Episode 39: Radiometric Dating and Young-Earth Creationism, Part 2
Recap: After going over the basics of radiometric dating in Episode 38, here I discuss some of the main young-Earth creationist complaints about the technique, and their arguments to try to invalidate it.
Puzzler: Is the geologic column ever seen complete on Earth? Why or why not?
Solution to Episode 35's Puzzler: The answer, practically speaking, is the Japanese space agency's SELENE mission, AKA Kaguya (かぐや), that arrived in orbit in late 2007.
The reason that I said this was a somewhat tricky puzzler is that, technically, any camera in orbit COULD photograph the Apollo sites IF the spacecraft were brought to a low enough orbit. But, none were until SELENE's combination of a high enough resolution camera and low enough orbit.
Q&A: This episode's question comes from David W. from Colorado, USA, who asks in a paraphrased way: "What about polonium halos in young-Earth creationists' claims?"
The answer is a bit long. First, polonium is a radioactive, unstable element where different isotopes have different half-lives that range anywhere from microseconds to a hundred years or so.
The issue is that polonium has been found in granite rock. Granite is an igneous rock by definition, meaning that most of it is volcanic, but it contains a variety of different crystals and minerals and a variety of different percentages of each. Granite forms deep within Earth, at least 1.5 km below the surface, and the accepted geophysics is that it takes millions of years to form and slowly intrudes into other rocks and is pushed up to the surface.
The idea of a polonium halo is that there are spherical regions of discoloration around polonium grains in the granite. The creationist argument is that if the granite took thousands or millions of years to solidify, then it should not show the polonium halos because by the time the granite cooled and solidified, the polonium would have all decayed.
This particular argument is advanced by Robert Gentry, who has a Masters degree in physics and held a research position at Oak Ridge National Lab. So he's no dummy. But, he's not a geologist, and that's important.
There is a much longer version of this story that I've linked to in the shownotes for this episode, but to put it succinctly, there are several problems with Gentry's methods and his conclusions. First, none of his samples were gathered by him, nor are they traceable. In other words, he was sent samples of rocks by different people and we don't actually know where they came from. This matters because part of Gentry's argument is that they come from original, ancient granites of Earth, some of the first rocks, but without any documentation of where they're from, we can't go into this. And there's evidence that they are not what he claimed they were.
Following that is a second problem: What he identified as polonium halos was based on work done in the 1910s when we didn't know the structure of the atom nor the crystal study of minerals. Gentry relied on basic assumptions of some researchers at that time -- a very simplified model, in other words - to make his conclusion. These simplified models were not supported at the time Gentry was doing his work in this area, and they're not supported now.
A third problem is that the halos could be made by other radioactive elements. Obviously there is no longer polonium present in the center, and so other elements that emit the same kind of radiation - of which there are many - could be the culprit. Radon is a likely contender.
New News Segment:
- Episodes 27 and 37: Another Wired article on outer space legal claims.
- This Wired article details some of the "weirdest" legal claims on things in outer space.
- One claim it talks about is James Mangan who claimed to found his own country (in 1949, in Illinois, USA) and laid claim to everything in space. The UN refused to recognize him as a country.
- Another was the story I always love to bring up of the Russian astrologer Marina Bayross who sued NASA for messing up her horoscope when NASA's "Deep Impact" mission smashed into comet Tempel 1. She seeked $300 million for moral damages. The suit was dismissed.
- A quote: "Humankind has a short collective memory, so the claimant is able to create some buzz before the story dies out — to be followed by a similar story, years later." --Virgiliu Pop, a space law researcher at the Romanian Space Agency
- Additional Resources
- Some Creationist Claims Related to Radiometric Dating
- Some Resources Critiquing the Creationist "Challenges" to Radiometric Dating
- TalkOrigins on Closed Systems
- TalkOrigins on Initial Conditions
- TalkOrigins on Constant Radioactive Decay Rates
- Old Earth Ministries refuting young-Earth creationist claims regarding radiometric dating.
- Resources for the volcanic rock dating: Old Earth Ministries on volcanoes in general or Mt. St. Helens specifically, TalkOrigins
- Biblical Chronologist on alleged radiocarbon dating anomalies.
- Additional Resources for the Q&A
- Relevant Posts on my "Exposing PseudoAstronomy" Blog
Claim: In the last episode, we talked extensively but superficially about radiometric dating. Rachael Acks was my guest and she explained the basic process of radiometric dating, how it works, and some of the known caveats of the method.
The problem for young-Earth creationists is that radiometric dating would seem to indicate that Earth, Mars, asteroids, comets, and the Moon -- in other words, objects that we have samples from on Earth -- are roughly 4.5 billion years old. Young-Earth creationism holds that Earth is only about 6000 years old.
And so, probably ever since the technique was developed, young-Earth creationists have tried to poke many holes in the method. Not a month goes by that one of the top three creationist institutions doesn't put out some article attempting to refute it yet again.
The topic is way too broad to address every claim and counter-claim in this episode. Instead, the approach here is that I'm going to break down the majority of the creationist claims I've read into a few different categories, provide an example or three, and then explore whether or not that example does what the creationists claim it does.
I'll also note that I'm adopting the term "creationist" in place of "young-Earth creationist" for this episode. I realize that old-Earth creationists are still creationists, but it's a long phrase and the "YEC" abbreviation gets old.
Category of Claims 1: Systems Aren't Closed
In episode 38, we talked about the requirement that a system be closed in order for radiometric dating to be valid for that sample. What this means is that none of the parent material can get in or out, and none of the daughter material can get in or out. You can think of this like an hourglass. If the hourglass has a leak, then your assumption about the ratio of parent to daughter is not going to be valid.
The creationist claim goes, "The idea that a system in nature could remain closed (that is, not influenced by any outside sources) for millions or billions of years is absurd to the highest degree." Of course, they offer no evidence to back this up, they simply rely upon human common experience of, like, kicking a rock and breaking off chunks of it to make you think that what they say is true.
Rachael and I talked about how this IS a valid assumption in cases that legitimate scientists use for age-dating materials. For example, if I drive five miles west, I hit the front of the Rocky Mountains. When no one's looking, I can take a rock hammer and start chipping away. I can go in and grab a part of rock that's far from the exposed surface.
If I then take that rock to a lab, they're going to go further inside it and take out individual mineral chunks and date those to find out when those minerals formed. I can 99.999% guarantee you that those minerals are a NEARLY perfectly closed system, where heavy elements are not going to have been exchanged with the environment. Rock is pretty darn solid.
Another way to think about this is that if the rocks were NOT closed systems, you would expect that the ages would vary across multiple samples of the rock or bone or whatever you're trying to date. But, when care is taken with the samples to be taken from non-weathered or eroded regions, the ages agree to within 1-3%. It is incredibly unlikely that the contamination would be perfect enough to affect all the ages in different kinds of minerals the exact same way -- and I would argue MORE unlikely than it not being a closed system.
Category of Claims 2: Decay Rates Have Changed
Another key part of radiometric dating that we discussed is that you have to know the decay rate of every isotope you're using, and it needs to be constant. Knowing the decay rate is straight-forward, even for isotopes with half-lives measured in the billions of years. Yes, there is scatter between different experiments, but overall we have a pretty good idea that, say, potassium-40 has a half-life of 1.248 billion years. Is it possible it's 1.249 billion? Sure. 1.245 billion years? Maybe. 1000 seconds? Absolutely not.
But this decay rate also needs to be constant. It can't be one thing today, and another in the past, and another in the future. If it changed, then that would make the math much more complicated, assuming we knew what those different rates had been and when.
And so creationists will simply say that it's changed in the past and it's changed in just the right way so that all the ages we get of thousands or millions or billions of years are wrong, that it's all capped off at 6000 years. The arguments for this among creationists are varied, and they get very technical, especially for creationists, so I'm not going to go into the individual claims.
Rather, what's the evidence that that the rates HAVEN'T changed in any significant way?
So, first off, we can turn to supernovae. They produce huge amounts of radioactive isotopes, and pretty much all our original radioactive material came from a previous supernova. Or god. Anyway, when these highly radioactive elements decay, they produce certain wavelengths of light with a certain intensity that is measurable and specific to the decay rate.
When the supernova an the neighboring Magellanic Cloud happened in 1987, that cloud 169,000 light-years away, astronomers monitored the rate of decay of radioactive elements. It matches what we measure on Earth, so we know that at least they've been constant between our galaxy and a neighboring satellite galaxy over the course of nearly 200,000 years.
Another line of evidence is that, if radioactive decay were fast enough in the past to make everything only 6000 years old, then the shear amount of radioactive material in Earth would have melted the entire planet. Unless somehow you're going to argue that, in addition to the rate being faster in the past, somehow it didn't release any energy, either.
A third line of evidence is that different radioisotopes decay in different ways, and yet when these different ones are used on the same sample, the ages are consistent. It's unlikely that enough changes to specific nuclear events could happen in tandem in just the right way to get uniform offsets like this.
A fourth is the point I alluded to earlier: Radioactive decay is dictated by the principles of quantum mechanics, and we can derive a prediction of what they should be from first principles of quantum mechanics. Any changes to the decay rate means that these fundamental physics constants must be different, again in just the right way to still allow everything else we see in the universe to be the way it is, but for different radioactive decay processes to happen faster in just the right way to get a 6000-year-old universe.
I suppose at this point, roughly half-way through the main segment, it's appropriate to mention that yes, one could argue this way, that God did it, but that's not science.
Category of Claims 3: Dating Methods Are Circular - "The fossils date the rock, the rocks date the fossils."
Breaking out from the fundamentals of radiometric dating, the third claim is that geochronologists argue that all of radiometric dating of fossils is a circular argument: The fossils date the rock, and the rocks date the fossils. In fact, to quote from the Creation-Evolution Encyclopedia: "This evolutionary fraud is simple enough: Evolutionists date the fossils by the rocks they are in, and they date the rocks by the fossils that are in them!"
This is not true. As Rachael explained last episode, geologists the world over had built up the geologic column over the course of around 200 years before radioactivity was even discovered. They used outcrops and layers from all over the world to construct this, and they saw what fossils were in each layer type.
After radiometric dating was discovered, the different layers were dated generally by dating volcanic rocks within and between the different layers. These absolute ages almost always supported the relative ages that had been constructed by geologists in the hundreds of years of study before radiometric dating.
It's only now that we have over 300 years of research in this area that a geologist can be fairly confident when they see, say, trilobites, that the fossils are in rock that dates to between the Cambrian and Permian periods, between very roughly 500 and 250 million years ago.
Category of Claims 4: Using the Technique Gives Demonstrably Wrong Answers
The fourth category of claims looks at actual examples of radiometricly dated material and says, "Ah ha! It's wrong!" For example, an entire section of Answers in Genesis' page-o'-links on radiometric dating is, "Are there examples of inaccurate results obtained from the potassium/argon dating method?"
There are two main examples of this that are often touted in young-Earth circles. The first has to do with potassium-argon or argon-argon dating of historic volcanoes. What "historic volcanoes" means is that these volcanoes erupted during human history and were recorded, so we know the exact year or years of the eruptions.
It should also be noted before I go further that both of these methods rely on isotopes with a half life of roughly 1.25 billion years. That means that the absolute youngest something can be in order to really use this technique is several thousand years old, and that's on modern equipment. If it's younger, then there won't be enough daughter element present in order to get any sort of meaningful age above the inherent uncertainty in the measurement.
In one study that the creationists point to, the YECs first failed to read the basic data table correctly, and then they misrepresented the results. This is detailed in an article on an Old Earth ministries website that I've linked to in the shownotes entitled, "Blind Leading the Blind."
In another example of volcanic material dating, the YECs went to date rocks from the 1986 Mount Saint-Helens eruption. Now, remember, they're using a technique that only works for samples at least thousands of years old. And, when the creationists went into the field, gathered their samples, and sent them to a lab, they sent it to a lab that specifically stated they could not age-date anything younger than 2 million years old. The lab returned ages between 0.34 and 2.8 million.
But the problem goes deeper. We briefly touched on this last time, but radiometric dating requires dating a single part of something. In a rock, that's the overall matrix, or individual crystals within it. You can't send a mixed chunk of rock and have it dated ... but that's what these young-Earth creationists did. And those samples of rock can contain crystals called xenocrysts that are solid at molten rock temperatures and so can be MUCH older than the volcanic rock.
The second set of examples has to do with radiocarbon dating methods. Creationists will point to studies of currently living or recently killed animals that were carbon-dated to be thousands of years old instead of 0.
These examples, though, were all pointed out by normal geologists who were talking about and describing what is known as the "reservoir effect." Basically, some animals that live in water can yield anomalously old radiocarbon dates because that water is in contact with limestone. Limestone has a lot of stable carbon in it, and that carbon gets incorporated into the animal. So if you were to blindly date the animal with radiocarbon, you'd get an excess of the daughter present, giving you an old age. If you didn't know about this effect. Which we do. And so take it into account.
What I like to summarize this category of claims as is basically misusing the technique. An analogy is that I recently purchased an iPad. Under the lines of argument of a young-Earth creationist with radiometric dating, I should loudly proclaim that iPads don't work because mine can't make me dinner. It's basically a blatant misuse of the tool in a way or method that it was never designed for, so of course you're going to get bad results.
Philosophical Claim: Radiometric Dating Provides the Needed Proof for Evolution of Long Timescales
Finally, I want to address a somewhat snide side-comment that I found on several creationist websites. An example comes from trueauthority.com which rhetorically asked the question, "Does radiometric dating provide the desperately needed 'proof' that evolutionists have long been searching for [of long periods of time]?"
This line of argument goes like this: First, evolution requires long periods of time, such as a minimum of hundreds of years for small speciation but more like 10s of millions of years for completely new body plans. Creationists often mock this as, "Evolutionists say that given enough time, evolution can do anything!" Creationists then will claim that if it weren't for radiometric dating, we wouldn't know how old Earth is and so they've tweaked the numbers so that radiometric dating shows an old Earth.
There are many, many problems with this line of argument. The most basic, and the one I'll go over, is that the timing doesn't work for this to be a valid argument.
Evolution was first formalized in the 1850s and subsequent decades. 2009 celebrated both the 200th anniversary of the birth of Abraham Lincoln and the 150th anniversary of the publishing of Darwin's treatise on the subject, "On the Origin of Species by Means of Natural Selection."
If you listened to my special podcast episode 36, or just happened to know on your own, you'll recognize that geologists and physicists had started to estimate the age of Earth over 150 years before Charles Darwin published his work. James Hutton, for example, in the mid-1700s looked at current geologic processes and estimated Earth's age to be on the order of millions of years.
It is true that the discovery of radioactivity put much better numbers on the ages, but the concept that radiometric dating exists solely for the purpose of providing enough time for evolution to happen is ludicrous.
And with all that said, I'll reprise what I said in the last episode and what I said during my Skepticamp talk: Radiometric dating is not perfect, but the science is well understood and the little niggling claims put forward by young-Earth creationists misinterpret, misunderstand, or just ignore how the technique should actually be used or applied.
The objective data, the BASIC data from the most ideal experiments and circumstances, all point to an ancient Earth that's over 4.5 billion years old. If you don't want to believe that, that's your prerogative. But if you're going to distort and misrepresent the science in order to bolster your views, then you open yourself to critique by scientists and those who know what they're doing.
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4:06am on Sunday, July 1st, 2012
Most Young-Earth Creationists (YECs) are not fully aware of the scientific evendice for an old earth, and feed this ignorance by taking the facts that feed their arguments from leading YECs who are crusading against Evolution and naturalism. I was once among them, and it's easy to fall into.”Scruffy Dan said This was the theory of creationism I was really addressing in my post. There have been countless scientific studies that provide support for an old earth”; most estimates place the earth at about 4.5 billion years old.Froehlich said One thing I went and did when I first started exploring Old-Earth Creationism (OEC) concepts, was I dug through Darwin's On the Origin of Species . I found it amusing to note that in several (I found three or four, I can get them if you like) places, Darwin says that his theory does not exclude God, and to include Him was not impossible. Darwin expressed fear that many Christians would see his theory as a threat to their faith in God, and thus r... read more »