The theory of relativity is an important pillar supporting modern physics along with quantum theory, but the open questions present in this theory require revolutionizing the perspective on relativity and mathematical foundations of relativity. We present a generalized theory of relativity, which becomes a consequence of a unified mechanics based on the universal quantum postulated as a primitive elementary particle constituting physical vacuum and matter. Our theory does not require the fun-damental postulates of the theory of relativity, such as the principle of relativity, the principle of the constancy of the speed of light, and the principle of equivalence, and needs only the universal quantum to formulate a new theory of relativity, but explains relativistic effects successfully. Our work shows that the idea for the unified space-time which gives the Lorentz transformation is not mathematically and physically justified. We first analyze from a new angle the concepts, principles and results of the special theory of relativity and prove that it is impossible to construct a theory of relativity using geometry in the Minkowski space. We introduce the concept of the universal quantum concretizing the concept of the ether and construct a consistent theory of relativity based on the concept of the density of universal quanta and of effective time of interaction, without recourse of Einstein’s relativity theory. We construct new relativistic dynamics and electrodynamics based on the effective time of interaction. We formulate a new theory of gravity able to explain relativistic effects, based on the concept of the universal quantum without using the concept of space-time. Thus, our work achieves the aim of constructing a consistent theory of relativity by means of a single mechanism based on the concept of the universal quantum in a unified way to include inertial frames and noninertial frames altogether.