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     HIS BOARD -- (805) 652-1478
          Sysop: Bob Harris



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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 
earth.

        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 
originate?

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 
place.(5)

        (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 
evolutionists.(15)

        (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.

CONCLUSION

        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 
handiwork.

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.

FOOTNOTES

(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: 
1902).
(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), 
124-132.
(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) 
115.
(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.


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