Universe-Mixing Disease

To put it another way, universe-mixing disease is the idea of writing a new story that takes what were originally separate universes and tries, retroactively, to make them into parts of the same whole. I say “tries” advisedly: more often than not, I'll choose to detach the new story and leave the original universes uncontaminated.

It is, of course, purely a matter of taste as to whether universe mixing is harmful. I don't like it, obviously, and in fact the point about detachment gets right to the heart of what I don't like, which is that in most cases universe-mixing strikes me as a particularly egregious form of bundling.

That's not to say that the bundling is necessarily intentional. For television shows and comic books, I'm sure it is, and I'm sure the marketing folks are well pleased with the results. For books, though, I'm willing to give the benefit of the doubt. Maybe once you've written a couple of books, and seen someone else mix universes, you naturally begin to wonder how your own universes might fit together. But what would I know?

So, anyway, whether transmitted by word of mouth among marketers or by imitation among authors, I do think the idea of universe mixing is contagious. (I think what I'm trying to say here is that it's a bit strident. If I'm trying to help create a science of memetics, I really should be more precise about these things.)

Finally, since the above is all a bit abstract, let me balance it against some nice concrete examples.

First, consider Asimov. His Foundation trilogy is one of my all-time favorites, a classic of science fiction, taking place in the distant future, on the scale of galaxies and millenia. He also wrote, among many other things, a series of detective stories taking place in the relatively near future, which I believe used the science-fictional setting mainly for atmosphere—I admit to not having read them recently, if at all. Then, decades later, he came up with a new story, in which the robotic protagonist of the detective stories, having survived for however many hundreds of thousands of years, shows up in the Foundation era … and gives Hari Seldon the key to psychohistory.

Second, consider Heinlein. Although his universe (in The Past Through Tomorrow, mostly) started out as a bunch of independent stories, it wasn't much of a stretch to put them together, and then the later stories fit right in to produce a nice whole. Later, though, Heinlein came up with another story, The Number of the Beast, in which the characters discover a way to travel not only through space and time but also into (other) fictional universes, starting with Barsoom and ending with who knows what. Along the way, if I remember correctly, they pick up people from various places and times in other Heinlein universes.