The ongoing pseudo-scientific multiverse mania continues, with the recent publication in the UK of a new book by John Gribbin promoting this to the public: In Search of the Multiverse.
Gribbin expounds at length the usual string theory anthropic landscape/multiverse ideology, carefully avoiding introducing any mention of the fact that there might be quite a few scientists skeptical about it. On the crucial question of testability he invokes Raphael Bousso, who:
hopes, and expects, that there will be ways to extract such broad rules of the behaviour of matter at what are low energies compared to the Big Bang, but high by the standards of everyday life, from string theory.
There’s no indication given about what these broad rules implied by string theory might be, just a hint that whatever they are, we’re not going to be able to test them anytime soon:
even the the technology of the Large Hadron Collider may not be up to the task of testing such predictions.
Like many multiverse fans, Gribbin wants to mix together the many worlds interpretation of QM and the string theory anthropic multiverse in cosmology, attributing this insight to Susskind, and ending the next to last chapter of his book with:
This pulls together everything discussed in this book so far in such a pleasing way that it is tempting to end it here. The Cosmic Landscape of string theory is just the many worlds theory of David Deutsch writ large, and with inflation included within itself.
Unfortunately he doesn’t end the book there, but adds a final chapter promoting his own interpretation of the significance of the multiverse. His idea is that we are the product of a baby universe created by some race of superior beings:
The intelligence required to do the job may be superior to ours, but it is a finite intelligence reasonably similar to our own, not an infinite and incomprehensible God. The most likely reason for such an intelligence to make universes is the same as the reason why people do things like climbing mountains or studying the nature of subatomic particles using accelerators like the LHC – because they can. A civilization that has the technology to make baby universes might find the temptation irresistible, while at the higher levels of universe design, if the superior intelligences are anything at all like us there would be an overwhelming temptation to improve upon the design of their own universes.
This provides the best resolution yet to the puzzle Albert Einstein used to raise, that ‘the most incomprehensible thing about the Universe is that it is comprehensible.’ The Universe is comprehensible to the human mind because it was designed, at least to some extent, by intelligent beings with minds similar to our own. Fred Hoyle put it slightly differently. ‘The Universe,’ he used to say, ‘is a put-up job.’ I believe that he was right. But in order for that ‘put-up job’ to be understood, we need all the elements of this book.
Personally, I think there’s an air-tight argument against this: any race of superior beings that produced a universe in which science descended into this level of nonsense would immediately wipe out their creation and start over. Since we’re still here, there can’t be such a race operating out there.
Gribbin also has a Sci-Fi novel entitled Timeswitch coming out soon.
In other multiverse news, FQXI has a story here promoting Andrei Linde, Renata Kallosh and their work on the string theory multiverse. Linde and a collaborator have a new paper How many universes are in the multiverse? on hep-th (by the way, why are these things not in qr-qc, since they’re “quantum cosmology” if anything is?). They come up with a number of 10 to the 10 to the 375 for the number of universes, and seem to argue that one needs to analyze all these to come up with predictions:
But when we study quantum cosmology, evaluate the total number of universes and eventually apply these results to anthropic considerations, one may need to take [the number of degrees of freedom of the observer] into account. Potentially, it may become very important that when we analyze the probability of existence of a universe of a given type, we should be talking about a consistent pair: the universe and an observer who makes the rest of the universe “alive” and the wave function of the rest of universe time-dependent.