Arguments

2. Radiometric Dating

The average YEC thinks that radiometric dating is the only form of dating which supports an ancient Earth (thus revealing ignorance of both science and history, since old Earth theories can be traced back more than two thousand years, and age estimates had already hit tens of millions of years in the late 18th century, many decades before Darwin published "The Origin of Species"). But since they labour under this scientifically and historically ignorant assumption, they think they can topple the entire weight of old Earth evidence if they can punch a hole in radiometric dating. Naturally, no effort is spared in this endeavour.

They "know" that potassium, Carbon-14, or whatever element they're testing decays at a certain invariable rate -- except they don't know that at all. Decay rates can change, and they don't know if the rate changed or not.

This is one of the oldest YEC attacks on radiometric dating: he thinks radioactive "decay rates can change", and that this therefore invalidates the concept of radiometric dating.

This is tantamount to claiming that the gravity of the Earth might have been 5 times stronger in medieval times, or that the boiling point of water might have been a thousand degrees a century ago. The decay rates of radioisotopes are driven by the quantum mechanics of barrier tunneling and the relative strengths of coulomb repulsion and nuclear binding energy which drive all nuclear interactions. If they were to change, this would mean that the characteristics of fundamental particles and forces are changing, which means that the behaviour of all matter in the universe is in a state of flux. Moreover, since they claim the Earth is just 6,000 years old, these sweeping changes would have been occurring right before our eyes, during recorded history!

Why, then, do Egyptian pyramids built 4500 years ago still stand? How did a 4800 year old California Bristlecone Pine tree (nicknamed "Methuselah") survive? Changes in physical constants such as the electric charge of electrons and protons or the strength of the nuclear binding force would have changed the fundamental behaviour of matter. Let's imagine that electromagnetism was much stronger in the past; this would help pry apart nuclei faster, thus increasing the rate of radioactive decay. However, it would also make solid objects stronger and more rigid, it would make fire burn hotter, it would change the melting points and densities of all materials, it would increase the coulomb barrier for nuclear fusion in the Sun (thus cooling and dimming it to the point that we would have frozen to death), it would drastically alter the electrochemical reactions used in living organisms, and that's just the tip of the iceberg! Alternatively, let's suppose that the strong nuclear force was much weaker in the past. This would also increase decay rates, with similarly severe side-effects. Large elements would become more radioactive, thus greatly increasing the background radiation and producing anomalous low mass radioisotopes. Worse yet, the binding energy of nuclei would be much smaller, so the energy yield of nuclear fusion would be much lower and the ancient Sun would have been so cool and dim that the Earth would have been a dark, frozen, barren rock.

Still think that radioactive decay rates might have been fluctuating wildly over the last 6,000 years? If so, you are obviously vulnerable to pseudoscience, and you must be a YEC. Have yourself committed to a mental institution right now. If not, read on. Did you ever notice that the YEC's propose alternate explanations for physical phenomena without bothering to crunch numbers? This does not sound particularly scientific to me; it's analogous to claiming that an arrow points in the right direction without bothering to show that it's long enough to reach the target.

So why don't we crunch the numbers for them? They like to say that we've only been measuring decay rates for a century or so, which isn't long enough to notice slow changes in decay rates that take billions of years to become significant. But they're forgetting something: they don't have billions of years. They claim that everything happened in just six thousand years, remember? Let's assign the variable µ to the current rate of decay of some radioisotope, and let's say it's been steadily dropping since Day One. If a 6,000 year old rock looks like it's 3.8 billion years old, this would suggest that its decay rate started off at more than 1¼ million times µ, and dropped at a rate of 1µ every 42 hours! We've been measuring decay rates for a long time now; have we detected such dramatic changes? Take a wild guess. We've also been observing the effects of faraway stars and supernovae which are far more ancient, and do they show any signs of these dramatic changes? Again, take a wild guess.

Also, they don't know if the amount of daughter material was originally zero.

This is an oft-used strawman attack. Radiometric dating does not necessarily depend on the assumption that none of the daughter material was originally present. If there's some compelling reason that the daughter material might not have been present in the original molten pool (eg. it's a noble gas and would have diffused out), then dating would be performed on that basis. However, under most circumstances the trick is to determine how much of the daughter material was originally present, rather than assuming the concentration was zero without doing any work to justify that assumption.

Let's say you're doing Uranium/Lead testing. Uranium decays into lead, so you can accurately determine an artifact's age by calculating the amount of uranium and lead, then plugging those figures into an equation with the decay rate, right? Well...

The ONLY way to ensure accuracy is to know the following:

  1. How much daughter material (lead) was originally in the artifact? (They don't know! If X amount of lead in the artifact is assumed to ALL be decayed from uranium, when in fact some lead was already there, the artifact could test much older than it really is -- and with no way to tell whether your figures are accurate!)
  2. Did the rate of decay remain constant? (They don't know! What if it accelerated? What if it slowed down?)

Based on these "facts," which are really assumptions, they measure the ratio of uranium to lead present in the artifact -- the only fact in this whole equation -- plug in their assumptions, and voila! Dinosaurs lived 65 million years ago! Right?

As usual, this is a horrific YEC oversimplification (and it includes a repetition of the laughable assumption that decay rates are variable). Lead, like hydrogen, has several naturally occurring isotopes. And just as with hydrogen and deuterium, the probabilities dictate that measurable quantities of naturally occurring lead will be found in a fixed ratio of lead-204 to lead-206. Chemicals don't "know" which isotope they're dealing with, because the electrical properties are identical. But we can tell the difference with sophisticated devices such as mass spectrometers. When uranium decays, it always decays into lead-206. Therefore, an unnaturally high ratio of lead-206 to lead-204 can only come from uranium decay, and since the half-life of U-238 is measured in hundreds of millions of years, a high ratio of lead-206 is completely incompatible with YEC.

Besides, I notice that our YEC friend ignores isochron dating techniques, which are a somewhat newer and even more accurate method. However, the explanation is a bit complicated (although it makes perfect sense once you think about it), so try to bear with me:

The isochron method dispenses with the assumption of fixed isotope ratios in the daughter element by using an ingenious trick. As before, it takes a three nuclides again: one parent, one daughter and one non-radiogenic isotope of the daughter. But this time, several samples are taken from chemically dissimilar minerals which were once part of a contiguous pool (this is the part that requires a skilled geologist, since proper identification is important). Each sample is plotted on a graph in which the X-axis is the ratio between parent and isotope #2 (the stable one), and the Y-axis is the ratio between isotope #1 to #2.

The ratio of isotope #1 to #2 would have been the same for all samples in the original pool of liquid matter, because their physical characteristics are virtually identical and there is no reason why one of them would preferentially group together in any particular place. As the liquid matter solidified and differentiated into various minerals, this ratio would remain constant for all the minerals because they had no way of "knowing" which isotope they were getting. Therefore, the Y values would have been the same for samples taken from any of the various minerals and a horizontal line could be drawn through all the points, regardless of the concentration of the parent.

As the rocks aged, the parent decayed into isotope #1, while isotope #2 remained constant. Therefore, the Y-values (ratio of #1 to #2) increased and the X-values (ratio of parent to #2) decreased. Each point moved up and to the left. The interesting part is that a mineral with twice as much parent nuclide would experience an upward shift which is twice as large (because there's twice as much decay), therefore all of the points which originally laid on a straight line will stay on a straight line, albeit one which is tilting upwards. Therefore, you can check the accuracy of isochron dating by simply checking whether the points lay on a straight line.

Our YEC friend isn't particularly clever, and more clever YECs have tried to discredit isochron dating rather than pretending that scientists have no alternative but to assume zero daughter isotope concentrations. Their attacks employ the usual pseudoscience tactics; they find examples where it won't work and claim that therefore, it never works. They point out that if an incompetent geologist incorrectly identifies samples from different parent pools as being from the same pool, and these samples just happen to produce points that lay on a straight line through sheer coincidence, then the method could potentially produce false dates which nonetheless verify as accurate by plotting on the line. The world is a big place, and I'm sure they can eventually dig up carefully selected samples to demonstrate this "failing". However, if you think about it, they're basically saying that if you apply it in an incompetent fashion, there is a small chance that it might not work! I'm sure this sounds convincing to some people, but not anyone with a brain. Mind you, some people also bought O.J. Simpson's story about how he's still looking for the real killers.

Continue to 3. Unsolved Mysteries

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