I would like to add a claim if you will to this thread since i am not familiar with uranium-lead dating, so maybe someone can shine some light to this claim that was made by someone i encounter in the past. I haven't got this answer yet, so i hope someone can help collaborate on it.
As i understand, not all lead come from uranium, as they produce naturally throughout the environment. I had someone told me this would make lead unreliable. However, in this case, the half life of uranium will be used since there is no new sources to replenish uranium in the sample. Thus, the remaining of uranium will help determine the age of the sample.
Can someone help verify this claim?
And here is my next question concerning the half life problem:
It takes a very long time for uranium to decay into lead. Who even lived that long to observe this? If this is not how they determine the half life, then in what method do they use to determine the half life? I think it has to do with calculations.