Antimatter is an exotic material made from particles that are the reverse of, or complement to, the particles of normal matter. When matter and antimatter meet, they annihilate each other, releasing tremendous amounts of energy. (TOS: "Obsession")
- In VOY: "Flesh and Blood" they create antiphotons, which do not make sense in real-world particle physics, because photons are their own antiparticle. So "antimatter", or at least "antiphotons", may be defined in terms of particle properties not yet discovered.
- The date is given as 2152 in the Starfleet Museum. The Enterprise (NX-01) is launched in 2151 in the Enterprise series.
- James Kirk claims that a pound of antimatter is sufficient to destroy the system—whereas the Sun happily annihilates 4 million tonnes of matter per second without any problems. Kirk's statement either is wild exaggeration, or indicates that 23rd-century antimatter is far more potent than the real-world equivalent.
Photon torpedoes use magnetically contained matter and antimatter in their warheads.