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# Magnetic fields and the science of biblical creation

The exponential decay of planetary magnetic fields is one of the strongest scientific arguments that supports the young age of the earth and the solar system. As such it is no surprise that skeptics attack this idea. D.O. from the United States writes concerning some such objections:

Hello Dr. Sarfati:
I have a couple of questions about Humphreys’s rapid decay model of Earth’s magnetic field. I couldn’t find anything on the CMI website that directly addresses these questions, but I apologize if I missed them.

One evolutionist I am debating argued that Lenz’s law implies that nature resists a change in magnetic flux. He used the example of “suddenly turn[ing] on a magnetic field going through a conducting loop, the loop will generate a current to form a magnetic field in the opposite direction to try and keep a magnetic flux of zero.” He says that “changing a magnetic flux generates an electromotive force that tries to oppose the change in flux” and used that to argue that fluctuation is much more likely than exponential decay when it comes to Earth’s magnetic field. Is his argument valid at all?

Also, is it true that if the magnetic field strength of the earth is decaying, its rotation speed must be increasing over time, to conserve angular momentum?

Thanks for your time and help.

CMI’s Dr Jonathan Sarfati responds:

Hi Mr O.

This evo really doesn’t know what he’s talking about. Yes, there is such a thing as Lenz’s Law, which states that an induced current is always in such a direction as to oppose the motion or change causing it. But it will not overcompensate the way he is claiming. Rather, the induced current is caused by the field decay, so it will be in the direction of the original field. The decay is a negative of the original, so the induced field will be a positive. But it will never be as great (otherwise a perpetual motion machine would be possible, and this violates the second law of thermodynamics). Thus such systems will decay exponentially, as is well known in physics (as explained in my article The earth’s magnetic field: evidence that the earth is young).

As for the second question, there doesn’t seem to be a connection, because the field has no mass, while angular momentum involves mass.

Hope this helps.

Thank you for your response, it was very helpful. Regarding the second question, I understand what you mean about angular momentum, but the reason I asked it is the evolutionist I was debating said that “a magnetic field is angular momentum density,” and then went on to say that if the magnetic field was decaying, the angular momentum would have to “go somewhere” and would cause an increase in the rotation speed of earth. Is there such a connection between the magnetic field and angular momentum?

Hi again

OK, then ask this critic some questions. We know that the rotational angular momentum of the earth (L0) is given by its angular velocity (ω) times its moment of inertia, which to a good approximation is given by the formula for a solid uniform sphere (I = 2 /5 Mr2). See more at Slipshod logic in Creation for Kids? (scroll down a fair way). OK, so what is his formula for the angular momentum of the magnetic field? Let him prove that it would cause a measurable slowdown by working it out quantitatively (if he can even find a formula).

Hope this helps.

Thank you for your insight. I asked the evolutionist what formula he would use for the angular momentum of the earth’s magnetic field, and he said:

“You haven’t had any actual education in electricity and magnetism, have you? A magnetic field is angular momentum density. It’s given by c^-2(r x (E x H) ) r, E, and H being the vectors of the position, electric field, and magnetic field, respectively. Where would the angular momentum go [in Humphreys’s model of magnetic field decay]?” I also found a website that discusses this formula [Weblink removed as per our feedback rules—Ed.]. What am I missing?

The evolutionist also claimed that Lenz’s law would imply that “the nature of magnetism is oscillatory because Nature Abhors A Change In Flux,” and that the correct graph for Humphreys’s model would be a “damped oscillator” rather than an exponential curve. Is this correct?

By the way, I am granting permission to publish any of our email exchange on the CMI website if you wish to, I would just ask that you use my initials and not my full name if you decide to do so.

Hi again

This formula is not relevant to what is being discussed here.

Exponential decay is a very well-known phenomenon, and the way it works here would not be a damped oscillator. Rather, Dr Humphreys himself has written an update in the CRSQ this year, and the main phenomenon is exponential decay (so where would angular momentum go in a typical RI circuit), as per the laws of electromagnetism. There is a small sinusoidal component, which doesn’t affect the long-term energy loss, but nothing like a damped oscillator.

Regards

Jonathan Sarfati

V.G. from the United States writes in response to The moon: the light that rules the night.

The link to support your site says that “They say the bible has been proven wrong by science. Whoever said that hasn’t been to creation.com.”

Hate to burst your bubble here guys, but I’ve been to this site, and I’m saying it. None of the “science” you’ve put up supports anything of creationism, and just goes to show that none of you really know what you’re talking about. The Bible does not classify as evidence. Not because it was written by people who weren’t there, but because it comes from the perspective of an imaginary being, God, who wasn’t there and to this day isn’t there. When I was a child, I believed in childish things such as God, the Devil, heaven, hell and angels. When I became older, I began to see reality as it really is, as opposed to the way I wanted it to be and put away those childish beliefs.

Thank you.

PS-The site has a good design, it’s just the content that sucks.

Jonathan Sarfati responds:

Hey V.

Maybe you will grace us with scientific support for your fact-free assertions, enough to persuade me and my colleagues who have earned doctorates in science Creationist qualifications. E.g. which scientific paper demonstrated that God is an imaginary being, and what was its evidence? Try also this paper: Atheism.

Glad you like the site design.

Regards

Jonathan Sarfati, Ph.D.

Published: 6 July 2013