Over 100 years ago, scientists discovered radioactivity and began realizing the potential of dating different objects using radioactive materials contained within them. They have since developed numerous techniques that utilize a suite of radioisotopes to date and crosscheck those dates. These studies provide strong evidence that Earth formed over 4.5 billion years ago. Because a 4.5-billion-year-old Earth conflicts with a popular interpretation of Genesis (called the “calendar day” or “24-hour day”), a group of scientists adhering to this interpretation decided to study the validity of radioisotope dating in order to assess how it might comport with a 6,000- to 10,000-year-old Earth. They called the study the RATE (Radioisotopes and the Age of the Earth) project.
Upon completion of the eight-year investigation, the team announced the results at a conference in 2005. Each speaker made a statement to the effect that the amount of radioactive decay seen in rocks indicates the Earth is billions of years old if decay rates remained the same. However, they argued that those rates accelerated at specific times in the past. They presented four types of data to buttress the argument.
1. Zircons are small, diamond-like minerals contained in certain rocks. The team analyzed zircons found in rocks extracted from a deep borehole in Fenton Hill, New Mexico. Radiometric dating of these rocks and zircons using uranium and thorium gives ages around 1.5 billion years. However, according to measurements of helium in zircons (the uranium decays produce helium) from different depths (and thus different temperatures), the RATE team calculated that the zircons formed around 6,000 years ago.
2. The RATE team reviewed the scientific literature and found measurements of carbon-14 in coal deposits. They also had a lab measure the carbon-14 content of diamonds and found amounts between 0.1 and 0.05 percent of present levels. This corresponds to dates around 50,000 years ago. However, other studies show that coal and diamonds formed millions of years ago. Based on the presence of carbon-14, the RATE researchers concluded that coal and diamonds cannot be more than 100,000 years old. They also took this as evidence that the decay rates changed during Noah’s flood so that any dates prior to the Flood are not valid.
3. During a literature search, RATE scientists found examples of certain formations that gave discrepant dates when analyzed using different radiometric dating methods. According to the RATE team, the explanation for the discrepant dates is an acceleration of the decay rates.
4. The formation of polonium halos in rocks was the final piece of evidence used to support one or more periods of accelerated decay in the past. The half-lives of the relevant polonium isotopes are a few days or less, and the polonium comes from much longer-lived decay products. Thus, to get enough polonium to decay in the same location before the rocks harden would require a period of accelerated decay during the formation of the rocks.
The RATE team also acknowledged that their model resulted in some problems. For example, they posited a period of accelerated decay during the creation week and during Noah’s flood. Theologically speaking, young-earth creationists believe having decay (and at accelerated rates) seems at odds with the repeated declaration from God that “it was good” and even “very good.” More significantly, the accelerated decay would pose heat and radiation problems, particularly during the Flood. Squeezing billions of years’ (at today’s rates) worth of radioactive decay into a few days or even a year would likely produce so much heat and radiation so as to vaporize Earth’s surface and sterilize all life.
An RTB response to the RATE study
I attended the RATE conference where the results were first publicized. Prior to the conference, young-earth creationists usually focused on pointing out specific examples of radiometric dating problems and simply concluded that the dates could not be trusted. Therefore, I applaud the RATE team for presenting a young-earth model that explains why scientists measured dates in the millions and billions of years. However, as an old-earth organization, RTB disagrees with the RATE team’s conclusions and provides various resources responding to criticism of radiometric dating, including the four evidences highlighted by the RATE team as support for a young earth.
Helium in zircons: Gary Loechelt, an expert in diffusion chemistry, approached RTB with a response to the “helium in zircon” data. According to his analysis, the helium-diffusion date can be brought in line with the uranium date (1.5 billion years) by applying a realistic diffusion model (instead of the simple one employed by the RATE team). He also identified other errors in the RATE team’s helium diffusion analysis and responded to a rebuttal of his critique by Dr. Russell Humphreys, one of the RATE team scientists. (Here is an RTB podcast describing Dr. Loechelt’s analysis and conclusion: http://www.reasons.org/cu-archives/cu-outline-2008#436.)
Carbon-14 in diamonds: Scientists have known about the low levels of carbon-14 in coal for a while; its presence in diamonds validates the measurements. Few scientists would dispute the measurements themselves, but some would pose two questions based on the levels measured by the RATE team:
- Was the carbon-14 introduced as contamination in the analysis process?
- Was the carbon-14 a background produced before the sample was extracted from its original environment?
Both contamination and environment background have been shown to give radiocarbon concentrations of similar magnitude of the RATE measurements. In contrast to the RATE assessment that radiocarbon dates are wrong, RTB makes a strong case for trustworthy radiocarbon dates that fit comfortably within the Christian worldview.
Discordant radiometric dates: The RATE team does identify certain examples where applying different radiometric methods to the same sample produces discordant dates. Although the dates may not match within the error bars, the dates in question all exceed one billion years and don’t vary by more than a factor of two. Furthermore, when surveying the whole field of radiometric dating, concordance and consistency, rather than discord, remain the norm. Even Andrew Snelling, the main geologist involved in the RATE project, acknowledges that “the quality and integrity of the radioisotopic data may often be doubtful on the one hand, but the concordances and a systematic consistency within the uniformitarian edifice remain.”1
Polonium halos: The RATE team’s description for producing polonium haloes represents a significant departure from previous young-earth explanations, namely that the haloes were created by fiat miracle directly. They now acknowledge that the haloes formed by a natural process. The RATE team argues for a rapid process, but RTB believes that “old-earth” processes provide a better explanation.
The RATE project represents the most serious attempt to reconcile the radiometric data—which points overwhelmingly to an ancient Earth and universe—with a few-thousand-years-old cosmos. Although at the time of publication, their results seemed to support a young earth and invalidate an old one, research since that time reverses the tables and further demonstrates the compelling nature of the old-earth model.
*Update added November 21, 2012:
After we posted this article, Dr. Russell Humphreys, a member of the RATE team, contacted us and requested that we include links to articles responding to some of the objections raised. We here include those links for the sake of completeness.
- Additional information on carbon-14: http://www.answersingenesis.org/articles/2007/11/30/feedback-rate-contamination (by Dr. John Baumgardner)
- Additional links related to helium in zircons:
- http://creation.com/images/pdfs/tj/j24_1/j24_1_14-16.pdf (by Dr. Russell Humphreys)
- http://creation.com/images/pdfs/tj/j24_3/j24_3_34-39.pdf (by Dr. Gary Loechelt)
- http://creation.com/images/pdfs/tj/j25_2/j25_2_74-77.pdf (by Dr. Russell Humphreys)