If the crew configure their transporters or take a path through the bajorian wormhole accordingly then travel into the mirror parallel universe from the Kelvin universe, will this mirror universe be a different one from the one they traveled to from the prime universe? Or does the one mirror universe act as a common place available to both the Kelvin and prime universe?
But if the mirror universe were truly parallel would it not have remained unaffected when Spock went back in time in the prime universe? If Spocks actions were to create 2 universe, why does it create 2 mirror universes too? Or does it work some other way?
Yes. Of course there's a mirror-Kelvinverse, AND a way for both them and regular Kelvinverse characters to access the regular MU. Why? Well, for one, there's no reason why there shouldn't be, and for another, there are interesting stories to be told that way.
In the comics, we've seen two Mirror Universes based on the Kelvin Timeline, plus Kirk from the Mirror Universe as seen in Mirror, Mirror has visited the Kelvin Timeline, though very briefly, along with Prime Universe Geordi La Forge.
I thought the Mirror Universe in the comics was pretty well done, including Singh, who was a pacifist Augment rather than a dictator. I found it quite interesting and enjoyable.
"Parallels" basically tells us that every choice made makes another universe, though it stands to reason that universes that branch off one another would be closer to each other than others. So the Kelvin Timeline would have a Mirror Universe, which is turn would have several parallel universe based on the choices of the Mirror Universe inhabitants.
I've never understood what the exact relation between a 'mirror universe' and alternate timelines (such as in Parallels) is. Is a mirror universe just a specific alternate timeline that has formed a particular strong connection to our prime timeline in some way? Or are they different phenomena altogether?
Mirror Universes if there is any IU explanation are universes that lead to the evil side of the manicheanean scale.
I always thought so, too - that the MU was just a very similar quantum branch to the Primevese, with some dark differences - until I saw the opening the the Enterprise MU episodes. Dude, their Earth *rotates the opposite direction*. That either means that the MU is a "separate creation" (whatever you take that to mean), or, that the branching was SO early that fundamental things like the general direction of rotation for the universe could be different. So okay, still a parallel universe, but one of a decidedly different class than the ones Worf dealt with in "Parallels".
I've always taken it literally. It actually does kind of work out, you can imagine that way back in cavemen times, there was a tribe that made a vital decision based on the direction the sun rises, and the snowball effects that developed on that decision being so different in the two universes resulted in one universe being good and the other evil.