Pet Peeves Carbon 14 Dating System

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Misapplication of the Carbon-14 Dating System

It seems as if the 'media' just doesn't care about accuracy when it comes to issues involving evolution. I'm not sure if their errors are due to ignorance on their part or the presumed ignorance of the intended audience. However, in practice, there is a great tendency to present outdated or outright incorrect information on this subject.

In this particular "peeve", I'd like to discuss the misapplication of radiocarbon dating. In the various media outlets you can readily find examples in which this dating system is being used to establish the age of everything from multi-million year old fossils to meteorites. Is this possible? The facts are that radiocarbon dating is limited to 'thousands of years', not 'millions', and to 'biological' samples, not 'mineral'. The remainder of this article will discuss in some detail the principals and the proper application of the radiocarbon dating system.

The radiocarbon dating system was devised by Willard F. Libby and his associates shortly after the end of World War II. Carbon-14 (¹⁴C), an unstable element on which their system of measurement depends, is created by the interaction of cosmic rays with Nitrogen-14 (¹⁴N, 7 protons/7 neutrons) in the atmosphere. The cosmic rays inject a foreign neutron into the nucleus of the Nitrogen atom, ejecting a proton in the process, causing it to be transformed into ¹⁴C (6 protons/8 neutrons). This event is gradually "undone" by a process called negative beta emission. The foreign neutron disintegrates into three particles: a proton, an antineutrino and an electron. The electron and antineutrino are expelled from the atom but the proton remains, adding its positive charge to the nucleus, resulting in the transformation of the atom into a stable isotope of nitrogen (7 protons/7 neutrons).

For a given initial quantity of ¹⁴C it takes a period of 5730 (+/- 40) years for half of the substance to disintegrate back into Nitrogen. In another 5730 years half of the remaining material will be lost and this continues in an unending fashion with the amount of ¹⁴C diminishing until it becomes virtually undetectable. This period of 5730 years is said to be the "half-life" of the unstable Carbon-14 atom.(Of course, new quantities of ¹⁴C are continuously being formed)

Due to the characteristics of the ¹⁴C atom, its wide dispersion and relatively short half-life, it would seem to be a perfect candidate for use in the measuring the age in biological specimens. It coexists in the atmosphere with the stable element Carbon-12 and both become 'bound' into carbon dioxide gas molecules. As a result, both ¹²C and ¹⁴C are incorporated in living matter either via the direct process of photosynthesis as in plants or, in animals, indirectly by ingestion of plant material and respiration.

It is assumed that the levels of cosmic radiation and the quantity of ¹⁴N, ¹²C and Oxygen (O) in the atmosphere are constant resulting in a predictable rate for the formation of ¹⁴C. The steady influx of ¹⁴C coupled with its depletion due to negative beta emissions, eventually leads to the total quantity of ¹⁴C reaching its own "balance point". In other words the amount being formed and the amount being depleted are the same, so the total quantity remains unchanged. This being the accepted "fact" makes it possible to measure and apply a ratio between ¹²C and ¹⁴C for the purpose of determining the age of organic samples.

Given the above information:

if you know the amount of ¹²C in a biological sample, which remains constant from the moment the specimen died. (no additional incorporation and ¹²C is stable)
if you measure the amount of remaining ¹⁴C and determine the current ratio between the two.
and bearing in mind the known half-life of ¹⁴C, the age of the specimen can be calculated.

For example, if the beginning ratio were 2:1 (¹²C :¹⁴ C) and the current amounts were found to be 2 : 0.25, you would know that the specimen was 11,460 years old because the amount of ¹⁴C has been reduced by a half, twice (1 / 2 / 2 = 0.25). As you may have deduced, the number of half-lives won't have to be very sizable before the amount of ¹⁴C is so miniscule as to be virtually undetectable. Current scientific thought limits the usage of this dating system to specimens not older than 40-50,000 years and not younger than 500 years. Advances in scientific method have improved accuracy but despite our best efforts, there is still a significant amount of error inherent to the process.

The error is caused by certain assumptions regarding the process that cannot be assumed. I've already discussed these above.

The quantity of Carbon-12, Carbon-14, Nitrogen-14, Oxygen and cosmic radiation in our environment is fixed.

This statement is untrue - environmental factors both within and outside the Earth's biosphere can and have adversely affected the total quantities of all these 'constants'.

There are known errors for which scientists routinely adjust their date calculations. For instance, specimens collected from the 5th Millennium B.C. seem to test about 800 years younger than they should which is an indication that there was a significant difference in the environment during that timeframe. There are also errors that have been discovered by comparing tree ring dating (dendrochronology), to radiocarbon dating. While these issues have been addressed to some degree, there is still a great deal of subjectivity and there are still many problems to be overcome in the solutions that are applied. Suffice to say, while the methodology is scientific and logical, transient factors render radiocarbon dating suspect and highly inaccurate. In fact virtually all dating systems which rely on radiological decay have inherent problems because of certain assumptions which cannot be verified with accuracy.

Author: John M. Fritzius date 01/19/05.

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