STRANGE as the idea of other universes is, it has become almost commonplace in physics. Parallel worlds are central to one interpretation of quantum mechanics. Inflation versions of the cosmological theory also imply that there is an infinite tree of branching universes. Cosmologists have even suggested that there could be parallel universes a millimetre away along some higher dimension.
In Parallel Worlds, Michio Kaku explores this conjectured multiverse with a particular end in mind. Our own universe is likely to become inhospitable to life one day, and Kaku believes that a sufficiently advanced civilisation might be able to escape…
