Radiocarbon dating is a method of determining the age of any organic object, or fossilized object that contained organic materials. Usually called simply "carbon dating," the method uses carbon-14, which has a fixed half-life. By determining the rate of decay in the carbon-14, the approximate age of the object can be determined. For example, a fossilized plant will have stopped accumulating carbon-14 when it died; this fixed amount corresponds to the amount of carbon-14 in the atmosphere at that time in history. During the fossilization process, the carbon-14 decays at a known rate, about 5,730 years -- this means that every 5,730 years, the amount of carbon-14 in a given sample will reduce by half. Using this information, the age of an organic fossil object can be determined. Carbon dating was first theorized by scientist Willard Libby in 1949.