Organic matter in the fossil record generally dates by carbon 14 (C14) dating to about 20,000 to 40,000 years. Other radioactive dating methods such as potassium/argon (K/Ar), rubidium/strontium (Rb/Sr), uranium/lead (U/Pb), thorium/lead (Th/Pb) and others that are based on decay of longer-lived isotopes often give ages in the millions or hundreds of millions of years for these fossils. Why is this? Why are the dates so different?
Many creationists believe that radioactive decay was faster in the past. However, in this talk I want to concentrate on reasons to believe the C14 dates are more accurate and that they give evidence that all life on earth is very young. If decay rates were faster in the past, then even the C14 dates could be too old.
How Carbon 14 Is Produced and Decays
Carbon 14 is an isotope of carbon with two extra neutrons in the nucleus. It is produced in the upper atmosphere. The rate at which this happens varies to some extent. Perhaps there was less C14 produced in the past, which would imply that even the relatively young C14 dates are too old.