I first encountered the concept of alternate worlds in prose when I read “The Gostak and the Doshes” (1949) by Miles John Breuer in The Arbor House Treasury of Science Fiction Masterpieces when I was nine or ten. The story is mostly about language and meaning, but it involves travel to a parallel universe by a method I still love: altering perception. The main character walks along a path and watches the trees beside him slide past while the moon hovers stationary above them, then consciously alters his viewpoint so that the moon appears to be sailing along through the stationary treetops. That perceptual shift is enough to shift him to a new world. That idea of other worlds all around us, flickering just beyond our vision, has enchanted me ever since.

Around the same time I read “Sidewise in Time” by Murray Leinster, the 1934 classic about a catastrophe that makes various parts of the Earth swap places with their counterparts in alternate universes; it was so influential they named the Sidewise Award for Alternate History after it, and it certainly made a big impression on me.

After reading those, I started to seek out stories and books about visits to alternate worlds, a habit I’ve kept up ever since. I’m going to tell you about some of my favorites now. This list is going to be idiosyncratic and personal, not definitive—“definitive” would be a PhD thesis worth of work—but it will definitely include a lot of great stuff you should go read. I’m going to limit myself (at least mostly) to works that involve multiple other realities—true multiverse stories, rather than portal fantasies or alternate histories. 

We have to start with Michael Moorcock, who either coined the word “multiverse” or granted the word its common meaning today; the dictionary says the definition is “a hypothetical space or realm of being consisting of a number of universes, of which our own universe is only one.” Moorcock’s Eternal Champion appears in various universes in various forms, including sword-and-sorcery fantasy and weird science fiction milieus, but that multiverse encompasses our own world too, and it includes all of Moorcock’s work. 

The Lovecraft Mythos has a multiversal aspect; some of the locales are other planets, sure, but there are other universes, too, where the geometry is different, not to mention the Dreamlands. I’ll spare you a million examples, but I will note that Elizabeth Bear wrote a wonderful story a few years back about inter-dimensional exploration in Mythos realms called “On Safari in R’lyeh and Carcosa with Gun and Camera” you can read at Tor.com. 

Roger Zelazny’s Chronicles of Amber series is a classic, where the one true World, Amber, casts a countless number of “shadow” worlds; those shadows include our own world, and other alternate realities, which certain powerful people from Amber can visit and even alter. (It gets more complicated as it goes on, but that’s the gist.)

Here’s a deep cut: Joe Haldeman’s poem “DX” (1987) is a harrowing piece about war, with the narrator watching his fellow soldiers senselessly die, and it’s made more powerful with the concluding stanzas, which start with “There are three other universes, like this:” and go on to imagine alternative outcomes. It’s more literary conceit than true multiverse, maybe, but it was a defining text for me when I read it as a fourteen-year-old at my county library. 

Glory Road by Robert A. Heinlein was a book I read as a child that burrowed way deep into my subconscious. Parts of it reallllly don’t hold up well, but as a kid I loved it—it’s a swashbuckling adventure romance across the multiverse! The sexism is a roadblock to re-reading, though. 

Like Moorcock’s oeuvre, Stephen King’s work all shares a single multiverse, too. His Dark Tower series is a giant sprawling epic that ranges through multiple worlds…including the worlds of other Stephen King novels, like The Stand and ‘Salem’s Lot, plus the “real” world where Stephen King wrote those books; King appears as a character in the series, so it’s multiversal and metafictional, incredibly ambitious and really weird. The Dark Tower is not perfect, but it’s almost 1.5 million words stretching over seven main volumes, plus ancillary material, so “perfect” would be a lot to expect; it is great, though. “Go then, there are other worlds than these” is a line burned in my mind for eternity. King has dabbled a lot in the multiverse, and being a big King reader as a kid probably had a lot to do with inculcating my love for such material. “Mrs. Todd’s Shortcut,” about a woman who figures out how to shorten her drives by cutting through other realities, blew my mind as a kid. The Talisman, written by King and the late Peter Straub, is mostly about a kid who goes on a quest through a parallel version of America called the Territories, but there’s a hallucinatory stretch near the end where the kid flickers through a variety of other realities, revealing the vastness of a true multiverse, and it broke my brain open when I was twelve. The much later sequel, Black House, hints at that true vastness, too. I also have a personal fondness for a King novel called From a Buick 8, about small-town cops who discover a car that isn’t really a car, and seems to have a portal to other worlds in its trunk. 

Clive Barker’s done a couple of great alternate-world tales, from Weaveworld (about a world hidden in a rug) to Abarat to The Great and Secret Show, but my favorite is Imajica, a weird sexy epic about a man traveling through five “Dominions”—dazzlingly bizarre alternate worlds—to uncover the truth about his past. 

Caitlín R. Kiernan’s work sometimes involves incursions from adjacent, and often inimical, realities, and her story “Onion” is one of my all-time favorites, about a support group for people who’ve glimpsed other realities, and had their lives profoundly damaged in the process. 

Iain Banks is like unto a god to me because of the Culture books, but his multiverse novel is Transition, about a secret organization that sends agents called “Transitionaries” to various parallel realities to meddle in their societies; there’s some pretty sharp commentary about Imperialism built in. 

Philip Pullman’s His Dark Materials series involves travel across alternate realities, some similar to our world, some wildly different; it gave us sapient polar bears wearing armor, which is all I needed to hear. There’s a TV adaptation that some people like.

Stephen Baxter  and the late Terry Pratchett co-wrote The Long Earth and its sequels, about an invention that lets people travel, one world at a time, through alternate versions of Earth, which are broadly similar to ours…but on which homo sapiens did not evolve. Other hominids did, though, sometimes, and they’re a threat…along with a distant catastrophe destroying outlying worlds. (Pratchett’s Discworld series occasionally hints at branching realities, and has invasions by inter-dimensional creatures at various times, too.)

The Ten Thousand Doors of January by Alix E. Harrow is a fantastic debut novel, about a girl who discovers there are other realities, and they can be accessed, if you can find the right doors. It’s a beautiful book about family and history and getting lost and being found. Harrow’s story “A Witch’s Guide to Escape: A Practical Compendium of Portal Fantasies” is also great, and one of a few short stories about alternate universes to win a Hugo Award. (Lawrence Watt-Evans’s marvelous “Why I Left Harry’s All-Night Hamburgers,” about a diner where visitors from various realities congregate, is one of them, and has good sequels, too. My own story “Impossible Dreams” is another Hugo winner about other worlds, but it’s just about a single alternate universe, so pfft. But: that story and many other multiverse and portal-fantasy shorts can be read in Other Worlds than These, an anthology edited by John Joseph Adams.

Brasyl by Ian McDonald is set in three different timelines, all vividly imagined versions of the nation of Brazil, one in 2006, one in 2032, and one in 1732. But it turns out they aren’t just different times; they’re different realities, and some of them are very strange indeed. McDonald combines speculative scope and fine character work as well as any writer working today.

Lev Grossman’s series, The Magicians Trilogy, beginning with The Magicians, is initially about grad students at a magical school who discover the fantasy world in a series of children’s books (inspired by C.S. Lewis’s Narnia) is a real place, but as things go on, they get wilder and more expansive, and include a liminal space called the Neitherlands that allows access to countless other worlds. (They’re cool books, made into a very different but also cool TV show.)

This Is How You Lose the Time War by Max Gladstone & Amal El-Mohtar, which I liked so much I chose it as a finalist for the Ray Bradbury Prize one year when I was a juror, is a starcrossed-lovers story in the form of letters between two operatives on opposite sides of a war that sprawls across a bizarre multiverse. The novella is having a whole new moment lately thanks to the magic of Twitter, something El-Mohtar wrote about for Slate.

The Space Between Worlds by Micaiah Johnson is set in a world where corporations exploit the multiverse, but you can only travel to an alternate world if you don’t have a counterpart doppelganger alive there—so people from incredibly dangerous or precarious backgrounds are highly sought-after. It’s a great adventure novel with a lot to say about the nature of exploitation. 

Charles Stross’s Merchant Princes series (and the spin-off volumes) are wonderful, chewy, surprising books about people who can travel to adjacent realities, mostly for purposes of smuggling and economic exploitation; they’re multiversal realpolitik, but no less dazzling for being so grounded. 

Paul Melko has done some very cool multiverse stuff, including story “The Walls of the Universe” (later expanded into a novel of the same name, which also has a sequel), about a farm boy who meets a version of himself from another reality and borrows his doppelganger’s device to go on an exploration of his own…but he discovers too late that he got scammed, and he can’t go back, only forward to new worlds, leaving him stranded in the multiverse. Great old-school adventure combined with some thoughtful speculation.

People rightfully love Seanan McGuire’s Wayward Children series, beginning with Every Heart a Doorway, about a boarding school for kids who went through portals to other worlds and returned profoundly changed. It’s a fantastic concept and she creates strange and moving stories with it. 

The Doors of Eden by Adrian Tchaikovsky is a big action-packed doorstop about people who can travel across versions of Earth where life evolved in wildly different ways—we get modern Neanderthals, sure, but also…genius fish with ice computers? Yes!

There are some great stories about people who spawn new realities, too. Ted Chiang’s “Anxiety is the Dizziness of Freedom” is about a device, commonly called the prism, that allows users to connect to an alternate reality and communicate with their counterparts there—but the alternate reality only starts to exist when the device is activated, causing the current timeline to branch and rapidly diverge. Like the best of Chiang’s work, it’s brilliant extrapolation and a moving personal story.

The Peripheral by William Gibson has a similar approach, with a time-travel twist; people in the future can create “stubs” that branch off from the main timeline at various points in history, and communicate with those stubs digitally, creating changes that propagate until the new realities are wildly different from the source world. It’s a great book, recently turned into a very good TV show, and has a sequel called Agency. 

Long before either of those, John Kessel’s Corrupting Doctor Nice and related stories involved time travel that created “moment universes”—traveling back in time causes the timeline to split from the moment of the traveler’s arrival, spawning a new and unconnected timeline, making the past ripe for pillage by the future. (There’s no stepping on a butterfly by accident and transforming your own future a la Bradbury’s “A Sound of Thunder” in these stories.)

Some of my favorite multiverses have a more personal vibe. The Midnight Library by Matt Haig is about a dying woman who has the opportunity to visit other realities to see how her life might have changed if she’d made different choices. 

Mr. Breakfast by Jonathan Carroll has a broadly similar premise—a man gets a magical tattoo that allows him to visit other timelines to see how his life would be different given other choices—but being a Jonathan Carroll book, it gets extremely weird very fast. (Carroll also did the great visit-an-alternate-world-in-dreams novel Bones of the Moon.) 

Lost Futures by Lisa Tuttle is literary horror novel about a grief-stricken woman who begins to obsess about paths not taken, and begins to travel to those alternative timelines (where things were mostly terrible in different ways)…when an alternate version of her tries to steal her life, things get even worse.

I wrote a couple of multiverse books myself, notably Briarpatch, about a strange tangle of implausible alternate realities, and the duology Doors of Sleep and Prison of Sleep, about a guy who finds himself in a new universe every time he wakes up. 

Go on, then; there are other worlds to read.

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