Gambling on the existence of other universes

Abstract: Speculations and theories about the existence of other worlds have a long history. In recent times, the arguments have shifted away from their typical philosophical and theological character to supposedly become more objective thanks to their scientific underpinnings. A prime example of this is the current parallel universes or multiverse theory, which has the support of a number of famous cosmologists. In this article, we contend that the claim for the existence of those parallel universes, as presented in Max Tegmark's book "Our Mathematical Universe", rests crucially on some questionable probability arguments involving infinity. As a result, a doubt is cast over the multiverse hypothesis: Is it more credible than the counterarguments based on philosophical and metaphysical considerations?