What do space empires fight over?

[Janx]

I'd had a though awhile ago, and saw a variant of it expressed in book 3 of the Expanse series.

Distance is measured in Time. As in how long did it take to cross the Atlantic, or get to Santa Fe, or send troops to Mars.

An empire is constrained by time. The speed of which they hear of trouble and the speed at which they can send troops.

If you can teleport an army of ships anywhere, like Riker's fleet at the ending of Season 1's Picard, then I reckon your empire can be pretty big. Put in some travel times and communication lag, and edges start forming on the map where disputes can happen.

 

[Horwath]

There can only be one reason.

Resources. The end.

Yes, you could name philosophies or religion or some racial supremacy BS. But that is just a tool to get people not in power to die for people in power, so people in power can get more wealthy.

Oldest story in the book. Every war was because of control of territory, that is control of resources.

If every planet(or coalition of planets) has abundance of resources, there is no need to spend your current resources on acquiring something you already have or can get it by simple honest trade.

No to mention that you will not get anyone enlisted, if all are well situated and have no real need for more resources. outside maybe few linatics and adrenaline junkies.

 

[Marandahir]

Specialty elements/compounds that are extremely rare and very hard/expensive to manufacture.

Bringing peace and order and justice to remote, crime-ridden worlds.

When the aliens attack randomly, and then the alliance strikes back, and then a thousand year war enacts that nobody quite remembers how it began.

 

[tomBitonti]

A different take on the Babylon 5 theme:

The Aleph Continuity had long retired to the great empty voids between galaxies. Their thoughts slowly cooled towards absolute zero in the billion light-year vastness.

Except, two refused to pass into quiescence: Brothers Harachim and Haranesh. Chim and Nesh to their followers. The one-time master architects of the Continuity, who had crafted structures that had spanned galaxies, in the aons distant glorious youth of the Continuity.

The brothers were unabashed and unrelenting. Spurned as gauche, they attempted to relive their early glories, meddling with young civilizations, driving these to ever and ever grander projects.

Inevitably, the brothers diverged. Conflict emerged -- driven by the vain aspirations of two who should have long ago joined others in the empty vastness. A galaxy could bear the face of only one of the brothers.

Be safe, be well,
Tom Bitonti

 

[Olgar Shiverstone]

The usual: Fear, Honor, Interest.

 

[fearsomepirate]

This is a world building question. What’s the conflict?

So if you have a galaxy full of space empires. Say a dozen at least, each covering a big swathe of the galaxy. And you assume that:

1) space/habitable places isn’t an issue. Space is big and they’re not short of land.
2) a single resource like Dune’s spice or Discovery’s dilithium is a well-mined trope you want to avoid.
3) you want to steer clear of “species” othering: assume they’re all human and have similar motives.

How do you create constant conflict between these space empires? If indeed you can after ruling out the above?

Give them radically different systems...any time this happens, some of the vassals of one will figure they'll have a better deal under the other, and vice versa. Helots didn't like living under Spartan rule. Athenian oligarchs didn't like democracy. Ionian Greeks didn't like the gold duties the Persians imposed on them.