Difference between revisions of "Carbon dating"
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*coal, natural gas, and carbonate rocks have yielded dates based on carbon dating between 30,000 and 60,000 years old; | *coal, natural gas, and carbonate rocks have yielded dates based on carbon dating between 30,000 and 60,000 years old; | ||
| − | *some unfossilized dinosaur bones have yielded dates between 10,000 and 50,000 years old; and | + | *some unfossilized dinosaur bones have yielded dates between 10,000 and 50,000 years old {{fact}}; and |
| − | *CO2 from gas wells have yielded dates less than 30,000 years old. | + | *CO2 from gas wells have yielded dates less than 30,000 years old. |
== References == | == References == | ||
<references/> | <references/> | ||
Revision as of 16:36, May 5, 2007
Carbon dating, or carbon-14 dating, is a method for comparing the ages of organic materials such as bones or things made from anything that once lived.
The technique is based on comparing the levels of C-14 and C-12 isotopes in the sample. When the sample was living, the ratio of C-14 to C-12 in the material is the same as in the atmosphere. But after death the C-14 isotope decays into N-14, while C-12 does not. The loss in C-14 is then used to estimate how long ago the sample died, which is typically the same as how long the sample existed.
Current rates of decay of C-14 are such that, if its rate of decay remained constant, then 50% would be list in 5730 years.
Limits of Carbon Dating
First, it is impossible to prove scientifically whether the rate of decay of C-14 has remained constant over hundreds or thousands of years. Some scientists have suggested, based on experimental observations, that the laws of physics do change over time.[1]
Second, estimating the age of material using carbon dating assumes that the ratio of C-14 to C-12 was the same in the past as today, which is also impossible to prove scientifically. "[T]he proportions of C-14 in the atmosphere in historic times is unknown. The C-14:C-12 atmospheric ratio is known to vary over time and it is not at all certain that the curve is 'well behaved.'"[2]
Third, "various plants have differing abilities to exclude significant proportions of the C-14 in their intake. This varies with environmental conditions as well. The varying rates at which C-14 is excluded in plants also means that the apparent age of a living animal may be affected by an animals diet. An animal that ingested plants with relatively low C-14 proportions would be dated older than their true age."[3]
Due to these fundamental limitations, the only scientific conclusion that can be drawn from carbon dating is that material X is older than material Y when X has lost more C-14 than Y has. It is not possible to determine, with any degree of scientific certainty, how much older X is than Y.
Known Errors in Carbon Dating
Even the staunchest advocates of carbon dating admit that it gives errors for material that is younger than 150 years or older than 50,000 years. The errors for material younger than 150 years is ascribed to changes in the ratio of C-14 to C-12 in the atmosphere.[4] The errors for material older than 50,000 years is ascribed to statistical uncertainties inherent in the loss of multiple half-lives.
Additional anomalous results from carbon dating, which reinforce its limitations, include:[5]
- coal, natural gas, and carbonate rocks have yielded dates based on carbon dating between 30,000 and 60,000 years old;
- some unfossilized dinosaur bones have yielded dates between 10,000 and 50,000 years old[Citation Needed]; and
- CO2 from gas wells have yielded dates less than 30,000 years old.
References
- ↑ "The idea that nature's laws change over time was proposed in the 1930s by one of the titans in the history of physics, Paul Dirac of England. According to Dirac's large numbers hypothesis, the force of gravity changed over time." See Keay Davidson, "Recent study forces scientists to rethink basic law of physics," San Francisco Chronicle[1]
- ↑ Nondestructive Testing (NDT) Resource Center, "Uncertainty in Carbon Dating"[2]
- ↑ Id.
- ↑ http://www.talkorigins.org/indexcc/CD/CD011.html
- ↑ http://www.creationwiki.org/Carbon_dating