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[[Image:C-14decay.JPG|framed|The first-order decay curve of carbon-14 based on the half-life of 5730 years.]]
The technique is based on comparing the levels of <SUP>14</SUP>C and <SUP>12</SUP>C [[isotope]]s in the sample.
<sup>14</sup>C is produced in the atmosphere by [[cosmic ray ]] [[neutron]]s replacing a [[proton]] in [[nitrogen]] (<sup>14</sup>N), producing <sup>14</sup>C.<ref name="TH">Higham, Thomas, [http://www.c14dating.com/int.html Introduction], Radiocarbon web-info.</ref>
<sup>14</sup>C is unstable and [[radioactive decay|decays]] back to <sup>14</sup>N, at the rate of 50% every 5,730 years (so after 11,460 years 25% will be left, after 17,190 years 12.5% will be left, and so on).
Despite this, however, caution is still necessary in accepting dates derived from carbon dating.
Claims have been made of the method being calibrated back to 10,000 years using [[dendrochronology]],<ref name="TH" /> however these older dates derived via dendrochronology have themselves been derived by using with the assistance of carbon dating,<ref>Batten, Don, [http://creationontheweb.com/content/view/2441 Tree ring dating (dendrochronology)] (Creation Ministries International).</ref>, making this circular reasoning.
=== Variable intake ===
Not all living things do have <sup>14</sup>C:<sup>12</sup>C ratios the same as the atmosphere. For example, it is well known that carbon dating cannot be used on many types of marine life due to reservoirs of "old" carbon held in sedimentary rocks. This problem is especially severe in shellfish or anything that eats shellfish; it is not unusual for freshly-killed seals to be dated as several thousand years old.
{{QuoteBox|...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 animal's diet. An animal that ingested plants with relatively low C-14 proportions would be dated older than their true age."<ref>Nondestructive Testing (NDT) Resource Center, [http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/Physics/carbondating.htm Carbon-14 Dating"]</ref>}}
Dating laboratories do not make any allowance for the change in atmospheric levels that would have occurred as a result of [[Great Flood|Noah's Flood]].
This means that radio-carbon dates cannot be used to prove that the Flood did not occur, because it ''assumes'' that it did not occur.<ref>Batten, Don, (Ed.) [http://www.creationontheweb.com/images/pdfs/cabook/chapter4.pdf What about carbon dating?] Chapter 4 of the ''Creation Answers Book''.</ref>
=== Solar-Earth effect ===
Scientists at Brookhaven National Laboratory and the Physikalish-Technische-Bundesandstalt in Germany have reported "unexplained periodic fluctuations in the [nuclear] decay rates of Si-32 and Ra-226... strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun." It is likely that similar discrepancies and fluctuations occur with other nuclear decay rates, such as that of <sup>14</sup>C. It remains for scientists to perform experiments to explore these emerging issues.<ref>[https://arxiv.org/abs/0808.3283 Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun Distance], Jenkins et al. Abstract: Unexplained periodic fluctuations in the decay rates of Si-32 and Ra-226 have been reported by groups at Brookhaven National Laboratory (Si-32), and at the Physikalisch-Technische-Bundesandstalt in Germany (Ra-226). We show from an analysis of the raw data in these experiments that the observed fluctuations are strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun. Some implications of these results are also discussed, including the suggestion that discrepancies in published half-life determinations for these and other nuclides may be attributable in part to differences in solar activity during the course of the various experiments, or to seasonal variations in fundamental constants.</ref>
== History ==
Carbon Dating was developed by [[Willard F. Libby]] and his team of scientists at the [[University of Chicago]] in 1949.<ref name="TH" />
They initially measured the 'half-life' (a term that Libby coined)<ref name="TH" /> as 5568±30 years, and this became known as the ''Libby half-life''.<ref name="TH" />
It was later measured more accurately to be 5730±40 years, now known as the ''Cambridge half-life''.<ref name="TH" />
== Widespread misunderstandings ==
Many people believe that carbon dating has proved that the Earth is millions or billions of years old, much older than the biblically-derived date of around 6,000 years.However, as explained above, carbon dating is incapable of providing dates in the range of millions or billions of years, and many scientists turn to [[Radiometric dating|other forms of dating]] to derive such extremely long time periods.
Some also argue that carbon dating should only be used on samples that fall within the range over which it can measure.
However, this begs prompts the question of how one might determine this prior to using carbon dating to determine thisthe age.
They further argue that dating much older items will result in anomalous dates, which might fall within the range that carbon dating can measure.
This is incorrect. Any sample that is older than the range that carbon dating will measure will record essentially zero <sup>14</sup>C, and can therefore not be confused with younger samples.
==See also==
*[[AMS]]
*[[Martin Kamen]]
*[[Willard Libby]]
== References ==
