[fluoridation]

> Of course, before the heat-death of the universe entropy-reducing systems will break down, but that's not an interesting observation.

Excuse the snark, but it's exactly as interesting as saying that some living systems are immortal until they're no longer immortal. If a protocell or a virus stops being alive (if we grant that it's alive) when it falls into a fire then it's not immortal just because it has no metabolism.

>Once started, their schedule (when they will deplete themselves, collapse, etc) is known and predictable, thus not alive.

Actually, no. For example, a star could hypothetically fall into another much larger than it and prolong its life, if we were to say that it lives. The only reason it's predictable is because a star can't move on its own to hunt weaker stars, and because (at least at this time in the history of the universe) stars are far enough apart that they rarely fall into each other. If that was a common occurrence it would be much more difficult to predict how long until a star burns out.

[grive]

I think you simply missed my point twice.

>> "Some external circumstances could change reducing them to a pile of oxides"

(or some other transformations I guess in case of fire.)

That was precisely not what I was talking about (or put another way if you still require abundant explicitness): not the kind of immortality I was describing. Maybe I was not clear enough.

> For example, a star could hypothetically fall into another much larger than it and prolong its life

Well, once again:

>> Of course they can still be impacted by external effects, but sustaining their own internal processes does not require such inputs