Since the atoms that make up me are billions of years old, and given the wild cycle of matter in nature, what is the probability that, for example, I contain at least a small percentage of atoms that were once someone’s penis? And if that’s the case, is it possible that at some point all people and all matter on Earth will be 100% made up of atoms that have been penises at least once?
In regards to the second part, I’d point out that earth isnt a closed system, and small amounts of new matter are constantly ending up on earth. Think things like meteors (if i remember correctly, a few dozen tons of them fall on earth daily) the very thin traces of gas in space (it’s not a actually a perfect vacuum) and certain types of cosmic radiation that happen to consist of atoms. As such, I’d imagine it’s unlikely we’d ever get every atom on earth having once been part of one.