As a classic science fiction franchise with hundreds of hours of world-building, Stargate has never shied away from the time-tested tropes of the genre. We’ve got aliens, of course. We’ve got time travel, and space ships, and cutting-edge tech. And we’ve got parallel universes.

What if the Stargate was never discovered? What if the Goa’uld invasion of Earth succeeded? What if the Wraith made it to Earth? Or, a little closer to home … what if Jack and Sam were allowed to hook up?

The shows explore how familiar events might have played out differently in another version of reality, and how the characters we know and love took other paths in another life. It makes for great science fiction storytelling, and a way to mix things up by putting our heroes in radically different situations. It’s also a cool idea to think that, somewhere in the multiverse, there are other versions of you and me living lives that are very similar, or very different, to our own.

We recently did a complete watch list of all of Stargate’s parallel universe episodes. And that got me thinking: what are the different storytelling devices that make these episodes work? And how might Stargate’s own theory of the multiverse help to fold together future movies and shows as the franchise inevitably diversifies?

So here we’ll take a longer look at Stargate’s exploration of parallel realities, how we’ve reached them, and generally how the multiverse functions on Stargate. And we’ll wrap up by considering how a multiversal theory could soften the blow a bit if Amazon and MGM decide to reboot this franchise.

WHAT ISN’T A PARALLEL UNIVERSE

Before we get started, my fellow nerds and splicers of the finer points of canon, let’s be clear what we are talking about with a “parallel reality” — and how that differs from, say, an alternate timeline. On Stargate these are not the same thing, strictly speaking (although one theory does allow for alternate timelines to also exist in parallel to our own).

The multiverse theory goes that, every time a person is confronted with a choice, reality “forks.” There actually is a world where you turned left instead of right, where you declined that offer to join the Stargate program, or where you took out Camulus instead of Cronus. Our choices don’t just represent possible worlds; they actually create them. Some of those realities are very much like our own, while others have more drift and more radical differences.

With parallel realities, those differences come about from the natural evolution of our infinite choices.

Stories of alternate timelines, on the other hand, result from some sort of time-travel event. Here a different version of the world we know exists because someone traveled in time and changed the past, rewriting our own universe (rather than creating another one). In stories like “Moebius” and Stargate: Continuum the team is attempting to undo changes to history in order to restore our reality to its original state. Or, in stories like “2010” and “The Last Man,” the team is trying to alter their own history to make events play out differently.

Altered timelines are not the same as what we’re calling a parallel reality — a second universe that co-exists along side ours, where a different SG-1 is going about its business each day.

So, with that distinction out of the way, here’s how Stargate has told parallel reality stories. Along the way we’ll talk quantum mirrors, punching through a black hole, and other ways you might find yourself in another universe.

QUANTUM MANIA

The discovery of an alien device in the first season of Stargate SG-1 thrust Daniel Jackson, and us as viewers, into our very first parallel universe story. In “There But For the Grace of God” Daniel touches the quantum mirror and feels a crackle of electricity across his body. But he doesn’t realize until returning home to Earth that he isn’t in Kansas anymore!

In this reality Earth is on the brink of invasion, as Apophis’ mothership draws near and even lands on top of Cheyenne Mountain itself. Jack O’Neill (not Hammond) is in charge of the base, Teal’c is leading the assault as First Prime, and Daniel himself never joined the Stargate program.

This is a classic tale of warning, perfectly captured by the title (“There but for the grace of God go I …”) and by the final scene. Daniel barely escapes with his life as the S.G.C. explodes. He returns through the mirror to find his friends searching for him. Daniel has a gate address of the planet where Apophis’ attack originated, and he is convinced that the same thing is about to happen to our world: “We’re all in very big trouble,” he warns. “They’re coming!”

The third season of the show followed up on this with another quantum mirror story, “Point of View.” Instead of Daniel, here Samantha Carter is at the center of the story. Dr. Carter is a part of the Stargate program in her reality but she never enlisted in the military. In fact, she’s married to her Jack O’Neill. When Apophis’ mothership lands on the mountain and the S.G.A. falls, Jack dies defending his people — and Sam escapes through the mirror with Major Charles Kawalsky (who had died in our reality two years earlier).

This introduced an original problem to traversing Stargate’s multiverse: entropic cascade failure. Evidently our subatomic structure doesn’t like it so much when there are two of us occupying the same universe. Dr. Carter begins experiencing life-threatening tremors, and it’s clear that she has to go back.

After our SG-1 go through the mirror and help summon the Asgard to save Earth, Jack and Sam say goodbye … and General Hammond orders the mirror destroyed.

The writers would need another device to cross between universes in the future. It would take several years, but eventually they found just such a tool: the Stargate itself.

RIPPLE EFFECT

The franchise did a lot of great episodes over the years where the Stargate itself malfunctions (… but that’s for another list!). So it makes sense that writer Joseph Mallozzi would land here as the point of entry for another story of intersecting realities. The gate normally uses wormholes through subspace to traverse great distances, only in Season Nine’s “Ripple Effect” that wormhole also intersects a black hole, causing a rift in the space-time continuum. A duplicate copy of SG-1 arrives at Stargate Command.

And then it happens again.

And again. And again.

The S.G.C. is becoming crowded not just with one alternate SG-1, but a whole lot of them. There’s a rebel Jaffa SG-1, a team of take-no-prisoners adventurers, and even a team with long-dead friends on it. The gate seems to be malfunctioning, and it’s up to the Carters to figure out why more SG-1s keep arriving through the gate (and how to get everyone home).

Our SG-1 eventually discovers that one of the teams deliberately caused the problem, crossing to another universe to try and steal a Zero Point Module. It was a stunning (and really interesting) turn of events, forcing us to realize that not only are there countless other versions of our heroes out there in the multiverse … but some of them are morally questionable, to say the least. They are, more or less, the bad guys. And they’ve found a way to use the gate to threaten our universe.

MERLIN’S DEVICE

Lt. Colonel Samantha Carter gets more than she bargained for when she goes experimenting with a piece of Ancient technology, created by none other than Merlin himself. Merlin’s computer was made to temporarily push matter into another dimension (that’s still inside our universe, mind you). In essence this makes a person “out of phase” with the normal world, and so invisible to everyone around them.

Sam has big ambitions, of course, so she wonders if the field can be expanded to include … maybe even a whole planet? In “The Road Not Taken” she accidentally shifts herself not just into another dimension but a parallel universe. Here Anubis’ invasion three years earlier forced the government to reveal the Stargate to the world. There was mass panic and numerous diplomatic incidents, and history unfolded very differently.

Now Lorne is the leader of SG-1, Hank Landry is President of the United States, and yep — the followers of the Ori are still on their way to conquer us all and make us worship false gods.

Though she’s clearly not their Sam, Carter is successful in getting the group to trust her. She completes her modifications of Merlin’s device, and successfully hides the entire planet Earth just in the nick of time! The Ori attack is thwarted, and Sam is a hero. Now she finds herself a public relations tool, and has to convince President Landry to let her go home.

While it doesn’t exactly come with an instruction manual, or a handy universe dialer like the quantum mirror, Merlin’s computer could still be used to tell parallel universe stories in the future. But when it came turn for Stargate Atlantis to visit some alternate realities, the writers came up with a much more stylish way to travel.

THE ALTERNATE REALITY DRIVE

In “The Daedalus Variations” Atlantis receives a signal from the Earth ship Daedalus, which has just shown up in orbit but is running silent. With no one answering comms, Sheppard’s team takes a Puddle Jumper to board the ship and investigate. There they find a copy of themselves lying dead — John Sheppard, Teyla Emmagan, Rodney McKay, and Ronon Dex.

Yikes.

The ship flashes all around them, and soon it becomes apparent what has happened. Daedalus has jumped from our reality to another, taking the team along for the ride. This version of the ship has a unique “alternate reality drive,” allowing it to travel the multiverse at will! That’s great when it’s working, of course … but right now the drive is on the fritz, and the team is stranded on a runaway train.

In one universe Atlantis is there on the planet’s surface below them, and in the next it’s gone. One moment they are threatened by the radiation of a red giant, then in the next the ship is under assault by a hostile clan of alien warriors.

This episode from writer Alan McCullough takes the multiverse theory from “Ripple Effect” and amps it up to 11. In at least one version of reality out there, someone figured out how to engineer a device that can move a ship from universe to universe, allowing them to explore parallel realities like our team explores other planets. Just imagine how cool this ship is when everything is working! Imagine an entire show full of adventures where a team crosses into a new universe every season, or even every episode.

The alternate reality drive also picks up an idea from back in the quantum mirror days: realities in the multiverse sit next to one another, literally in parallel, in a sort of fixed order. Kawalsky had taught Daniel how to dial the mirror backward and forward to find the right universe. Now, to get the team home, McKay has to attenuate the drive so that Daedalus travels through these same realities in reverse. They backtrack through each universe — even enduring another alien onslaught — until they reach their own version of Atlantis, and jump ship.

It’s brilliant, and while we never see this Daedalus (or those aliens) again in canon, the idea would make for a fantastic and off-the-wall Stargate series that always keeps the audience guessing.

THE BRIDGE

This wasn’t the first time that Atlantis had tangled with parallel realities, mind you. The Z.P.M. itself draws energy from a pocket universe, so the temptation was always there for Rodney to try the same thing on a larger scale. With Project Arcturus things went horribly wrong (to the tune of five sixths of a solar system), but with help from his sister Jeannie he believed he had finally cracked the problem.

The episode is “McKay and Mrs. Miller,” and here the two genius siblings — with a notable assist from Radek Zelenka — create a bridge to another universe, through which to draw massive amounts of power for the city. In theory this would allow Atlantis to power its shield at full strength without so much as dimming the lights, or dial home to Earth whenever we want.

The device is powered up and at first it looks to be a huge success. But then something … or rather someone comes through. It’s that universe’s version of “Rod” McKay, cool and suave and really needing you to shut that thing down because it’s destroying his universe! The build-up of exotic particles on his side of the bridge are creating a tear in the fabric of their universe.

While of course the problem is eventually resolved and “Rod” returns to his Atlantis, this episode adds a lot to our understanding of parallel worlds on Stargate. McKay was betting on bridging to an uninhabited universe, so it’s worth noting first that this one was very much full of people. This suggests that populated universes may be much more plentiful than he speculated. It’s also fascinating that two universes were bridged in an open and ongoing way (rather than the instantaneous flash of a quantum mirror or an alternate reality drive, where the gap is crossed very quickly … probably in order to avoid damage from something like the accumulation of exotic particles).

Finally, “McKay and Mrs. Miller” delivers storytellers yet another tool for moving characters from one universe to another (and back again). The reality bridge is human-made technology that can allow for two-way travel, and it opens up infinite worlds for stories and crossovers.

STARGATE’S MULTIVERSAL FUTURE?

As we look ahead to the future of Stargate storytelling under the stewardship of Amazon Studios and MGM, it’s worth asking whether different takes on the Stargate formula might live alongside the TV universe fans have come to know and love the world over. A hard reboot of the canon certainly isn’t what we want, and there are strong arguments that suggest that Amazon could do real harm to the Stargate brand and its enduring fandom if it chose to go this route right away. We want Amazon and MGM to continue the existing universe with a fourth series from Brad Wright.

That said … one could imagine alternate versions of the Stargate story living alongside our own, as a sort of “parallel universe.” Thinking about it this way means that a reboot would not wipe away the existing canon, but sit beside it as yet another parallel reality — one more corner of the infinitely expanding multiverse.

There is already precedent for this in Stargate’s history. When Wright and his Stargate SG-1 co-creator Jonathan Glassner adapted the original Stargate feature film for television, they made a few key alterations to the premise and to the characters. Ra was not the last of a dying race, the Jaffa are pawns in the Goa’uld empire, and the Stargate goes to many thousands of worlds. Sha’uri became “Sha’re,” Jack’s son Tyler became “Charlie,” and the Stargate program was suddenly in Cheyenne Mountain instead of Creek Mountain.

As viewers we accepted the premise that this was the same world from the film, only one year later and with mostly different actors. Daniel Jackson was living with the people of Abydos, and Colonel O’Neill had retired following the successful mission that blew up Ra.

In the television series’ continuity the 1994 feature film is not definitively set in a parallel reality … but it actually would explain a few things.

That would mean that Richard Dean Anderson’s Jack and Michael Shanks’ Daniel had a very similar adventure together, but one that we the viewers never actually saw. And the Kurt Russell and James Spader version of these characters might have had very different lives after their movie ended — perhaps in adventures more in keeping with Dean Devlin and Roland Emmerich’s original trilogy plans, or the series of five novels written by Bill McCay.

The multiverse theory suggests — within Stargate canon! — that perhaps these two versions of Stargate have their differences because they took place on parallel worlds.

That’s interesting to me as a science fiction fan. It’s a fascinating way to use the canon itself to explain inconsistencies across multimedia adaptations, which have drawn upon the creative instincts of different writers and artists. Maybe it even carves out a little bit of space for a Stargate “beta canon,” where things like novels and comics can be allotted more weight, as true, canonical stories that are simply set in a parallel reality.

And, last but not least, it gives me a little room to endure what could be Amazon’s looming decision to start the Stargate story over again. Whatever comes next — whomever the creator and whatever story they aim to tell — can never undo or replace Stargate as I know it and love it. It’s simply another layer of that same multiverse that has already been crossed by the likes of Daniel Jackson, Samantha Carter, Cameron Mitchell, and John Sheppard.

Which parallel reality storytelling device is your favorite? Would you like to see a TV series or movie set in a different version of the Stargate universe? Let us know in the comments!