Locality is the reach-out-and-touch-someone principle, the idea that, in order for one thing to affect another, something must reach across the distance between them—maybe an electrical signal, as in the case of telephones, maybe the force of gravity, as with Earth’s pull on a teacup you let slip. For most of us most of the time, the physical world works that way, but there are reasons to believe that locality isn’t a fundamental feature of the universe, that some things can be connected without anything passing between them. In this new book, published in November, science writer George Musser gives us a primer on nonlocality, exploring some fabulously bizarre issues in modern physics: quantum entanglement—the idea, repeatedly demonstrated, that what happens to a certain particle here can instantly affect one elsewhere, whether across the room or across the universe; a problem with black holes—the possibility that what gets into a black hole might reemerge later; and the cosmic horizon problem—why galaxies on opposite sides of the universe bear similarities though it seems they could never have been subjected to shared influences.
Though quantum entanglement will be familiar to anyone who keeps up with science news, these are knotty issues, and Spooky Action at a Distance—the title comes from a phrase of Einstein’s—doesn’t entirely untie them. Musser assumes a touch more knowledge on the part of readers than necessary. A few sentences recapping such things as the photoelectric effect or gauge fields would’ve helped. Similarly, Musser’s explanations of recent and current work sometimes left me scratching my head, though that may be the fault of my head. For instance, his account of the holographic principle and of theorist Juan Maldacena’s AdS/CFT proposal was less clear than others I’ve read. But explaining such concepts must be nearly as difficult as working with them, and for the most part Musser does it well.
An implication of the work discussed in this book is that space as we ordinarily think of it may not really exist. As Musser puts it in one of his chapter titles, spacetime is doomed; in the words of cosmologist Sean Carroll, “Space is totally overrated, whereas time is underappreciated.… I think that time is going to last.… Space, on the other hand—totally bogus.” However that plays out, in our macro world time still matters, and in one small way the text of this book has already fallen behind: a fascinating thing that the book suggests you can do on your own—obtain a graph of Facebook relationships via the Wolfram Alpha site—is no longer possible. But Musser’s use of it, as a prelude to his discussion of something amusingly called “quantum graphity,” is still illuminating.
On the whole, Spooky Action at a Distance is an enjoyable, surprisingly light, almost dancing survey of some profound scientific questions and their interplay with philosophical issues. Readers with a taste for the latter may enjoy seeing how Leibniz’s concept of monads, which I haven’t seen mentioned in ages, figures in. But science isn’t only a product; it’s also a process, and this book is partly a story of how, when, and sometimes whether particular scientists have engaged with the issue of nonlocality. Musser captures science in the forge, as it’s being made, by men and women who are struggling, with each other as much as with the concepts, to make sense of what seems to be a strange logical variety of nonsense. (For more on the social aspects of science as discussed in this book and others, see Adam Gopnik’s recent New Yorker article.)
The X-Files used to proclaim, in the title sequence of almost every episode, “The truth is out there,” a pithy double entendre suggesting both that the truth remains to be conclusively determined and that it’s pretty weird. As Musser makes clear in this book, the same can be said of nonlocality.
(Notes: I read an advance proof but determined via Amazon’s Look Inside feature that the wording about the Facebook graph remains the same. This review also appears on Goodreads.)