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.
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.
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.
Picture a swimmer competing in a 1,500 metre race and an observer with an accurate wristwatch.
We note that at the instant the swimmer touches the end of the pool our wristwatch reads and 53 seconds.
How long has the competitor taken to swim the race?
When I have asked an audience this question they have looked at me incredulously and said, “Starting time?
” They realize that you cannot know how long the swimmer took unless you knew the time on the wristwatch when the race started.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.And you have to check to make sure he touches the end for each lap.Without these observations you cannot be sure that the time is valid.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.