Here's the drill. Reactionless drives, faster than light travel, those good things that make your Empire possible, requires exotic matter. As we have yet to find a way to find exotic matter let alone collect it, you need NBEs (Non-Biological Entities -ghosts or spirits in laymen's terms) who show much of the same properties of dark and negative matter.
I have already pointed out the downsides. NBEs often do not like pushing our ships around and sometime get loose and wreak vengeance. Some NBEs are just what you call evil and seek to harm all life. But there's more.
FTL takes you into Ghost Space. At the very least Ghost Space is a second home to the NBEs and maybe other things. But you need it to travel between stars in weeks or months and not centuries. A ship engaging its ftl gets its NBEs to open a wormhole which requires repulsion force. You could try to get the effect with electromagnetic forces, providing you could convert say, Jupiter, to energy. NBEs are way easier than strip mining a gas giant. Not to mention the Solar System would only be good for one or two jumps.
Ghost Space is usually called Overspace. Ghost drives are referred to as overdrives by techies who don't want to sound poetic. Overdrives are capable of different speeds. At the lowest speeds the ships is merely taking a splash in Overspace. At higher levels you're getting your feet wet and take care you don't get in over your head. When a ship goes too deep in Overspace and/or stays too long NBE's start to notice it. Then they tell their friends and family or whatever they have and then they start to party.
Most crews do not wish to attend such a party. Bad things happen. Whole crews get possessed or terrorized into acts of madness. Non-psionic crew suffer from visions. The visions are never anything they want to see. Dementia and direct telekinetic attacks follow. Making an entire ship NBE proof is just not possible. It would interfere with the operation of the Ghost Drives among other things.
Most ships have a safe area in case stuff gets surreal. It was named after the old term for radiation shelters in archaic ships: the bio well. If the ship gets noticed the crew nd passengers pile in, seal the hatch and hope nothing hitches a ride. Mostly it works. Some merchants and traders who use capsules ferried by commercial carriers can afford to shield their entire capsule.
Sometimes a crew emerges into a trashed life module. Other times the airlocks are opened or equipment is vandalized. Objects may be missing or broken.
Those are the lucky crew. As I said. Sometimes, something hitches a ride back with you and your psionic starts wishing they took up plumbing instead. That's the point where the merchant with the deluxe capsules release their docking clamps and send a distress cal for pick up. Screw the cargo it's insured. Screw the carrier crew too.
Oddly, mankind feel the Galaxy is worth all this.