Accelerated nuclear decay extinguishes ‘extinct nuclides’ argument
Published: 2 November 2007 (GMT+10)
image by FrankH, wikipedia.org
There are many arguments for an old earth, and one that is widely used is the ‘extinct nuclides’ argument. Notice I use the word ‘argument’ and not ‘measurement’ because we cannot measure age directly. That’s because we can’t travel back into the past to make observations. All ages quoted are based on arguments about evidence observed in the present. They are all based on assumptions and scenarios about the past. When we consider these assumptions and scenarios, we find that the idea of a young earth, one that is consistent with the biblical timescale, is entirely plausible.
Most radioisotopes that we find naturally at the present time are ones with very long half-lives of close to a billion years or longer. Old-earth proponents argue that the short-lived nuclides did exist in the past but they have since become extinct. Their absence, old-earthers claim (based on this assumed scenario), is conclusive evidence that the solar system formed longer ago than the span of these half lives.
Let’s take Aluminum 26 (Al-26) as an example. When produced artificially today, it decays with a half-life of 710,000 years into Magnesium 26 (Mg-26). Mg-26 is stable, comprising about 11% of all the stable Magnesium (the rest being Mg-24 and Mg-25) found in nature today. But Al-26 does not exist in nature today, except as generated by cosmic rays near the surface of bodies in space. Minerals deep within meteorites have been found with evidence of having once contained Al-26.1 Those minerals contain only the daughter Mg-26, not the other two stable kinds of magnesium, and they look as if they had been locally melted by the heat of Al-26 decay.2
Roger Wiens, Hugh Ross, and other old-earthers argue that early in its history the meteorite contained some Aluminum 26, and that it decayed into Mg-26 slowly over the alleged billions of years since then. Because the Al-26 half-life is short compared to billions of years, it would all be gone today. Hence, they claim, the ‘extinct nuclide’ Al-26 is evidence that the alleged eons actually occurred.
But there are alternative scenarios: one is that the Al-26 decayed very rapidly during an episode of accelerated nuclear decay, a short period in the earth’s past when long half-life elements decayed billions of times faster than today. The Radioisotopes and the Age of the Earth (RATE) research initiative3 found a number of independent lines of evidence pointing to several such episodes in the recent past. Enough decay occurred during the episodes to produce billions of years worth of nuclear decay in such atoms as Uranium 238 and Potassium 40. If the Al-26 atoms suffered even a small fraction of such decay acceleration, they would be extinct today. Moreover, if that decay occurred rapidly, it would produce the local heating observed in the meteorites, which is difficult to explain otherwise.
So the concept of ‘extinct nuclides’ is not in itself evidence for large amounts of time, but only for large amounts of nuclear decay. Although I explained this to Drs. Wiens and Ross face-to-face in 2005, they make no mention of this new evidence and explanation in their subsequent publications. It’s as if they do not want to know about it, or have not understood this simple point.
- Podosek, F.A. and Swindle, T.D., Extinct radionuclides; in: Meteorites and the Early Solar System, University of Arizona Press, Tucson, AZ, 1988, pp. 1093–1113. Return to Text.
- Bizzarro, M., Baker, J.A., Haack, H. and Lundgaard, K.L., Rapid timescales for accretion and melting of differentiated planetesmals inferred from 26Al - 26Mg chronometry, Astrophysical Journal 632(part2):L41-L44, 2005. Return to Text.
- Vardiman, L., Snelling, A., and Chaffin, E.F. (eds.), Radioisotopes and the Age of the Earth, Vol. II, Results of a Young-Earth Creationist Research Initiative, Institute for Creation Research, El Cajon, CA and Creation Research Society, Chino Valley, AZ, 2005. Return to Text.