Today’s New Reason To Believe

by Gary H. Loechelt, Ph.D.

Dr. Loechelt received his doctorate in the science and engineering of materials from Arizona State University in 1995, and currently works as an electrical engineer at ON Semiconductor in Phoenix, Arizona. This work was conducted on his personal time and does not reflect the views or business interests of his employer.

Part 1 discussed the results of a helium diffusion study conducted by a young-earth research program called RATE for Radioisotopes and the Age of The Earth. In an attempt to reconcile young-earth beliefs with geologic data, the RATE group promotes the idea that nuclear decay rates were accelerated in the recent past.

In my analysis of the RATE study, I discovered five specific flaws in their work, two of which were discussed in detail in the previous article. Even though these errors proved serious enough to invalidate their conclusions, the question remains as to whether the existing data can be reconciled with an old earth. This article explores that question in greater detail. In particular, I demonstrate that once the errors in the RATE model are corrected, both the nuclear decay “clock” and the helium diffusion “clock” are in excellent agreement with an old-earth model. This article summarizes highlights from my research; for those interested in the details of my model, I have also written an in-depth technical paper on the subject.

In reviewing the two main RATE reports (Helium Diffusion Age of 6,000 Years Supports Accelerated Nuclear Decay and Helium Diffusion Rates Support Accelerated Nuclear Decay), I discovered an error in the data analysis. The RATE team used a prior estimate by Robert Gentry for the total amount of helium produced from nuclear decay. However, Gentry’s own calculation was off by a factor of over three. Once this error was corrected, the fraction of helium remaining in the zircon samples dropped considerably, as can be seen in the following figure, which compares the original RATE estimates with the revised measurements.

The RATE argument is based upon the claim that there is still a lot of helium in these zircons. However, according to the corrected calculations these zircons actually contain far less helium than the RATE researchers originally thought, which weakens their case.

Next, I corrected errors in the geometry and boundary conditions of their diffusion model. The RATE team used an effective radius that was too large (30 μm versus 20 μm). Furthermore, their model included a second mineral called biotite, surrounding a zircon core. Although zircons are often embedded in larger flakes of biotite, they treated this second mineral as if it had the same material properties as zircon despite the fact that their own data showed that the diffusivity of helium in biotite was orders of magnitude higher. With such a high diffusivity, a biotite envelope would offer little resistance to a migrating helium atom once it left the zircon crystal. Therefore, I chose the more realistic boundary condition of zero helium concentration at the zircon/biotite interface.

Although the foregoing corrections were worth doing for the sake of rigor and accuracy alone, their impact on the final results was not as significant as the correction made for the two errors discussed last week. First, the RATE researchers used a constant temperature profile over time in their model. In contrast, I used a geologically reconstructed thermal history that was highly non-uniform over time.

Second, the RATE researchers used a simple kinetic model in their diffusion study. This type of model ignores the possibility that helium atoms behave differently depending upon their location in the crystal, with atoms in the vicinity of defects moving more readily than those that are in the bulk crystal. Instead, I incorporated a multi-domain diffusion model which takes this effect into account. This type of model has been used by several leading scientists in the noble gas thermochronology field (see for example: Reiners and Farley, 1999, pp. 3850-53; Reiners et al., 2004, pp. 1872-74; Shuster, et al., 2003, pp. 28-29; Shuster, et al., 2005, pp. 669-70).

What is the consequence of all these corrections? As the figure below shows, the revised old-earth model agrees well with the measured helium retention data. For comparison, predictions of the original young-earth RATE model are plotted as well.

The old-earth model matches the revised measurements better than the young-earth model. The RATE team claimed that essentially no helium would be left in these zircons if they were more than a few thousand years old. However, by direct computation, I have demonstrated otherwise. The helium content and the 1.5 billion year radiometric age of these zircons are in agreement. Since no anomaly exists, there is no scientific need to postulate the existence of exotic physics, like accelerated nuclear decay, to explain the phenomenon.

Not only does this result deprive the accelerated nuclear decay hypothesis of its best case, it actually counts as evidence against accelerated nuclear decay. Two independent clocks (nuclear decay and helium diffusion) are now in agreement on the billion-year-age of these rocks. Consequently, the notion of accelerating natural processes becomes an untenable scientific position, and one must read nature’s clocks at face value. Obviously RTB and young-earth creationism remain at odds. However, the RATE group posited a model and subjected it to scientific testing. And for that they are to be commended.

Notes:

About my credentials and background, I have a B.S. in physics and a Ph.D. in materials science and engineering. For the last 13 years, I have been employed in the semiconductor electronics industry doing computer simulation and modeling. Although the field of semiconductors may seem far removed from geology, the two disciplines actually have a lot in common. By far the most important semiconductor material is silicon, which is also the primary constituent of rocks and minerals in the earth’s crust. Furthermore, an important process in the manufacturing of semiconductor devices is the diffusion of impurity elements. Because of its economic importance, the solid state diffusion of atoms in the silicon system has been studied more thoroughly than almost any other material.

by Gary H. Loechelt, Ph.D.

Dr. Loechelt received his doctorate in the science and engineering of materials from Arizona State University in 1995, and currently works as an electrical engineer at ON Semiconductor in Phoenix, Arizona. This work was conducted on his personal time and does not reflect the views or business interests of his employer.

Radiometric dating methods have long been a target of young-earth creationists, and for good reason. Rock ages obtained by these dating methods, usually ranging from millions to billions of years, directly contradict belief in a 6,000 year old earth. For years, the young-earth community had attempted to discredit radiometric dating by essentially claiming that very little nuclear decay has occurred since the formation of the earth.

However, this strategy began to change in 1997, when Dr. Steve Austin, Dr. John Baumgardner, Dr. Eugene Chaffin, Dr. Don DeYoung, Dr. Russell Humphreys, and Dr. Andrew Snelling, all prominent young-earth scientists, met to discuss the “problem” with radiometric dating. The ensuing eight-year research program, called RATE for Radioisotopes and the Age of The Earth, acknowledged that much larger quantities of nuclear decay have occurred in most geological processes than could be explained by an earth only a few thousand years old. In effect, young-earth creationists of the 21st century finally accepted what mainstream science had known since the early 20th century, namely that nuclear decay was the best and perhaps only viable explanation for the isotopic patterns observed in rocks and minerals today.

Conceding the occurrence of billions of years’ worth of nuclear decay created a major dilemma for people believing in a 6,000-year-old earth. The only possible solution, apart from abandoning a young-earth position altogether, was to postulate that nuclear decay rates were accelerated in the recent past. The goal of the RATE project was to find evidence to this end.

To test the hypothesis, researchers sought cases in which nuclear decay could be compared against some other natural phenomenon. Think of radioactive nuclei as a clock that ticks (i.e. decays) at a known rate. The only way to demonstrate that nuclear processes “ticked” faster in the past was to compare their decay rates to another, more accurate clock.

Most of the cases documented by the RATE team proved to be weak tests for their hypothesis. The notable exception was a helium diffusion experiment using zircon mineral samples from deep geothermal wells in Fenton Hill, New Mexico. The RATE team claimed that when they compared the nuclear decay clock with their helium diffusion clock, they found a large discrepancy. Apparently, the nuclear decay clock recorded an elapsed time of over a billion years, whereas their helium diffusion clock recorded an elapsed time of only a few thousand years. Taking the helium diffusion time as the more reliable measurement, the researchers claimed that they had found convincing evidence for accelerated nuclear decay.

However, this apparent result is not as simple as merely reading time from a stopwatch. The helium diffusion clock used by the RATE team was actually a complex mathematical model describing the process of helium diffusion from zircon crystals. One may legitimately ask, “How well did they read their diffusion clock?” After following their research for many years, I conclude that they read this clock poorly. The RATE study contained at least five specific flaws in the data analysis and modeling that were serious enough to invalidate their conclusions. Let’s focus on the two biggest errors.

First, the RATE model used a constant temperature over time. Several lines of geologic evidence indicate that the thermal history of Fenton Hill has been anything but uniform. Recent (geologically speaking) volcanic activity has raised the ground temperature at the site to over twice the typical value across the continent. These elevated temperatures have been sustained for a relatively short period of time on a geologic timescale. Therefore, the use of a constant temperature by the RATE team demonstrates a misunderstanding of the thermal history of the site. The following figure contrasts their constant temperature profile to a realistic time-dependent one.

As shown, the temperature over the last 500 million years was well below the current temperature.

The second error committed by the RATE research team was more subtle. The modeling of the helium diffusion clock required an underlying model for the helium diffusion kinetics (i.e. the manner in which temperature affects the motion of atoms). Using data from a laboratory experiment in which gas released from a zircon sample was measured at different temperatures, they extracted the parameters for a simple kinetic model. The problem with this model is that it treated all helium atoms the same, regardless of whether they were in the bulk crystal or near a defect. Most helium atoms will lie in portions of the undisturbed crystal, whereas only a small fraction will lie in the vicinity of a defect. At low temperatures, the small fraction of atoms near a defect will be mobile, whereas the vast majority of atoms will only begin to move at higher temperatures.

Essentially, there are distinct populations of helium atoms in the solid, each with different diffusion properties. Many leading scientists in the noble gas thermochronology field use more complex diffusion models that take this effect into account. Not only did the RATE researchers choose a simplistic model, but also their lack of discussion of the subject suggests that they were unaware of the existence of alternate kinetic models.

Taken together, these two errors alone prove serious enough to invalidate the helium diffusion argument for supporting accelerated nuclear decay. However, the question still remains as to whether the existing data can be reconciled with an old earth. This topic will be the subject of next week’s article.

See the RATE project reports here:

Radioisotopes and the Age of the Earth (RATE)

Nuclear Decay: Evidence For A Young World

New RATE Data Support a Young World

Helium Diffusion Age of 6,000 Years Supports Accelerated Nuclear Decay

Helium Diffusion Rates Support Accelerated Nuclear Decay

by Dr. Jeffrey Zweerink

Imagine working a puzzle with pieces made by machines using different scales. It’d be like attempting to fit a child’s ten-piece puzzle with the tiny pieces of a complex jigsaw puzzle. While the pictures might be the same, pieces made using a 2:1 scale would never fit with pieces made using a 3:1 scale. The Institute for Creation Research’s RATE team makes the claim that scientists using radioisotopes to date rocks are trying to assemble such a bizarre puzzle.

The RATE researchers contend that radioactive decay occurred at an accelerated rate in the past, which renders radioisotope dating techniques completely obsolete and unreliable. Scientists can test this contention by comparing radioisotope dates for rocks with corresponding dates derived from cyclical variations in Earth’s orbit and rotation axis, which change the sedimentation rate.

As reported in Science, a team of Earth scientists performed a calibration of the Ar⁴⁰/Ar³⁹ dating method using two geological formations separated by a well-determined number of variations in Earth’s orbit. The time-separation recorded by the variations in sedimentation depends on well-understood cyclical variations in Earth’s orbit. This separation is compared to the radioisotope dates obtained from each of the two geological formations. Based on the calibration, the measured age of the formation increased by just over half of a percent, which reduced the uncertainty in the age by a factor of ten.

These results provide an example where more data serve as a test of two competing models. According to the RATE model, the dates determined by the astronomical forces should not correlate with the dates derived from radioisotope measurements because the decay rates changed dramatically in the past—much like mismatched puzzle pieces. In contrast, the constant decay rates of RTB’s model (which agrees with the prevailing scientific model concerning the age of the Earth and universe) mean the dates should correlate well. For further examples showing the consistency and reliability of radioisotope dating see Roger C. Wiens’ article on the American Scientific Affiliation website.