The book of well-known Russian scientists systematically presents a new theoretical approach to studying nature's fundamental phenomena using the hypothesis of the physical vacuum, or the ether, as some environment in which all the processes develop. In the proposed studies, the ether is represented as some one-component continuous media that satisfies generally accepted conservation laws: of matter and momentum. From the appropriate two equations, a number of consequences are obtained to which a physical interpretation is given. For the first time, 150 years after studies of Faraday and Maxwell, it is shown that these single premises mathematically give basic physical laws established experimentally: the Maxwell equations, the Lorentz force, the Gauss theorem; the laws: Coulomb, Biot - Savard, Ampere, electromagnetic induction, Ohm, Joule - Lenz, Wiedemann - Franz, universal gravitation, and etc. Details of mechanisms of many processes, that seemed previously paradoxical, have been disclosed. A method of the model substantiation adopted in the mathematical modeling methodology allows to conclude that the presented mathematical model of the ether adequately describes electromagnetic and gravitational processes. Qualitative and quantitative analysis of hundreds of known and new experimental facts allows in the methodology of physics, as science summarizing the experiments data, to confirm a conclusion about the existence of the ether (physical vacuum). The content of the book is based on the works of authors done during the last fourteen years. Many results are published for the first time. The book is intended for specialists in the field of electrodynamics, electrical engineering, gravity and kinetics, as well as for graduate students and students, interested in the fundamental principles of these scientific directions. This book is unique in terms of the comprehensive consideration of the problem and the depth of its analysis.