As summer brings thoughts of vacation, why not consider stopping off on one of the many Parallel Earths of science fiction? There's an infinite number of possibilities available to you - and here are some of our favorites.
Even before most people had heard of Erwin Schrödinger, we knew that there were plenty other Earths out there; we'd seen Star Trek's Mr. Spock with a goatee, or watched the Justice League and Justice Society meet up thanks to a crystal ball. I've already written about my undying love for the concept, and I'm not alone; sci-fi loves to offer glimpses of the roads less taken, whether they're character-based or somewhat more... epic. Consider the following while planning a summer trip to another world:
What Mad Universe
If you're looking to get away from it all, you could do much worse than decide to take a break on the parallel Earth from Fredric Brown's 1949 novel. Admittedly, you'd have to avoid being accused of being an alien spy when you try to spend your money, but isn't that a chance you'd want to pay to visit a world where spaceflight was accidentally discovered in 1903, and astronauts are pin-up girls?
Eye in the Sky
Of course, you'd have to be careful of your own subconscious if travel to parallel Earths followed the rules of Philip K. Dick's 1957 novel, where alternate realities were entirely subjective manifestations of your own state of mind. Unless, of course, your state of mind was completely relaxed because you're going on vacation. Oh, the tangled web we weave...
Doppelgänger/Journey To The Far End Of The Sun
Who doesn't wish that scientists could still discover a parallel Earth on the opposite side of the sun, as in this classic 1969 movie written by Gerry and Sylvia Anderson, creators of Thunderbirds, UFO and Space: 1999? The idea was recycled three years later in Marvel Comics' Warlock stories (and later in their Heroes Reborn arc), but Doppelgänger's world - where everything is reversed from ours, including writing, thanks to the wonders of flipping film - remains the one to beat. Imagine getting away from it all in a world where everything is backwards.
The Eternal Champion
Michael Moorcock's Multiverse works slightly differently than most, in that each world includes facets of people, instead of multiple versions of the same people, and each world may be vastly different from the one you're familar with. This may be a plus for your holiday, of course; experience something entirely new, and be less likely to run across a more successful, happier and healthier version of yourself in the process. (Much more traditionally multiversual, but feeling like it should be mentioned in the same breath as Jerry Cornelius: Matt Fraction's comic Casanova, where the hero is trapped in a parallel Earth, replacing the him that had died there.)
With this summer's movie, Starfleet's finest have finally come up with a parallel timeline (including an Earth, so it counts, thank you very much) that measures up to the show's classic Mirror Universe. Out of all the revamps and reboots that we've seen, this is one of the few that made the choice to make the revamp the center of the story and patiently explain that history may have been changed, but all that did was create a new parallel timeline. Pandering to the original show's fanbase? Sure - but doing so in such a way that it doesn't stop the movie for everyone else. Yes, the crew of the Enterprise have played around in the timestream many of times, but the new Movie-Earth lines up so well with Mirror-Earth and OriginalSeries-Earth that it's really only a matter of time before some comic or novel seeks to cross them all over in a Spock-centric altern-orgy, and I for one can't wait. As it is, Trek doesn't just offer one utopian future, but two; your choice depends on just how much time you feel like you want to spend with William Shatner.
What was the ingredient that made this show more than just an X-Files wannabe with an eccentric scientist and a cow? The sudden, surprise introduction to a war with a parallel Earth (complete with explanation of the multiverse concept for newbies, above). Admittedly, the glimpses we've seen of the alternate Fringe world(s?) haven't been especially alluring to those seeking a quiet getaway - It all seems to be explosions, Charlies with scars and grim skies, unless you're in a shining New York with multiverse magnet Leonard Nimoy and his newspapers that mention JFK still being alive (Maybe we should call this parallel Earth-StereotypicalRightWingViewOfADemocraticFantasy?) - but there's a downside to every vacation spot.
Like Quantum Leap (or, if your tastes run to a slightly later vintage, The Time Tunnel) before it, Sliders took the idea of characters just trying to get back home and ran with it... Ran across the multiverse, that is (A similar idea was behind the earlier, and much less successful Otherworld television series from the mid-80s). Five seasons of hopping between Parallel Earth San Franciscos on a television show budget demonstrated a wide variety of possible alternate worlds out there, including an Earth where Britain won the Revolutionary War leading to the British States of America, an Earth where a zombie plague has been unleashed, an Earth where dinosaurs are still alive, and an Earth where Ancient Egyptian is the dominant culture. Sadly, they didn't find an Earth without shitty CGI effects, but it was the 1990s. As a model for how to spend your summer, I'm torn whether or not to recommend it. Maybe you should ask yourself how much you really love San Francisco.
Less one potential getaway than a superpowered version of Orbitz, DC's superhero line loves the idea of a multiverse like almost none other; their original multiverse came from the company trying to come up with ways of haphazardly adding characters from other publishers without confusing things too much as much as anything, but the current version is much more structured... and finite. For one thing, there are "only" 52 Earths, now. Here are the ones we know about. Pick your favorite:
Earth 0 is the "core" Earth, the one that all "regular" stories take place on and - more importantly for the purposes of this post - the one that was the basis for the 51 alternate Earths that are known to exist within DC's current multiverse. Of those 51, the following have been identified:
Earth-1 is, essentially, the Earth that most comic fans grew up reading about - Think of it as "Earth Super Friends."
Earth-2 is an Earth that missed out on all of the Silver Age of comics, so there's no Hal Jordan Green Lantern (or Green Lantern Corps at all, for that matter), nor a Barry Allen, Wally West or Bart Allen Flash. For all intents and purposes, it's the same as DC's original Earth-2.
Earth-3 is an Earth of reversed moralities - the Justice League is the Crime Syndicate, Clark Kent is the villainous Ultraman, Lex Luthor is a superhero, and so on.
Earth-4 is as close to Earth Watchmen as you're likely to get outside of the Watchmen series; it's an Earth where only the Carlton characters who inspired Moore and Gibbons' series exist.
Earth-5 is an Earth where the only superheroes are Captain Marvel and his associated Shazam Family of characters.
Earth-6, Earth-7, Earth-32, Earth-37, Earth-38, and Earth-39 are all Earths where the variations are fairly minor, and very continuity based:"What if Batman became Green Lantern?" - That kind of thing.
Earth-8 is a parody of Marvel Comics' Ultimate Earth, where the Avengers are represented by "The Meta Militia."
Earth-9 is the home to the Tangent Comics characters, who bear the same names as the more familiar characters, but are in all other respects different.
Earth-10 is a world where the Nazis won World War II, and home to the guilt-ridden super-Nazi Uberman.
Earth-11 is an Earth where genders are reversed, so you have Superwoman, Batwoman and Wonderman instead of the more familiar versions of the characters.
Earth-12 is an Earth you're very familiar with; it's officially the world of Batman Beyond, which also means that it's the parallel Earth where all the Bruce Timm DC cartoons took place.
Earth-13 is the Earth where many of DC's Vertigo line apparently occurs.
Earth-15 used to be an Earth where all crime had been eliminated by particularly successful superheroes... but then it was destroyed by Superboy Prime, just to prove how much of an asshole he can be. Of course, it theoretically was rebuilt
Earth-16 is the home planet of the Super-Sons, AKA Batman Junior and Superman Junior. Yes, that's right; Superman and Batman got married (not to each other), had sons, and named them after themselves. Don't ask.
Earth-17 is a post-apocalyptic Earth where nuclear apes rule. I promise you, I'm not making this up.
Earth-18 is an Earth where the world is still in Wild West times, complete with cowboy versions of the Justice League.
Earth-19 is an Earth where the world is still in Victorian times, complete with a Batman who has hunted down Jack the Ripper.
Earth-20 is "Pulp-Earth" - essentially, a parallel world where everything is as if it was a pulp novel.
Earth-21 is the Earth from the wonderful DC: The New Frontier series by Darwyn Cooke.
Earth-22 is the Earth from Kingdom Come, Alex Ross and Mark Waid's cautionary tale about why superheroes can't save the world, except for when they can.
Earth-26 is an Earth of smart, talking animals; it was "rendered uninhabitable" during 2007's Captain Carrot And The Final Ark series because funny animal books apparently are silly and not what the audience wants, but then reconstituted at the end of Final Crisis.
Earth-30 is the Earth from Red Son, where Superman landed in communist Russia.
Earth-31 is the Earth from The Dark Knight Returns series, so it's all mutants with sharp teeth and old grumpy Batman.
Earth-33 is an Earth where all of the familiar superheroes are now suddenly (magically, one might say) magicians, with names like "Batmage" and "Lady Flash, Keeper Of The Speed Force."
Earth-34 is an Earth where the British Empire still exists, and is ruled by a tyrannical despot called King Jack.
Earth-40 is an Earth where there are no public superheroes, just superpowered spies who work for the government. Which, if nothing else, would make James Bond movies more fun.
Earth-43 is a parallel Earth plagued by vampires, who have managed to turn Batman into one of their number. There are all manner of other mythical beasts as well, so this is pretty much "Horror Earth".
Earth-44 is Robot Earth; the main superheroes of this Earth are robotic versions of the Justice League.
Earth-48 is, unlike Earths 18 and 19, an Earth far in the future, where humanity is extinct after an intergalactic war has wiped out all native life on the planet.
Earth-50 is the Earth of DC's Wildstorm line. Again, post-apocalyptic, currently.
Earth-51 is, post-Final Crisis, the home to all of Jack Kirby's creations for DC Comics, following it having been yet another post-apocalyptic Earth. At least this one was repurposed for something constructive.
(There are also some Non-Numbered Earths (or, to be completely correct, Earths we don't know the numbers of yet), which include an Earth where Superman and Wonder Woman are black, an Earth where everyone resembles a manga character, and an Earth "just like our own" where superheroes are just the stuff of fiction.)
The 2005 South African/Canadian co-production gave us a glimpse at the parallel Earth you should really try to spend some time in: the Gammaverse, where everything is perfect, humanity has worked out how not to squander our resources, and you'll have no trouble getting a hotel room at an affordable rate. Just remember to ignore any offer of a budget weekend in the Alphaverse; it may sound exciting ("Alpha" just sounds good in general, right?), but it's pretty much the hellhole that give you anecdotes but also various forms of disease during your short stay. And if someone suggests a stay in the Betaverse, remind them that that's where you already live and go find a new travel agent. (For more class-based alternate worlds, Warren Ellis' Anna Mercury may be what you're looking for.)
Additional research and reporting by Sarah Hope Williams.