Five questions dominated the ARW on Physics and Materials Science of High Temperature Superconductors, of which this book forms the permanent record. Briefly, these are: (i) How close are we to a unified theory? The consensus is that we are not. (ii) Flux pinning: can it be achieved in bulk materials? Still an open question. The following three questions are related. (iii) Can grain boundary contributions be brought under control? (iv) What is the real requirement for purity and general chemistry control? (v)What is the practical outlook for bulk products - tapes and wires? One of the conclusions is that the geometry and dimensions in thin films are the key parameters that facilitate the realization of high current densities and, consequently, their commercial application. On the other hand, the very large number of poorly understood microstructural, chemical and mechanical variables involved in the preparation of bulk materials are currently prohibiting large scale commercialization of wires and tapes.
