In a quantum mechanical two-slit experiment one can observe a single photon simultaneously as particle (measuring the path) and as wave (measuring the interference pattern) if the path and the interference pattern are measured in the sense of unsharp observables. These theoretical predictions are confirmed experimentally by a photon split-beam experiment using a modified Mach—Zehnder interferometer.

The article traces the origin and development of the concept of social skills in first and foremost American academic discourse. As soon as the concept of social skills was coined, the concern for people lacking such skills started and has been on the increase ever since. After the analysis of the academic history of the concept follows an examination of the implementation of a range of assessment instruments and training programmes related to social skills in contemporary Danish welfare institutions. The (...) analysis forwarded in the article thus demonstrates how an intellectual idea may develop and travel - and on its journey connect to pre-existing cultural logics and societal concerns. The idea of social skills has through its development been made uncontroversial – everybody wants to be skilful. The concept does, however, convey an individualistic view on social life and imposes a reflexivity over own performance on the participants. Further, its normative character contributes to a problematization of those who are perceived to lack these skills. (shrink)