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,3proposed that the earth’s magnetic field was caused by a decaying electric currentin 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.

Evolutionist responses

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….

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