Antimatter Power

Antimatter power is the most efficient method of energy generation currently known to humanity. It is primarily used to power the gateway stations that maintain wormholes between star systems in human space. However, it is also used aboard large space-superiority capital ships, which would struggle to be powered by the much less efficient fusion alternatives.
Antimatter production and power generation (and antimatter in general) is strictly regulated by most human states, including the United Leagues of Earth. Notably, only recognised governments can use antimatter in space, while it is entirely prohibited on habitable worlds. Few states are permitted by the ULE to produce antimatter of their own, with the Federal Republic of Zeta Tucanae being the only such polity in the Outer Systems. Violation of antimatter restrictions is widely considered one of the few actions that could cause the ULE to use military force against another state, though it has never more than threatened to do so.