THE multiverse is dead, long live the multiverse. A radical new way of looking at quantum mechanics suggests that even the multiverse will come to an end.

A popular view of the multiverse says that our universe is just one of an ever-inflating multitude of discrete "bubble" universes. These bubbles are eternally budding off new universes even as individual universes age and die.

But a new view of quantum effects – the brainchild of Sean Carroll at the California Institute of Technology and his colleagues – challenges this picture. It is also potentially very useful to quantum theorists, as it does away with some thorny issues that currently dog cosmology, including a particularly baffling paradox involving disembodied consciousnesses known as "Boltzmann brains".

Carroll's insight comes from a fresh way of looking at random motions known as quantum fluctuations.

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