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During the period of a plant's life, the plant is taking in carbon dioxide through photosynthesis, which is how the plant makes energy and grows.
Animals eat plants, and some eat other animals in the food chain.
In the 1940s, scientists succeeded in finding out how long it takes for radiocarbon to disappear, or decay, from a sample of carbon from a dead plant or animal.
Willard Libby, the principal scientist, had worked in the team making the nuclear bomb during World War 2, so he was an expert in nuclear and atomic chemistry.
The radiocarbon method was developed by a team of scientists led by the late Professor Willard F.
Libby of the University of Chicago after the end of World War 2.
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)].
The person who wrote these words lived in the 1800s, many years before archaeologists could accurately date materials from archaeological sites using scientific methods.
Most of the carbon on Earth exists in a slightly different atomic form, although it is chemically speaking, identical to all carbon.
It is called 'radio'-carbon, because it is 'radioactive'.
This means that its atomic structure is not stable and there is an uneasy relationship between the particles in the nucleus of the atom itself.
Because carbon is very common on Earth, there are alot of different types of material which can be dated by scientists.
Below is a list of the different kinds of materials which can be dated: Libby tested the new radiocarbon method on carbon samples from prehistoric Egypt whose age was known.I have tried here to answer some of the frequently asked questions that I receive from students via email, as well as providing some basic information about scientific dating methods.