It seems that all probable realities exist in potential, but some more
actualized than others, perhaps by how widespread the consensus is.
Oh, God, oh hell, oh damn, you would have to bring this stuff up!! *groan* *sigh* Okay, here goes nuthin'...
I am currently up to my eyebrows in that. I've managed to sort it out to the extent that I fairly certain of two things:

1. all conceivable realities exist, but most of us are very focused on only a small handful of those infinite spaces.
2. There are at least two layers of hellish dub-in between a spiritual being which is apparently "located" in this physical universe, and perception of what is quote "real" endquote.

For any of you who might be familiar with traditional occult terminology, I have recently become painfully aware of what is sometimes called the "abyss of hallucinations."

The totality of existence seems to be arranged like this:
There is a causal beingness which is all creation. This causal beingness plays a game of being aware by dividing itself in a number of ways, placing some of its divided parts at "know", but others at "unknowable". These parts are further divided by arranging for them to not know one another, separating them and thus creating space(s). All spirits, all thought, all emotion, all efforts, all matter -- in an infinite number of universes -- are parts of this causal beingness. Individuals such as ourselves are separated awarenesses which have self commanded (forget that paranoid implantation crap, that's lower level stuff which occurs inside a physical universe) to not know, not be, all the other awarenesses. In addition to that, individuals such as ourselves are also a spacial location inside a universe, which is used as a point from which to view that universe. So there's two levels to a person: the individual (which is "outside" the physical universe), and the individual's viewpoint in this space.

There have been anecdotal reports of people waking up in the higher beingness and discovering that they as an individual are having a multitude of viewpoints in various places. A certain other researcher who eventually failed was informed of this fact by some of his clients back in 1952 but the poor redhead didn't follow up on the information, and spent the rest of his career attempting to accomplish nothing beyond cleaning up people's dirtied locations assumed in the space of this universe. Which is doomed to fail because the only thing which can clean the mud off the face of the POV is the individual which is NOT inside the physical universe. Which is why to do zero point, by the way! :)

The viewpoint in the universe has a number of serious problems which arise simply because it IS a viewpoint. Reality is created WITHIN the aware beings, i.e. IT IS PERVASIVE in nature. So any view which is separate from that viewed (object oriented perception) is both distorted and incomplete. And because the perception of a viewpoint locked into a single physical universe's time track is so bad, it denies almost as much as it fails to perceive, leading to the blacking out of much of its awareness in present, past and future. Which leads us to that damned "abyss of hallucinations" again. Instead of stripping away the blackness and invisibility used to make things unreal, the viewpoint uses its immense powers of creativity to fantasize a new "reality" atop the blackness. Of course it is only a reality for one (which is the true state of affairs at the top too, though the "one" at the top is everything serenely aware of being fragmented.), and no other viewpoint sees what that viewpoint sees. Strictly speaking, that's crazy.

This becomes really hairy when processing and meditating. As one's awareness increases two things are happening simultaneously:
1. The viewpoint is waking up as the individual, which is aware of spaces and alternate realities beyond this single physical universe time track.
2. The layers of blackness and invisibility is coming off unevenly, revealing hidden considerations of disability and unawareness, which in turn is filtered through the ideas and fixed mental anchor points which the viewpoint is clutching desperately to keep from spinning. These fixed ideas are used to generate further hallucination by taking a disability or unawareness and clothing it in some sort of fantasy narrative framework in order to explain it. Even if the "why" isn't hallucinated and an actual past incident which occurred in the presence of the viewpoint is found, it is still a partial lie because there is never any reason for a creation, and that includes the creation of a disability. To use another groups terms: not only is there no prior reason or justification for an "overt" (a harmful act) which the person commits, neither is there a prior reason for a motivator (a harmful event which happened "to" a person). Reasons are all lies because there are no time tracks where the individual really exists. There is only creation, which has no reasons. So the entire matter of "probable realities" as mentioned above becomes little more than sorting out what creations are are intended to cover up other creations, which of them are solo, which are shared, which belong to other individuals and have been *ahem* "borrowed", and what assignments of sequence and association are assigned to various realities. That latter is a higher level activity similar to the sorting out process undergone in what another group calls "NOTs". Much of the advanced NOTs style handling in the group's splinters -- such as upper levels of Capt Bill, and the Ananda rundowns -- are fully immersed in the mad activity of filtering their perceptions of their own cases through fixed ideas (as I mentioned above), and these poor bastiches dub in even worse things than the ghosts of dead space aliens. They get wins but they also get trapped into fighting "evil" forces in their own minds, not unlike the practitioners of Kabbalah-based magick with their Qliphoth. (At least they seem to be getting at correct assignments of what creations are whose...)

This is the situation encountered by magicians when they start out, and is sometimes dubbed the "lower astral plane." Calling it that, or calling it the Abyss of Hallucinations, doesn't explain it. Those are just fancy names. The truth is that any beingness, whether a single viewpoint locked into one time track or an individual separate awareness above time tracks, is a creator. You and I and everyone are creators. And our activity is solely and only to create realities, apparently the more the better. Which seems to have become quite a mess, as we have lost track of most of what we are creating.