How can the radiometric dating of different meteorites determine the age of the earth? Wouldn't radioactive decay have already been occurring in all of those meteorites long before they hit earth? Wouldn't dating only show when the unstable nuclides in that meteorite were created, not when the earth was created? If you went and measured a decaying nuclide in a metiorite which had traveled for 500 million years before striking earth, then the dating of that metiorite would not tell us the age of the earth it would instead give us an age measurement at least 500 million years older then the earth actually is because that nuclide was decaying long before it managed to hit earth's surface.
Also assuming this does somehow get accounted for, how would determining the age of all these various meteorites allow us to estimate the earth's age? Wouldn't this only give us a lower bound on the earth's age? How do we know there doesn't exist some older meteorite out there indicating the earth is older then 4.5 billion years?
This is not a duplicate of the question asking about why measure meteorites not rocks, I am talking about meteorites and my question is regarding how dating can take into account when the rocks became part of earth as opposed to when the nuclides being dated first came into existence. Its not like the unstable nuclides within a metiorite suddenly decided to start decaying when they hit earth. They started decaying the minute they came into existence, including the time before they hit earth.