The Speed of Information
The lightspeed barrier may have been broken, thanks to the Bergenholm field, but the single greatest obstacle to any sort of coordinated, interstellar association is still communications. Without the Bergenholm, the lightspeed barrier remains a solid wall, and despite attempts and creating “Bergenholm tunnels,” no one has yet managed to move radiation faster than the speed of light.
There have been successful experiments with quantum entanglement communicators, but they are expensive, extremely limited—there are only two terminals possible, so communication must happen between two relatively fixed points—and extremely slow. Manipulating the linked particles in such a way to send a clear message is extremely difficult. The only viable method of communication using quantum entanglement is therefore to use relatively simple codes.
This means that for any sort of interstellar communications, courier ships have become an absolute necessity. Depending on the region of the galaxy, these can be dedicated drone ships with established routes between star systems, freighters passing through, carrying mail that might reach its intended recipient hundreds or thousands of hours later, or even one-use, one-way message missiles.
Dedicated drone ships can carry cargo as well as messages, but most have only very simple routes. The drones are only capable of dealing with so many contingencies. There have been many drone ships lost over the centuries. Some have later been found, adrift, far from their targets. Others have been lost permanently.
Freighters can still be lost in the deeps, but are generally considered more reliable over any distances longer than a single star-to-star hop. Actual crewmen can usually cope with emergencies better than AI systems. There are factions in the galaxy who aren’t happy with this, but they tend to be a minority, especially after such events as the Qinglong Wars.
Message missiles are even more limited than drone ships. They consist of little more than a powerplant, a small drive, a Bergenholm, data storage, and a transmitter. A message missile can be programmed to make for a target star system and go inert within a certain distance from the star. Once there, it then transmits the message on a particular frequency, often with encryption. They are largely used by long-range exploration vessels, that cannot count on a freighter or drone ship where they are headed. The obvious weakness lies in the fact that a message is immediately broadcast to anyone listening as soon as the missile goes inert. However, most missiles have little enough delta-v that to attempt any rendezvous would be impossible.
Communications and Interstellar Associations
The inherent slow pace of communication is what has, to date, precluded any sort of strong interstellar empire or government. Certain alliances have managed to form, but they are by necessity loose associations. Direct governance over interstellar distances is impossible.