World government

notion of a single common political authority for all of humanity

A world government, global government or world state is a concept of replacing nation states with a single country spanning the whole Earth (or some other planet). The trope can be found in science fiction, the New World Order conspiracy theory, Marxist thought, etc. No global government is currently in known to be in the planning stages, the closest things to a world government were empires and are political unions like the European Union and African Union, as well as intergovernmental cooperation organizations like the United Nations.