energy lost from the dipole part.
I said, “hope,” because it appears that since 1967, nobody has yet published a calculation of non-dipole energies based on newer and better data. So that is what I will do below. It turns out that the results quash evolutionist hopes and support creationist models." 27 Emphasis Added
Another major problem with old-earth beliefs in this regard is the timing of the earth's last reversal. Old earth believers claim that it took place 780,000 years ago; however, at current rates of decay, only about 10,000 years ago the earth would have been so hot that no life could have survived on its surface. And even if we assume that in the past the earth's magnetic field decayed much slower than today, then we are still only looking at about 20,000 years ago that life could have existed on the earth. This means that the old-earth dates for the earth's past magnetic reversals (arrived at using radiometric method) are probably incorrect. This is due to the fact that radiometric methods all require at least three assumptions, and often many more.
Wow! You are making it tough on me. Now I have to review my physics, and lo and behold, what do I find? The fundamental assumptions are wrong, so everything that flows from them will be incorrect. The change in the earth's magnetic field do not change exponentially, but linearly. The initial reports used by creationists made that assumption, and Humphrey's (who is an unabashed creationist) used the exponential assumption uncritically. We could spend hundreds of pages dissection all of the other errors in these arguments, but..."garbage in, garbage out" sums it up.