Radiometric and radiocarbon dating
The realisation that radioactive materials emit rays indicated a constant change of those materials from one element to another.
The New Zealand physicist Ernest Rutherford, suggested in 1905 that the exact age of a rock could be measured by means of radioactivity.
Carbon-14 has a half-life of 5,730 ± 40 years— during the succeeding 5,730 years.
Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.
Scientists, using rigorous methods have established a process to eliminate this problem by calibrating radiocarbon dating results to items of a known age.
And this isn’t really an assumption as the decay rates have been tested in the laboratory for a hundred years or so, we have an example of a natural nuclear reactor where we can measure the various products and determine the decay rates (and the fine structure constant), and we can observe the past by looking deep into the past of the universe. The sigh isn’t for the effort of writing, it’s for the effort of finding all the references.
For example: after the it forms a component of all organic compounds and is therefore fundamental to life. Libby of the University of Chicago predicted the existence of carbon-14 before it was actually detected and formulated a hypothesis that radiocarbon might exist in living matter.
In some cases there have been downright fossil frauds, but the latest research indicates there were no feathers at all.
The Manot Cave, a natural limestone formation, had been sealed for some 15,000 years. Gihon Spring was crucial to the survival of its inhabitants, and archaeologists had uncovered the remains of a massive stone tower built to guard this vital water supply. In a new paper, the authors explain how harvesting data from tree-rings could revolutionize the study of ancient civilizations such as the Egyptian and Mayan worlds. Researchers have used radiocarbon measured in deep-sea fossil corals to shed light on carbon dioxide levels during Earth's last deglaciation.
Fossil corals have the unique advantage that they ...