so electrons, other elementary particles etc. are completely

>>8729752
In practice, yes, particles are equivalent. But there can be isotopes with more neutrons, or the atoms can be ionized, so not all the oxygen molecules are exactly the same.

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>>8729806
but each variations are all locally identical yes? why is it not possible to assign a "name" to a fundamental particle?

>>8729817
Because everything is delocalized

>>8729752
No, I can distinguish the particles in terms sense of being at two different positions, however I can not distinguish them if I exchange their positions.

>>8729752
>does that imply the oxygen molecules i breath in are also everyone else's at the same time?

we all breathe the same air if that's what you're asking. of course the o2 already inside of you won't be inside another person at the same time.