Carbon dating time rangeThere are two main applications for radiometric dating. One is for potentially dating fossils (once-living things) using carbon-14 dating, and the other is for dating rocks and the age of the earth using uranium, potassium and other radioactive atoms. Note that, contrary to a popular misconception, carbon dating is not used to date rocks at millions of years old. Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry. Neutrons that come from these fragmented atoms collide with C to be useful in age estimates. This is a critical assumption in the dating process. It cannot be used directly to date rocks; however, it can potentially be used to put time constraints on some inorganic material such as diamonds (diamonds could contain carbon-14). Cosmic rays from outer space, which contain high levels of energy, bombard the earth’s upper atmosphere. Some isotopes of certain elements are unstable; they can spontaneously change into another kind of atom in a process called “radioactive decay.” Since this process presently happens at a known measured rate, scientists attempt to use it like a “clock” to tell how long ago a rock or fossil formed. Assumptions in the scientific community are extremely important.