One of the major canon questions about Star Trek: Discovery and its trip to the Mirror Universe has finally been resolved thanks to this week’s episode: why no one knew about it in The Original Series.
Season 1 Episode 14, pretty aptly titled “The War Without, The War Within,” was largely filler — literally filling the audience in on all that’s happened while Discovery was in the Mirror Universe, and readying for a bold mission in the finale, with the fate of the Federation in the balance.
You see, since the Discovery overshot their return to their home universe, returning nine months after they left, the Klingon War has gone…not so well for the good guys. They’ve lost most of Starfleet, dozens of systems, and now the Klingon stand ready to attack even Earth.
In a last ditch effort to stop the Klingons, the Discovery is going to go behind enemy lines and attack Kronos, the Klingon home world — but to do so requires more spore drive shenanigans.
In all of this set-up for what looks to be a really intriguing final episode of the first season, we got a pretty surprising answer to one of the biggest lingering questions about Discovery’s foray into the Mirror Universe: how come no one knew about it?
Well, that was one of many loose ends tied up in this week’s episode. In a strategy meeting between Burnham, Saru, and Stammets with guests Admiral Cornwell and Sarek, who were surprised to see the Discovery, and her crew, alive.
You see, when the USS Discovery jumped to the Mirror Universe, the ISS Discovery took their place. Sometime, probably pretty shortly thereafter, the Klingons destroyed the ISS Discovery, thinking it was actually the Prime Universe discovery, neatly wrapping up that loose end.
Cornwell and Sarek were more than a little surprised about the fact that not only do alternate universes exist, but the crew of the Discovery brought back Emperor Georgiou to their universe.
Despite that they surprisingly kind of went with the flow in the face of that pretty mind boggling information, thanks to Sarek mind-melding with Saru to determine that they were telling the truth.
So, if a prestigious Vulcan and a high-ranking Star Fleet Admiral know about the Mirror Universe, how come it isn’t widely known within the federation by the time of The Original Series? One word: Cover-up.
Sarek and Cromwell proposed keeping the existence of the Mirror Universe a secret, completely covering it up, because of how the existence of parallel universes would be received by the public.
For example, if you had lost a loved one and knew there was another universe where they were still alive, most people would be obsessed with trying to get there, and that would create a whole host of problems. Not to mention that they probably don’t want to deal with the Terrans.
Of course, the ship’s crew still knows about the Mirror Universe, so you have a bunch of loose ends there, but I’m not sure how sane someone would seem if they started claiming alternate universes are real — not to mention the fact that it was a black ops, top secret ship anyways.
While the existence of the spore drive and its capability to jump dimensions still presents a big plot hole by itself, but ultimately the same excuse could be used: they destroyed the drive and covered up the technology because of its ability to access alternate universes.
So, there you have it: the loose end presented by having a major arc of Discovery’s first season set in the Mirror Universe has been resolved, and the crew of the Enterprise can be well and truly shocked by Mirror Spock’s goatee nine years down the road.