Is Carbon Dating Accurate?

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Is carbon dating accurate?

Is carbon dating accurate? Only to a certain extent. In order for carbon dating to be accurate, we must know what the ratio of carbon-12 to carbon-14 was in the environment in which our specimen lived during its lifetime. Unfortunately the ratio of carbon-12 to carbon-14 has yet to reach a state of equilibrium in our atmosphere; there is more carbon-14 in the air today than there was thousands of years ago. Furthermore, the ratio is known to fluctuate significantly over relatively short periods of time (e.g. during the industrial revolution more carbon-12 was being produced offsetting the ratio a bit).

Carbon dating is somewhat accurate because we are able to determine what the ratio was in the unobservable past to a certain extent. By taking a carboniferous specimen of known age (that is, a specimen which we are able to date with reasonable certainty through some archaeological means), scientists are able to determine what the ratio was during a specimen's lifetime. They are then able to calibrate the carbon dating method to produce fairly accurate results. Carbon dating is thus accurate within the timeframe set by other archaeological dating techniques. Unfortunately, we aren't able to reliably date artifacts beyond several thousand years. Scientists have tried to extend confidence in the carbon dating method further back in time by calibrating the method using tree ring dating. Unfortunately, tree ring dating is itself not entirely reliable, especially the "long chronology" employed to calibrate the carbon dating method. The result is that carbon dating is accurate for only a few thousand years. Anything beyond that is questionable. This fact is born out in how carbon dating results are used by scientists in the scientific literature. Many scientists will use carbon dating test results to back up their position if the results agree with their preconceived theories. But if the carbon dating results actually conflict with their ideas, they aren't too concerned. "This attitude is clearly reflected in a regrettably common practice: when a radiocarbon date agrees with the expectations of the excavator it appears in the main text of the site report; if it is slightly discrepant it is relegated to a footnote; if it seriously conflicts it is left out altogether." (Peter James, et al. (I. J. Thorpe, Nikos Kokkinos, Robert Morkot and John Frankish), Preface to Centuries of Darkness, 1991)

So, is carbon dating accurate? It is for specimens which only date back a few thousand years. Anything beyond that is problematic and highly doubtful.



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