system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune] Is the "Known Universe" really the entire known universe? Or is it just the Milky Way and its satellite galaxies?

We know that Shaddam IV, Paul Atreides, and Leto II Atreides were Emperors of the Known Universe, and that Arrakis is the center of it. However, is it really the entirety of the known universe? Or is it just our home galaxy plus its satellite galaxies? Is there an explanation on how big the Known Universe actually is?
gpt
By "known", Imperial types usually mean "actually surveyed and catalogued by one of the Proper People(tm)"

IOW, they automatically exclude whatever they don't already own as being "unimportant enough to count".

So, it's not even the whole galaxy. It's a few hundred lightyears around Earth, maybe a few thousand. It doesn't even include all of the space that humanity spread out to during The Scattering following the reign of Leto II.