The relevance of the perfect cosmological principle to the universal model is enormous. The universe can either be Euclidean and infinitely large and old, or spherical and limited in space and time. Which one is correct, which one is abiding physics laws and explains all observations? Observations show that the universe must be spherical and thus limited in space and time. The consequences are: no “dark energy”, no or little “dark matter”, explanation of cosmic inflation, explanation of fast rotational speed of far stars and star clusters, and an elegant EMRW-model in space-time of the universe.