Antimatter is not only the imagining of the writers of the Star Trek science fiction series. It is a real physical phenomenon and is manufactured right here on Earth, and observed in space. The main antimatter production centers on Earth: Fermilab in Batavia, Illinois; CERN in Switzerland. Producing antimatter uses vast amounts of energy, far more than it can release in matter-antimatter annihilation reactions, so antimatter is not an energy source, but rather, a means to store energy. This process is so inefficient that antimatter will likely only be economical for uses which demand incredibly high energy density per unit mass, such as space propulsion.