A couple years ago, I ran across a Get Fuzzy comic strip (see below) relevant to the multiverse. It plays off a popular confusion people encounter when dealing with probabilities and large sample sizes.
P.S. The Get Fuzzy comic strip below in the original article is from December 23, 2007.
The main point is that given a large enough sample size, every possibility happens. This conclusion rests on the assumption that the monkeys' typewriters never jam.
Many multiverse advocates use a similar argument to explain the highly improbable appearance of our universe and its ability to support life. If this single universe constitutes all physical reality, then its highly improbable nature provides evidence for a supernatural Designer. If some mechanism routinely spawns new universes with different physical laws and constants, then our universe becomes inevitable.
Cosmic inflation appears to provide just such a mechanism. And string theory indicates that a vast number of different possible laws of physics and their associated constants are possible. However, a recent article in Physical Review D indicates that the cosmic inflation mechanism may jam the typewriters.
Typically, cosmologists use a quantity referred to as a scalar field to describe the mechanism of inflation. Although it is common to use only a single scalar field in inflation models, a realistic model will likely require more than one. In cases requiring more than one field, the research described in the article shows that such models typically exhibit "naked timelike singularities." Stated another way, these models exhibit a boundary to time. The existence of these time boundaries means that inflation must come to an end.
Returning to the typing monkeys analogy, the timelike singularities effectively jam the typewriters. Such a jam may mean that a multiverse doesn't produce enough universes for one like ours to arise. Clearly more research remains, but this article highlights that numerous obstacles exist for the naturalist who wants to use the multiverse to avoid evidence for a supernatural Creator/Designer.
If you would like to see a question about the multiverse addressed in this forum, send it to firstname.lastname@example.org.