The author of a well-known course in quantum mechanics devotes this monograph to fundamental questions of quantum mechanics, which are fundamental to the understanding of this important theory. The author pays special attention to the analysis of the relationship of the microsystem with the macro environment, in particular, the analysis of the macroscopic device. The concept of the author is not generally accepted and well-known, and this makes the book particularly interesting. The book is intended for a wide range of physicists, theorists and experimenters interested in the basics of modern theory. It will also be useful and interesting for philosophers engaged in the methodology of modern natural science.