If we assume that physcialism is true and all that there is, then we can safely assume that what we think of as subjective experience and consciousness, is driven by the atoms in our brain and the particular arrangement of those atoms. But then we can reason that another person has a different set of atoms and a different arrangement of those atoms in his brain that forms a different "subjective experience"- since I know not what it's like to be another person but I know all there is to be me, I am assuming it's down to the different and distinct atoms of their brain and their particular arrangement. And so we can ask ourselves just how many atoms in the brain are responsible for subjective experience and how many we can safely get rid of/ replacing before we have a different subjective experience.
And the fact that:
Radioactive decay and the changing of neurons means the exact set of atoms and arrangement of those atoms which formed my brain when I first had what I would call "consciousness" are probably not 100% same
Those initial atoms and current atoms in my brain, had such a remote likelihood of forming my brain (of all the atoms in the universe)
Therefore, can one conclude that it's far more likely that what we would denote as subjective experience isn't necessarily tied to the atoms in our brain or their arrangement (otherwise for example, for all I know I didn't exist 10 years ago, and I just believe so because I have memories from 10 years ago), meaning it's more likely that there is some other explanation alongside physicalism, or that physicalism also implies "open individualism" (based on my above arguments)?