Antimatter Jet Propulsion
Antimatter jet propulsion is a high-tier method of propulsion for interstellar spacecraft in human society which uses the energy emitted from the annihilation of hydrogen and antihydrogen in order to produce a particle jet that propels the spacecraft to around 90% light speed. It was developed as a massive joint engineering effort between CORE Heavy Industries, Voima Tech Industries, Metatron, as well as the European Space Agency (ESA), the Central Martian Space Agency (CMSA), and the Interdimensional Research Treaty Organisation (IRTO). The technology became humanity's gateway to interstellar travel, enabling the first interstellar flights.
When the propulsion system is active, any area of the ship exposed to the particle beam becomes an instant death zone, restricting the passage of crew members until the burn ends. When acceleration is complete, the ship then coasts for the majority of its journey until it is required to decelerate. Once the destination approaches, the entire ship is flipped 180 degrees and the thrusters are then fired a second time to decelerate. The acceleration and deceleration burns combined are calculated to use exactly one hundred percent of the antimatter in the containment vessels.
Fuel
Besides the advances in material science required, antimatter propulsion requires a large amount of antimatter, and in turn, insane amounts of power. The only facilities in the Solar System capable of producing such amounts of power are singularity reactors. Originally the production of antimatter would also be performed in planet-side facilities adjacent to reactors connected by superconducting links, but the catastrophic consequences of a containment failure forced regulations to be passed that banned planet-side mass antimatter production facilities and forced them to be relocated to orbit.
The sheer amount of power required dwarfs all other energy consumers, making antimatter fuel one of humanity's most expensive commodities. Operating one's own singularity reactor is effectively the "holy grail" for any organisation undertaking interstellar travel operations, but the infrastructure and regulatory costs to do so are staggering. Some of the newest capital ships even feature their own singularity reactors, making them partially self-sustaining.