At the start, let me clarify that my main concern is not the age of the earth, the moon, or the solar system, but rather the age of life, that is, how long has life existed on earth.
Many dating methods seem to give about the same ages on meteorites.
We are told that of all the radiometric dates that are measured, only a few percent are anomalous.
This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points.
In two half-lives, half of the remainder will decay, meaning 3/4 in all will have decayed.
In general, in n half-lives, only 1/(2^n) of the original parent material will be left.
Assuming we start out with pure parent, as time passes, more and more daughter will be produced. A ratio of infinity (that is, all daughter and no parent) means an age of essentially infinity.
By measuring the ratio of daughter to parent, we can measure how old the sample is. Each radioactive element has a half-life, which tells how long it takes for half of the element to decay.
However, this causes a problem for those who believe based on the Bible that life has only existed on the earth for a few thousand years, since fossils are found in rocks that are dated to be over 500 million years old by radiometric methods, and some fossils are found in rocks that are dated to be billions of years old.If these dates are correct, this calls the Biblical account of a recent creation of life into question.After study and discussion of this question, I now believe that the claimed accuracy of radiometric dating methods is a result of a great misunderstanding of the data, and that the various methods hardly ever agree with each other, and often do not agree with the assumed ages of the rocks in which they are found.Potassium is about 1/40 of the earth's crust, and about 1/10,000 of the potassium is potassium 40.Uranium decays to lead by a complex series of steps. Thus we obtain K-Ar dating, U-Pb dating, and Rb-Sr dating, three of the most common methods.