A multiverse that produces many space-time continuums (infinite or otherwise), is plausible, since we have relatively well-supported cosmological theories that naturally predict such.
Not actually true at all, really. Of course, there are many cosmologists and others who use the term "predict" to include e.g., "would require" (in the say that string theories "predict" supersymmetry because string theories require SUSY at a foundational level), or "in retrospect" (the way that the Dirac sea and his Hole Theory "predicted" both positrons and antimatter more generally), and worse. But the basis for multiverse cosmologies are largely about fine-tuning and unnaturalness, i.e., that the empirical and theoretical basis for the standard model of cosmology yields something that seems contrived, designed, unnatural, etc., in a number of ways that feel too uncomfortably similar to the introduction of pre-Copernican princniples which place us at the center of a universe:
"Despite the growing popularity of the multiverse proposal, it must be admitted that many physicists remain deeply uncomfortable with it. The reason is clear: the idea is highly speculative and, from both a cosmological and a particle physics perspective, the reality of a multiverse is currently untestable...For these reasons, some physicists do not regard these ideas as coming under the purvey of science at all.
Since our confidence in them is based on faith and aesthetic considerations (for example mathematical beauty) rather than experimental data, they regard them
as having more in common with religion than science."
&
"To the hard-line physicist, the multiverse may not be entirely respectable, but it is at least preferable to invoking a Creator. Indeed anthropically inclined physicists like Susskind and Weinberg
are attracted to the multiverse precisely because it seems to dispense with God as the explanation of cosmic design"
(emphases added)
Both quotes are taken from the editorial introduction to the volume
Carr, B. (Ed.). (2007).
Universe or multiverse?. Cambridge University Press.
A similar volume by some of the same specialists and some new contributors was produced two years ago and is worth reading:
Fine-Tuning in the Physical Universe.
Or, more simply, from a series that is less intended for specialists (but still produced by an academic publishing company in a edited monograph/volume series, in way that peer-reviewed journals are) :
"'miraculous' features of the standard model that seem to be carefully designed for the existence of life can also be understood if we take the view that we live only in one of the many universes which satisfies the conditions for life to exist."
&
“Suppose there was only one universe.
Then it would be very difficult to explain miraculous features of our universe, such as the structure of elementary particles and the value of the vacuum energy, without resorting to some sort of creator.
In the multiverse picture, however, there are an enormous number (10^500 or more) of different universes, so some of them possess these miraculous features that lead to intelligent life, without a help of any creator. This, of course, does not prove that there is no such creator, but given that a goal of science is to try to understand our physical nature as much as possible without relying on such an almighty person, the approach of the multiverse is exactly that of science.” (emphasis added)
Quoted from
Y. Nomura (2018) Misconceptions about the Multiverse. In Y. Nomura, B. Poirier, & J. Terning (Eds.):
Quantum Physics, Mini Black Holes, and the Multiverse: Debunking Common Misconceptions in Theoretical Physics (Part III: Misconceptions about the Multiverse). Springer.
Now, statements like the above are contentious, in that it is perfectly acceptable to feel that cosmological models which have fine-tuning, naturalness, and related issues are problematic without believing that they have anything to do with a designer (even if they appear to introduce design-like qualities). But the point is that the evidence for such models is based on aesthetics and intuition about existing, supported theories being too seemingly contrived or requiring too great a number of coincidences and so forth. It is only in the sense that multiverse cosmologies or aspects thereof are thought to (in some cases) remove these issues is it the case that they are "predicted". But by that logic, so is God. So no, they aren't predicted.
