So it's widely known that our universe contains hundreds of millions/billions of galaxies. However all of 40k seems to only deal with the Milky Way galaxy. The only other mention(that I know of) is that the Tyranids are thought to be from another galaxy invading ours. So my question is, does the Warp/Immaterium only apply to a Galaxy or the Universe? Is there an Immaterium for each galaxy along with possible Gods? If the Immaterium IS for the whole Universe surely the Chaos Gods would be mentioning other galaxies, races, wars etc along with who knows how many other Gods existing from collective psychic gestalts or beliefs etc., have they? Are they actually influencing races across the Universe? Even the Imperium, who I can only imagine know the depths the Universe goes to(I mean we do now in our time to an extent, we know its HUGE and galaxies exist), seem to be completely uninterested in exploring beyond our boundaries. What gives?