Is the Earth’s magnetic field about to flip?
Published: 1 April 2003 (GMT+10)
A new science fiction movie is being released called The Core. In this movie, the Earth’s core stops rotating and our planet’s magnetic field collapses. Since the field shields us from dangerous charged particles from the sun, it must be restarted, so scientists are sent deep inside the Earth to jump-start the rotation.
Dr Larry Newitt, an expert on geomagnetism with the Canadian-Government–funded Geolab, says that The Core:
‘… is composed of a few scientifically plausible ideas mixed with a large dosage of sheer nonsense. It should be fun.’
However, Dr David Whitehouse, BBC News Online science editor, said in an article Is the Earth preparing to flip?:
‘It is not just the plot for a far-fetched science-fiction disaster movie. Something unexplained really is happening to the Earth’s magnetic field.’
So what are these unexplained phenomena?
Earth’s magnetic field is decaying
Dr Whitehouse says:
‘But something else is happening to the Earth’s magnetic field: it is getting weaker.’
And Dr David Kerridge, of the British Geological Survey, said:
‘There is strong evidence that the field is decreasing by about 5% per century.’
This is not so well known to the public, but it has been known to creationists since the 1970s, when electromagnetism expert (and physics professor) Dr Thomas Barnes pointed this out. By using standard physics, he showed that this was most likely due to a decaying electric current. And this decay could not have been happening for more than about 10,000 years, otherwise the current would have melted the Earth. This has long been powerful support for the Biblical timescale.
One way of long-agers avoiding this conclusion is to suppose that the magnetic field is generated by a self-sustaining dynamo (electric generator). Here, the magnetic field is somehow generated by circulating molten metal, and this of course relies on the Earth’s rotation. The Core presupposes that this model is correct, because if the Earth’s core stopped rotating, the field would be extinguished under this model, but not under Barnes’ model. However, Barnes’ model is based on sound physics and is rejected only because of the ‘short’ age implications; while there is no satisfactory dynamo theory, which is accepted mainly because it allows ‘long’ ages.
Evolutionists have also claimed that magnetic field reversals are the answer to the problem Barnes raises, and claim that they occur over intervals of thousands of years. Whitehouse says, although not in the context of Barnes’ theory:
‘Looking back in the geological record it is clear that on average such events occur about every 250,000 years. However, it has been 750,000 years since the last reversal—so we are certainly overdue.’
However, evolutionists have no plausible mechanism. But creationist physicist Dr Russell Humphreys proposed that during the Genesis Flood, tectonic plates plunged down far enough to cool the outer core rapidly (see Catastrophic Plate Tectonics). The change in convection patterns would cause rapid field reversals, and cause the field energy to decay even faster. Humphreys predicted that such rapid reversals would be recorded in lava flows that cooled, from outside to inside, over only a few days. This prediction was dramatically confirmed only three years later.
In fact, Dr Whitehouse’s comment is further support for this. As he says, under the uniformitarian theory, we are long overdue for a reversal. But if all reversals occurred during the Flood year, then there is a very good reason why we have not had any reversals since then.
Similarly, Whitehouse said:
‘Some researchers suggest that it could be the start of a geomagnetic reversal, when the strength of the Earth’s magnetic field decreases and then returns a few thousand years later with the north and south magnetic poles reversed.’
However, once again, the declining field strength is best explained by an exponential decay of the field due to a decaying electric current. While this decay will weaken the shielding effect, there is no experimental reason to believe it heralds another reversal.
It seems that Dr Newitt was right about The Core, but for some different reasons from what creationists would think. The movie should be worthwhile if it inadvertently alerts the public to the decay of the field, and its implications for the age of the Earth. It should also be a good opportunity to explain the best scientific explanation for the magnetic field and correct the errant notions of the dynamo theory promoted in the film.
- The earth’s magnetic field: Evidence that the earth is young and Dr Humphreys’ papers referenced therein.