and in a larger sense, how multiple timelines work. This is going to be a long one. I apologize. First proposition: time itself is consistent and generally flows in one direction. Tangential timelines that are "correctable" are by the nature of causation themselves going to be corrected. Despite the drama involved they must and always will have been corrected, such as the Enterprise C incident, year of hell, etc. While these may appear to be "alternate timelines" they are in fact tangential processes that can never be fully explored as they only exist as variances to those experiencing them. To these scenarios the Red Angel Suit (i.e. Daedalus Project) is not of use in such scenarios. We like to think of time, due to proliferation of many worlds hypothesis and popular media as a kind of mystical dimension like an infinite series of library cards we cannot perceive. Useful for story writing and navel gazing. Let us propose instead that those "Realities" are in the same universe as we are in, as a universe by a certain definition includes everything, they must have their own locations within the confines of a non-finite universe. At certain amounts of size, the cosmological principle becomes manifest on a Hubble-sphere scale, meaning distances of an observable universe. Those patterns become replicated at cosmos level distances, meaning this non-finite universe is infinitely filled with near replicas of our Hubble-sphere. Minor variances would make things in these locations at both large and exceedingly smaller distances either the same for all practicable purposes or in some cases quite different. These are, then, the "alternate universes." Because of their range outside of our own observable phenomena the existence of them cannot violate causation. However they are still within the same universe. To traverse them, one would need to be able to use stable wormholes, or create them, or find paths from them. This would explain random events of crossing into universes that might seem linked, such as the Mirror Universe. Or it might require the use of a cosmological medium such as the spore network, itself evolved to adapt and thrive somehow using those connections, or an event like a the Romulan nova. While primarily those events have generally been random, the Red Suit appearantly was a leap in technology to actually find, create or otherwise use those links between spaces mind mindbogglingly far apart in both space and in some cases time, within the universe. It's not traveling between alternatives insomuch as its traveling across the universe.
Interesting thoughts! If I understand you correctly then I've been toying with the idea of "pocket timelines" for a while too. The best example IMO is that of Cause And Effect where the Ent-D spent 17 days cycling through the same events 30-40 times and Starfleet didn't (or couldn't) notice! It might be deduced that the Ent-D was somewhere other than the main universe, in a "pocket" of sorts created by the temporal anomaly
...Then again, Starfleet generally doesn't notice if a starship goes on a quest for, oh, six months or so. And conversely, accessing the outside universe (say, a commnet or the UFP timebase) is a chore no matter where you are, universe-wise. Was Miri's planet merely displaced in space from some far corner of this multiply redundant universe? Timo Saloniemi