Life in the Multiverse

The latest Scientific American features a cover story on Life in the Multiverse: Could the strange physics of other worlds breed life? The magazine earlier this year fired a third of its staff and replaced its editor (the new editor has a column this month about the Multiverse and Star Trek).

I don’t think one can blame the new editor for this though. Over the last few years, Scientific American has made multiverse pseudo-science stories a staple of its coverage of science. See for instance Parallel Universes, The String Theory Landscape, The Great Cosmic Roller-Coaster Ride and Does Time Run Backwards in Other Universes?

Update: Alejandro Jenkins and Gilad Perez, the authors of the Scientific American piece, pointed out to me something that I really should have made clear in this posting, that their arguments about the possible implications of a multiverse are of a different nature than those in previous Sci Am articles. They are arguing not for or against a multiverse, but against some popular anthropic arguments that try and explain the values of fundamental constants as being necessary for life. Anyway, my apologies to them for not making this clear, and here’s something they sent me explaining in more detail their point of view:

The title of our article in the current issue of Scientific American –as well the first bullet for the “Key Concepts” — might give the impression that our work argues for the reality of the multiverse, but this isn’t really the case.

Our research suggests skepticism about the usefulness of anthropic selection arguments when applied to particle physics (see the references below). The anthropic argument seems reasonably convincing when applied exclusively to the cosmological constant, as Weinberg did in 1987. But our own work shows that the parameters of the strong and weak interactions could be significantly different from what they are, without there being any obvious obstruction to the evolution of organic life. This means that the anthropic principle might not be enough to explain the microscopic laws of particle physics. In this sense, then, our story counter-balances the claims made previously by other experts about many of the parameters of the Standard Model being obviously “fine-tuned for life” (and therefore admitting an anthropic explanation).

Our work is simply based on varying the parameters of the Standard Model and trying to understand how things would change from what we see in our world. It is true, though, that this intellectual exercise is motivated in part by the expectation from inflationary models (and from certain speculative proposals for the physics at the Planck scale) that the fundamental physics might produce many distinct universes besides our own.