Testing the radiocarbon dating method
Looking at the graph, 100% of radiocarbon in a sample will be reduced to 50% after 5730 years.In 11,460 years, half of the 50% will remain, or 25%, and so on.Limitations and calibration: When Libby was first determining radiocarbon dates, he found that before 1000 BC his dates were earlier than calendar dates.He had assumed that amounts of Carbon-14 in the atmosphere had remained constant through time.In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.Although relative dating can work well in certain areas, several problems arise.Radiocarbon is then taken in by plants through photosynthesis, and these plants in turn are consumed by all the organisms on the planet.So every living thing has a certain amount of radiocarbon within them.
Because atmospheric carbon 14 arises at about the same rate that the atom decays, Earth's levels of carbon 14 have remained fairly constant.
In the late 1940s, American chemist Willard Libby developed a method for determining when the death of an organism had occurred.
He first noted that the cells of all living things contain atoms taken in from the organism's environment, including carbon; all organic compounds contain carbon.
After an organism dies, the radiocarbon decreases through a regular pattern of decay. The time taken for half of the atoms of a radioactive isotope to decay in Carbon-14’s case is about 5730 years.
Half-lives vary according to the isotope, for example, Uranium-238 has a half-life of 4500 million years where as Nitrogen-17 has a half-life of 4.173 seconds!