The Dynamo Model
Creationists have pointed out for many years that the rapid decrease in the strength of the earth's magnetic field demands a young age for the earth. The major creationist model of the earth's magnetic field has succeeded in making a number of risky predictions, the most recent verified prediction being the discovery of remnant paleomagnetism in the famous Martian meteorite that was claimed to harbor life.
For the past several generations the ad hoc response of old-earth believers has been that the magnetic field must be supported by a dynamo of some sort (basically a giant planetary electrical motor). Since the field strength is varying and has probably reversed in the past it is necessary to believe that this dynamo has fluctuated, stopped, started up again in the opposite direction and so on over time. There is just one problem: none of the various dynamo models has actually worked. This means they were basically speculation, not established scientific hypotheses despite textbook dogmatism.
Recently, Gary Glatzmaier of Los Alamos and Paul Roberts of UCLA have claimed to have established the first working dynamo model. You can view their web page yourself. Notice how, as usual for evolutionists, they dogmatically assume one conclusion (that the magnetic field is dynamo-powered) rather than admitting a dynamo is (if they ever get it working!) just one possibility.
Does the model work? It does show a reversal occurring. But it is still no good for claiming that a dynamo powers the earth's magnetic field for the following reasons:
1. The supercomputer model yielded a reversal over a period of 1200 years. This is much faster than the hundreds of thousands of years I used to see touted as the length of time reversals required, but much too long to accomodate the field evidence. Records of reversals found in thin lava layers by secular scientists have forced a revolution in recent years, and it is now recognized that the reversals took place in a matter of days or weeks (within the cooling time of individual lava layers); not over millenia! (cf. R.S. Coe, M. Prevot & P. Camps, "New Evidence for Extraordinarily Rapid Field Change During a Reversal," Nature 374:687-692.) Needless to say this requires globally catastrophic mechanisms.
As an aside, I wonder when old-earthers will admit all the dating schemes that relied on reversal data and long times for reversals are wrong and that those dates will need to be scrapped? And what does that say about other methods that supposedly "corroborated" the erroneous multi-hundred-thousand year reversals?
2. The authors assumed a high electrical conductivity for the core fluid of the earth, 400,000-600,000 mhos/meter. This is more than ten times too high based on lab data (30,000 mhos/meter), or even the creationist estimates based on observed field decay (40,000 mhos/meter). Humphreys notes, "with more realistic conductivities, the simulation would be more likely to fail."
3. The simulation yields a current toroidal magnetic field of 150 Gauss within the earth's core. Actual measurements suggest the true value is nore more than 1/10 that value.
4. Observation of the earth's magnetic field indicates a net westward drift of smaller-scale aspects of the field; the simulation yielded no such result.
In addition, D.R. Humphrey's reversing free-decay model for the magnetic field has another advantage over dynamo models: it has a number of successful predictions under its belt regarding the strength of magnetic fields on other planets, and the past existence of magnetic fields where none exist now. Dynamo model predictions have been wildly off (sometimes by 5 orders of magnitude, a factor of 100,000). Nor do dynamo models handle other planets well when they don't or barely rotate (see Mars rock reference) or if they are frozen solid.
In short, the decades of diligent work by very intelligent dynamo theorists give us all the more conviction that the earth is young and its magnetic field is in free decay.
Reference:
Humphreys, D. Russell, "Can Evolutionists Now Explain the Earth's Magnetic Field?," Creation Research Society Quarterly, 33(3):184-185.
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