Decaying Magnetic Earth?
Can you please explain whether or not the magnetic field of
the earth is decaying? If so, at what rate? Can we determine the age of
the earth from this rate?
Ah, the creationist magnetic dating argument. Yes, measurements taken over
the past hundred or so years indicate that the magnitude of the earth's
magnetic dipole moment is decreasing. Geologic evidence shows that the
earth's magnetic field has switched directions many times, so it's possible
that we're approaching another zero point. That doesn't tell us anything at
all about the age of the earth.
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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Update: June 2012