This book deals, in an original manner, with fundamental problems concerning the physical systems between small and large scales. It fills a gap in the existing literature due to recent developments in modern physics. Comprehensively organized into six chapters, the authors examine topics in modern physics and offer a unitary and original treatment of the fundamental problems of the dynamics of physical systems, as well as a description of the nuclear matter within a framework of general relativity. They demonstrate that some physical phenomena studied at two different resolution scales (e.g. microscale, cosmological scale), apparently with no connection between them, become compatible by means of the operational procedures acting either as some "hidden" symmetries or harmonic-type mappings. This book is a valuable reference for students, researchers, and university and high school teachers working in the fields of mathematics, physics, and chemistry. Book jacket.