Those who promote the reliability of the method spend a lot of time impressing you with the technical details of radioactive decay, half-lives, mass-spectroscopes, etc.
Many people assume that the dates scientists quote of millions of years are as reliable as our knowledge of the structure of the atom or nuclear power.
And radioactive dating is so shrouded with mystery that many don’t even try to understand how the method works; they just believe it must be right.
Keep that in mind when you think about working out the age of something. Actually, knowing the starting time is still not enough.
During the race you have to watch the swimmer and count how many laps he has swum so you know that he has done 1,500 metres.
That is why you need three timekeepers to independently record the times during the race to meet the standard needed to enter the record books.
Would it make any difference if the watch we were using was more accurate? You could talk about the tiny quartz crystal and the piezoelectric effect used to provide a stable time base for the electronic movement.
But the basic concept of radioactive dating, sometimes called radiometric dating, is not difficult, especially since all of us regularly calculate how much time has passed: for example, since our birth, or since we started on a walk.
A swimming race is a familiar situation that illustrates the simple principles involved in measuring time.
Carbon 14 is continually being created in the Earth's atmosphere by the interaction of nitrogen and gamma rays from outer space.
Since atmospheric carbon 14 arises at about the same rate that the atom decays, the Earth's levels of carbon 14 have remained constant.
Once we understand what we actually need to do we can apply the same principles to radioactive dating, and see if the methods do what they are claimed to do.