Why can't treat the Universe as another society? The universe pursues largest negative action, by replacing negative action with the corresponding pursued quantity, the Universe can be explained as a system pursuing happiness, profit or knowledge. So sciences about largest negative action pursuit, largest happiness pursuit, largest profit pursuit and largest knowledge pursuit can be unified into one: Science of Pursuit. Result of pursuit is system expansion, just like universe expansion, economic development and knowledge progress. If all possible systems can exist, the system expanding the fastest will be the largest after enough long time, and is called the Universe. From "Truth Evolutionism", freedom creates the world. Fermi-Dirac distribution and Einstein-Bose distribution means different ownership. In fact, private ownership means any two pursuers cannot occupy the same state. All possible states that cannot be occupied simultaneously can be expanded as the superposition of anti-symmetrical wave functions. On the other hand, all public owned states can be expanded as the superposition of symmetrical wave functions.