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Wednesday, December 29, 2010

Decay Rates are not Constant?

Ok, now that I have the attention of the young earth creationists, I can report on a just published study in the journal Earth and Planetary Science Letters (Nebel et al., 2011 "Evaluation of the 87Rb decay constant by age comparison against the U–Pb system, v301, p.1-8).
The paper is significant because it proposes the first revision since 1977 for the decay constant of 87Rb. Steiger and Jager (1977) calculated a decay constant of 1.42 x 10-11 yr-1. Nebel and colleagues used analyses on the same rock samples to recalibrate the 87Rb decay constant by comparison with the U-Pb system. The 'new' decay constant is 1.393 x 10-11 yr-1. That may not seem like a significant revision, but it means that age determinations using the 'old' constant are off by about 2%. Sorry creationists, but the new constant makes things about 2% OLDER so definitely not a find in your favor. Perhaps more interestingly, it appears to be moving back toward the 'old' standard of 1.39 x 10-11 yr-1. We'll have to wait and see if the new 'constant' holds up to further analysis, but certainly in the examples given by the authors it brings the U-Pb and Rb-Sr ages into better agreement.

Oh and just in case you take refinement of this numerical value to signify that decay rates are not constant, that is not what the paper is about. It's about refining the exact value of the decay constant which is subject to both analytical and experimental error. Nevertheless, this isn't going to result in the Earth becoming 6000 years old.


Joe Meert

Thursday, December 23, 2010



Discovery by UF geologist rekindles debate on origins of multi-cellular life

Filed under Research, Sciences on Wednesday, December 22, 2010.
GAINESVILLE, Fla. — A recent discovery by a University of Florida geologist may lend support to the theory that one of the defining moments of evolution may not have occurred as currently thought.
While studying the ancient microcontinents that make up the geography of central Kazakhstan in Asia, geological sciences professor Joe Meert and colleagues uncovered evidence that multi-cellular organisms may have evolved 100 million years earlier than previously thought, well before the Cambrian Era. His findings are published online today in the journal Gondwana Research.
The Cambrian era is known for an explosion of multi-cellular life, including the first hard-shelled organisms. Most modern species can trace their evolution back to this event, which is unique in the evolutionary record. Prior to the Cambrian era, the fossil record becomes more cryptic, as the soft-shelled organisms of the era leave relatively few fossils. The prevailing theory is that multi-cellular life developed just after a series of glacial episodes 750 to 653 million years ago.
Meert discovered the fossilized remains of two Ediacara fauna, Nimbia occlusa and Aspidella terranovica, in a rock formation that predates the earliest glacial period by more than 50 million years.
“I am sure that the fossils will be controversial due to their enigmatic nature and the fact that they are more than 100 million years older than similar fossils” Meert said.
While the findings may support the theory than metazoan life developed much earlier than previously assumed, the exact nature of Nimbia Occlusa remains a subject of controversy. Scientists are split on whether it is a multi-cellular animal, a bacterial colony, or a microbial mat. The new fossils are identical to those that appear in the fossil record up to 150 million years later, meaning it passed through tectonic, climatic, oceanic, and atmospheric events without significant change.
The research was supported by the National Science Foundation.

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