ABSTRACT
Quantum measurement theories are interesting mainly because of the fundamental questions. Since quantum mechanics is primarily a theory of small, simple systems, it could a priori be expected that a full description of this formalism would be possible in a language that would refer only to the objective properties of such small systems. Unless quantum physics is objectively false in some of its predictions, limitations of such a kind are unavoidable. The chapter argues that such limitations extend to systems of arbitrary finite size and of arbitrary complexity. As a matter of fact, this is the first and perhaps the most significant conclusion in investigation of the conceptual foundations of quantum physics. An equally tenable standpoint is to assert that truly infinite systems have special features of their own that make them fall outside the realm of elementary quantum mechanics. Implicitly or explicitly, nonseparability is indeed present in all the various interpretations of the quantum rules which have been set forth.
