Antimatter
From Starbase 900 Wiki
Matter whose electrical charge properties are the opposite of "normal" matter. For example: a proton has a positive charge but an antiproton has a negative charge. When a particle of antimatter is brought into contact with an equivalent particle of normal matter, both particles are annihilated, and all their mass is released as energy. The controlled annihilation of matter and antimatter is used as the power source for the warp drive systems used aboard Federation starships. Because of the highly volatile nature of antimatter, it has to be stored in special magnetic containment vessels, also known as antimatter pods, to prevent antimatter from physically touching the storage vessel or any other part of the ship.