Wednesday, February 15, 2006
Helium diffusion studies survive criticism
One of the projects undertaken by the RATE (Radioisotopes and the Age of The Earth) team was a study of the high helium retention of ancient crustal rocks:
Humphreys DR, Austin SA, Baumgardner JR, Snelling AA, ‘Helium diffusion rates support accelerated nuclear decay’, pp.175-195 in: Ivey R.L. (editor), Proceedings of the Fifth International Conference on Creationism, Creation Science Fellowship, Pittsburgh, PA; 2003.
Humphreys DR, Austin SA, Baumgardner JR, Snelling AA, ‘Helium diffusion age of 6,000 years supports accelerated nuclear decay’, Creation Research Society Quarterly 2004;41(1):1-16.
http://www.creationresearch.org/crsq/articles/41/41_1/Helium.htm
Two decades ago, there were reports of surprisingly high amounts of nuclear-decay-generated helium in tiny radioactive zircon crystals (embedded in mica) from the Jemez Granodiorite (Precambrian) of New Mexico. Up to 58% of the helium expected from 1.5 billion years of decay was still in the zircons. Why hadn’t the helium diffused out of the zircons and into the atmosphere? Astonishingly, borehole temperatures and measurements of diffusion coefficients indicate that the zircons could have retained the observed levels of helium only if the time scale of diffusion was about 6,000 years. This suggests that a large amount of helium has been generated by nuclear decay but that it was generated so recently that it has not had time to escape from the zircons by diffusion. This is consistent with accelerated nuclear decay in the Earth’s recent past.
A lengthy – and somewhat ‘waffly’ – critique of this work by Kevin Henke appeared on 17 March 2005 on the anti-creationist Talk Origins website:
Henke KR, ‘Young-earth creationist helium diffusion “dates”: archived original version’
http://www.talkorigins.org/faqs/helium/original.html
This soon led to an ongoing web debate between Henke and RATE investigator Russ Humphreys who replied to Henke’s first critique on 27 April 2005:
Humphreys DR, ‘Helium evidence for a young world remains crystal-clear’
http://www.trueorigin.org/helium01.asp
On 24 November 2005, Henke responded by revising and updating his original article:
Henke KR, ‘Young-earth creationist helium diffusion “dates”: fallacies based on bad assumptions and questionable data
http://www.talkorigins.org/faqs/helium/zircons.html
Then, on 6 January 2006, Humphreys replied to Henke’s second attempt to refute the helium data:
Humphreys DR, ‘Helium evidence for a young world overcomes pressure’
http://www.trueorigin.org/helium02.asp
It has been fascinating to see this exchange develop – but it seems to me that Humphreys’ original conclusion, which is that the helium diffusion data point to young age, is still pretty robust. So far, Henke has failed to find a “show-stopping” flaw in the argument. But why not read the articles and see for yourself?
Humphreys DR, Austin SA, Baumgardner JR, Snelling AA, ‘Helium diffusion rates support accelerated nuclear decay’, pp.175-195 in: Ivey R.L. (editor), Proceedings of the Fifth International Conference on Creationism, Creation Science Fellowship, Pittsburgh, PA; 2003.
Humphreys DR, Austin SA, Baumgardner JR, Snelling AA, ‘Helium diffusion age of 6,000 years supports accelerated nuclear decay’, Creation Research Society Quarterly 2004;41(1):1-16.
http://www.creationresearch.org/crsq/articles/41/41_1/Helium.htm
Two decades ago, there were reports of surprisingly high amounts of nuclear-decay-generated helium in tiny radioactive zircon crystals (embedded in mica) from the Jemez Granodiorite (Precambrian) of New Mexico. Up to 58% of the helium expected from 1.5 billion years of decay was still in the zircons. Why hadn’t the helium diffused out of the zircons and into the atmosphere? Astonishingly, borehole temperatures and measurements of diffusion coefficients indicate that the zircons could have retained the observed levels of helium only if the time scale of diffusion was about 6,000 years. This suggests that a large amount of helium has been generated by nuclear decay but that it was generated so recently that it has not had time to escape from the zircons by diffusion. This is consistent with accelerated nuclear decay in the Earth’s recent past.
A lengthy – and somewhat ‘waffly’ – critique of this work by Kevin Henke appeared on 17 March 2005 on the anti-creationist Talk Origins website:
Henke KR, ‘Young-earth creationist helium diffusion “dates”: archived original version’
http://www.talkorigins.org/faqs/helium/original.html
This soon led to an ongoing web debate between Henke and RATE investigator Russ Humphreys who replied to Henke’s first critique on 27 April 2005:
Humphreys DR, ‘Helium evidence for a young world remains crystal-clear’
http://www.trueorigin.org/helium01.asp
On 24 November 2005, Henke responded by revising and updating his original article:
Henke KR, ‘Young-earth creationist helium diffusion “dates”: fallacies based on bad assumptions and questionable data
http://www.talkorigins.org/faqs/helium/zircons.html
Then, on 6 January 2006, Humphreys replied to Henke’s second attempt to refute the helium data:
Humphreys DR, ‘Helium evidence for a young world overcomes pressure’
http://www.trueorigin.org/helium02.asp
It has been fascinating to see this exchange develop – but it seems to me that Humphreys’ original conclusion, which is that the helium diffusion data point to young age, is still pretty robust. So far, Henke has failed to find a “show-stopping” flaw in the argument. But why not read the articles and see for yourself?
# posted by Nemagraptus @ 2:49 PM 
