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THE MYSTERY OF THE EARTH'S MAGNETIC FIELD
by Russell Humphreys, Ph.D.
The earth's magnetic field has been a mystery to man ever since
13th-century philosophers first noticed lodestones (magnetic
rocks) turning north.(1) In 1600 A.D., William Gilbert, Queen
Elizabeth's physician, shed light on the mystery by showing that
"the terrestrial globe itself is a great magnet."(2) Today,
scientists think the earth is an ELECTROmagnet; the source of the
magnetic field is probably a large electric current--billions of
amperes--circulating in the earth's fluid core. But there is
still a mystery today: HOW DID THE CURRENT GET STARTED, AND WHAT
KEEPS IT GOING? Scientists, who assume that the earth is old,
conjecture that complicated flows of the fluid in the core
somehow started the current and have maintained it for billions
of years. However, such "dynamo" theories are complex,
implausible, and incomplete. In the last two decades, they have
run into serious problems from magnetic observations on earth(3)
and in the solar system.(4)
In 1971, Dr. Thomas Barnes, a creationist physicist,
proposed that NOTHING keeps the current in the core going except
its own inertia.(5) His simple and rigorous "free-decay" theory
would mean that the current is running down slowly, like a
flywheel without a motor; thus the strength of the earth's
magnetic field would be steadily decreasing over the
centuries.(6) Barnes cited some historical data(7) (not well
known at the time) showing that the overall strength of the
earth's field has indeed steadily declined by about 7% since
1835, when it was first measured. The decay rate depends on the
electrical resistance of the earth's core, and the observed rate
is consistent with the estimated resistance of materials at core
temperatures and pressures.(6)(8) The field strength should
decrease by a constant percentage each year, and the data are
consistent with such a decrease, implying that the field loses
half its strength every 1400 years. Such a rapid decay could not
have continued for more than about 10,000 years; otherwise the
initial strength of the field would have been impossibly high.
Since the field probably started when the earth was formed, the
present rapid decay of the field is strong evidence for a young
Old-earth proponents, however, correctly point out that
the earth's magnetic field has not always decayed
smoothly.(9)(10) Archaeomagnetic (magnetism of pottery, bricks,
etc.) data indicate that the present steady decay started around
500 A.D. For several millennia before that, the overall strength
of the field had fluctuated up and down significantly.
Paleomagnetic (magnetism of geologic strata) data provide
persuasive evidence that the field reversed its direction scores
of times while the fossil layers were being laid down.(11) Since
the field has changed so violently in the past, old-earthers ask,
how do we know the present decrease in the field is a decay, not
a fluctuation or a reversal? Furthermore, if a "dynamo" process
did not start up the current in the core (as is becoming obvious
by the problems with the theory), then how did the current
HISTORY OF THE FIELD
This article summarizes five technical papers I have
published to answer such questions. The discriminating reader
will want to read them to understand more fully the model which
is only summarized below. Figure 1 shows what I think is the
history of the earth's magnetic field. It can be divided into
the following five episodes:
(1) CREATION. In 1983, I pointed out that when God
created the earth's original atoms He could have easily created
the earth's magnetic field also, merely by bringing the atoms
into existence with the spin axes of their nuclei all pointing in
the same direction.(12) Many atomic nuclei spin, and thereby
generate tiny magnetic fields. There were so many spinning
nuclei in the earth at creation that, if aligned, their fields
would have added up to a large field of sufficient magnitude. As
thermal collisions disoriented the nuclear spins, the laws of
electricity predict a startup of an electric current within the
core of the earth to sustain the field. The resulting initial
field strength is consistent with the present geomagnetic data
and a 6,000-year age for the field. Thus we have a plausible
explanation for how the current in the core got started.
In 1984, I extended my theory to the sun, moon, and
planets,(13) explaining the magnetic fields measured by the space
probes of the last few decades, and predicting the approximate
strength of the fields of Uranus and Neptune. In 1986, Voyager 2
verified the Uranus prediction,(16) and we should find out about
Neptune in early 1990.
(2) PRE-FLOOD DECAY. After creation (and the Fall), the
electric current in the earth's core would decay slowly, as would
the field, for 1656 years, until the Genesis flood. During this
period, the field would have been more than ten times stronger
than it is today, thus shielding the earth from cosmic ray
particles more effectively, reducing the production of carbon 14
in the pre-flood atmosphere, and making the earth a healthier
(3) RAPID REVERSALS DURING THE FLOOD. In 1986, I
suggested that there was a powerful release of energy in the
earth's core at the beginning of the Genesis flood, and that the
resulting strong movements in the core field produced rapid
reversals of the earth's magnetic field, about one per week,
during the year that the flood was laying down the fossil layers
at the earth's surface. General physical laws allow rapid
reversals, a likely physical mechanism exists to cause the
reversals, and observations of the sun's magnetic field
demonstrate reversal cycles in nature today. This rapid-reversal
model not only explains the general features of the paleomagnetic
data, but also some specific features which have puzzled
(4) POST-FLOOD FLUCTUATIONS. The disturbances in the
core fluid during the flood would disrupt the electric current,
chopping much of it up into small swirls oriented in different
directions. Then the earth's field during and after the flood
would not have the simple "dipole" (two poles, north and south)
shape it has today. Instead, it would have a more complex shape,
with strong "higher-order" components: quadrupole (four poles),
octopole (eight poles), etc. Paleomagnetic data confirm the
existence of such components in the field in the past. Standard
electromagnetic theory predicts that, after the flood, the
higher-order components would die away faster than the dipole
part. Because the higher-order components can have either
polarity, the strength of the field would fluctuate up and down,
as different components died away at different rates.
Figure 2 shows world-averaged archaeomagnetic data.(16)
Since the dates conventionally assigned to the data points are
based on radiocarbon dating, I have plotted the data on a time
scale crudely corrected for changes in the percentage of carbon
14 in the atmosphere since the flood. The curve shown is a
statistical fit using just the three simplest of dozens of
possible components. The data need to be re-analyzed, allowing
for a more complex field shape, but the curve fits the main
features of the data, in particular, an initial rise and fall,
the broad maximum at about the time of Christ, and the
subsequent, steady decay.(15)
(5) RECENT DECAY. Around 500 A.D., the last remaining
higher-order component became small compared to the main dipole
component, and the field decayed smoothly after that.
Though complex, this history of the earth's magnetic
field agrees with Barnes' basic hypothesis, that the field has
always freely decayed. I have merely made explicit two features
which were always implicit in the free-decay theory: (a) that
motions in the core fluid can disturb the field, and (b) higher-
order modes of decay are possible. Both of these features have a
firm basis in theory, experiment, and natural phenomena. In
contrast to dynamo theories, the reversals and fluctuations I
picture DISSIPATED ENERGY. The field has always been losing
energy despite its variations, so it cannot be more than 10,000
years old. We now have simple explanations for the field's
origin, history, and present state. In this light, the earth's
magnetic field is no longer a mystery; it is a testimony of God's
Dr. Humphreys is an ICR Adjunct Professor of Physics and a
physicist at Sandia National Laboratories, Albuquerque, New
Mexico. The Laboratories have not supported this work, and they
neither affirm nor deny its scientific validity.
(1) Pregrinus, Petrus, Epistole de Magnete (1279). Trans. by
Silvanus P. Thompson, EPISTLE OF PETER PERIGINUS OF MARICOURT, TO
SYGERUS OF FOUCAUCOURT, SOLDIER, CONCERNING MAGNETS (London:
(2) Gilbert, William. DE MAGNETE (1600). Trans. by P. Fleury
Mattelay in GREAT BOOKS OF THE WESTERN WORLD, Vol. 28, R.M.
Hutchins, ed. (Chicago: Encyclopedia Britannica, 1952).
(3) Lanzerotti, L.J., et al. "Measurements of the large-scale
direct-current earth potential and possible implications for the
geomagnetic dynamo," SCIENCE 229 (5 July 1985), 47-49.
(4) Parker, E.N. "Magnetic fields in the cosmos," SCIENTIFIC
AMERICAN 249 (Aug. 1983) 44-54, see remarks on Mercury and Mars,
p. 52. Hood, L.L. "The enigma of lunar magnetism," EOS 62 (21
April 1981) 161-163. Dirscoll, E. "That magnetic moon: How did
it get that way?" SCIENCE NEWS 101 (27 May 1972) 346-347. For
comments, see ref. 13.
(5) Barnes, T.G. "Decay of the earth's magnetic moment and the
geochronological implications," CRSQ 8 (June 1971) 24-29.
(6) ---- "Electromagnetics of the Earth's field and evaluation
of electric conductivity, current, and joule heating of the
earth's core," CRSQ 9 (Mar. 1973) 222-230. Decay rate implies
conductivity of 40,000 mho/m.
(7) McDonald, K.L. and R.H. Gunst. "An analysis of the earth's
magnetic field from 1835 to 1965," ESSA Technical Report IER 46-
IES 1 (July 1967) U.S. Govt. Printing Office, Washington, D.C.,
Table 3, p. 14.
(8) Stacey, F.D. "Electrical resistivity of the earth's core,"
EARTH AND PLANETARY SCIENCE LETTERS 3 (1967), 204-206. Likely
core materials imply conductivity of roughtly 33,000 mho/m,
agreeing with ref. 6.
(9) Young, D.A. CHRISTIANITY AND THE AGE OF THE EARTH (Grand
Rapids: Zondervan, 1982), pp. 117-124.
(10) Dalrymple, G.B. "Can the earth be dated from decay of its
magnetic field?" JOURNAL OF GEOLOGICAL EDUCATION 31 (March 1983),
(11) Humphreys, D.R. "Has the earth's magnetic field ever
flipped?" CRSQ 25 (Dec. 1988), in press.
(12) ---- "The creation of the earth's magnetic field," CRSQ 20
(Sept. 1983) 89-94.
(13) ---- "The creation of planetary magnetic fields," CRSQ 21
(Dec. 1984) 140-149.
(14) ---- "The magnetic field of Uranus," CRSQ 23 (Dec. 1986)
(15) ---- "Reversals of the earth's magnetic field during the
Genesis flood," PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE
ON CREATIONISM, Vol. II (Pittsburgh: Creation Science Fellowship,
362 Ashland Ave., 1986), 113-126.
(16) Merrill, R.T. and M.W. McElhinney. THE EARTH'S MAGNETIC
FIELD (London: Academic Press, 1983), 101-106.
* CRSQ: Creation Research Society Quarterly, Box 14016, Terre
Haute, Indiana, 47803.