This is the first volume of the series entitled «Physics at the Turn of the Millennium.» This book contains three chapters. The first chapter deals with the fundamentals of a new interdisciplinary scientific direction, physics of open systems, whose origin was associated with the work of outstanding researchers of the nineteenth century. Among them are physicist L. Boltzmann, mathematicians A. Poincar and A. Lyapunov, and biologist Ch. Darwin. The second chapter covers the physics of solids. This study is of a paramount importance because it allows obtaining information about the structure of matter in living and nonliving nature as well as about materials used in technologies. The third chapter analyzes the branch of physics related to new possibilities of large-scale application of semiconductors in diverse fields of science and technology. The book is intended for everyone who is interested in the problems of modern physics.