Namely the really far end of the scale. This is called on the Alternate History Internet communities the Alien Space Bat (read Sufficiently Advanced Alien) continuum. This one is a very simple point of divergence: suppose that in the present we discover the existence, proven, of the many-worlds theory of quantum mechanics in one of the more flamboyant/sci-fi esque possibilities where a portal opens and people step out of another universe. Following this initial contact, we discover that there are truly infinite universes where everything that has ever been or ever will be can exist and does exist. Suppose also that in this process we discover non-human intelligences that are bizarrely alien to us (and we to them) and that this goes for them, too.
Now, as the quantum theory is infinite, we would discover that a staggering number of universes contain no life at all, and we would discover all the myriad ways that a general nuclear exchange or earlier detonation of the Yellowstone supervolcano could happen and reduce civilization as we know it. We would also discover equivalent universes to both our fiction and to that of the aliens of other dimensions. We would of course also discover a tremendous number of timelines where the religions, ideologies, and cultural systems we take for granted do not exist and are never likely to exist in the immediate, the medium, or the far future. What would be the cultural impact of this discovery?
Personally I think a great many science fiction fans would be ecstatic at first until they realize that in a truly infinite universe, things like the Domination of Draka (perhaps the most dystopian of all science fiction series, making 1984 look like Paradise), Galactus, and all the mythological Gods, Demons, and Eldritch Abominations of fiction *also* exist. I think religious fundamentalists would herald these dimensions as demonic illusions and advocate exorcist experiments to destroy them. Which of course would not work. I think also that it would force a fundamental revision and broadening of our understanding of reality, especially if people started using technology from the more bizarre universes to accelerate the technology of our own artificially, presuming such a concept would work. I also think that this kind of contact would lead to new ideologies, including new versions of nihilism that would hold that since everything happens somewhere, and that since parallels of individuals in this world also exist in great quantities that whatever they do does not matter, as there are parallels of themselves who would be far superior to them as individuals.
What say you?