On solutions of problems of 20th century physics and foundations of theoretical physics of 21st century

During three quarters of 20th century, due to successes of experimental physics, significant progress occurred in the foundations of theoretical physics, and the result of this joint development is the modern physical picture of the world. But in the last quarter of this century, all progress has been reduced to speculative mathematical models without any experimental basis and hope for confirmation. Moreover, the formation of the basic theories of physics, general relativity, quantum mechanics and quantum field theory, still remained incomplete due to ambiguities and a number of fundamental problems in their foundations and important applications. In the previous review article (Zakir, 2020), the main part of these problems was considered and solutions for them, proposed by the author in 2006-2020, were summarized. This review is its revised version, supplemented with several new problems and their solutions found by the author in 2021-2022. Unlike other attempts proceeded from speculative hypotheses, the proposed formulations of basic theories and their applications are based on physical principles following from experimental facts. As a result, the basic theories, which remained successful mathematical models only, finally became consistent physical theories. Problems of a «technical» nature, which have arisen due to deviation from the basic principles, are removed by strict following to these principles. Other problems have been solved by introducing new principles or changing old ones, but also on the basis of facts. Therefore, these solutions, in one form or another, will enter the new physics that is initiated by them. The contours and prospects of the theoretical physics of 21st century are considered. The causes of the crisis in the foundations of theoretical physics of the 20th century and ways to overcome it are discussed. It is shown that the main cause of the crisis was the departure of the scientific community from the methodology and ethics of the natural sciences, and the theoretical physics of 21st century is now being formed as a result of a return to them.