Cliff Lundberg writes
in message <4.1.20000302113555.0097e840@pop.sfo.com>:
> Stephen E. Jones wrote:
>
> >As the effect cited seems to increase the rate of decay, and
> >evolutionists are already being squeezed for time in the origin
> >of life and the Cambrian Explosion, if it turns out that they
> >have "a percent or so" less time than originally thought, they
> >will be even more squeezed!
>
> Early Cambrian macroevolution is the inevitable conclusion.
> There's no other way to save evolutionary theory. It is interesting
> that geologists may have gone overboard, always looking for the
> most impressive ages, with the encouragement of Darwinian
> gradualists, who need all the time they can get. I wonder just
> what the size of the adjustment would be when applied to the
> Cambrian. Presumably the effect is greater the further back you
> go.
Somehow, this "adjustment" went from uncertain in Jones' article
to all but certain in your post. Keep the following statements
from the article in mind:
| Such fine distinctions matter, for example to researchers who are
| using the decay of potassium-40 (half-life of 1.25 billion years)
| to sort out the mass extinction of 250 million years ago (Science,
| 15 May 1998, p. 1007). But, although potassium-40, like beryllium-7,
| decays by electron capture, its innermost electrons-the ones most
| likely to be snagged-are more strongly shielded from external
| effects. The potassium ion has two complete shells of electrons
| protecting its two innermost electrons, whereas the beryllium ion
| has none. Thus, researchers expect the effect of chemical form on
| potassium-40 to be far less than on beryllium-7.
| But that won't stop Huh from trying to check the constancy of this
| clock. Even now he is counting decay rates of rubidium-83. It has
| an electronic structure that provides even more shielding than does
| potassium-40, but its 86-day half-life will make experiments
| reasonably quick to perform. In a few months, he'll know if ancient
| days are even a tiny bit closer than we thought.
Keep an eye out for :
Huh, C.-A. and L.-G. Liu (2000) "Precision measurements of the
half-lives of some electron-capture decay nuclides: 7Be, 54Mn,
83Rb, and 84Rb."
J. Radioanalytical & Nuclear Chemistry (in press).
This archive was generated by hypermail 2b29 : Thu Mar 02 2000 - 16:55:50 EST