Reply to your 1st sentence: I haven't said "opposite".. I have said "different".

Shakespeare may have lived before the two universes diverged. ~> Please, explain...

@SachinShekhar There's a theory that the point of divergence was actually shown onscreen: What Zefram Cochrane did when the Vulcans made First Contact.

@Izkata Mirror universe is a parallel universe.. Not parallel timeline / alternate reality.

@bitmask You are suggesting me to look at parallel universe while advocating about parallel timeline.

@SachinShekhar It was called the "mirror universe" because of how the Federation was militaristic in that universe; it has never been firmly established whether it has always existed, or was caused by a timeline split. All we really know is that it is somehow the "closest" universe to the primary one.

@Izkata Nice to see your definition of mirror universe, but you must recall that "There was no Federation in prime universe when mirror universe episodes of ST:ENT were broadcasted." In my sense, it was called mirror universe because prime directives of average humanity (nature of humans) were mirrored.

@Izkata It was indeed a parallel universe.... Not a parallel timeline diverged from prime one. Out of universe, when timeline shifts/splits are presented, the characters are same with same nature. It was indeed not a timeline split.

@SachinShekhar I'm not sure what you're getting at. The ship found in the mirror universe episodes of ENT was the USS Defiant, the ship lost at the beginning of TOS The Tholian Web. It fell through time as well as universes.

@bitmask You can't apply theories of timelines over universes.

@SachinShekhar Yeah, the timeline changed around them, except for the episodes where it didn't, such as in DS9 when O'Brien was jumping hours forward in time, or VOY when Seven was recruited to stop Braxton...

@Izkata Then, you are getting it wrong. Archer of mirror universe clearly said that USS Defiant was 100 years from future. It was future tech due to which he was able to threaten whole empire.

@SachinShekhar No, that's exactly what I said. TOS takes place about 110-115 years in the future from ENT, and the mirror universe ENT crew do realize it's from the future and another universe in the first part of In A Mirror, Darkly, when they're going through the ship's computer. There's nothing contradictory here.

@Izkata Then, how did you say, "It was mirror universe because the Federation was militaristic in that universe."

@SachinShekhar That's the name it was given in the primary universe (by the characters, IIRC) during TOS (and we all call it that name), and at that time the Federation existed.

@Izkata +1 :) But, you shouldn't use such IQ in discussion as you know the past (when there wasn't any Federation), too. :)

IQ?

@SachinShekhar IQ? (Haven't been in chat before, is @ needed to send one of the alerts?)

Yes @ is needed to send alert.

@Izkata By IQ, I mean logic. As your IQ is developed with more events than Kirk and crew, you shouldn't apply logics of them in this discussion...

Still not sure where the confusion is:

* The name "mirror universe" came about in TOS, due to the Federation and its occupants being "mirrored" into the militaristic society - IIRC, this name was what it was called in-universe

* Out of universe, we call that one the same thing for clarity

* The name "mirror universe" is not definitively saying that it is completely separate, rather than a timeline split

Out of universe, its better to say that average humanity directives were opposite.