The difference between an alternate reality, an alternate dimension, and an alternate timeline is which movie or show explains the difference. The science fiction world confuses these concepts all the time. There were a couple of episodes in Stargate SG-1 where they made fun of the confusion.
The alternate dimension idea is simple and clear. Time and space are measured in 4 dimensions, or 4 axes. We represent them by T, X, Y, and Z in 4-dimensional graphics. But a long time ago some science fiction writers used the term for stories where people went to alternate worlds or universes.
An alternative reality is an alternate universe. But that’s sounds strange if you believe our physical universe is just one of many physical universes that burst into existence from a primeval source. Some people call it the great cosmic foam.
The multiverse theory is really several theories. One theory says that a new universe is created every time you have to make a decision. There might be an infinite number of such universes bursting out from each other every second.
Another multiverse theory says that many universes burst out of a cosmic foam. These exist side-by-side but that doesn’t mean there is another you or me in another universe. Those universes might operate by different physical laws.
Here are three television shows that explored themes based on alternate universes, timelines, realities, and dimensions.
Stargate Franchise
I’m treating the franchise as a single show because many of the main actors from Stargate SG-1 appeared on Stargate: Atlantis. The franchise’s official position was that alternate realities branched off from the main reality based on decisions people make. The infinite number of alternate realities meant that you could find a universe where someone didn’t exist, or lived an entirely different life.
They took this concept far enough to show several different technologies capable of transferring people and materials from one alternate reality to another. In the first season episode “There But for the Grace of God” on Stargate SG-1, Dr. Daniel Jackson accidentally activates an alien device – a “quantum mirror” – that sent him to an alternate universe.
Daniel was able to get back to his own reality. The mirror was used in another episode where an alternate Captain Samantha Carter and Major Kowalski came to the primary reality looking for help.
In the Stargate: Atlantis episode “McCay and Mrs. Miller”, Rodney McCay invented a process that could transfer energy from another universe to the primary one. He and his team hoped they’d be able to tap into that other universe’s energy to power Atlantis’ systems. Instead, they created a disruption in the fabric of the other universe’s space-time. The alternate Rodney McCay found a way to use the space-time bridge to come and advise Atlantis Prime of what was happening on his side.
In another episode, “The Daedelus Variations”, the AR-1 team from Atlantis Prime investigated a Daedelus battle cruiser that mysteriously appeared above Atlantis. The ship was using an alternate reality drive invented by another Rodney McCay to shift between universes. AR-1 Prime was accidentally carried into several universes before Rodney was able to reverse the drive’s course and send the ship back the way it had come.
Alternate dimensions figured into stories involving lepton radiation, where characters were shifted “out of phase” so that they remained in contact with the Earth’s surface but living creatures (including other personnel) passed right through them. The characters passed out-of-phase through alien technologies they didn’t really understand.
Alternate timelines figured in episodes like Stargate SG-1‘s “2010” and Stargate: Atlantis‘ “The Last Man”, where events in the future were prevented from happening by time travel. Time travel is was a popular theme in these shows, and history was changed more than once. The time travel happened because of alien technology, sometimes accidentally because of flares on stars the wormholes passed too close to, and sometimes because of alien technology. In the movie Stargate: Continuum, the alien creature B’aal built a time machine based on monitoring hundreds of stars in real-time through subspace, so that he could send a wormhole to any planet’s history that he wanted to.
Fringe
J.J. Abram’s bizarre show about unusual, and hard-to-explain events starred Anna Torv, Joshua Jackson, Jasika Nicole, John Noble, and Lance Reddick as government agents and contractors who explored unusual phenomena. Their work was monitored by mysterious bald-headed men informally known as Observers.
Over the course of 5 seasons the show gradually revealed that John Noble’s character, Dr. Walter Bishop, had discovered a way to monitor an alternate reality. He was looking for a way to cure his dying son, Peter, of a disease. The alternate Walter Bishop saved his son but Walter Bishop Prime failed. So he built a bridge to cross into the alternate reality, where he stole the other Peter and took him back. Walter’s equipment was destroyed, trapping Peter in the prime reality.
As a grown man, Peter (Joshua Jackson) was recruited by FBI Agent Olivia Dunham (Anna Torv) to take custodial responsibility for his father, who had spent 15 years in a mental instituion. It turns out the Walter’s brief visit into the alternate reality had set into motion events that led to the two universes threatening each other. Walter’s partner, Dr. William Bell, became a multi-billionaire who secretly crossed between the two realities, working to save both universes from their ultimate destruction.
Meanwhile, the Observers slowly became more involved with the Fringe Division’s cases. It turned out they were seeking a mysterious boy whom one of their own had stolen from the future. The Observers were agents sent back in time to protect their timeline, in which they had replaced natural humanity with their own mutations.
The 5th season of the show tied up all the twisted threads, but it wasn’t a very satisfying season. The two universes were saved, Peter was reunited with his natural father but ultimately chose to stay with Walter Bishop Prime, and the Observer civilization was defeated when Walter took the mysterious boy back to the future where he could be studied to prevent the rise of the Observers.
Fringe was most interesting and satisfying during its first three seasons. The fourth season was not as good as the earlier seasons but it kept the audience interested enough to keep watching. But the fifth season changed many things about the show, taking the audience into a future timeline where some of the characters were older and some had been preserved by an artificial amber invented by Walternate in the alternate reality. From that point forward, almost nothing in the show really made sense, given that Peter and Olivia – who had been trapped in the amber were rescued by their daughter.
Counterpart
J.K. Simmons has played J. Jonah Jameson, the crazy newspaper editor, in the Marvel universe for many years. He’s appeared in all the Spiderman movies and many animation shows. But he has acted in other shows and movies.
In 2017 Simmons was cast as the lead in a show about a man working for a secret United Nations agency. His character, Howard Silk, has worked for the agency for 30 years and he has no idea of what it does. He has progressed only to a level where each day he goes into a special room where he passes coded messages to a man in a room that looks like a mirror version of his.
One day Howard learns that the people he has been communicating with are from an alternate reality that branched off from the main reality 30 years in the past. The United Nations created the agency to monitor the alternate reality and those of its people that crossed back into the prime reality. Everyone on Earth had a duplicate in the alternate reality who began following their own path in their timeline.
Howard is drawn into a conflict in which his counterpart plays a much more active and important role on the other side. He learns that the alternate people are not simply duplicates who always existed. There was only one reality prior to an accident 30 years in the past. The other reality has its own agency that monitors the bridge and engages with the prime Earth’s agency.
Unlike Stargate and Fringe, the science and technology of interuniversal travel isn’t central to Counterpart storylines. This show is about how the characters who know about the accident the divergent universes deal with each other and the differences in their political histories. It’s a character-oriented show that explores science fiction from a very different angle.
Conclusion
There are other shows and movies that deal with alternate timelines, universes, and dimensions. The Marvel cinematic universe had its own take on these things.
Science fiction loves to take its audience on “what if” adventures in alternate existences. True reality probably doesn’t work like this. Even if there are other universes beyond our own, we’ll never be able to interact with them. And the probably don’t branch off from ours just because someone decides to turn left instead of right.
But it’s fun to think about how things might play out just because of one person’s small decision.