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Author Topic:   Carbon 14 in fossils?
RAZD
Member (Idle past 1432 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 6 of 40 (101557)
04-21-2004 12:12 PM
Reply to: Message 5 by JonF
04-20-2004 10:28 PM


Re: part of article
I also saw this on Dr. Wiens page:
There are only three quite technical instances where a half-life changes, and these do not affect the dating methods we have discussed.
1. Only one technical exception occurs under terrestrial conditions, and this is not for an isotope used for dating. According to theory, electron-capture is the most likely type of decay to show changes with pressure or chemical combination, and this should be most pronounced for very light elements. The artificially-produced isotope, beryllium-7 has been shown to change by up to 1.5%, depending on its chemical environment (Earth Planet. Sci. Lett. 171, 325-328, 1999; see also Earth Planet. Sci. Lett. 195, 131-139, 2002). In another experiment, a half-life change of a small fraction of a percent was detected when beryllium-7 was subjected to 270,000 atmospheres of pressure, equivalent to depths greater than 450 miles inside the Earth (Science 181, 1163-1164, 1973). All known rocks, with the possible exception of diamonds, are from much shallower depths. In fact, beryllium-7 is not used for dating rocks, as it has a half-life of only 54 days, and heavier atoms are even less subject to these minute changes, so the dates of rocks made by electron-capture decays would only be off by at most a few hundredths of a percent.
That being said I don't think the depth factor would be significant for the diamond dating anomaly and would expect it to correlate with radioactivity the way such anomalies do in coal.

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RAZD
Member (Idle past 1432 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 34 of 40 (455337)
02-11-2008 10:19 PM
Reply to: Message 30 by Jason777
02-11-2008 9:28 PM


Hey Jason777.
That diamond dated 58,000 years old.
Actually should have been reported as {limit} -- as this is the practical limit of C-14 dating due to interference from several factors. Many much older things will date at this limit, or rocks that don't have carbon (so no C-14).
If something dates 5,800 years old is that 1/10 background level?I think we have a problem here.
(1) it goes the other way - an inverse relationship
(2) carbon-14 dating is based on the radioactive decay of C-14 in an exponential curve:
Every 5,730 years that passes there is half as much as there was before.
See How Carbon-14 Dating Works | HowStuffWorks
Enjoy.
Edited by RAZD, : an not and

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