What is radiocarbon dating
Atmospheric carbon-14 rapidly reacts with oxygen in air to form carbon dioxide and enters the carbon cycle.
Plants take in carbon dioxide through photosynthesis and the carbon-14 makes its way up the food chain and into all living organisms.
However, once the organism dies, the amount of carbon-14 steadily decreases.
By measuring the amount of carbon-14 left in the organism, it's possible to work out how old it is.
It is often used on valuable artwork to confirm authenticity.
For example, look at this image of the opening of King Tutankhamen's tomb near Luxor, Egypt during the 1920s.
You might remember that it was mentioned earlier that the amount of carbon-14 in living things is the same as the atmosphere.
This is why radiocarbon dating is only useful for dating objects up to around 50,000 years old (about 10 half-lives).
Once the organism dies, the amount of carbon-14 reduces by the fixed half-life - or the time required for half of the original sample of radioactive nuclei to decay - of 5,730 years, and can be measured by scientists for up to 10 half-lives.
Measuring the amount of radioactive carbon-14 remaining makes it possible to work out how old the artifact is, whether it's a fossilized skeleton or a magnificent piece of artwork.
Radiocarbon dating has been used extensively since its discovery.
Examples of use include analyzing charcoal from prehistoric caves, ancient linen and wood, and mummified remains.
Libby was awarded the Nobel Prize in chemistry for his work in 1960.