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Author Topic:   Quick radiometric dating question- misused techniques
Coyote
Member (Idle past 2137 days)
Posts: 6117
Joined: 01-12-2008


Message 10 of 40 (516867)
07-27-2009 6:38 PM
Reply to: Message 9 by Kitsune
07-27-2009 6:03 PM


Re: Why too old.....
In radiocarbon dating the point at which the sample's signal is lost amid the background signal marks the upper limit.
This is somewhat dependent on equipment, shielding, etc., but for most laboratories the limit is currently not much over 50,000 years. With older equipment in past decades it could be in the 35,000-40,000 range.
Experimental results are occasionally being obtained back more toward 80,000 years using the AMS (Accelerator Mass Spectroscopy) method, but those ranges are not ready for prime time.

Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

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 Message 9 by Kitsune, posted 07-27-2009 6:03 PM Kitsune has not replied

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Coyote
Member (Idle past 2137 days)
Posts: 6117
Joined: 01-12-2008


Message 13 of 40 (516875)
07-27-2009 8:35 PM
Reply to: Message 12 by NosyNed
07-27-2009 7:17 PM


Re: Reporting ....
You might know the most minute of details for C14 dating at least:
I've submitted nearly 600 samples, and well as lectured on the subject and done one monograph. This is on the archaeological end, not the intimate details of the processing.
If the sample's signal is lost in the background how is that reported?
In the context of this discussion there is an important difference between: The sample is 50,000 years old and the sample is at least 50,000 years old.
When a sample returns a measured age you get a figure such as 10,000100. If the C13 is measured as well you will get the conventional age (corrected for C13), and that is expressed in the same way.
If the sample is old enough to be lost in the background radiation it would be expressed as >50,000 (for example).
Do you have actual reports?
Here is a link to a blog showing how creationists missed the ">" sign (probably from not knowing what it meant) and used the resulting dates on natural gas to "prove" a young earth, when in fact they were expressing the limits of the equipment being used:
http://blog.darwincentral.org/...e%E2%80%9D-%E2%80%94-part-v
This link has references to an article in Radiocarbon. (I assume this is what you mean by "actual reports."

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