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Author | Topic: The isochron method has been questioned? | |||||||||||||||||||||||||||
Lili Junior Member (Idle past 5959 days) Posts: 11 Joined: |
Hi, I found this old article at Answers In Genesis, which claims that the isochron dating method has been questioned. Since it's coming from AIG, I'm skeptical of the claims and I wanted someone who knows more about isochron dating to give their opinion of the article.
quote: Edited by Adminnemooseus, : Added some blank lines in quote section.
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AdminNosy Administrator Posts: 4754 From: Vancouver, BC, Canada Joined: |
Thread moved here from the Proposed New Topics forum.
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kongstad Member (Idle past 2870 days) Posts: 175 From: Copenhagen, Denmark Joined: |
If you look at talkorigins, the article in question is discussed:
Chris Stassen, Talkorigins writes:
Isochron Dating Lately it seems that some creationists have latched onto Zheng (1989), and reference this paper as if it disproved isochron dating and made room for a young Earth. The paper is a discussion of potential problems of Rb/Sr isochron dating, with examples of instances where these problems are known to have occurred. However, the paper is not terribly helpful to the young-Earth cause. Zheng discusses four ways in which an incorrect isochron could result: 1. Protracted fractional crystallizationRequires a slow cooling period on order of ten million years, which is not possible on a young Earth. Also, the effect is very slight: in the only example which Zheng produces (first entry in Table II on p. 14), the "incorrect" age (437 10 Ma) is not very different from the actual age (415 10 Ma). 2. Inherited (for example, by partial melting)Discussed previously; requires special circumstances and almost always induces a fair amount of scatter in the isochron plot. Requires ancient source material (the "inherited" age matches the age of the source), which is not available on a young Earth. 3. Mixing isochronDiscussed previously; in most cases detected by the mixing plot test. 4. Apparent isochron by metamorphismDiscussed previously; requires special circumstances and results in an age in between original time of crystallization and the metamorphic event that partially reset the isochron. Requires ancient source material, which is not available on a young Earth. While each of these processes can be invoked to explain a few confusing or conflicting dating results, none could reasonably be expected to account for all (or even most) isochron dating results which are incompatible with a young Earth.
To this I will add some comments. The purpose of AIGs criticisms of agemeasuring methods is to cast doubt on whether the earth is old. Zheng discusses som ways that the isochron dates may be wrong. Now if you look at the four methods of producing confusing results, three of them require an old age for the earth. Method on requires cooling over millions of years, this is incompatible with a 6.000 year old earth. The second is inheriting age from other materials, but the other materials can only have that age if they themselves are old. The fourth describes resetting the isochron, which would show a younger age than the real date. Only the third method would give older ages without reuiring the earth to be old, but as is said, this will most often be detacted by other means. /Soren
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Lili Junior Member (Idle past 5959 days) Posts: 11 Joined: |
Yes, Zheng's article cannot be used to support a young earth. However, based on the excerpts from his paper, the isochron method seems to be quite unreliable.
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Chiroptera Inactive Member |
However, based on the excerpts from his paper, the isochron method seems to be quite unreliable. Sure, that is why dishonest creationists quote-mine excerpts. A true understanding of the paper and the science in general shows that the isochron method can be trusted. Progress in human affairs has come mainly through the bold readiness of human beings not to confine themselves to seeking piecemeal improvements in the way things are done, but to present fundamental challenges in the name of reason to the current way of doing things and to the avowed or hidden assumptions on which it rests. -- E. H. Carr
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Percy Member Posts: 22392 From: New Hampshire Joined: Member Rating: 5.2 |
Hi Lili,
I'd like to echo what Chiroptera just said, but by focusing on just one part of your post:
Lili writes: However, based on the excerpts from his paper... Exactly. Based upon what this creationist chose to quote from the paper, you've concluded it argues that isochron dating is unreliable. The paper does no such thing. For me, one of the biggest mysteries of creationists is their extensive use of misrepresentation. Quoting out of context to make something seem supportive of creationism when it absolutely isn't is one of the most common tools in the creationist toolbox. Presumably creationists sincerely believe in all the positive qualities expressed in the Bible, especially honesty, yet to battle evolution they will pause not an instant to mischaracterize what scientists say. To listen to creationists quoting scientists and scientific papers you'd think there must be a huge number of geologists who reject radiometric dating, of cosmologists who reject the Big Bang, and of biologists who reject evolution, but it just isn't so. When you consider that creationists have even quoted what they purport to be anti-evolutionary statements from as strident an anti-creationist as Stephen Jay Gould then it becomes obvious that their characterizations just can't be trusted. Doesn't seem like the way to earn a ticket through the pearly gates. --Percy
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kongstad Member (Idle past 2870 days) Posts: 175 From: Copenhagen, Denmark Joined: |
In a way you are right. Isochron methods aren't reliable.
That is, even when using Isochron methods of dating you cannot always be sure on the date, unless you try to evaluate your results. What the referenced paper does is it helps increase the reliability of the Isochron dating methods, by identifying some instances where it could fail. The thing is, measuring age is not like taking cash out of an ATM machine. You will always have to consider a lot of parameters before you can reach an age, and an estimate of how precise your result is. Some of the potential error sources in the article can be tested for by analysis on the isochron, and some of them can be tested for age by using other age determining methods. So yes, isochron dating is unreliable, but more reliable than C14, and in many cases it is very reliable. Determining cases where it is less reliable, does not make other cases less reliable.
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