So, for instance, there are branches of the multiverse in which I never allocated time to writing this Manifesto, and spent the time mixing down some of my music recordings instead. There are branches where I did write this Manifesto, but made it slightly less silly by omitting this sentence. Etc.
Borges envisioned a multiverse-like cosmos in his story "The Garden of Forking Paths," but quantum theory made the notion more concrete, via positing it as a solution to the "quantum measurement problem." Roughly speaking, quantum theory comes out much simpler if one assumes we live in a multiverse rather than a conventional, single universe.
Beyond the Multiverse
Quantum theory doesn't do it, but one can also go beyond the multiverse. One can imagine a family of multiverses, where each one is based on certain assumptions that span all their branches. For example, one could have multiple multiverses each obeying different laws of physics. Then one would have a multi-multiverse.
And why stop there?
Ultimately one arrives at a multi-multi-...-multi-verse, which I have given the name "Yverse,", defined as
Yverse = multi-Yverse
A Y-verse is, to put it crudely, a set of branches, each of which is a Yverse. This is different from an ordinary multiverse, each of whose branches is not a multiverse but an ordinary universe.
The mathematics and physics of Yverses remains to be elaborated!
What Is this "Place" We Live?
Why am I bothering to throw these speculations at you?
Mainly to make the point that the cosmos may be a much subtler and odder place than we currently understand.
Quantum theory, which currently baffles us so profoundly, may just be scratching the surface of deeper models and understandings of reality, which transhuman minds will comprehend.
We should not be so narrowminded and egomaniacal as to assume that our current understanding of the universe -- or our current, wild-ass speculations -- are anywhere near complete or correct.