For consideration, A space opera setting I'm smart enough to conceive of, but not smart enough to write. A sci-fi story that accepts responsibility for breaking physics and leans into the consequences.
Reactonless drives exist. They are explicitly weapons.
Reactonless drives exist. They are explicitly weapons.
Like Atomic power or ironclad warships before them, having a gravity drive makes you a superpower capable of dictating terms to anybody who lacks them.
This is not a world where scruffy nerf herders complete the kessel run in any amount of parsecs. It's a world of great power diplomacy and mutually averted destruction.
Civilian space traffic uses torch drives, which are relegated to the status of mostly harmless by gravity drive equipped warships that can fly circles around them.
FTL either does not exist, or requires fixed wormholes arranged in a way that does not permit causality violations... or so most people believe.
If it were possible to travel faster than light freely, it would be possible to violate causality. Such a vessel would not only make gravity drive equipped warships obsolete, it could change history making conventional politics itself obsolete.
This is why I'm not smart enough to write this story. It would be about a ghost ship from the future altering history in such a way as to ensure it's eventual creation and protect the interests of a polity that does not yet exist.
The people of the past might speculate about the existence of the dreadnought (SOMETHING has to be sabotaging their attempts to build one of their own) but it always exists just offshore of observed causality.
