Some advice for pastors on how to handle science

In 2011, Barna Research published the results of a five-year study in which they interviewed a large number of young people to find out their reasons why they no longer attend church. The full results of their findings were published in a book called You Lost Me: Why Young Christians are Leaving Church and Rethinking Church, and a summary of the results was posted in an article on their website titled Six Reasons Young Christians Leave Church.

The third reason that they gave was that many churches come across as antagonistic to science:

One of the reasons young adults feel disconnected from church or from faith is the tension they feel between Christianity and science. The most common of the perceptions in this arena is “Christians are too confident they know all the answers” (35%). Three out of ten young adults with a Christian background feel that “churches are out of step with the scientific world we live in” (29%). Another one-quarter embrace the perception that “Christianity is anti-science” (25%). And nearly the same proportion (23%) said they have “been turned off by the creation-versus-evolution debate.” Furthermore, the research shows that many science-minded young Christians are struggling to find ways of staying faithful to their beliefs and to their professional calling in science-related industries.

For what it’s worth, I don’t think that the problem is due to any inherent conflict between Christianity itself and science. Rather, it’s because most Christians don’t know how to respond to science. Most pastors don’t know how to advise them either, because they don’t have any scientific training themselves. But that’s okay: that’s not your job. Nevertheless, there are some things you can — and should — do to provide leadership in this respect.

Claims about science demand an informed Christian response.

Like it or lump it, we live in a scientific world. Just about every aspect of our lives is influenced or even controlled by scientific discoveries and research. Many of us work in science-related industries, or have science-related jobs. Furthermore, when matters of public policy are at stake, the first question that policymakers ask is, what does science have to say about the subject? Whether we are talking about stem cell research, or cloning and genetic engineering, or sexuality and gender, or the environment, or abortion, or child discipline, or human origins, or monetary policy, or artificial intelligence, or the Internet, we will have to address claims presented in the name of science.

One of my friends at church is a PhD cell biologist with a special interest in the issue of stem cell research. She has done a lot of work fact-checking the various claims and counter-claims surrounding embryonic stem cell research in particular, and has testified on several occasions before the House of Commons Science and Technology Committee. We need more people in the Church like her.

But such people need to know what they are talking about. They also need to be supported by the rest of the Body of Christ, and consequently we need to make sure that our own approach to science is sensible, honest, informed, and responsible. You cannot expect the world to take you seriously on moral or spiritual issues if you are spouting demonstrable nonsense on empirical, testable matters. Nor can you expect to raise up people to speak on science if they are encountering passive-aggressive, suspicious, or hostile attitudes towards the subject from other people in the church, or if they are being expected to make claims that they know for a fact to be untrue.

There are people who make a business out of lying to Christians about science.

In 1 John 4:1, we read this:

Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world.

Science is a prime target for professional liars, because many claims are not easy for the layman to fact-check. Some claims are not even easy for professional scientists to fact-check, especially if they are particularly complex or specialised. On the other hand, many scientists are particularly skilled in the art of fact-checking anyway, and so if you encourage suspicion or distrust towards science, or even if you just encourage intellectual laziness in general, you will make your audience all the more vulnerable to people lying about just about anything.

Some people lie about science purely for profit. They know how to make all the right evangelically-correct sounding noises, but they are ultimately motivated by making money, not disciples. Others lie to Christians for sport, to make fools of us and undermine our credibility as effective witnesses for Christ. (The Well to Hell hoax was one notorious example.) And some of them do so for political reasons. It’s quite possible, for example, that evangelical climate change scepticism is partially funded, at least indirectly, by the oil industry.

Bad attitudes to science are a very real problem in evangelical circles.

Now the majority of Christians that I know — including many who are sceptical about evolution — have a healthy and responsible attitude towards science. The fact that I live in the UK rather than the USA may help there, if this recent study is anything to go by. But I’ve encountered enough of the wrong type of attitude to be aware that it is very much a problem.

There are certain people out there who believe that just because they have read a bunch of articles by Answers in Genesis, or watched some videos, and because they haven’t been “brainwashed” by a science degree, that means that they know more about science than “secular scientists.”

Yet these are the very people who will quite happily trot out the most staggeringly ignorant falsehoods imaginable. They frequently don’t even know young-earth creationism itself very well, let alone the “other side.” It’s common to hear them repeat arguments that even Answers in Genesis and tell them to avoid, such as Paluxy River tracks, moon dust, or NASA computers finding the “long day” of Joshua chapter 10.

When it comes to attempting to refute what real scientists actually do and teach, they don’t even do the most basic fact-checking. They often aren’t aware that radiometric dating actually involves measuring things, and they will happily tell you that Sir Arthur Keith wrote something about evolution being unproven and unprovable four years after he died. One of them told me that DNA is “just carbon,” while another of them tried to convince me that the scientific community takes a laissez-faire attitude to fraud — by referring me to an article in The Guardian about a scientist being sent to prison for fraud. It’s hard to get more clueless than that.

They are completely unable to answer even the most basic objections in a meaningful way. Their stock answer is usually “It’s just an assumption” or “It’s just an interpretation” — a response that not only doesn’t answer your question, but is very often simply not true. Yet if you point any of this out to them, they respond by accusing you of “compromise,” or “trusting man’s fallible wisdom instead of God’s infallible Word,” or even “speaking with the voice of the serpent.” I’ve even on one occasion had one such person tell me that I had a “spirit of science” that was “making it difficult for me to hear God.”

It is attitudes such as these that people are thinking of when they talk about Christianity as being antagonistic to science. But sometimes these attitudes get expressed in more passive-aggressive ways. Snide remarks about “secular science” or “putting your faith in science” are one example. Another example is using the terms “evolution” and “evolutionist” interchangeably with “atheism” and as a derogatory umbrella term for everything about science that you don’t agree with, even if it has nothing to do with biological evolution whatsoever.

These attitudes are driving away both unbelievers and Christians alike. Do not allow them to undermine your ministry.

Don’t be afraid to admit that you don’t know what you don’t know.

The biggest problem that the Barna survey highlighted in respect to science was that respondents felt that “Christians are too confident they know all the answers.”

Of course, when you’re out in evangelism, or witnessing to colleagues at work, you’ll be asked questions that put you under pressure. When your work colleagues are asking you, “Where did Cain get his wife?” you’ll be anxious to come up with something. But the correct answer to this question — and the one that your non-Christian friends and colleagues will respect you the most for — is, quite simply, “I don’t know.” The Bible doesn’t tell us, so any answer we come up with will be wild speculation at best.

It’s the same with other questions related to the creation and evolution debate. If you haven’t had any formal training in the subject, the best answer you can give is to tell them you don’t know because you’re not a scientist, and refer them to the BioLogos forums.

If there’s one thing about creation and evolution that you need to teach your people more than anything else, it is this: there is no shame in admitting that you don’t know what you don’t know. Remember that honesty is sometimes the best evangelistic strategy. Trying to convince people that you know what you’re talking about when it’s quite obvious that you don’t will just sound dishonest. Remember too that our faith is about the completed work of Christ on the Cross, and not about the incomplete work of Adam and Eve on their pet dinosaur.

Seek counsel from the trained scientists in your church.

Scientists are trained in critical thinking. Some Christians view critical thinking, reason, or “scientific scepticism” as the antithesis of faith, but it needn’t be. On the contrary, it should be seen as a line of defence in your battle against deception, to help you flush out liars who might want to take advantage of you, undermine you, or make a fool of you.

For this reason, you need to take the scientists in your church seriously. If a scientifically trained church member expresses concerns to you about what is being taught in your church about science, try to find out what the problem is. If you have no scientific training yourself, get them together with other trained scientists in the church to either allay their concerns or to propose a recommendation on how to respond. That way, every matter can be established on the testimony of two or three witnesses. But don’t just ignore them: they could be crying for help, or warning you that you are walking into a trap.

The Stem Cell Monk blogger suggests appointing a science officer in your church — or, better, a science council. This is an idea that you should perhaps seriously consider. Just make sure the people you appoint are properly qualified.

Do not allow anyone with no scientific training to teach about science in your church.

James 3:1 says this:

Not many of you should become teachers, my fellow believers, because you know that we who teach will be judged more strictly.

Anyone that you allow to teach in your church is being placed in a position of trust. In particular, it is a position of trust certifying that they know what they are talking about, that their facts are straight, and that their sources of information are accurate. As a teacher, not getting your facts straight about a subject which you are teaching is a serious breach of trust, especially if it is about something you claim to be important.

I am constantly coming across people telling me that they have lost their faith because they discovered that what had been taught to them by their pastors, their youth leaders, or their Sunday school teachers about evolution and the age of the earth was simply not true. Christian academics in the sciences whom I have spoken to report that time and time again they are confronted with undergraduates coming to them in floods of tears, all of them with the same question: “what else have they been lying to me about?”

This is why I keep saying, over and over again, that you need to make sure your facts are straight. If you believe you must reject evolution, you need to make sure that you are rejecting what scientists actually teach about it in reality, and not a garbled cartoon caricature of it. On the other hand, if you are claiming to have the support of science, you must make sure that the support you claim follows the rules of science.

There is much more to teaching science-based apologetics than spoon-feeding your group with videos. Such an approach may build faith in church on a Sunday, but when they take it into the office, the lab, the classroom or the marketplace on a Monday, it will be tested. You need to be able to teach people to answer objections and to avoid bad arguments. You can’t do that if you believe that DNA is “just carbon,” or that radiometric dating is “guessing at best.” You can only do that if you fully understand how science works, and for that you need to be able to handle the maths, be trained in laboratory procedure, learn how to think in the rigorous, exact, disciplined manner that science demands, and understand the strict standards of quality control that scientific research is expected to meet.

For that reason, if anyone believes that God is calling them to teach in your church about creation and evolution, or any other science subject — whether from the pulpit, or in a small group, or in Sunday school — you should require them to be qualified to do so.

That means a university degree in a relevant Natural Sciences subject at least. Specifically: physics, biology, geology or astronomy.

They should either have one or be willing to get one. If they have any concerns about “brainwashing,” ask them why they don’t trust God to protect them in it. And if they still aren’t willing to start by getting a degree, you should seriously question whether their calling is genuine in the first place.


YEC Best Evidence 6: helium in radioactive rocks and the importance of critical peer review

Back in August, I wrote about the RATE project and its extraordinary claim that nuclear decay rates had been accelerated by a factor of a billion during the Creation Week and Noah’s Flood. We also saw that they had reported some extraordinary problems with this hypothesis — notably, that it would have released enough heat to boil the oceans and melt the earth’s crust many times over. Yet despite this, they were confident that these problems could be resolved, and at the same time they claimed that they actually had evidence to support their hypothesis. One of the claims that they made is the sixth of Answers in Genesis’s ten best evidences for a young earth — that radioactive rocks contain too much helium.

Before I get into the technical details of this claim, I’ll start by making one very important point.

Complex claims are easy to get wrong, difficult to get right, easy to fudge, and difficult to fact-check.

I’ve worked in enterprise software development for over a decade now, and one problem that I see in one codebase after another is developers making things far more complex than necessary. Doing things the hard way is more fun and gives you new skills with which to pad your CV, but in the end of the day, the extra complexity just results in systems that are fragile, full of bugs, and extremely difficult to maintain. Some people refer to that kind of over-engineering as “stealing from your client.” It is for this reason that computing pioneer Edsger W Dijkstra came up with the maxim that “simplicity is prerequisite for reliability.”

The same principle applies to any area of science. The more complex it is, the easier it will be for mistakes and fallacies to creep in, whether by accident or design, and the harder it will be to spot them. Accordingly, such claims will need to be scrutinised all the more rigorously.

The problem is compounded even more with this claim by the fact that, at the time of the RATE project, helium diffusion in zircons was a very immature field of study, with only a small number of published papers on the subject. Jonathan Baker, a Christian geologist, has this to say about it:

I am willing to bet that if you presented Dr. Humphrey’s research in detail to the geology department at any university, you would find a handful of geologists at most that would be able to follow the arguments without spending several hours reading up on the methodology. The modeling of helium diffusivity in zircon grains is a very complicated, math-intensive process that requires a particular expertise to apply properly. This method was developed only recently (hence the lack of data before 1999), and has been studied by a relatively small number of researchers over the past 10 years. The results can be extremely useful to geologists, and so hundreds of published studies have made use of helium data from zircons, but very few people are familiar with the laboratory procedure.

The upshot of this is that a study such as this one will need to be peer reviewed to within an inch of its life by subject matter experts — aggressively, mercilessly and relentlessly, and all the more so given that it is being made in support of an extraordinary claim about accelerated nuclear decay that would easily qualify for a Nobel Prize if it had any merit. To an untrained observer, this can appear petty and nitpicking, but it is essential. Anything less would also give a free pass to anti-vaxxers, homeopathy, astrology, water divining, reading tea leaves, and tobacco companies trying to prove that smoking does not cause cancer.

Do zircon crystals contain too much helium?

As we’ve already seen, zircons are tiny crystals of ZrSiO4 whose properties make them particularly well suited to uranium-lead radiometric dating.

When uranium decays to lead, it releases helium in the form of alpha particles, which then get trapped in the crystalline structure. Over time, these are expected to diffuse out of the zircons and into the surrounding rocks. If you know how much lead is in the zircons, you can calculate how much helium was produced by the decay. This value is called Q0. You can then measure the amount of helium that is left, Q, and calculate a ratio, Q/Q0, which tells you how much must have diffused out.

The RATE team studied some zircons that had been retrieved from a borehole in Fenton Hill, New Mexico, and concluded that this value, Q/Q0, was higher than it should have been given the zircons’ radiometrically determined ages of 1.5 billion years.

They then came up with a “Creation model” that attempted to better explain the data. This model started off with a burst of accelerated nuclear decay giving rise to modern levels of uranium, lead and thorium, and an initial helium concentration, Q/Q0, of one. They claimed that when all the different values were plugged into their model, the final value of Q/Q0 = 0.58 indicated an age of 6,000 ± 2,000 years. This is pretty attractive to YECs, because very, very few of their claims of evidence for a young earth attempt to pin down its age precisely in this way — most of their other arguments merely attempt to discredit conventional old-earth results.

Simplifying assumptions.

Noble gas diffusion rates in crystals depend on a large number of different factors, including temperature, pressure, anisotropy (different diffusion rates in different directions), edge effects, and defects and impurities in the crystal structure. The theoretical calculations are complex, and it is very difficult to study it experimentally as well.

The RATE team’s study makes several simplifying assumptions. There’s nothing unusual or untoward about this: many models in physics do the same, otherwise the maths would be nightmarishly complicated. However, when you do so, you need to demonstrate that the simplifications concerned would not significantly affect your results.

The RATE team claimed that their simplifications would only affect the results by “a factor of two or so,” or “an order of magnitude or so.” However, they did not provide any calculations or other evidence to back up their claims that the effects were as insignificant as they claimed. Furthermore, factors of two or so, or of an order of magnitude or so, are most certainly not trivial. It only takes a handful of them to mount up to the difference between thousands and billions.

One such simplification was to treat the zircons as if they were isotropic — that is, that the diffusion happens at the same rate in every direction. Now zircons are anisotropic (for crystals geeks among you, they have a tetragonal lattice with a point group symmetry of 4/mmm and a unit cell of dimensions a=6.607Å, c=5.982Å), but at the time of the RATE project, the effect of their anisotropy on helium diffusion was unknown. However, a 2007 study by Reich et al (abstract) (full version) has since shown that diffusion rates between the different directions vary by up to five orders of magnitude at room temperature, and only become anywhere near isotropic at temperatures above 580°C. The abstract to Reich et al concludes with this advice:

These results suggest that the anisotropic nature of He diffusion at temperatures near the closure temperature should be considered in future diffusivity experiments. Furthermore, care should be taken when making geologic interpretations (e.g., exhumation rates, timing of cooling, etc.) from this thermochronometer until the effects of anisotropic diffusion on bulk ages and closure temperature estimates are better quantified.

Does it stand up under pressure?

Another simplifying assumption made by the RATE team was that diffusion rates would not be significantly affected by pressure. Again, at the time of the RATE project, the exact effects of pressure on helium diffusion rates in zircons had not been studied. In defence of this assumption, they pointed to some studies of argon diffusion in glasses, such as rhyolite obsidian, and gives some plausible-sounding, but nonetheless hand-waving, reasons why helium diffusion in zircons should be affected to a much lesser extent.

However, Kevin Henke, a geology professor from the University of Kentucky, responded to this claim by pointing to a study by Dunai and Roselieb (1996) that showed that at high pressures of 250 bars, helium would take tens to hundreds of millions of years even at high temperatures (700°C) to partially diffuse out of garnets. He also pointed out that garnets have much more in common with zircons, being “hard” silicate minerals, and consequently that this would be much more representative of zircons than rhyolite obsidian.

Did the RATE team stick to the scientific method?

On page 29 of the RATE project’s report, we see this seemingly innocuous comment:

After consulting with Dr. Gentry, we have corrected, in the fourth column, two apparent typographical errors in the corresponding column of his table. One is in the units of the column (which should have been 10-9 cc/μg instead of 10-8 cc/μg); the other is in sample 4 of that column. The crucial fractions in column five were correctly reported, as we have confirmed with our data.

Kevin Henke asks this question about these corrections:

How and when were the “typos” related to the helium measurements (Q values) in Gentry et al. (1982a) discovered? Were the original laboratory notes consulted to correct the typographical errors? If not, how were they reliably corrected? Were the values corrected independently of any of Dr. Humphreys’ results or were the values “corrected” to comply with Dr. Humphreys’ results? (R. V. Gentry never replied to my emails on this issue.)

This is a very important question. One does not simply “correct typographic errors” in scientific results. The original lab notes would have to be consulted, independent evidence would need to be provided that these corrections really were warranted, and if the integrity of the data could not be established, the whole data set would have to be thrown out and the experiment re-done. In the absence of such independent confirmation, “correcting typographic errors” in this manner is an unacceptably sloppy shortcut. To their credit, they acknowledged that this was what they had done; if they had not done so, it would quite possibly have constituted scientific fraud.

How not to respond to peer review.

There have been several different critiques of the RATE team’s helium diffusion experiments by subject matter experts, many of them evangelical Christians. Here are some of the key ones:

  • Gary Loechelt proposes a more realistic multi-diffusion domain model which shows that the measured values of Q/Q0 are consistent with the 1.5 billion year age of the zircons. He has also written a reply to the RATE team’s response to his critique.
  • Kevin Henke provides the most detailed and thorough critique of the RATE project’s claims. His tone is scathing at times, and he does spoil it somewhat by attacking their religious presuppositions, but many of his points are valid ones that do need to be addressed.
  • Timothy Christman points to other studies of helium diffusion in zircons which give completely different results from the RATE team’s findings.
  • Rodney Whitefield points out further ways in which the data reported by the RATE team does not support their conclusions of excess helium.

Russell Humphreys responded to the critiques of the RATE team’s research in an article on in April 2005, another article on on January 5, 2006, and again in an article on in November 2008. Gary Loechelt replied to these responses in April 2009, and Henke’s latest revision of his critique, which also addresses the RATE team’s responses, is dated June 20, 2010. I am not aware of any later responses from the RATE team.

In his 2005 response, Dr Humphreys made the following observations:

The first thing to notice about Henke’s issues is how few of them there really are.  For example, of the fifteen items above, six of them (4, 5, 6, 8, 9, 12) boil down to only one issue, how much helium was deposited in the zircons.  Several other items repeated themselves similarly.

The second thing to notice is how peripheral they are.  Not one of them has any chance of solving Henke’s real problem:  how to keep helium in leaky minerals for over a billion years.

Third, notice how petty most of them are. One of my challenges in answering those charges was to find different words describing their basic character: “molehill, not a mountain … distinction without a difference … haggling … ridiculous quibble … inconsequential … majoring on minors … irrelevant”. Eight of the items (1, 2, 3, 6, 7, 10, 11, 12) fall into that class.

Three points are of note here. First of all, it isn’t clear how the six issues he cites as boiling down to one really do refer to the same issue. They may have the same end result in common, but they all refer to different errors in determining that end result. Furthermore, there are numerous other errors that he does not even attempt to address. Dr Henke’s list of unanswered questions includes no less than sixty-six that are of a purely technical nature.

Secondly, Humphreys provides no calculations to prove that the objections really are as petty and inconsequential as he claims that they are. As we have seen from Reich et al and Dunai and Roselieb, pressure and anisotropy alone are sufficient to bring us right back from thousands to billions. In any case, even if the other objections really are “only a factor of two or so” or “only an order of magnitude or so,” he needs to demonstrate that their cumulative effect really would still be as inconsequential and petty as just considering them individually.

Thirdly, anyone who has had any significant experience in science or technology will tell you that even seemingly “petty and inconsequential” mistakes can completely undermine the validity of your results. As a software developer, I get confronted with such examples several times a day. To dismiss critiques as “petty and inconsequential” in such a cavalier manner encourages Christians to adopt a sloppy and casual attitude towards science and technology — and in many other areas of science, such an attitude can — and does — kill people.

No matter how “petty” and “inconsequential” you think it is, there are only three appropriate responses in science to a peer reviewer’s criticisms. Either fix the problem, prove that it is as inconsequential as you think it is, or retract your claim. The RATE team’s responses do none of these.

In any case, an error of ±2,000 years in a final result of 6,000 years is an error of 33%. This is an enormous error. It is far, far larger than anything seen in conventional radiometric dating, in which error bars can be tighter than one part in a thousand. Furthermore, it clearly does not account for the multiple “factors of two or so” or “an order of magnitude or so” for the simple reason that just one “factor of two or so” means an error of ±50%, which is one and a half times as large. Bearing in mind that we are dealing with extrordinary claims about accelerated nuclear decay that would easily qualify for a Nobel Prize if they had any merit, results with errors this large are simply far too weak to be credible.

Even if the study did have some merit, it is not at all clear how it supports the idea of accelerated nuclear decay in the first place. In fact, given the RATE team’s own admission that accelerated nuclear decay would have generated massive quantities of heat, this would have expelled most if not all of the helium from the zircons anyway, and so the fact that we find any helium in zircons at all is pretty strong evidence against the RATE team’s own model.

Since the RATE project, there have been numerous other studies of helium diffusion in zircons. As far as I am aware, none of them have confirmed the RATE team’s findings. The figure of 6,000±2,000 years for the age of the zircons appears to be based more on miscalculation, circular reasoning, and improper data handling practices than on the actual age of the earth.

Featured image credit: James St John

A few facts about zircons

Before we discuss the sixth of Answers in Genesis’s ten best evidences for a young earth, a little background knowledge is in order. Their argument about helium in radioactive rocks concerns zircons — small crystals of zirconium silicate (ZrSiO4). They are some of the most reliable and accurate “timestamps” that YECs claim rocks don’t come with.

They occur in all different types of rocks throughout the earth’s crust, and have several interesting properties that make them particularly well suited to the purpose. Consequently they crop up frequently in more informed discussions about the age of the earth.

A large zircon crystal.
(Source: Wikimedia Commons)

The most important feature of zircons is that they accept certain elements into their crystalline structure as impurities, but not others. They can contain up to about 1% uranium when they first form, but they strongly reject lead. This is because uranium atoms have the right size and valency to fit into their crystalline structure, whereas lead atoms do not. A freshly formed zircon crystal will contain no more than a few parts per trillion of lead (Gehrels, 2010); anything more than that must be radiogenic in origin. One part per trillion corresponds to about four months’ worth of radioactive decay.

Another important property is that they are very hard (7.5 on the Mohs scale of hardness — somewhere between quartz and topaz). That, and their small size (typically a fraction of a millimetre) makes them strongly resistant to weathering. Zircons also have a very high melting point — over 1,800°C — and a closure temperature well in excess of 1,000°C. The closure temperature is the temperature above which the impurities in the zircons start to become mobile and can thus diffuse out, thereby resetting the radiometric “clocks.”

Uranium decays to lead via a number of intermediate elements, with a half-life of 700 million years for 235U → 207Pb, or 4.5 billion years for 238U → 206Pb. Naturally occurring uranium consists of about 99% 238U and only about 0.72% 235U.

What does this mean for the age of the earth? For starters, if there has been any leakage, lead will have been preferentially lost, while if there has been any contamination, uranium will have been preferentially gained. This means that the U-Pb model age of the zircons will always be a lower limit. If it is incorrect, the zircons will be older than the naive dating method indicates. This does not help the young-earth cause.

In fact, it gets better than that. Because there are two isotopes of uranium, which decay at different rates, it is possible to determine not only whether there has been any leakage, but also when, and to what extent. This is done using a concordia diagram.

More importantly, this also means that after six thousand years, zircons should not contain more than about eighteen parts per billion of lead. Thus, any zircons which contain significantly more than that will blow the young earth timecale right out of the water. As for accelerated nuclear decay — which, as we’ve already seen, is science fiction — that would have released enough heat to melt the zircons and reset the “clocks.”

Since lead atoms do not fit naturally into a zircon’s crystal structure, zircons that have seen a large amount of decay tend to become brittle, eventually completely losing their crystalline structure and becoming amorphous. This process is called metamictisation. On heating, the impurities will anneal out, restoring the crystal structures of the zircons to their original, pristine condition. Again, we should not expect to find metamict zircon crystals in a young earth.

In practice, uranium-lead dating of zircons is one of the most reliable and accurate radiometric dating methods that scientists have at their disposal. It can give ages that are accurate to between 0.1% and 1%.

Now of course there is another product of uranium-lead nuclear decay: helium from alpha particles. What happens to the helium? That is the subject of next week’s post.

Featured image credit: Wikimedia Commons

YEC Best Evidence 5: has the Earth’s magnetic field always been decaying?

When I first saw the fifth claim on Answers in Genesis’s list, I thought it was the most unconvincing of the lot. It takes direct observations of the decrease in the earth’s magnetic field over the past 150 years and extrapolates them backwards exponentially, to show that just 20,000 years ago, you would have ended up with a magnetic field so strong that the heat released by the processes needed to generate it would boil the oceans.

What does the evidence say?

The most glaring problem with this argument is that there is no evidence whatsoever that the decay over the past 150 years is part of a long-term historical trend, let alone an exponential one. In fact, there is a lot of evidence that it isn’t. Far from decreasing exponentially, the earth’s magnetic field fluctuates chaotically and even reverses altogether from time to time. This is exactly what you would expect from a hot, roiling mass of molten metal, and that being the case, attempting to extrapolate backwards into the past, as this argument does, is just flat-out nonsense.

We can measure the historic strength of the earth’s magnetic field by examining magnetic particles in ancient pottery of known ages, and going further back in time from ancient lava flows and the ocean floor. Such measurements from all around the world tell us that the earth’s magnetic field reached a maximum about two thousand years ago, that its long term average for the past several hundred thousand years was about half of what it is today, and that it has reversed in polarity on numerous occasions throughout the earth’s history, at random intervals varying between a few tens of thousands and many millions of years, with an average of three reversals per million years. (See e.g. Korte et al., 2011; Nilsson et al., 2014.)

Modelled history of the dipole moment of Earth’s magnetic field over the past 9,000 years, based on magnetic field intensities recorded by archaeological and geological samples. From Nilsson et al (2014).

Where does the earth’s magnetic field come from anyway?

Despite the absurdity of this naive extrapolation, Andrew Snelling is asking a valid question here: namely, why does the Earth have a magnetic field at all? If the earth is billions of years old, why hasn’t it decayed into oblivion? What is keeping it going? And why does it have the configuration that it does?

Convection in the outer core. Source: USGS via Wikipedia

We know about the basic structure of the earth from seismic studies. It consists of a solid inner core, a liquid outer core, a mostly solid mantle, and a solid crust. The core is heated by mechanisms such as radioactive decay, latent heat of crystallisation as the inner core grows, and gravitational separation of heavy and light elements in the outer core. This heating gives rise to turbulent, convective currents, and these currents then generate a magnetic field which sets up a feedback loop making it somewhat self sustaining in strength and orientation.

This conventional model is called the dynamo model. It is described by a set of non-linear partial differential equations that are extremely complex and that behave chaotically, but it has good explanatory power, and computer models of the geodynamo have successfully explained aspects of the evidence such as past reversals.

Is the dynamo model broken?

The “Rescuing Devices” (sigh, here we go again…) section of the article gives a number of objections to the dynamo model. First of all, Dr Snelling claims that it contradicts some basic laws of physics. However, he doesn’t say which laws of physics it contradicts.

It turns out that the “basic laws of physics” refers to Cowling’s Theorem. It’s a massive stretch to describe this as “basic” — Cowling’s Theorem is complex and requires university-level mathematics to understand it. YEC literature available on the Internet makes no attempt to even explain what Cowling’s theorem is, but merely relegates it to a footnote. However, this argument was outlined in a book called Origin and Destiny of the Earth’s Magnetic Field by Thomas G Barnes.

This critique of Barnes’s book points out that he wasn’t getting his facts straight. Cowling’s Theorem does not rule out the geodynamo altogether; instead, it merely places restrictions on what kinds of fields it can generate. In particular, it only says that an axially symmetric current can not sustain an axially symmetric dynamo. Since the currents in the earth’s core have an asymmetry introduced by Coriolis forces from the earth’s rotation, Cowling’s Theorem is not the problem for the geodynamo that Barnes makes it out to be.

The second objection to the dynamo model is that it “fails to explain the modern, measured electric current in the seafloor.” In support of this claim, we have a footnote referencing Lanzerotti et al (1985). It is not at all clear how this particular paper supports this particular assertion.

Computer simulations of the dynamo.

The third objection to the dynamo model is that it fails to explain the many geomagnetic reversals, “computer simulations notwithstanding.”

In actual fact, computer simulations have managed to explain geomagnetic reversals. The simulations concerned were run by Gary Glatzmaier and Paul Roberts, who published their findings in Nature in 1995. Here is a video of the results of their simulation:

In response to this, Snelling merely provides a reference in a footnote: D. Russell Humphreys, “Can Evolutionists Now Explain the Earth’s Magnetic Field?” Creation Research Society Quarterly 33, no. 3 (1996): 184–185. I can’t find an online copy of this article. It’s not listed in the abstracts for that edition of CRSQ, so I presume it’s no more than a letter to the editor. Unfortunately the CRSQ is completely paywalled so I can not say what the reasoning is here, let alone whether or not it is correct.

In any case, “evolutionists” do not study the earth’s magnetic field. They study biological evolution.

The young earth model.

The computer simulations of Glatzmaier and Roberts clearly falsify YEC claims that dynamo theory has been unsuccessful in explaining the Earth’s magnetic field. However, it is worth saying a word or two about the YEC approach.

The YEC model was first outlined by Thomas G Barnes in 1971, who proposed that the magnetic field resulted from a freely decaying current in the core. However, this model has since been modified to try to account for geomagnetic reversals, and so they now propose that it was stirred at the start of Noah’s Flood, giving rise to a rapid succession of geomagnetic reversals followed by large fluctuations up to the time of Christ, then a steady exponential decay over the past two thousand years. This is illustrated by this graph from the Institute for Creation Research:

Figure 1

In other words, having dismissed anything other than an exponential decay as a “rescuing device,” they have had to ditch the exponential model themselves! If this isn’t a “rescuing device” by their own standards, then what is?

In any case, there’s also the question about whether this model is consistent with the evidence that we see today.

The number of reversals in the geological record runs into the hundreds. If these all took place during the Flood, they would have to be taking place at a rate of one a day or more. In such a model, it seems extremely unlikely that we would see any clean-cut reversals. Instead, we would see multiple poles popping up all over the place, and local magnetic fields would be changing faster than volcanic rocks could solidify. The magnetic remanence seen in cores taken from the ocean floor would be a complete jumble — if in fact there were any magnetic remanence to speak of at all.

In the Atlantic Ocean, deep sea cores from the ocean floor show a clear “banding” of magnetic reversals, and these are correlated on either side of the mid-oceanic ridge, as well as with drill core data from all over the world. We would not expect to see these correlations at all in a model where reversals happen on a daily basis.

Magnetic stripes on the ocean floor.

The earth’s magnetic field may be weakening at present, but this fact provides no support whatsoever for a young earth. The assumption of exponential decay on which this argument is build is demonstrably false and acknowledged by YEC scientists themselves to be inconsistent with the data. Elsasser’s dynamo model may have had unresolved questions thirty years ago, but these have since been solved, and it has proven itself to be very successful in explaining the nature of the Earth’s magnetic field. On the other hand, it is the YEC model which has serious shortcomings in explaining the data and which requires absurd “rescuing devices” in order to keep its head above the water.

Featured image credit: NASA Marshall Space Flight Center (via Flickr)