This has to do with figuring out the age of ancient things.
If you could watch a single atom of a radioactive isotope, U-238, for example, you wouldn’t be able to predict when that particular atom might decay.
Knowing about half-lives is important because it enables you to determine when a sample of radioactive material is safe to handle.It then takes the same amount of time for half the remaining radioactive atoms to decay, and the same amount of time for half of those remaining radioactive atoms to decay, and so on. The amount of time it takes for one-half of a sample to decay is called the half-life of the isotope, and it’s given the symbol: It’s important to realize that the half-life decay of radioactive isotopes is not linear.For example, you can’t find the remaining amount of an isotope as 7.5 half-lives by finding the midpoint between 7 and 8 half-lives.The first lesson, Isotopes of Pennies, introduces the idea of isotopes.The final lesson, Frosty the Snowman Meets His Demise: An Analogy to Carbon Dating, is based on gathering evidence in the present and extrapolating it to the past.
It is one of three known processes for carbon fixation.