Multiverse Science Fiction

“Jewelled, the multiverse spread around him, awash with life, rich with pulsating energy,” (Moorcock). Indeed, Multiverse Science Fiction is a rich playground for writers and is literally full of infinite possibilities.

So, what is a multiverse? The definition is tweaked by each writer, but generally speaking it a multiplicity of universes branching out from every moment in time, of which our universe is only one. This means that in addition to a multiplicity of universes there is also a multiplicity of selves—each of us would exist in each of the other universes, though we may be a bit different in each one. Prompts some identity questions, doesn't it?

The plot of a story within this sub-genre must inevitable come to transportation. A character in the story must find a way to interact with another universe. Characters may be able to control which universe they go to, or not. As characters explore other universes they may find only slight differences among the universes, or drastic differences like the very nature of the physical world. Travel devices are common—think the show Sliders, which has a handheld device that opens worm holes—but gates are even more common.

Other Features of Multiverse Science Fiction

Level of Real Science
Low-Moderate. Physics has an interest in the idea of the multiverse, so science can be a real and integral part to a Multiverse story. Given our limited understanding and perception the science has to go beyond our current scientific understanding—but that's exactly what sci fi is supposed to do.
Level of Grand Ideas/Social Implications
>High. The possibility of infinite universes and infinite selves leads to many many questions. The biggest question Multiverse Sci Fi has to tackle is that of our origin. The big bang theory is now just an event that helped our universe branch off from the greater multiverse—a multiverse to which we are still connected. The idea shakes the foundations of many worldviews.
Level of Characterization
Variable. In Multiverse Sci Fi writers can take a traditional approach to character development, in which case all types of characters are possible. Or, writers can take a more postmodern approach to characterization—by presenting a more fragmented character, who has selves in multiple universes, each a little different than the next. This creates complex characterization and questions the very nature of identity.
Level of Plot Complexity
High. When dealing with the possibility of infinite universes and infinite selves plots tend to get complicated. There will plenty of intertwining of story/character/themes and plenty of movement in a Multiverse story.
Level of Violence
Variable. Multiverse Sci Fi has many variables and possibilities and the nature and level of any violence is part of these variables. Some stories involve detailed accounts of war and other stories are more spiritual and transcendent.

Related Science Fiction subgenres

Alternate and Parallel Worlds Science Fiction. Multiverse describes a “universe” that is made up of multiple alternate and/or parallel worlds that intersect. Multiverse is dependent on these two sub-genres, though it is distinct from them.
Time Travel Science Fiction. Time travel, especially the time travel paradox, assumes there is a multiverse—even if the story doesn't say so explicitly. The multiverse theory means that if you travel to the past and change something, the paradox is avoided by creating a new universe that branches off from yours.

Popular Multiverse Science Fiction Books

1 The Eternal Champion series

By Michael Moorcock. You can't talk about multiverses and not mention Moorcock. This is a sprawling series that has heroes jumping all over the universes and time itself. While many of the novels are more fantasy, there are a few that have some sci fi elements.
2 In War Times

By Kathleen Goonan. Part historical fiction and part sci fi tale with a bit of multiverse thrown in—though the characters don't quite understand that they are experiencing the multiverse.
3 Brasyl

By Ian McDonald. There are three different story lines and sets of characters that will eventually converge in interesting ways. Spoiler, the multiverse comes into play in a big way with an Amazon frog.
4 The man in the High Castle

By Philip K. Dick. A central theme in Dick's work is that there is no single base reality, but rather a multiplicity of realities that are all equally real. The novel is about a world where the Nazis and Japanese won WWII and the alternate reality where they didn't.
5 Keeping It Real

By Justina Robson. The first book in the Quantum Gravity series, begins after a quantum bomb tears about the fabric that keeps different universes/dimensions apart. A scientific premise with quite a bit of fantasy elements included.
6 Cascade Point

By Timothy Zahn. This series of stories feature a faster than light drive with an interesting side effect—when activated you see alternate versions of yourself. Travel to these alternate universes is not easy, but you can peer into them.
7 The Coming of the Quantum Cats

By Frederik Pohl A fun take on the multiverse theme—a great scientist invents a machine to travel between universes, only to have it stolen by another version of herself who wishes to use it to become a multiversal conqueror.
8 His Dark Materials

By Philip Pullman. Characters travel to many alternate universes in this young adult series with the use of a few powerful items.
9 The Number of the Beast

By Robert A. Heinlein. This book manages to unite the timeline of every story Heinlein ever wrote. It follows four geniuses who embark on a crazy romp through the multiverse and discover that every fictional universe ever imagined is real.
10 Alternities

By Michael P. Kube-McDowell. The gate house is a guarded secret because of its militaristic potential. But for one member of the Guard, the gates are a chance to start his life over.
11 Amber series

By Roger Zelazny. Science Fantasy about the multiverse and the one world that spawns them all. A classic and highly recommended for any science fiction or fantasy fan.
12 The Dark Tower

By Stephen King. The multiverse, parrellel universes, and a gun slinger that can save the multiverse. What more can you ask for? The Dark Tower is the single body of work that ties together every book ever created by King. Read it.