In this book I have tried to present in a semi-popular version, the most important points of the great unity of modern science, that combines mathematics and physics into a majestic whole, that of the geometry of curvature and the theory of gravitation. Mathematics here appear as an instrument of discovery, it is this application of mathematics to the solution of physical objects which constitutes the essential characteristic of theoretical physics. Here we intend a general brief introduction to the course of general relativity, where Einstein redefines the gravity in terms of a new concept of "curvature" of space-time, from Riemannian spaces to the gravitational waves. Also I give the main models of the Universe, in the context of the general theory of relativity.