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.