In particle physics and quantum chemistry, antimatter is the extension of the concept of the antiparticle to matter, whereby antimatter is composed of antiparticles in the same way that normal matter is composed of particles. For example an antielectron (a positron, an electron with a positive charge) and an antiproton (a proton with a negative charge) could form an antihydrogen atom in the same way that an electron and a proton form a normal matter hydrogen atom. When antimatter and matter come into contact they annihilate each other with almost 100% efficiency, with explosive force. Huge amounts of gamma rays are produced, threatening nearly instantaneous death for any organic beings close by. Physicist Richard Feynman described the reaction of matter and antimatter as mirror images whose physical processes proceed in opposite directions through time--associating those inverse processes (theoretically) results in a sudden release of the total energy contained in both processes. Antimatter is the most dense fuel conceivable by physics in the Confederation. While voidhawks' and blackhawks' distortion field do not expend fuel (as they draw energy directly from the vacuum of space), the density of the energy source they draw upon pales in comparison to a store of antimatter.
Due to the fact antimatter and matter cannot touch, no physical barrier can be used to store antimatter, a strong magnetic field must be used. The Lady MacBeth is unique (at least among ships in the Confederation Navy's good graces) in that it is equipped with the components necessary to contain and utilize antimatter.
Antimatter was used in anti-matter bombs and combat wasps. The destructive power of antimatter (as demonstrated against the planet Garissa) was the impetus that led to the formation of the Confederation. One of the Confederation Navy's primary duties prior to the possession crisis was policing the ban on the use, production, sale and transportation of antimatter. Criminal syndicates have formed with the singular purpose of producing antimatter in remote stations hidden out of the view of the Confederation Navy. One such antimatter station is used by Capone's Organization to give his fleet an edge against the Confederation Navy.
A more benign use of antimatter is as a starship fuel. Adamist starships rely on reaction drives, which burn fuel to expel propellant, imparting acceleration on a ship. Delta-v is the total acceleration output available to a given spaceframe/engine/fuel system and a starship's delta-v is essentially its maximum range. Antimatter provides orders of magnitude greater delta-v than equal amounts of deuterium and helium fuel, massively increasing the specific impulse (maximum acceleration) of a starship and its maximum trip duration and range.