The Universal Empire Profile

One thought that has been meandering around my head for a couple of decades now is using the Traveller Universal World Profile to describe interstellar states.

By definition, such a state would have starport class A. The size, atmosphere and hydrographics codes don’t really work, although given that most Traveller states focus on controlling the communications routes between worlds rather than the worlds themselves, you could set them to 000. It’s the last half of the UWP that intrigues me the most.


On average, a group of 36 worlds will have one Population 10 world, two Population 9, three Population 8 and so on, which will give it a total population of 12,345,654,321. That’s using the standard Traveller rule of 2d6-2 for Population; the Mongoose space opera and hard science options are interesting, but too much work to figure out, as Population then depends on a lot of other factors.

The Imperium is said to have 11,000 worlds; that’s enough for any local fluctuations to cancel each other out, giving it a total population of 3,772,283,264,750.

Or in UWP terms, Population 12. The other major states in the Traveller universe are smaller, but not by a factor of ten, so we can use that as a rough guide to the population of any star nation.

(As an aside, the average population across that group of 36 worlds would be 342,934,842. Notice that the couple of really big population worlds skew the average a lot; the most common population is 100,000, on one world in six.)


This is 2d6-7 + Population. With Population 12, your interstellar empire has a Government type ranging from 7 (if you rolled a 2) to 17 (if you rolled a 12), with the most likely outcome being 12. In the canonical Traveller universe, we have:

  • Government Type 7 (balkanised): Aslan Hierate, Vargr Extents.
  • Government Type C (charismatic oligarchy): The Third Imperium, the Zhodani Consulate. You could make a case for the Imperium being Government Type B, but the Emperor’s personal influence on the Marches is minimal – for example, the entire Fourth Frontier War happened before he had time to respond – so I think actual power lies with the nobility and the Navy.
  • Government Type D (religious dictatorship): The Two Thousand Worlds, the Solomani Confederation. I put these at D because their loyalty is more to abstract ideals than to a group of sophonts.

With only six data points, that spread could happen by chance; but maybe there is an extra dice roll modifier I haven’t taken into account.


2d6-7 + Government. Range: 2 to 17, most likely is 12. However, anything over 9 is much the same. This is the rating that makes least sense, since it suggests any interstellar empire aims for rigid totalitarian control of its citizens. I rationalise this by analogy with the Imperial Rules of War; if you disturb the Imperium, it comes down on you like a ton of bricks, but as long as you don’t wake the sleeping giant by messing with its sovereignty or economy, it’ll leave you alone – not because it wants to, but because even a stellar empire doesn’t have enough money and troops to keep an eye on everyone, all the time.

The difficulty for the freebooting adventurer is that the rules are not codified; the Imperium makes them up as it goes along, so you’re never quite sure what will draw its attention. However, as the high tax revenue, high tech level, high troop levy worlds are those with Population 9 and 10, any star empire would focus its legal muscle on those – and we find that they have generally high law levels.


There are too many variables for an analysis as simplistic as this, but somewhere in your 11,000 worlds is a Population 10 world with Size 0 and a Class A starport (probably just the one), and that has a Tech Level of 1d6+13. So the best tech level in your empire is probably in the range 14-19, and in Traveller’s Charted Space we find that the racial capital worlds typically have TL 14-15.


You can represent an interstellar empire by a UWP code something like A000CCC-E, if you’re prepared to stretch the rules a bit. If, like myself, you are wont to run random adventures without necessarily generating a bunch of worlds, you can use that as shorthand for the empire as a whole.

This exercise also reminds me how powerful and flexible the Traveller world generation and coding rules are. They have not changed significantly since 1977, unlike pretty much every other aspect of Traveller. Marc Miller definitely got it right there.


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