Unsolved problems in fundamental physics

Fundamental problems of current relevance are listed based on the critical revision of long-known facts and ideas and reflecting the numerous recent discoveries about elementary interactions and the structure of the Universe. The paper avoids the notion of teleology and considers the typical “WHAT FOR” and “WHY” questions as mere abbreviations for “Does a (possibly yet unknown) Law of Nature exist with which the property or phenomenon under study can be explained?” The list of problems reflects the personal interests of the author and so does not claim to be comprehensive.