Originally posted by RJHinds
Okay, refute this one:
By combining the measure rate of helium diffusion out of the zircons and retention data of nuclear-decay-generated helium in microscopic zircons in precambrian granitic rock an age of 6,000 ± 2,000 years is obtained. The data strongly supports the hypothesis of episodes of highly accelerated nuclear decay occurring within thousands ...[text shortened]... ndicate a Young Earth
http://www.icr.org/article/both-argon-helium-diffusion-rates-indicate/
I spent a little time with the first link. What I could figure out was this:
1) The authors (avowed creationists of course) accept that X amount of uranium-to-lead decay has occurred in certain rock samples based on the present ratio of uranium to lead in the samples.
2) They also got measurements of the amount of helium in the samples, which would be present in the rock as a result of alpha particle emission in the uranium-to-lead decay process.
3) They compared U/Pb ratios to the helium content of the rock samples (made of zirconium, biotite, etc.), and noted a helium deficiency. That is, some of the original helium must have escaped from the rock through a process of diffusion.
4) Running on an assumption that the Earth is only 6000 years old, they calculated what the helium diffusivity of the rock must be in order to explain the observed helium deficiency given that X amount of uranium decay must have occurred. They predict a degree of helium diffusivity that is many orders of magnitude greater than accepted values. This is necessary because they are assuming that Y amount of helium must have leaked out of the rock in 6000 years instead of over a billion years.
5) They measured the helium diffusivity of the rock and found a value that agrees with their calculations.
6) By these wiles, assuming that their helium diffusivity measurements are wholly accurate, they inexorably lead the reader to a fork in the road: either the helium diffusivity of the rock is not constant, or radioactive decay processes are not constant. Guess which way they go? It's a no-brainer: they draw the incredible conclusion that the
radioactive decay rate of uranium nuclei must be variable, and in particular must have been many orders of magnitude greater sometime over the course of the last few millennia or centuries -- with the substantial amount of helium generated by the accelerated decay wafting into the ether thanks to a helium diffusivity they "measured" to be many orders of magnitude greater than accepted (and empirically verifiable) science.
7) There's this line in the article: "The data also resoundingly reject the Uniformitarian model. The points of that model are the values of diffusivity required to retain the observed amounts of helium for 1.5 billion years at today's temperatures in the rock unit. However, uniformitarian thermal models of the rock unit require that the temperatures have been
higher in the past." But wait! If it were true that radioactive processes occurred at a greater rate in the past than they do today, then higher rock temperatures are precisely what would result, yes? So we have a rather entangled conflict here -- a conflict that could perhaps be resolved by pushing the age of the Earth upward again, to something significantly greater than 6000 years but not so high as five billion years. Except that we would then have to rejigger our helium diffusivity prediction and get a new value that does
not agree with our measurements. Oh dear.
I'll note just a few more things: there is no peer review here, and no replication of the experimental results. Also there's no explanation for how the decay rate of uranium (and other radioisotopes) could be increased a million-fold without melting the Earth's crust and destroying all life. What we have is an article of propaganda, trussed up in science's clothing, but having little to do with science. There ought to be a law against such mendacious rubbish. And I haven't even mentioned the other ways the theory of an "old Earth" (and an even older universe) is supported by observation -- ways having nothing whatsoever to do with radioisotopes.