We don't even know what's going on, but we do computer simulations of it
A universe containing life like ours is probably more common in the multiverse than previously thought, according to new theoretical studies.
Sadly the multiverse is a part of pulp fiction and about as solid science as Star Trek time-travel wormholes. It's a way to avoid having to solve the hard problems while feeling pretty good about it.
The idea of multiple universes existing in parallel has gained traction in the last few decades
This is a mistaken belief that is generated by looking at the flashy dubious papers, lavishly illustrated popular science output and sellable bookware. There is not even a consenseus on what the Multiverse is (the interpretations range from Everett Multiverses (a new universe on each decoherence, an incoherent idea if there ever was one) to Linde Multiverses (one infinite universe with many domains) to Guth Multiverses (eternal inflation with universe bubbles) to String Landscape Multiverses (I don't even know in what the Stringoverse Landscape lives).
The Degenerated Science that is the Multiverse (soon to be merged with SJW-ness into the Multicultiverse, I imagine) is deservedly ripped at the Multiverse Mania part of Peter Woit's Blog.
In particular, we read: New Year’s Multiverse, January 2017 and from 15 Years of Multiverse Mania, January 2018:
Back in 2003-4 I never would have believed that the subject would end up in the state it finds itself in now. With the LHC results removing the last remaining hope for observational evidence relevant to string theory unification, what we’ve been seeing the last few years has been a concerted campaign to avoid admitting failure by the destructive tactic of trying to change the usual conception of testable science. Two examples of this from last week were discussed here, and today there’s a third effort along the same lines, Quantum Multiverses, by Hartle. Unlike the others, this one includes material on the interpretation of quantum mechanics one may or may not agree with, but of no relevance to the fundamental problem of not having a predictive theory that can be tested. ....
.... A good place to look for information about the current state of string landscape [one special form of the multiple interpretations of the "Multiverse"] calculations is at the website for this workshop. The idea that the problems of this subject can be solved by “modern techniques in data science” seems to me absurd, but for a different point of view, look at the slides of Michael Douglas. For something more sensible, try the talk by Frederik Denef, which describes some of the fundamental intractable problems:
-> You don’t have a complete theory, with only some non-perturbative corrections known, no systematic understanding of these.
-> Dine-Seiberg Problem: When corrections can be computed, they are not important, and when they are important, they cannot be computed.
-> Measure Problem: Whenever a landscape measure is strongly predictive, it is wrong, and when it’s not, we don’t know if it’s right.
-> Tractability Problem: Whenever a low energy property is selective enough to single out a few vacua, finding these vacua is intractable.
Denef does make some very interesting comments about where modern techniques in data science might actually be useful: dealing not with the landscape of string vacua, but with the huge landscape of string theory papers (e.g. the 15,000 papers that refer to the Maldacena paper).