Addendum: Answering sceptical objections
Exponential Decay?
Some sceptics have claimed that an exponential decay curve is wrong, and a linear decay should have been plotted. Now, both exponential and linear decay curves have two fitted parameters:
- Exponential decay (i = Ie-t/τ) requires the parameters I and τ.
- Linear decay of the general form y = mx + c requires the gradient m and y-intercept c.
If the fit were similar, there is no statistical reason to choose one over the other. The fit is very similar for the limited range of data available, with no significant difference between the two.
However, it is a well-accepted procedure in modelling of regression analysis to use
meaningful equations to describe physical phenomena, where there is a sound theoretical basis for doing so. This is the case here. Currents in resistance/inductance circuits always decay
exponentially, not linearly, after the power source is switched off. For example, in a simple electric circuit at time t with initial current I, resistance R and inductance L, the current is given by
i = Ie-t/τ, where τ is the time constant L/Rthe time for the current to decay to 1/e (~37%) of its initial value. For a sphere of radius a, conductivity σ and permeability μ, τ is given by 4σμ/π.
A linear decay might look good on paper, but its physically absurd when dealing with the real world of electric circuits. In fact, linear decays are rare in nature in general. Conversely, exponential decay is firmly rooted in electromagnetic theory.
Thomas Barnes, who first pointed out magnetic field decay as a problem for evolutionists, was a specialist in electromagnetism and wrote some well-regarded textbooks on the subject. But most of his critics are crassly ignorant of the subject.
Another important point is that these calculations point to a
maximum age of the earth. Even if the sceptics were right about a linear decay, it would still point to
an upper limit of 90 million years, and this is far too young for evolution.
A final point is that if the decay really were linear, we havent got much time left before the earths magnetic field disappears!
Multipole components of the field
Some sceptics have claimed:
only the dipole-field strength has been decaying for a century and a half
the strength of the nondipole field (about 15% of the total field) has increased over the same time span, so that the total field has remained almost constant. Barnes assumption of a steady decrease in the fields strength throughout history is also irreconcilable, of course, with the paleomagnetic evidence of fluctuations and reversals [in the geomagnetic field] (Ecker, 1990, 105)
The authority turns out to be an anti-creationist
dictionary compiled by an anti-Christian librarian with, as far as we are aware,
no scientific training! Dr Humphreys answered in July 2001:
Litany in the Church of Darwin: The non-dipole part of the earths magnetic field shall save us! That is indeed an old and dismissive evolutionist argument. Tom Barnes discussed it in his papers during the 1970s. I discussed it near the end of my paper A Physical Mechanism for Reversals of the Earths Magnetic Field During the Flood.
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Over 90% of the field is dipolar (two poles, one north and one south), but the rest of it is non-dipolar, or multipolar, such as the quadrupole part (two north and two south poles), the octopole part (four north and four south poles), etc. Just imagine the fields from bar magnets tied together at various angles to one another.
In the 1970s, the evolutionists claimed that the very large
energy (units are Joules or ergs) disappearing from the dipole part of the field is not really converted into heat, but is somehow being stored in the non-dipole part, later to be resurrected as a new dipole in the reverse direction. Some papers showed that the average
field intensity (units are Teslas or Gauss) of some of the non-dipole parts is increasing slightly.
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But
field intensity is not
energy. To get the total energy in a component, one must square the intensity in a small volume around each point, multiply by the volume and a certain constant, and add up all the resulting energies throughout all space. The non-dipole intensities fall off (with increasing distance from the earths center) much faster than the dipole intensity, so the non-dipole parts are not able to contribute nearly as much energy to the total as the dipole part. That means the small increase in some non-dipole
field intensities does not appear to represent nearly enough
energy to compensate for the enormous energy lost year by year from the dipole part.
I have my doubts that the paper referred to actually proves the point the evolutionists want to make, that non-dipole
energy gain compensates for dipole
energy loss. Not only does my eyeball estimate above disagree, but the theory of reversals in my 1990 ICC paper disagrees [As shown below, Dr Humphreys no longer has his doubtshe (and anyone who checks the numbers) now
knows that the evolutionist claim is fallacious]. It says that some energy will go into non-dipole components, but not nearly enough to compensate for the energy loss from the dipole part. The reversal process I propose is not efficient; it dissipates a large amount of energy as heat. I discussed this, including non-dipole parts by implication, in the second-to-last section (The Fields Energy Has Always Decreased) of my
Impact article on the ICR website.
As further evidence, I used the authoritative International Geomagnetic Reference Field datamore than 2500 numbers representing the earths magnetic field over the whole twentieth century. The bottom line is this:
In the most accurately recorded period, from 1970 to 2000, the total (dipole plus non-dipole) energy in the earths magnetic field has steadily decreased by 1.41±0.16%. At that rate, the field would lose at least half its energy every 1500 years, give or take a century or so. This supports the creationist model that the field has always been losing energyeven during magnetic polarity reversals during the Genesis floodever since God created it about 6000 years ago.
The evolutionists, on the other hand, have no workable, mathematically-analyzable theory of reversals. They are claiming that whatever process actually caused the reversals was 100% efficientthat the total energy in their hoped-for future dipole field will be equal to the total energy which was in the dipole field at its last peak (about the time of Christ). That is, their faith in a billion-year age for the field requires them to believe that each cycle is resurrected phoenix-like from the ashes of the previous cyclewith no losses.
Put another way, the Church of Darwin requires them to believe that the
Second Law of Thermodynamicsthat all forms of energy devolve down to heatdoes not apply to planetary magnetic fields. Sound familiar?
Later, Dr Humphreys published The Earths magnetic field is still losing energy,
CRSQ 39(1)111, March 2002, which explains the above and more in detail (see
full article, and his
Creation Matters laymans summary
The Earths Magnetic Field: Closing a Loophole in the Case for its Youth, March/April 2002both off site).
Reference