Similarly, when all the atoms of the radioactive element are gone, the rock will no longer keep time (unless it receives a new batch of radioactive atoms).
Many people have been led to be skeptical of dating without knowing much about it. In spite of this, differences still occur within the church.
For example, most people don't realize that carbon dating is only rarely used on rocks. A disagreement over the age of the Earth is relatively minor in the whole scope of Christianity; it is more important to agree on the Rock of Ages than on the age of rocks.
Wiens has a Ph D in Physics, with a minor in Geology.
His Ph D thesis was on isotope ratios in meteorites, including surface exposure dating.
Most processes that we are familiar with are like sand in an hourglass.
In exponential decay the amount of material decreases by half during each half-life.
Radiometric dating--the process of determining the age of rocks from the decay of their radioactive elements--has been in widespread use for over half a century.
There are over forty such techniques, each using a different radioactive element or a different way of measuring them.
This paper describes in relatively simple terms how a number of the dating techniques work, how accurately the half-lives of the radioactive elements and the rock dates themselves are known, and how dates are checked with one another.
In the process the paper refutes a number of misconceptions prevalent among Christians today.
Most of the elements in nature are stable and do not change.