The idea of a galactic empire, one well-explored by science fiction writers, is that our Galaxy is effectively governed by one or more ancient, highly advanced civilizations. That a galactic empire might exist has also been the subject of serious scientific speculation, despite the fact that we have so far not encountered any signs of a major alien presence among the stars. In fact, there are several valid reasons why we might not be aware of a technologically superior race in our midst (see extraterrestrial intelligence, more advanced than us). There is the possibility, too, that if a Galaxy-wide empire does not exist now, it may do so in the future if mankind is able to establish efficient, faster-than-light modes of interstellar communication and transport.