Present-day physics is based on two fundamental theories: General relativity including gravity describes spacetime. Quantum physics describes minimal portions occurring in nature. However, we live in one world. Now, we unify these theories! For it, we start with four basic physical principles, each founded by observation and by thought experiment, independently. These principles essentially are special relativity, the equivalence principle, Gaussian gravity and the fact that vacuum is a physical reality, the dynamics of which can be derived from the other three principles. Using these principles, we derive the postulates of quantum physics, and, in a semiclassical limit, we derive general relativity. Using our unification, we provide a solution of the EPR - paradox: In general relativity, the velocity of light is the highest velocity. In contrast, correlations among so-called entangled quanta can spread faster than light. Now, our unification implies that correlations among entangled quanta can spread faster than light. Moreover, our unification implies a list of solutions of fundamental problems. For instance, our unification implies dark energy, the density of the vacuum observed in cosmology. Furthermore, we provide several tests of our unification. Our results are in precise accordance with observation, whereby we do not apply any fit, of course. On the basis of the four basic physical principles, we derive our results explicitly. This is essential scientifically. Additionally, every interested reader can derive all results on her or his own. Thus, readers are enabled to check the unification on their own. Thereby, you can achieve a high level of founded independent thinking and deciding. In this manner, you can gain many insights about nature, and you can develop your self-esteem.