DELAYED-CHOICE EXPERIMENTS AND RETROACTIVE APPARENT OCCURRENCE IN THEQUANTUM-THEORY OF MEASUREMENT

The concept of retroactive apparent occurrence, the main ingredient of Wheeler's delayed-choice thought experiments, is systematically incor porated into the quantum theory of measurement (in the framework of th e recent review of Busch, Lahti, and Mittelstaedt). Besides, the (gene ral) notion of individual-system measurement is introduced, and, due t o it, premeasurement is defined by a truly minimal condition. Finally, retroactive apparent occurrence is made use of to derive apparent obj ectification in measurement. The derivation is discussed in the framew ork of the quantum mechanical approach to the objectification problem.