  Schroedinger's wave function shows many aspects of a state of incomplete
knowledge or information ("bit"): (1) it is usually defined on a space of
classical configurations, (2) its generic entanglement is, therefore, analogous
to statistical correlations, and (3) it determines probabilities of measurement
outcomes. Nonetheless, quantum superpositions (such as represented by a wave
function) define individual physical states ("it"). This conceptual dilemma may
have its origin in the conventional operational foundation of physical
concepts, successful in classical physics, but inappropriate in quantum theory
because of the existence of mutually exclusive operations (used for the
definition of concepts). In contrast, a hypothetical realism, based on concepts
that are justified only by their universal and consistent applicability, favors
the wave function as a description of (thus nonlocal) physical reality. The
(conceptually local) classical world then appears as an illusion, facilitated
by the phenomenon of decoherence, which is consistently explained by the very
entanglement that must dynamically arise in a universal wave function.
