Waving not drowning

Another of my reviews, this from WSJ

It is their house style that puts the “Mr” in!

Book Review: ‘The Perfect Wave’ by Heinrich Päs
Does the neutrino, the ‘outlaw’ particle that weighs less than one millionth of the weight of an electron, hold the secret to the universe?
By
John Gribbin
April 15, 2014 6:56 p.m. ET

Some science books are good because they tell you a lot about science. Some are good because they present their examples and argument in very well written prose. A few do both. “The Perfect Wave” is one of the few.

Heinrich Päs is a particle physicist who loves his work, and it shows. That work mainly has to do with the elusive particles known as neutrinos, which have very little mass and no electric charge, and which travel very nearly at the speed of light, scarcely deigning to interact with any other particles as they zip not only through the universe but also through the solid Earth (and your body as well). Mr. Päs dubs the neutrino the “outlaw” particle because ofits bizarre properties. Why should we bother with it? Well, for a start, “although every single neutrino weighs less than one millionth of the weight of the tiny electron . . . they are so abundant that altogether they contribute about as much mass to the universe as all the stars combined.”

A couple of years back, neutrinos made headlines when results from a European experiment suggested that they might actually travel faster than light (and therefore backward in time). The experiment turned out to be faulty—there was a loose cable somewhere. But Mr. Päs suggests, in what he confesses is a speculative extrapolation from the current standard model of physics, that neutrinos really might be able to travel in time.

Yet that is merely the denouement of his intriguing story, which starts out with the ancient Greeks and carries us smoothly forward through the 20th-century development of particle physics to the present day frontiers of respectable speculation. “The Perfect Wave: With Neutrinos at the Boundary of Space and Time” provides a conventional but well-presented introduction to the mysteries of quantum mechanics, including the obligatory mention of Schrödinger’s cat, which is both dead and alive at the same time. Quantum aficionados will recall that, in 1935, Erwin Schrödinger devised this “thought experiment” in which a cat in a sealed room will die if a radioactive atom decays but will remain alive if the atom does not decay. According to the quantum rules, it remains suspended in an either/or state until someone looks to see what is going on.

Like an increasing number of his contemporaries, Mr. Päs suggests that the best resolution to the puzzles of quantum theory (such as the mystery of Schrödinger’s dead-and-alive cat) lies in the so-called Many Worlds Interpretation, or the multiverse, in which all possibilities are realized. So, for example, there is one universe with a dead cat and one with a live cat—not a single reality in which the cat is dead and alive at the same time. These universes do not interact with one another, and there is no direct evidence to prove they exist. But the recent discovery of gravitational ripples from the dawn of time suggests to some cosmologists that the idea should be taken seriously, as these ripples are evidence for the theory that the universe expanded rapidly after the Big Bang. Mr. Päs explains various scenarios for such an “inflation,” including that of “eternal inflation, in which new baby universes keep popping up like bubbles out of nothing.”

Mr. Päs is careful to build up to multiverse theory gradually, via the ideas of string theory—the notion that what we think of as “particles” (such as the electron) are actually tiny loops of vibrating “string.” This requires the possibility that our three-dimensional universe(four-dimensional if you include time) is embedded in some set of higher dimensions—an explanation that attracts Mr. Päs, in no small measure because it “could protect time travelers from ludicrous paradoxes, and in this way make time travel a meaningful physics concept.”

You have to like a scientist who can admit to such a sentiment. And, indeed, the scientific discussion in “The Perfect Wave” is leavened by the author’s account of his own life as a young researcher, excited by new discoveries and struggling to get his own ideas recognized. We meet the physicists who work at research centers such as the European particle physics laboratory CERN, and we learn about the ups and downs of “postdoc” life: ups when traveling the world to conferences in exotic places and doing work you love; downs with appointments that last for only two years at a time, with low pay. But clearly, for people like Mr. Päs, the ups outweigh the downs.

Along the way “The Perfect Wave” introduces the reader to some of the key players in the neutrino story, including Ettore Majorana, a figure as mysterious as the particle itself. A close contemporary of Werner Heisen berg and Niels Bohr, he was a near-recluse who scribbled ideas and calculations on cigarette packets, then threw the packets away when he had finished, usually without bothering to publish his results. Majorana becameodder and odder, and on March 26, 1938, he disappeared, probably after boarding the Naples-Palermo ferry. But he took with him his passport and all his money, seemingly ruling out suicide.

I will leave it to Mr. Päs to explain the significance of Majorana’s work to the story of neutrinos and the significance of neutrinos to the story of time travel. But Majorana’s ideas still make waves today: They “could, for example, make the neutrino responsible for the fact that the universe consists of matter with barely any antimatter, or explain why neutrinos could convey information about a Grand Unified Theory of all particles and forces.” This, remember, is the sober, “responsible speculation” part of the story. If contemplating such possibilities is the sort of thing that appeals to your taste, I can highly recommend “The Perfect Wave” as a pleasant and provocative way to gain insight into the way physicists think, and into the way the universe (probably) works.

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