Episode 9: Earth's Decaying Magnetic Field
Recap: It's a fact that Earth's magnetic field strength is decreasing. Young-Earth creationists use this to argue Earth is only a few thousand years old. Is this plausible?
Puzzler: Let's say that you are at Earth's magnetic north pole - where it is on the surface. You have a compass needle suspended by a thin thread, so it can move in any direction. How would it be aligned? And, would your answer be different if you were at the magnetic south pole, and if so, how; if not, why?
Solution to Episode 8's Puzzler: If you got the sphere spinning rapidly enough, a rarefaction would occur in the center and that it would take on a flattened sphere shape, also known as a biaxial ellipse. The short axis of this would be oriented along the north-south spin axis while the two long axes would be towards the equator. The reason for this is that the centrifugal force pushes the material outwards from the center, tangential to the direction of spin. this means that if you're spinning around a north-south axis, your motion outwards is going to be a straight line away from that axis. Centrifugal force on material at the equator is going to be greater than that near the poles because the equator is effectively moving around more quickly than if you're just below the poles. So, the material near the poles is not going to get flung out as much, it's going to tend to stay where it is, and hence why the rarefaction that forms will not extend as far to the surface at the poles.
Q&A: How do astronomers tell the difference between various types of supernovae?
There are four types of supernovae events, and unhelpfully, they are named Type 1a, 1b, 1c, and II. Some further sub-divide Type II into IIP and IIL, but I won't do that for this explanation.
ALL supernovae classification comes from the kind of light they emit and how much over what period of time. That's really the ONLY classification method, and it's later modeling that astronomers use to try to figure out what kind of explosion can produce that kind of light signature.
Type II supernovae are the kind that most of us are probably familiar with. It's the kind where a star much more massive than the sun can no longer fuse elements. The lack of fusion means there is no outwards pressure, the star collapses, and the resulting heat creates a massive explosion in which a lot of things happen. The light from these is very bright for a longer period of time than the Type I supernovae, and they also contain certain types of hydrogen absorption lines in their spectra.
Type I supernovae, as a general rule, LACK any hydrogen lines in their spectra. Type Ia marks the presence of a strong silicon line (Si II @ 6150 Å); Type Ib has a helium line (He I @ 5876 Å) with no strong silicon; and Type Ic has either weak or no helium or silicon lines.
The origins of these are thought to come from binary star systems. Type Ia is where you have a white dwarf star in a binary system that accumulates material onto its surface, leeching off its companion. When it accumulates enough material that it weighs more than 1.38 times the sun, it collapses into a neutron star in a Type Ia event.
Type Ib and c are not as well understood. The thought is that they are somewhat like Type II supernovae - big stars that blow up - but that the outer regions of hydrogen that normally surround these stars have somehow been lost.
- Sources for Audio Clips and Quotes
- References Used and Additional Resources
- Earth's Decaying Magnetic Field
- Earth's Present-Day Magnetic Field
- Wandering Magnetic Poles and a Dynamic Field
- Earth's Reversing Magnetic Field
- Crustal Magnetic Polarity on Earth (yes, Dr. Hovind, there ARE magnetic reverslas)
- Russel Humphreys' magnetic field model
- Science article on magnetic reversals that Hovind cites. (Hall & Robinson, 1979)
- Link to Dr. Coe and Pévot's article
- Kent Hovind's "Doctoral Dissertation"
- For the expansion on Admiral Byrd's Diary (from Episode 8):
- Comet Elenin is no more.
- Resources for Terms and Concepts
- References and Resources for the Q&A
- Relevant Posts on my "Exposing PseudoAstronomy" Blog
Transcript of the Main Material:
Claim: The basic claim in this case is that Earth's magnetic field has been directly observed to be declining for the past several hundred years, and it's been determined through other methods to have been declining for a few thousand. Young-Earth creationists frequently claim that if you extrapolate this backwards in time, you reach a point about 10,000 years ago when the magnetic field was simply too strong to have been able to allow life to exist, therefore Earth was created recently, not billions of years ago.
Quick Refute: In a few words, this is fairly silly because you can't just take a trend from a hundred years and extrapolate it back thousands, and we also know that the field has reversed many times, which refutes the idea that it's just decayed from a high point 10,000 years ago. Case Closed.
Okay, I guess we have more time in this episode, so I'll go into some more detail.
People discovered magnetism centuries ago, and it was really explored and formalized by – what I fondly refer to – as the Old Dead White Guys between about the 1700s and 1800s. (Yes, I realize that women and non-white people have made significant contributions to science and continue to do so, and that the Arab world kept science going while Europe was in the dark ages. But, let's be objective: Most of the basic fundamentals of science today were figured out by white European men between the 1600s and early 1900s. I'm talking Newton, Copernicus, Galileo, Kepler, Gauss, Kelvin, Maxwell, Einstein, and Schrödinger here.)
Moving on, ship captains used Earth's global magnetic field to navigate, but even in the 1700s, they realized that Earth's magnetic field changes from year-to-year. In fact, they had to purchase new maps to correct for magnetic pointings to actually know where they were. Without a correct and current map, they could be off by tens or hundreds of miles — something significant when that reef is coming up in 10 seconds.
Around the turn of 1900, scientists were able to start to accurately measure the global magnetic field strength. They have continued to measure it over the past century. What has been found is that the field strength is decreasing. That is a fact. Between 1900 and 2000, the field strength has decreased by very roughly 6%. Based on crustal rocks, we have been able to tell that the decline is about 35% from what it was about 2000 years ago, and it seems to have accelerated a little bit over the past few years.
Another interesting tidbit of information is that in the 1920s, geologists noticed that some volcanic rocks were magnetized in the opposite direction to the current magnetic field. When more and more like that were found, and when they were dated, it was discovered that Earth's magnetic field has gone through many reversals throughout its history. The last one was about 780,000 years ago. Or, if you're a young-Earth creationist, it was during the Flood ... but more on that later.
We also know that the current magnetic north pole is moving, traveling towards Russia at something like 50 km per year, while the south magnetic pole is moving somewhat more slowly these days, but it moved more quickly in the early 1900s.
What this does is paint a picture of a dynamic process that creates a global magnetic field that changes with time, the change being to its strength, specific pole locations, and even overall orientation.
Enter the young-Earth creationists.
Creationist Scenario 1
Creationists actually don't agree on a false conclusion from the data and from their reading of the Bible to present to the masses. So first we'll go over what I call "Scenario 1," which is promulgated by people such as the now incarcerated Kent Hovind. I actually have not been able to find any other creationist who believes this, but we'll ignore that for now.
The so-called "Dr." Hovind makes the claim ... [clip from "Creation Science Evangelism" series, DVD 6.1]
The scenario can then be summarized as what I said originally: He believes Earth's field has been on an exponential decay since Creation a few thousand years ago and that means Earth is young because the field would have been too strong to (a) be physically possible or (b) to allow life to exist. This is based on the current trend.
Seems plausible, except we DO have that pesky thing of magnetic reversals, despite what Kent Hovind wants to believe. And that thing about extrapolating past trends for 100x the length we observe the current trend for something that's as dynamic as a magnetic field is pretty stupid.
Taking feedback from the last episode, I'll quickly address a few of the other things Hovind stated:
Perhaps the most important is the quote from the Science article stating, "It is clear that the simple model of uniformly magnetized crustal blocks of alternating polarity does not represent reality."
Fairly damning. Let's look at the next sentence: "Clear reversals of polarity with depth are observed."
This is an obvious, clear, and blatant example of quote-mining. Hovind takes one sentence out of context to claim one thing when the scientists who wrote the paper clearly meant the exact opposite.
The other item is his statement, "Earth has lost 10% of its magnetic field strength in the last 150 years. It's ... evidence that the Earth's magnetic field is getting weaker. ... That means it used to be stronger. If you go back in time ... the magnetic strength would have been too great for life to exist here, because of the heat generated."
Simply put, other than the fact that the field is decreasing now, nothing in there is true.
The third point I want to mention is the whole, "Evolutionists have to find an answer for the problem [of Earth's magnetic field declining, so they say] 'it must be going through reversals.' It has never been observed to reverse, it's only been observed to decline."
Well, first, there's something ironic about this man saying we've never seen it reverse therefore it hasn't happened, whereas he believes everything in the Bible but he's never seen it.
Second, nobody's ever seen gravity, but we see its effects. True, humans have not had the instruments nor been around to observe a reversal before, but we can see the EVIDENCE for it in the maps I'll post to the show notes.
And this is a man who used to be a school teacher.
Creationist Scenario 2
Enter Creationist Scenario 2, which was proposed by another creationist, Dr. Russell Humphreys. Humphreys actually can legitimately call himself a doctor as he does have a Ph.D. in physics from Louisiana State University. This is in contrast with Kent Hovind who's degree is from a diploma mill around 100 km south of me. Hovind's thesis starts out by saying, "Hello, my name is Kent Hovind. I am a creation/science evangelist. I live in Pensacola, Florida." Hovind's thesis also contains a poem he wrote while thinking about something one day. But I digress ...
Dr. Humphreys accepted that magnetic field reversals actually happened, so to some extent he doesn't plunge his head into the sand and ignore everything about modern geology. But, while he accepts that reversals happened, he compresses all magnetic field reversals into the time of Noah's Flood. After the Flood, it increased again until it had a high point when Jesus was born, and then it decayed as we see it now.
Before the Flood, the field was at the same exponential decay that Hovind thinks, and so the basic premise in why Earth must be young is the same as before. (I'll also have an image of Humphrey's model in the show notes.
If you want to run this forward, supposedly, we started at a high field intensity during creation, it decayed, then dropped to zero at the beginning of the flood, reversed a lot really quickly, started to climb back up to reach a relative high around the time of Jesus – I guess he had a magnetic personality – and then continued to decay as before like nothing happened.
I'm reminded of the disclaimer during the South Park episode about Scientology that stated, "YES, SCIENTOLOGISTS REALLY BELIEVE THIS!" Yes, young-Earth creationists really believe this, at least some of them. I'm really not sure what else to say here — it's just kinda laughable; it makes no sense, and it's pretty much 100% up to the creationists to provide any evidence for it. For example, they could provide rock ages showing the reversals that date to the Flood. Except that they don't believe in radiometric dating.
I should also note that the evidence shows there have been dozens if not hundreds of these reversals throughout time. Now, my understanding was the Judeo-Christian biblical flood lasted 40 days. And then roughly a year before they went away (um, where?). So you'd need to flip that field something like once every three days for that to work out, just FYI.
A Test for Scenario 2?
Some creationists do claim that this second scenario can be tested. To quote from the Creation Ministries International: "Dr Humphreys also proposed a test for his model: magnetic reversals should be found in rocks known to have cooled in days or weeks. For example, in a thin lava flow, the outside would cool first, and record earth's magnetic field in one direction; the inside would cool later, and record the field in another direction."
It's important to note at this point that this would not actually be evidence for that model, it would just be evidence that the magnetic field can change polarity rapidly. They'd still need to somehow date it to that time. But moving on ...
The CMI article that stated Dr. Humphreys' test claims that two researchers, Robert Coe and Michel Prévot, found just such examples where lava that must have cooled within 15 days had a full reversal within the layer. To quote from the CMI article: "Three years after this prediction, leading researchers Robert Coe and Michel Prévot found a thin lava layer that must have cooled within 15 days, and had 90° of reversal recorded continuously in it."
Their work was done in 1989, and actually published in a reputable journal as opposed to a creationist one. With the wonders of the internet, and people posting their papers on their personal websites, you can view it yourself, and I'll link to it in the shownotes. IF you're a close reader, you can quickly see that the Creation.com article does misstate their research, for their paper clearly states they found evidence of a change of 3°/day, which means it would be 60 days for a full 180° flip, or 30 days for a 90° flip.
But to get into this more, I actually contacted Dr. Coe, who is a faculty member at UC Santa Cruz in the Earth and Planetary Sciences department. I explained the situation and asked him for his views on the matter. To quote his e-mail response:
"In both our papers proposing a rapid field change hypothesis it was for episodes during a reversal. We explicitly stated that there was no evidence suggesting that the reversal occurred in less than the several thousand years duration typical for polarity changes. We have recently been working more on that same reversal, and our paper should be published this month (Jarboe et al., Geophysical Journal International). In it we show that the second directional jump is almost certainly due to a temporal gap in the lava-flow succession rather than rapid field motion.
"I wish you well in your campaign against creationism."
I think if the main author of the paper the young-Earth creationists cite says that they have misinterpreted his work, we can lay this to rest, despite the article's claim: "This was staggering news to them and the rest of the evolutionary community, but strong support for Humphreys' model."
With all that said, in the end, it's up to the creationists to provide actual independent evidence that their model is correct. Hovind is WRONG, there are magnetic field reversals. Humphreys is WRONG, you can't compress dozens of field reversals into a single year through any natural process. In the end, if you want to just claim goddidit (all one word), then just have the guts to say that. Don't try to distort or lie about the science to promote your beliefs.
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