In Star Trek Discovery Season 2 Episode 11 Perpetual Infinity, the mirror Philippa Georgiou says:

You have obviously confused me with my sentimental prime universe counterpart. I'm Terran.

(emphasis mine)

As far as I know, this is the first and only time the term 'prime universe' is used in-universe. Are there other instances where this naming is used in-universe? And, wouldn't the mirror Georgiou think that her universe is the prime one?

(Transcript here)

  • 6
    Yeah, Mirror-Georgiou's comment doesn't make any sense in-Universe. Why would anyone not consider their Universe as the prime one? The writers dropped the ball on that one. – Rebel-Scum Feb 9 at 19:25
  • From her perspective I agree she would consider her universe to be the prime universe, but those from "our" prime universe would not. Perhaps she is using those terms so that she doesn't confuse those with "our" perspective (she also referred to herself being from the mirror universe in a later episode). – billoverton Feb 13 at 13:23


The term "Prime Universe" is something that is used out of universe to better distinguish between the various timelines and dimensions that we see in Star Trek. For us, it's the "prime universe", because (apart from Star Trek 2009 and later) all the adventures we see on-screen are told from the perspective of that specific universe.

The Mirror Universe was not the Mirror Universe before Discovery

Note that the term "Mirror Universe" has also not been mentioned in-universe prior to Discovery: this nickname was only part of several episode titles, such as "Mirror, Mirror" (TOS), "Through the Looking Glass" (DS9) or "Through a mirror, darkly" (ENT).

In-universe, Discovery recognized the parallel universe as a mirror universe

In Season 1, Episode 10 of Discovery, the Discovery crosses over to the Mirror universe. Initially, they don't know where they are (they find the records on the U.S.S Defiant later in the episode), but they quickly recognize the parallel universe for a mirror image:

BURNHAM: I'm downloading the Klingon raider's logs Images, battle plans, intelligence that we found from the core. And so far, we can conclude that we are indeed in a parallel universe. But one not governed by the Federation, but by a fascistic, human-only organisation known as the Terran Empire. Most places and ships that are found in our universe, like the Cooper, exist here. The same goes for people.
TYLER: You mean, we could literally meet another version of ourselves?
BURNHAM: Theoretically, yes.
BURNHAM: The Terrans appear to be the antithesis of us, in every way. They're an oppressive, racist, xenophobic culture that dominates all known space, and they're ruled by a faceless emperor.

(Discovery: Despite Yourself)

They (Or at least Burnham) quickly start referring to their counterparts of the other universe as their mirror counterparts:

LORCA: I'm gonna run with Mister Saru's theory in the hope that we don't bump into ourselves and blow our cover. Burnham.
BURNHAM: Modifying our ship's signature to match that of mirror Discovery.
BRYCE: Captain.
LORCA: Hold on, Lieutenant!
BRYCE: They're saying if we don't respond that we should prepare to be fired on.
LORCA: Open a channel. Audio only.
BURNHAM: Belay that. I'm sorry, but you can't take it, sir. I'm examining the crew manifest of mirror Discovery. You're not its Captain.

(Discovery: Despite Yourself)

It makes sense to use the wording "prime universe" in this dialogue

By the time of Season 2, Episode 11 of Discovery, Mirror-Gergiou has been for quite some time in the Prime Universe. It would make total sense for her to refer to "her" universe as the mirror universe (basically using the same term that others are also using in-universe) and the prime universe as the "prime" one.

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