The Ultimate Guide to the Multiverse

Yet another cover story about the Multiverse can be found this week at New Scientist, which calls it The Ultimate Guide to the Multiverse. As just one more in a long line of such stories over the last decade, a trend that shows no signs of slowing down, one can be pretty sure that this is not yet the “ultimate” one, nor even the penultimate one.

The content is the usual: absolutely zero skepticism about the idea, and lots of outrageous hype from the usual suspects (Bousso, Tegmark, Susskind, etc.) We’re told that scientists are now performing tests of the idea, even at the LHC. The LHC test has been a great success: Laura Mersini-Houghton used the multiverse to predict that the LHC would not see supersymmetry, and that prediction has worked out very well so far. There’s a companion editorial Neutrinos and multiverses: a new cosmology beckons, which tells us that the multiverse is now orthodoxy, backed by “almost everything in modern physics”:

The widest crack of all concerns a theory once considered outlandish but now reluctantly accepted as the orthodoxy. Almost everything in modern physics, from standard cosmology and quantum mechanics to string theory, points to the existence of multiple universes – maybe 10⁵⁰⁰ of them, maybe an infinite number.

If our universe is just one of many, that solves the “fine-tuning” problem at a stroke: we find ourselves in a universe whose laws are compatible with life because it couldn’t be any other way. And that would just be the start of a multiverse-fuelled knowledge revolution…

These are exciting, possibly epoch-making, times.

This past week also saw the premiere of the Multiverse episode of Brian Greene’s Fabric of the Cosmos series on PBS. It’s more or less an hour-long infomercial for the Multiverse, with the argument against it pretty much restricted to some short grumpy comments by David Gross about how he didn’t like it. Brian’s pro-multiverse argument was that many new advances in physics are all pointing to a multiverse, and he showed support for the idea as resting on a three-legged structure. One of the legs was string theory, and I’ve described elsewhere recently how circular reasoning makes this one very shaky.

The multiverse propaganda machine has now been going full-blast for more than eight years, since at least 2003 or so, and I’m beginning to wonder “what’s next?”. Once your ideas about theoretical physics reach the point of having a theory that says nothing at all, there’s no way to take this any farther. You can debate the “measure problem” endlessly in academic journals, but the cover stories about how you have revolutionized physics can only go on so long before they reach their natural end of shelf-life. This has gone on longer than I’d ever have guessed, but surely it has to end sooner or later, and I have no idea what rough beast will slouch onto future covers of New Scientist and episodes of Nova a few years down the road.