We reconsider a well known problem of quantum theory, i.e. the so called
measurement (or macro-objectification) problem, and we rederive the fact that
it gives rise to serious problems of interpretation. The novelty of our
approach derives from the fact that the relevant conclusion is obtained in a
completely general way, in particular, without resorting to any of the
assumptions of ideality which are usually done for the measurement process. The
generality and unescapability of our assumptions (we take into account possible
malfunctionings of the apparatus, its unavoidable entanglement with the
environmment, its high but not absolute reliability, its fundamentally
uncontrollable features) allow to draw the conclusion that the very possibility
of performing measurements on a microsystem combined with the assumed general
validity of the linear nature of quantum evolution leads to a fundamental
contradiction.Comment: 17 pages, Latex, to appear in Phys. Lett.
