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).
Early attempts at establishing an absolute time scale utilized the following concepts: declining sea levels, cooling of the Earth, cooling of the Sun, Earth tidal effects, sediment accumulation, and changes in ocean salinity.
Using changes in Earth's temperature or the Sun's use of energy failed because energy from nuclear reactions was unknown.
The interest in Rontgen’s discovery would launch the second scientific revolution; the first being launched by the work of Galileo (Asimov, 1984, pp 514-515).
The unstable or more commonly known radioactive isotopes break down by radioactive decay into other isotopes.
As a result, there is a changing ratio of carbon-14 to the more atomically stable carbon-12 involves actually counting individual carbon-14 atoms.
This allows the dating of much older and smaller samples but at a far higher cost.
Following death, however, no new carbon is consumed.
Progressively through time, the carbon-14 atoms decay and once again become nitrogen-14.
decay or the rate of other cumulative changes in atoms resulting from radioactivity. The various isotopes of the same element differ in terms of atomic mass but have the same atomic number..