Antimatter

The opposite of matter.

Bringing the two into conjunction is widely believed to produce a cataclysmic Explosion. Antimatter appears in science fiction Continua, such as Star Trek, Doctor Who etc etc.

If you are a physicist, and this article's brevity and vagueness irritates you, please feel free to correct it. If you are curious on the matter of antimatter and are not a physicist, we suggest you google it.