An interesting article in New Scientist:
A measure for the multiverse
03 March 2010 by Amanda Gefter
Despite the many virtues of the multiverse, Ellis is far from alone in finding it a dangerous idea. The main cause for alarm is the fact that it postulates the existence of a multitude of unobservable universes, making the whole idea untestable. If something as fundamental as this is untestable, says Ellis, the foundations of science itself are undermined.
One of the guests at Ellis’s party doesn’t see it that way. Raphael Bousso of the University of California, Berkeley, has also been grappling with the multiverse, and in the past few months he has found a way round the troubling problem of unobservable universes. At a stroke, he has transformed the multiverse from a theory so problematical that it threatens to subvert science, into one that promises predictions we can test. His insights are steering physicists along the path to their ultimate goal of uniting quantum mechanics and gravity into one neat theory of everything.
Read the whole article at New Scientist.