The earth’s magnetic field: evidence that the earth is young
March 1998; updated August 2014
The earth has a magnetic field pointing almost north-south—only 11.5° off. This is an excellent design feature of our planet: it enables navigation by compasses, and it also shields us from dangerous charged particles from the sun. It is also powerful evidence that the earth must be as young as the Bible teaches.
In the 1970s, the creationist physics professor Dr Thomas Barnes noted that measurements since 1835 have shown that the field is decaying at 5% per century1 (also, archaeological measurements show that the field was 40% stronger in AD 1000 than today2). Barnes, the author of a well-regarded electromagnetism textbook,3 proposed that the earth’s magnetic field was caused by a decaying electric current in the earth’s metallic core (see side note). Barnes calculated that the current could not have been decaying for more than 10,000 years, or else its original strength would have been large enough to melt the earth. So the earth must be younger than that.
The decaying current model is obviously incompatible with the billions of years needed by evolutionists. So their preferred model is a self-sustaining dynamo (electric generator). The earth’s rotation and convection is supposed to circulate the molten nickel/iron of the outer core. Positive and negative charges in this liquid metal are supposed to circulate unevenly, producing an electric current, thus generating the magnetic field. But scientists have not produced a workable model despite half a century of research, and there are many problems.4
But the major criticism of Barnes’ young-earth argument concerns evidence that the magnetic field has reversed many times—i.e. compasses would have pointed south instead of north. When grains of the common magnetic mineral magnetite in volcanic lava or ash flows cool below its Curie point (see side note) of 570°C (1060°F), the magnetic domains partly align themselves in the direction of the earth’s magnetic field at that time. Once the rock has fully cooled, the magnetite’s alignment is fixed. Thus we have a permanent record of the earth’s field through time.
Although evolutionists have no good explanations for the reversals, they maintain that, because of them, the straightforward decay assumed by Dr Barnes is invalid. Also, their model requires at least thousands of years for a reversal. And with their dating assumptions, they believe that the reversals occur at intervals of millions of years, and point to an old earth.
The physicist Dr Russell Humphreys believed that Dr Barnes had the right idea, and he also accepted that the reversals were real. He modified Barnes’ model to account for special effects of a liquid conductor, like the molten metal of the earth’s outer core. If the liquid flowed upwards (due to convection—hot fluids rise, cold fluids sink) this could sometimes make the field reverse quickly.5,6 Now, as discussed in Creation 19(3), 1997, Dr John Baumgardner proposes that the plunging of tectonic plates was a cause of the Genesis Flood (see online version). Dr Humphreys says these plates would have sharply cooled the outer parts of the core, driving the convection.7 This means that most of the reversals occurred in the Flood year, every week or two. And after the Flood, there would be large fluctuations due to residual motion. But the reversals and fluctuations could not halt the overall decay pattern—rather, the total field energy would decay even faster (see graph above).8
This model also explains why the sun reverses its magnetic field every 11 years. The sun is a gigantic ball of hot, energetically moving, electrically conducting gas. Contrary to the dynamo model, the overall field energy of the sun is decreasing.
Dr Humphreys also proposed a test for his model: magnetic reversals should be found in rocks known to have cooled in days or weeks. For example, in a thin lava flow, the outside would cool first, and record earth’s magnetic field in one direction; the inside would cool later, and record the field in another direction.
Three years after this prediction, leading researchers Robert Coe and Michel Prévot found a thin lava layer that must have cooled within 15 days, and had 90° of reversal recorded continuously in it.9 And it was no fluke—eight years later, they reported an even faster reversal.10 This was staggering news to them and the rest of the evolutionary community, but strong support for Humphreys’ model. (See also Dr Humphreys’ online article The Earth’s magnetic field is young.)
A ‘force-field’ around the earth.
The earth’s magnetism is running down. This world-wide phenomenon could not have been going on for more than a few thousand years, despite swapping direction many times. Evolutionary theories are not able to explain properly how the magnetism could sustain itself for billions of years.
The earth’s magnetic field is not only a good navigational aid and a shield from space particles, it is powerful evidence against evolution and billions of years. The clear decay pattern shows the earth could not be older than about 10,000 years.
Update, 29 August 2014: recently, geophysicist David Stevenson at the California Institute of Technology admitted the problems that the earth’s magnetic field poses for long-age dogma:
Right at this moment, there is a problem with our understanding of Earth’s core and it’s something that’s emerged only over the last year or two. The problem is a serious one. We do not know understand how the Earth’s magnetic field has lasted for billions of years. We know that the Earth has had a magnetic field for most of its history. We don’t know how the Earth did that. We have less of an understanding now than we previously thought we had a decade ago of how the Earth’s core has operated throughout history.11
The Humphreys Proposal
Dr Humphreys proposed that God first created the earth out of water.1 He based this on several Scriptures, e.g. 2 Peter 3:5 which concludes that the earth was formed out of water and by water. After this, God would have transformed much of the water into other substances like rock minerals. Now water contains hydrogen atoms, and the nucleus of a hydrogen atom is a tiny magnet. Normally these magnets cancel out so water as a whole is almost non-magnetic. But Humphreys proposed that God created the water with the nuclear magnets aligned. Immediately after creation, they would form a more random arrangement, which would cause the earth’s magnetic field to decay. This would generate current in the core, which would then decay according to Barnes’ model, apart from many reversals in the Flood year as Humphreys’ model states.
Dr Humphreys also calculated the fields of other planets (and the sun) based on this model. The important factors are the mass of the object, the size of the core and how well it conducts electricity, plus the assumption that their original material was water. His model explains features which are deep puzzles to dynamo theorists. For example, evolutionists refer to ‘the enigma of lunar magnetism’2—the moon once had a strong magnetic field, although it rotates only once a month. Also, according to evolutionary models of its origin, it never had a molten core, necessary for a dynamo to work. Also, Mercury has a far stronger magnetic field than dynamo theory expects from a planet rotating 59 times slower than Earth.
Even more importantly, in 1984, Dr Humphreys predicted that the field strength of Uranus was about 100,000 times the evolutionary predictions from their ‘dynamo’ theory. The two rival models were tested when the Voyager 2 spacecraft flew past these planets in 1986 and 1989. The field for Uranus was just as Humphreys had predicted. Dr Humphreys’ prediction for the field strength of Neptune aligned with the evolutionary prediction, because this planet has a high heat outflow.3 But Neptune’s field was still different in other important ways from the evolutionary dynamo prediction: the tilt and offset.4 Yet many anti-creationists call creation ‘unscientific’ because it supposedly makes no predictions!
Humphreys’ model also explains why the moons of Jupiter that have cores have magnetic fields, while Callisto, which lacks a core, also lacks a field.5 (See Dr Humphreys’ online article Beyond Neptune: Voyager II Supports Creation)
Materials like iron are composed of tiny magnetic domains, which each behave like tiny magnets. The domains themselves are composed of even tinier atoms, which are themselves microscopic magnets, lined up within the domain. Normally the domains cancel each other out. But in magnets, like a compass needle, more of the domains are lined up in the same direction, and so the material has an overall magnetic field.
Earth’s core is mainly iron and nickel, so could its magnetic field be caused the same way as a compass needle’s? No—above a temperature called the Curie point, the magnetic domains are disrupted. The earth’s core at its coolest region is about 3400–4700°C (6100–8500°F), much hotter than the Curie points of all known substances.
But in 1820, the Danish physicist H.C. Ørsted discovered that an electric current produces a magnetic field. Without this, there could be no electric motors. So could an electric current be responsible for the earth’s magnetic field? Electric motors have a power source, but electric currents normally decay almost instantly once the power source is switched off (except in superconductors). So how could there be an electric current inside the earth, without a source?
The great creationist physicist Michael Faraday answered this question in 1831 with his discovery that a changing magnetic field induces an electric voltage, the basis of electrical generators.
Imagine the earth soon after creation with a large electrical current in its core. This would produce a strong magnetic field. Without a power source, this current would decay. Thus the magnetic field would decay too. As decay is change, it would induce a current, lower but in the same direction as the original one.
So we have a decaying current producing a decaying field which generates a decaying current … If the circuit dimensions are large enough, the current would take a while to die out. The decay rate can be accurately calculated, and is always exponential. The electrical energy doesn’t disappear—it is turned into heat, a process discovered by the creationist physicist James Joule in 1840.
This is the basis of Dr Barnes’ model.
Some sceptics have claimed that an exponential decay curve is wrong, and a linear decay should have been plotted. Now, both exponential and linear decay curves have two fitted parameters:
If the fit were similar, there is no statistical reason to choose one over the other. The fit is very similar for the limited range of data available, with no significant difference between the two.
However, it is a well-accepted procedure in modelling of regression analysis to use meaningful equations to describe physical phenomena, where there is a sound theoretical basis for doing so. This is the case here. Currents in resistance/inductance circuits always decay exponentially, not linearly, after the power source is switched off. For example, in a simple electric circuit at time t with initial current I, resistance R and inductance L, the current is given by i = Ie-t/τ, where τ is the time constant L/R—the time for the current to decay to 1/e (~37%) of its initial value. For a sphere of radius a, conductivity σ and permeability μ,τ is given by μσa²/π².
A linear decay might look good on paper, but it’s physically absurd when dealing with the real world of electric circuits. In fact, linear decays are rare in nature in general. Conversely, exponential decay is firmly rooted in electromagnetic theory.
Thomas Barnes, who first pointed out magnetic field decay as a problem for evolutionists, was a specialist in electromagnetism and wrote some well-regarded textbooks on the subject. But most of his critics are crassly ignorant of the subject.
Another important point is that these calculations point to a maximum age of the earth. Even if the sceptics were right about a linear decay, it would still point to an upper limit of 90 million years, and this is far too young for evolution.
A final point is that if the decay really were linear, we haven’t got much time left before the earth’s magnetic field disappears!
Multipole components of the field
Some sceptics have claimed:
‘… only the dipole-field strength has been “decaying” for a century and a half … the strength of the nondipole field (about 15% of the total field) has increased over the same time span, so that the total field has remained almost constant. Barnes’ assumption of a steady decrease in the field’s strength throughout history is also irreconcilable, of course, with the paleomagnetic evidence of fluctuations and reversals [in the geomagnetic field] (Ecker, 1990, 105)’
The ‘authority’ turns out to be an anti-creationist dictionary compiled by an anti-Christian librarian with, as far as we are aware, no scientific training! Dr Humphreys answered in July 2001:
Later, Dr Humphreys published ‘The Earth’s magnetic field is still losing energy’, CRSQ 39(1)1–11, March 2002, which explains the above and more in detail (see full article, and his Creation Matters layman’s summary—The Earth’s Magnetic Field: Closing a Loophole in the Case for its Youth, March/April 2002—both off site). The abstract of the CRSQ paper reads:
‘This paper closes a loophole in the case for a young earth based on the loss of energy from various parts of the earth’s magnetic field. Using ambiguous 1967 data, evolutionists had claimed that energy gains in minor (“non-dipole”) parts compensate for the energy loss from the main (“dipole”) part. However, nobody seems to have checked that claim with newer, more accurate data. Using data from the International Geomagnetic Reference Field (IGRF) I show that from 1970 to 2000, the dipole part of the field steadily lost 235 ± 5 billion megajoules of energy, while the non-dipole part gained only 129 ± 8 billion megajoules. Over that 30-year period, the net loss of energy from all observable parts of the field was 1.41 ± 0.16 %. At that rate, the field would lose half its energy every 1465 ± 166 years. Combined with my 1990 theory explaining reversals of polarity during the Genesis Flood and intensity fluctuations after that, these new data support the creationist model: the field has rapidly and continuously lost energy ever since God created it about 6,000 years ago.’
- K.L. McDonald and R.H. Gunst, ‘An analysis of the earth’s magnetic field from 1835 to 1965,’ ESSA Technical Report, IER 46-IES 1, U.S. Govt. Printing Office, Washington, 1967. Return to text.
- R.T. Merrill and M.W. McElhinney, The Earth’s Magnetic Field, Academic Press, London, pp. 101–106, 1983. Return to text.
- T.G. Barnes, Foundations of Electricity and Magnetism, 3rd ed., El Paso, Texas, 1977. Return to text.
- Measurements of electrical currents in the sea floor pose difficulties for the most popular class of dynamo models—L.J. Lanzerotti et al., Measurements of the large-scale direct-current earth potential and possible implications for the geomagnetic dynamo, Science 229:47–49, 5 July 1986. Also, the measured rate of field decay is sufficient to generate the current needed to produce today’s field strength, meaning that there is no dynamo operating today, if it ever did. Return to text.
- D.R. Humphreys, Reversals of the earth’s magnetic field during the Genesis Flood, Proceedings of the First International Conference on Creationism, Creation Science Fellowship, Pittsburgh, 2:113–126, 1986. The moving conductive liquid would carry magnetic flux lines with it, and this would generate new currents, producing new flux in the opposite direction. See also the interview of Humphreys in Creation 15(3):20–23, 1993. Return to text.
- Humphreys, D.R., Physical mechanism for reversals of the earth’s magnetic field during the flood, Proceedings of the Second International Conference on Creationism, Creation Science Fellowship, Pittsburgh, 2:129–142, 1990. Dr Barnes, who had opposed field reversals because no mechanism could be demonstrated, responded (p. 141): ‘Dr Humphreys has come up with a novel and physically sound approach to reversals of the magnetic field.’ Return to text.
- D.R. Humphreys, Discussion of J. Baumgardner, Numerical simulation of the large-scale tectonic changes accompanying the Flood, Proceedings of the First International Conference on Creationism, Creation Science Fellowship, Pittsburgh, 2:29, 1986. Return to text.
- The field intensity (B) fluctuated up and down during and after the Flood, but the total field energy always decreased. For the technically minded, the energy is the volume integral of B2. Return to text.
- R.S. Coe and M. Prévot, Evidence suggesting extremely rapid field variation during a geomagnetic reversal, Earth and Planetary Science 92(3/4):292–298, April 1989. See also the reports by Dr Andrew Snelling, Fossil magnetism reveals rapid reversals of the earth’s magnetic field, Creation 13(3):46–50, 1991 The Earth’s magnetic field and the age of the Earth, Creation 13(4):44–48, 1991. Return to text.
- R.S. Coe, M. Prévot and P. Camps, New evidence for extraordinarily rapid change of the geomagnetic field during a reversal, Nature 374(6564):687–692, 1995; see also A. Snelling, The principle of ‘least astonishment’, Journal of Creation 9(2):138–139, 1995. Return to text.
- Cited in: Folger, T., Journeys to the Center of the Earth: Our planet’s core powers a magnetic field that shields us from a hostile cosmos. But how does it really work? Discover, July/August 2014. Return to text.