repost:
Actually, the term used was “alternate quantum realities.”
And Geordi Data had a diagram of the time continuum up on the panel when he was trying to explain Worf’s predicament. Here let me find it…
Done: https://www.youtube.com/watch?v=MzUEu7Gb7Cg
DATA: I believe the quantum fissure we discovered is a fixed point across the space time continuum. A keyhole which intersects many other quantum realities.
TROI: What do you mean, quantum realities?
DATA: For any event, there is an infinite number of possible outcomes. Our choices determine which outcomes will follow. But there is a theory in quantum physics that all possibilities that can happen, do happen in alternate quantum realities.
WORF: And somehow I have been shifting from one reality to another.
LOOK AT THAT DIAGRAM. That is what the multiverse space-time continuum looks like in Trek. They all exist. When a choice is made—when any action takes place that could have had an alternate outcome—one or more new alternate timelines diverge from that event.