Denise O'Leary offers us a nice summary of the multifarious theoretical contrivances dreamed up to explain away the fact that the astonishing fine-tuning of our universe points to the existence of an intelligent designer of the cosmos.
The theories manufactured to avoid that conclusion range from the multiverse, to many-worlds, to the notion that our universe is a simulation developed by a higher intelligence in some other world (Why anyone would argue that there's a transcendent intellect out there powerful enough to create a world and personal enough to create personal beings while at the same time arguing against the existence of the God of theism is a bit of a puzzle).
In fact, there's no empirical evidence for any of these theories. They're embraced because they afford shelter from the dreaded theistic conclusion and because they could be true in the same sense that it's possible that a meteorite will fall from the sky and come to rest perched delicately on the tip of your car's antenna.
Advocates embrace the "It could happen therefore it probably did happen" defense because when in the throes of philosophical desperation any possibility is going to look appealing, even if it means abandoning theoretical criteria held dear by thinkers for centuries.
For instance, these hypotheses flout one of the prime criteria for a "good" scientific or philosophical explanation, the principle of simplicity or parsimony. This is the principle that requires that a proffered explanation explain the relevant data more simply than its competitors if it is to be preferred to its competitors. There's nothing simple, however, about trying to explain the existence of our highly fine-tuned world by positing an infinity of other worlds, particularly when the alternative is to posit a single intelligent agent.
There are numerous other difficulties with these theories as well, as we've discussed from time to time at this site. For one last example we might ask if there really are an unimaginable number of worlds comprising the multiverse, what produced them? From whence did they arise? No one has any idea. Indeed, if there were not the need to somehow avoid the "God conclusion" it's doubtful that these theories would be entertained for more than a few seconds by anyone other than science fiction writers.
Anyway, for a good overview of the current state of desperation among naturalistic scientists and philosophers check out O'leary's column.