The brochure is intended for the reader familiar with physics and mathematics in the scope of high school. We sought to present the most difficult problems in such a way as to give the reader an idea of scientific argumentation, of the substantiation of our statements. This inevitably led to a large number of formulas, unusual for a popular science brochure. However, the given formulas do not go beyond elementary mathematics and, moreover, usually receive a visual interpretation. For the reader, it may be unusual to freely handle numerical multipliers, for example, lowering the factor 3 in the number In most of the questions we consider, such ordinal estimates are quite acceptable. The exact accounting of numerical factors is either not feasible or not essential, t. e. Nothing will change in the quality of the results .. The most important modern application of the general theory of relativity is the construction on its basis of cosmology, often called the science of the world as a whole. We prefer to call it the science of the Metagalaxy. Most of the text is devoted to the problems of cosmology and related problems of cosmogony, t. e. Theory of the Formation of Celestial Bodies .