Antarctica is the only continent on Earth without a sovereign government or a native human population. While several countries, including Argentina, Australia, Chile, France, New Zealand, Norway, and the United Kingdom, have made territorial claims, these are not universally recognized. The continent is governed by the Antarctic Treaty System, which was signed in 1959. This unique international agreement sets aside the continent as a scientific preserve, establishes freedom of scientific investigation, and bans military activity on the continent. This makes Antarctica the only place on the planet that belongs to no one and everyone at the same time. There are no cities, no permanent residents, and no time zones, though researchers follow the time of their home countries or supply hubs.