Reconsidering the Relation Between “Matter Wave Interference” and “Wave–Particle Duality”

Interference of more and massive objects provides a spectacular confirmation quantum theory. It is usually regarded as support for "wave-particle duality" in an extension this duality even "complementarity". We first give outline the historical development these notions. Already here it becomes evident that they are hard to define rigorously, i.e. have mainly heuristic function. Then we discuss recent interference experiments large complex molecules which seem function "duality". However, show diffraction {\em delocalized} center-of-mass wave depends on interaction localized} structure molecule with element. Thus, display "dual features" at same time, contradicts usual understanding wave-particle duality. conclude notion deserves no place modern physics.