I know that metaphysics has to do with the fundamental nature of reality. I am just not sure if a multiverse is considered fundamental
- One might want to check out the very similar post Should multiverse theories be rebranded as meta physics?.
I will not dare to answer your question myself, since I have no clear definition of metaphysics up my sleeve. Because of this lack of experience, I can also not give you a good compendium. The following is what I found after a quick search:
I'll just mention another public-comments post, dealing with these issues: Landscaping The Cosmic Garden.
There is a book called Worlds Without End. The Many Lives of the Multiverse by Mary-Jane Rubenstein which sais the following in the book's description:
In their very efforts to sidestep metaphysics, theoretical physicists propose multiverse scenarios that collide with it and even produce counter-theological narratives.
Again: I haven't thoroughly looked through these sources. I hope you invoke on an interesting intellectual progress though, wishing you a fruitful and enjoyable contribution to science.
Metaphysics is the name of a book by Aristotle; and not named by him; it meant simply 'after the physics'; and simply suggested that it was to be read in that order - or understood in that order. Its only much later that it had the connotation that is now generally given to it.
Aristotles metaphysics critiques the notions of his Physics - questions of Place, Time, Body, the Continuum and what is to be understood as a principle of nature ie a Law.
Given this, I'd suggest that it is in one sense, and isn't in another; which isn't that helpful...(personally I tend to think of it as esoteric physics).