Depletion of Earth's Magnetic Field
by Thomas G. Barnes, D.Sc.
There are three important force fields associated with planet earth, a gravitational field, an electric field, and a magnetic field. The gravitational field attracts us to the earth, preventing us from flying off into space as the earth rotates. The earth's electric field is very unstable, producing electric storms from place to place and at unpredictable times.
The earth's magnetic field is due to a huge electric, current, billions of amperes, circulating in the core of the earth. But the main complication lies in the fact that there are a multitude of extraneous sources which produce distortions in the magnetic field. As a consequence, the earth's magnetic field is very complex. The instability sometimes shows up as tremendous magnetic storms, blocking out transoceanic radio transmissions. There are all kinds of anomalies resulting from distortions in the magnetic field. There are many unpredictable variations in the magnetic field with time and location.
Navigators do not depend on their magnetic compass as much now as in early days. When navigators do use the magnetic compass they have up-dated magnetic charts to provide corrections for gross deviations in the earth's magnetic field from place to place over the globe. This helps them correct their bearings for "false" directions indicated by the compass, but the charts can not correct for all the distortions.
In spite of all the distortions of the magnetic field there are
modern data-reductions methods of taking an epoch of worldwide
data and "washing" out the "noise" (distortions)
and obtaining the basic field. The basic field is that field produced
by the current circulating in the core of the earth. This basic
field is called the dipole field. It is similar to the
magnetic field of a single magnet located near the center of the
earth and having a north and south pole, hence the name dipole.
It is sometimes referred to as the earth's main magnetic
field. The dipole magnetic field is the magnetic field of
interest in this paper.
RAPID DECAY OF THE EARTH'S MAGNETIC FIELD
It is known that the earth's magnetic field is decaying faster than any other worldwide geophysical phenomenon. A comprehensive ESSA Technical Report1 gives the values of the earth's magnetic dipole moment (the vector which gives the strength and direction of the magnet) ever since Karl Gauss made the first evaluation in 1835. The evaluations have been made about every 10 or 15 years since then. Each evaluation required accurate worldwide readings over an epoch (a year or so) and special mathematical reduction to "wash" out the "noise." These reliable data clearly show this relatively rapid decay. The report stated that on a straight line basis the earth's magnetic field would be gone in the year 3991 A.D. But decay is exponential and in this case has a half-life of 1400 years.
A relatively recent NASA satellite preliminary report shows a
rapid decay in the earth's magnetic field. No knowledgeable scientist
debates the fact of the rapid decrease in the earth's magnetic
field, nor does he question that the associated electric current
in the core of the earth is using up energy. The present rate
of loss is seven billion kilowatt hours per year. The earth is
running out of that original energy it had in its original magnetic
PREDICTABLE DEPLETION OF
THE EARTH'S MAGNETIC FIELD
The original source of the earth's magnetic field was the original electric current circulating in the core of the earth. No one knows how that electric current got started any more than one knows why the earth was originally spinning on its axis. The two are not related but they are both original states of the earth.
The electric current and its associated magnetic field have been decaying ever since the origin of the earth. One might ask why the current did not die out faster? Faraday's induction law prevented it from dying out faster. As the magnetic field diminishes it induces a voltage which opposes the decay, extending its life-time. The large scale of this phenomenon accounts for such an extended life. The radius of the core of the earth is 3.473 x 106 meters. The total physics of this problem is formidable but it has been solved.2,3 The solution predicts the decay. It yields the half-life equation:
Half-Life = 2.88 x 10 -15 (Conductivity) (Radius)
where the half-life is in years, the radius in meters, and the conductivity is in mhos/meter.
Sir Horace Lamb came up with the equivalent of this equation in 1833. As mentioned in the previous section, statistical analysis of the data yields a half-life of 1400 years. Lamb did not have a good value for the conductivity and therefore could not make a good prediction, but he did know that it would last for thousands of years, and that it was a plausible explanation of the earth's magnetic field. It is still the only good theoretical/mathematical explanation. Now it can be used to evaluate the electric conductivity of the core of the earth, because the data show a 1400 year half-life. The value of the electric conductivity of the core is, from this equation, equal to 4.04 x 104 mhos/meter. This is a very reasonable value for molten iron under the temperatures estimated for the earth's core. This is the only good means of making that evaluation of the conductivity of the earth's core.
Working backwards in time many thousands of years, this equation
yields an implausibly large value of the magnetic field and of
the electrically generated heat stored in the earth's core. (See
ICR Technical Monograph: Origin and Destiny of the Earth's
Magnetic Field4) A reasonable postulate was shown
therein to yield an upper age limit of 10,000 years.
REFUTATION OF THE REVERSAL HYPOTHESIS
To protect their long-age chronology, evolutionists hold to a reversal hypothesis. The magnetic field is said to have remained at essentially the same value during geologic time, except for intervals in which it went through a reversal, dying down to zero and rising up again with the reverse polarity. The last reversal is supposed to have taken place 700,000 years ago.
The reversal hypothesis has no valid theoretical support. That is acknowledged in a recent Scientific American article: "No one has developed an explanation of why the sign reversals take place. The apparent random reversals of the earth's dipole field have remained inscrutable."5 Neither are there any dependable data to support the reversal hypothesis. Reference has already been made to the multitude of magnetic disturbances, "noise," that make it so difficult to evaluate the earth's magnetic dipole moment, even when using absolute measurements over the whole earth. Yet it is absolutely essential that one evaluate the earth's magnetic moment if he is to claim to know the state of the earth's magnet at that time.
The tremendous amount of data on magnetic anomalies is important in exploration because they are evidences of the nonuniformities where one might expect minerals, etc. But they are useless insofar as history of the earth's dipole magnet is concerned.
In reference to the claims that the magnetization patterns on the sea floor relate to a history of the earth's magnetic field and continental drift, A.A. and Howard Meyerhoff give a lengthy refutation and very firmly conclude: "The so-called magnetic anomalies are not what they are purported to be—a 'taped record' of magnetic events during the creation of the new ocean floor between continents."6
One of the factors that makes rock magnetization completely undependable as evidence for the so-called reversals is the self-reversal process that is known to exist in rocks, totally independent of the earth's magnetic field. Richard Doell and Alan Cox state that: "The reversed magnetization of some rocks is now known to be due to a self-reversal mechanism. Moreover, many theoretical self-reversal mechanisms have been proposed … However, in order definitely to reject the field-reversal hypothesis it is necessary to show that all reversely magnetized rocks are due to self-reversal. This would be a very difficult task since some of the self-reversal mechanisms are difficult to detect and are not reproducible in the laboratory."7 It is interesting to note that these authors attempt to shift the burden of proof to the opponents of the reversal hypothesis but in so doing they demolish the reliability of the very data upon which they depend.
J.A. Jacobs states that: "Such results show that one must be cautious about interpreting all reversals as due to a field reversal and the problem of deciding which reversed rocks indicate a reversal of the field may in some cases be extremely difficult. To prove that a reversed rock sample has been magnetized by a reversal of the earth's field, it is necessary to show that it can not have been reversed by a physico-chemical process. This is a virtually impossible task since physical changes may have occurred since the initial magnetization or may occur during certain laboratory tests."8
A strong conflict is exposed when a direct comparison is made between 1) the real-time evaluations of the magnetic dipole field by Gauss et al, and 2) the magnetic "field" evaluations deduced following evolutionary assumptions about the magnetization in rocks and artifacts.
Over the last two centuries the work of Gauss et al has shown a continuous depletion of the earth's magnetic field. That is generally accepted as fact, whereas the magnetized rock-artifact method fails to show any trace of this trend. 9
The only valid theoretical mathematical explanation and the only tenable data support the conclusion that the earth's magnetic field was created with a sizable amount of original magnetic energy and has been continuously decaying ever since and that it is headed for extinction in a few thousand years. Looking backwards in time there is a limiting age because there is a limit as to how much magnetic energy the earth could have had originally. Reasonable postulates as to the maximum magnetic field the earth could have had limit its age to a few thousand years.
The reversal hypothesis which has been proposed to extend the magnetic field back billions of years has neither a valid theoretical/mathematical basis nor observational support. The paleomagnetic data upon which it depends for support do not correlate with the state of the earth's magnetic field, namely its magnetic moment.
1. McDonald, K.L. and R.H. Gunst, Earth's Magnetic Field 1835 to 1965, ESSA Tech. Rept. U.S. Dept. Com., 1967, pp. 1 & 5.
2. Lamb, H., Phil. Trans., London V. 174, 1883, pp. 519-549.
3. Barnes, T.G., Creation Research Society Quarterly, Vol. 9 (1), 1972, pp. 47-50.
4. Barnes, T.G., Origin and Destiny of the Earth's Magnetic Field, ICR Tech. Mon. No. 4, 1973.
5. Carrigan, C.R. and David Gubbins, "The Source of the Earth's Magnetic Field," Sci. Amer., Feb. 1979, p. 125.
6. A.A and Howard Meyerhoff, "The New Global Tectonics", Amer. Assoc. Petr. Geolo., Bul. V. 56 (2), 1972, p. 337.
7. Doell, Richard and Allan Cox, Mining Geophysics, V. 11, Soc. Expl. Geophysicists, 1967, p. 452.
8. Jacobs, J.A., The Earth's Core and Geomagnetism, MacMillan, pp. 105-106.
9. Burlatskaya, S.P., "Change in Geomagnetic Intensity in the Last 8500 Years," Inst. of Terrestrial Physics, USSR Acad Sci., 1969, p. 547.