This question probably verges on pseudo-science and probably sounds like gibberish, so please pardon me. But I'll ask it anyway.
In an ideal lab experiment there is generally a separation between the system to be studied and the apparatus (environment). The two are considered 'unentangled' before the decoherence occurs, right?
However, the environment in itself can also be considered an entangled system (like the previous system) to be observed by humans.
We could then naively conclude that our flesh and form constitutes the true observer.
But all our bodily substance is also coupled to the environment. So who then is the one truly causing the decoherence?
Separate all the entangled material from the human body, what do you get?
What physical structure within us constitutes the eternally unentangled and irreducible observer?
Perhaps my line of thinking is wrong, maybe the entity does not exist outside the Hilbert Space. Then is the the observer entangled with the observed? So would that not mean that the observer can cause his own decoherence?
It might seem like gibberish, but I really don't know what the present status on this question is int the physics community. If there are any papers on the matter please do provide the link. This question nags me all the time.