Radio active dating
To achieve stability, some ‘particles’ are ejected from the atoms, and these moving ‘particles’ constitute the radioactivity measured by Geiger counters and the like.
The end result is stable atoms of the ‘daughter’ elements lead, argon, and strontium respectively.
However, it is with the interpretation of the chemical analyses of the radioactive parents and resultant daughters that the problems with radioactive dating of rocks begin.
In order to interpret these chemical analyses, geochronologists must make three vital assumptions, otherwise the radioactive ‘clock’ cannot be made to ‘read’ the ‘age’ of the rocks.
Now this ‘clock’ works because the initial conditions are known—that is, all the sand grains are in the top glass bowl and none are in the bottom one.
If there is already some sand in the bottom glass bowl, then unless this amount is known the hourglass ‘clock’ cannot ‘tell’ the time.
Or, some uranium might have been deposited by groundwaters into the sample, thus making it appear younger than what it really is.
This is done in specially equipped laboratories with sophisticated instruments capable of very good precision and accuracy, so in general there is no quarrel with the resulting chemical analyses.
However, not all meteorites have the same uraniumthorium-lead isotopic composition, so why should the isotopic composition of these particular meteorites be considered to be the ‘correct’ composition for the earth at its origin rather than some other composition found in other meteorites?
Furthermore, even if today’s scientists believe they have the methods, for example graphical and mathematical, for determining how much of the daughter isotope might have been present either at the origin of the earth or the origin of the rock being dated, no one can ever be sure that these ‘answers’ are correct, because there was no scientist present at the beginning to observe those initial conditions, even though the scientists’ calculations may be extremely logical.
In the case of the initial conditions, no scientist can ever be sure as to what they were, because no scientist was present here on the earth at its origin.
Thus the amount of daughter isotope that has actually been derived from the parent isotope by radioactive decay is unknown, since some of the daughter isotope might have been present with its respective parent isotope at the time of the earth’s origin.