With radiocarbon dating, the amount of the radioactive isotope carbon-14 is measured.Compared to some of the other radioactive isotopes we have discussed, carbon-14's half-life of 5,730 years is considerably shorter, as it decays into nitrogen-14.
When the isotope is halfway to that point, it has reached its half-life.
There are different methods of radiometric dating that will vary due to the type of material that is being dated.
With rubidium-strontium dating, we see that rubidium-87 decays into strontium-87 with a half-life of 50 billion years.
By anyone's standards, 50 billion years is a long time.
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.
The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay.
The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life.
And this would also include things like trees and plants, which give us paper and cloth.