Antimatter

Antimatter, material composed of antiparticles, which are identical in mass and behavior to electrons, protons, and neutrons but have opposite electrical charges.

Matter and antimatter are both annihilated when they collide, and other particles, such as photons (quanta of energy) are released. Antimatter is rare and short-lived in our part of the universe, where matter predominates. The first antiparticle, the positron (antielectron), was discovered by Carl D. Anderson in 1932. In 1997 three scientists received the Nobel prize for developing a method to cool off antimatter using a laserbeam, in order to make particles more managable and to prevent annihilation.

See also: Antigravity.