(This article(s) is translated into English by Richard L. Amoroso)

The thesis contains a comprehensive overview of various works of the author and his studies on 5D (projective) relativity theory and its application for the clarification of cosmology and star formation processes developed by Vefasser’s earlier theory. The first part provides an explanation of the projective theory of relativity (which can be read independently of other work) in the expanded form developed by the author in 1944; the invariant J = X^mu X_mu, viewed as a constant in the older version of the theory, is treated as a scalar field. Even though in my first investigations this expansion of the theory seemed to lead to a considerable complication of the formula apparatus, a very simple implementation of the mathematical theory is now possible. The second part deals with the physical interpretation of the mathematical relationships thus obtained, with the establishment of the field equations – the variability of the size of J makes it possible to give corresponding mathematical precision for Dirac's idea of a gravitational constant that changes with cosmological time – and with the application to cosmology and star formation, according to the results of Ludwig and Müller, who provided the systematic execution of my model of the cosmos and star formation developed from Dirac’s principle. Finally, relationships between the theory presented and the facts.