Abstract

The Special Theory of Relativity represents a fundamental symmetry of physics, and is based on two fundamental principles, namely the Special Principle of Relativity and the Principle of the Constancy of the Speed of Light . It has been a common tendency, both among physicists and philosophers of physics, to regard these two principles as two separate independent indemonstrable assumptions at the foundations of the STR. My original goal was to derive the two fundamental principles of the STR, and especially the Light Principle, from a more fundamental starting point, and possibly to reduce the two principles to one, yet more general, principle. In the process, but at the same time and as an independent project, the necessity of a new method and formalism became evident. This method is an alternative way of studying symmetries in physics , other than the usual way in terms of symmetry transformations, and may be called the method of Discriminations and Discrimination Factors . After a careful study of the two fundamental principles of the STR and other related issues, the DDF method is developed, independently from the theory of relativity. Subsequently the method is used in order to unify the two fundamental principles of the STR into one more general principle. Actually, the more general principle follows from the DDF method, and particularly from a certain fundamental principle of the DDF method, when it is applied for the case of the STR. Then, the two fundamental principles of the STR are derived from the more general principle ; these derivations can also stand as independent derivations of the two fundamental principles of the STR, as they can also be considered directly in terms of the same fundamental principle of the DDF method mentioned above. Finally, it is shown that the more general principle is in fact more general than even the conjunction of the two principles, as other useful statements can be derived from it