For example, creationist writer Henry Morris [Morris2000, pg.Offering in 1952 his new radiocarbon method for calculating the age of organic material (the time interval since the plant or the animal died), W. Libby clearly saw the limitations of the method and the conditions under which his theoretical figures would be valid: A.Radiometric dating is self-checking, because the data (after certain preliminary calculations are made) are fitted to a straight line (an "isochron") by means of standard linear regression methods of statistics.The slope of the line determines the date, and the closeness of fit is a measure of the statistical reliability of the resulting date.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.When objects of the Old Kingdom and Middle Kingdom of Egypt yielded carbon dates that appeared roughly comparable with the historical dates, Libby made his method known.It is rapidly oxidized in air to form carbon dioxide and enters the global carbon cycle.Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes.
The impact of the radiocarbon dating technique on modern man has made it one of the most significant discoveries of the 20th century.First, it was noticed that, when radiocarbon dated, wood grown in the 20th century appears more ancient than wood grown in the 19th century.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. The short answer is that the underlying physics behind radiocarbon dating was worked out, by many people, between the 1910s and 1940s. They measured the actual carbon-14 remaining in these, and found that it was very close to the predicted amount. There's a nice review here of how radiocarbon dating was developed: . Arnold and Libby knew how much carbon-14 should be remaining in these objects, given their known ages.