Wormhole Gateways

Wormhole gateways are the primary method of interstellar travel utilised by humanity. They are large space stations powered by antimatter reactors that function by linking two points in space with a stable wormhole, allowing for near-instantaneous travel between distant locations. For reasons that are not fully understood, owing to their Cetian origins, gateway stations must be positioned at least 4 astronomical units away from objects (almost exclusively stars) of a certain mass threshold in order to function correctly. The required distance does not scale based on the mass of the object. Intra-system gateways have been experimented with by humanity, but thus far have proven elusive.
Gateways require extremely high amounts of energy to open, and considerable amounts to maintain. Thus they rely on expensive antimatter power generation. The high upkeep cost was one of the contributing factors to the Antimatter Crisis, and the crisis primarily affected wormhole gateways, causing severe disruptions in interstellar travel. Gateway maintenance is still very inconsistent in the Outer Systems, with most Star States struggling to maintain the old Earth-built gateway stations. Even where such stations are maintained, they frequently undergo planned outages to conserve precious antimatter, making interstellar travel more difficult in the region than in other areas of human space. Those regions of settled space that lack operable wormholes are largely disconnected from the rest of human space, and are known as the Lost Systems.