There was an old lady who swallowed a fly: ‘The universe might make more sense if it were not alone… The idea of multiple universes is a surprisingly attractive one.

Two deep problems would go away if the universe were not, in

fact, universal, but were merely one example of an infinitely

large class of such objects. These problems are the true

nature of the uncertainty principle, and the “anthropic

principle”—the coincidence that the universe seems to be set

up with precisely the right conditions for human-like life to

evolve within it. Unfortunately, the sorts of “multiverse”

proposed to resolve these two problems are different.’ The Economist