Oldest radiocarbon dating
To understand this process we must first understand a little bit about the atoms themselves and how they get their names.Most carbon atoms have six positively charged protons and six uncharged neutrons.
To check on the method before applying it on various historical and paleontological material, Libby chose material of Egyptian archaeology, under the assumption that no other historical material from over 2,000 years ago is so secure as to its absolute dating.Most nitrogen atoms have seven protons and seven neutrons, so their atomic mass is 7 7 = 14.The fact that it has seven protons is what makes it nitrogen.Suess explained the phenomenon by the fact that the increased industrial use of fossil carbon in coal and in oil changed the ratio between the dead carbon C12 and the C14 (radiocarbon) in the atmosphere and therefore also in the biosphere.In centuries to come a body of a man or animal who lived and died in the 20th century would appear paradoxically of greater age since death than the body of a man or animal of the 19th century, and if the process of industrial use of fossil, therefore dead, carbon continues to increase, as it is expected will be the case, the paradox will continue into the forthcoming centuries.Organisms at the base of the food chain that photosynthesize – for example, plants and algae – use the carbon in Earth’s atmosphere.
They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all the way to apex predators, like sharks.
But as the method was refined, it started to show rather regular anomalies.
First, it was noticed that, when radiocarbon dated, wood grown in the 20th century appears more ancient than wood grown in the 19th century.
Rasmus Nyerup's quote reminds us of the tremendous scientific advances which have taken place in the 20th century.
In Nyerup's time, archaeologists could date the past only by using recorded histories, which in Europe were based mainly on the Egyptian calendar.
We know that it is older than Christendom, but whether by a couple of years or a couple of centuries, or even by more than a millenium, we can do no more than guess." [Rasmus Nyerup, (Danish antiquarian), 1802 (in Trigger, 19)].