Radioactive decay is a natural process and comes from the atomic nucleus becoming unstable and releasing bits and pieces.
These are released as radioactive particles (there are many types).
However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.
So, we rely on radiometric dating to calculate their ages.
Radioactive dating is a method of dating rocks and minerals using radioactive isotopes.
Other critics, perhaps more familiar with the data, question certain aspects of the quality of the fossil record and of its dating.This decay process leads to a more balanced nucleus and when the number of protons and neutrons balance, the atom becomes stable.This radioactivity can be used for dating, since a radioactive 'parent' element decays into a stable 'daughter' element at a constant rate.Until this century, relative dating was the only technique for identifying the age of a truly ancient object.By examining the object's relation to layers of deposits in the area, and by comparing the object to others found at the site, archaeologists can estimate when the object arrived at the site.If one knows how much of this radioactive material was present initially in the object (by determining how much of the material has decayed), and one knows the half-life of the material, one can deduce the age of the object.