Willy Vereb said
How's that any less believable than any other technology you see in Sci-Fi?But yes, administration and bureaucracy are both considerable issues in the Empire. It's another thing which makes them "slow" in general.As for the numbers that's just what you get if you populate every single habitable planet in a territory as large as the Empire.There are 60 billion habitable planets in the Milky Way and the Empire owns 1/6th of them.At average each planet has the population of circa 2.5 billion people. Then you have the people living in colonies and artificial environments to make up the full number of 27 quintillion.Yes, they're pretty overpopulated and this is the main driving force behind the Empire's attempts to expand.As for how did humanity grew from billions to quintillions of people under about 5000 years... there's a dark secret behind it.
It's not a question of technology, it's a question of communication and coordination. Mankind, on Earth, is barely able to effectively govern itself. To send a request from one of the trillion colonies to some manner of regional authority would be like playing the grandest game of telephone in the history of universe. The fact that sixty billion worlds all consistently fly the same flag is a miracle in itself, let alone the fact that the Imperium isn't, to put it bluntly, in perpetual war with itself in order to maintain itself. The fact that they all use the same warships, armor, and weaponry despite being limited to cheekily named Warhammer 40k STCs would imply that they have a logistics system beyond even the scope of high sci-fi AI.
Now, I already punched the numbers into a calculator. I'm not concerned with how we reached said numbers, despite my opinion that they're simply ludicrous, but that said numbers are simply unsustainable from a sociopolitical standpoint. That's sixty billion worlds that a central authority has to keep track of. Sixty billion worlds and twenty seven quintillion people, all somehow not neglected or interested in divorcing themselves from a monolithic, supposedly backwards superstate.