The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained.Research has been ongoing since the 1960s to determine what the proportion of in the atmosphere has been over the past fifty thousand years.For example, two samples taken from the tombs of two Egyptian kings, Zoser and Sneferu, independently dated to 2625 BC plus or minus 75 years, were dated by radiocarbon measurement to an average of 2800 BC plus or minus 250 years. Carbon dioxide produced in this way diffuses in the atmosphere, is dissolved in the ocean, and is taken up by plants via photosynthesis.
This was revised in the early 1960s to 5,730 years, which meant that many calculated dates in papers published prior to this were incorrect (the error in the half-life is about 3%).
For consistency with these early papers, and to avoid the risk of a double correction for the incorrect half-life, radiocarbon ages are still calculated using the incorrect half-life value.
Measurement of radiocarbon was originally done by beta-counting devices, which counted the amount of beta radiation emitted by decaying atoms in the sample and not just the few that happen to decay during the measurements; it can therefore be used with much smaller samples (as small as individual plant seeds), and gives results much more quickly.
The development of radiocarbon dating has had a profound impact on archaeology.
Radiocarbon dating has allowed key transitions in prehistory to be dated, such as the end of the last ice age, and the beginning of the Neolithic and Bronze Age in different regions.
In 1939, Martin Kamen and Samuel Ruben of the Radiation Laboratory at Berkeley began experiments to determine if any of the elements common in organic matter had isotopes with half-lives long enough to be of value in biomedical research.When living things die, they stop taking in carbon-14, and the radioactive clock is "set"!Any dead material incorporated with sedimentary deposits is a possible candidate for carbon-14 dating.In addition to permitting more accurate dating within archaeological sites than previous methods, it allows comparison of dates of events across great distances.Histories of archaeology often refer to its impact as the "radiocarbon revolution".The ratio of λ is a constant that depends on the particular isotope; for a given isotope it is equal to the reciprocal of the mean-life – i.e.