The Mystery of the Missing Antimatter , Helen R. Quinn and Yossi Nir , Princeton U. Press, Princeton, NJ, 2008. $29.95 (278 pp.). ISBN 978-0-691-13309-6
In the February 2003 issue of Physics Today, Helen Quinn published a fascinating article, “The Asymmetry Between Matter and Antimatter” (page 30), which discussed the unexplained prevalence of matter over antimatter in the cosmos. I remember reading and rereading that article several times, making sure I was citing her insights correctly for an astrophysics text I was updating at the time. So, when I was asked to review Quinn and Yossi Nir’s The Mystery of the Missing Antimatter, it took me only about 10 seconds to send back my e-mail response: “Helen Quinn is always knowledgeable and interesting. I’ll be very pleased to review the book.”
Why is the cosmic matter–antimatter asymmetry so intriguing? It is because we now know that the universe once was immensely hot. In thermal equilibrium, photons, baryons, and antibaryons would have been roughly equally abundant. Today, however, photons outnumber protons by roughly a billion to one, and antiprotons are essentially absent, created almost exclusively in rare, exceptionally violent cosmic explosions. Evidently, matter and antimatter annihilated early as the cosmos cooled during expansion, leaving behind an abundance of photons and tiny amounts of matter that had exceeded the primordial antimatter by just one part in a billion. The question the authors address is how that tiny excess of matter over antimatter might be explained.
With its beguiling title and fanciful cover, the book appears designed for youngsters and other interested lay readers. No tables, no heuristic diagrams, no bibliography interrupt the text. The only equation is E = mc 2. A few fanciful illustrations sprinkled throughout the text show Wonderland’s Alice running through an accelerator to catch an electron in a butterfly net; an elephant sitting on a chair that is breaking under its weight; and a donkey surrounded by pails of water, unable to decide from which one to drink.
But Quinn and Nir’s book is definitely not a popularization. Books written for the general public require careful introduction of unfamiliar matter, which the authors largely neglect. The expression E = mc 2 first appears on page 22 as “the energy of [a] particle at rest.” The reader has to wait until page 170 to find that c stands for the speed of light. Similarly, on page 20, the authors write about an early cosmic temperature “above 1032 kelvin,” but the kelvin is not defined until page 24, in the following chapter. The needs of novices remain unmet. The deeper the reader delves into the text, the more apparent it becomes that this is a book that mainly scientists will appreciate.
For me, and I suspect for most physicists, the greatest attraction is observing how Quinn, a professor of physics at SLAC, and Nir, a professor of physics at the Weizmann Institute of Science in Israel, systematically tackle the matter–antimatter asymmetry problem. They reject one possibility after another until only a few alternatives appear viable. The greatest hurdle to mastering the contents of the book is the authors’ deliberate choice to present their complex arguments almost entirely in prose form. That makes it difficult even for a professional physicist to fully appreciate their points. A set of carefully designed diagrams could have provided, an overview, which is hard to cull from page after page of text.
Frequent distractions arise whenever the names of high-energy-physics Nobel laureates appear. The flow of the text is then sidelined to provide the full name and dates of birth and death (unless still living) for each awardee, plus the year when the prize was awarded. In contrast, for unexplained reasons, other notable physicists such as J. Robert Oppenheimer, Hendrik A. Lorentz, and Robert A. Millikan are not referred to by more than surname, making it difficult for unfamiliar readers to know who they are.
Although the publisher advertises the book as “a history of ideas,” much of that history is confined to a 38-page appendix. Titled “Timeline of Particle Physics and Cosmology,” it is a compendium of paragraphs, each highlighting and dating a significant advance in high-energy physics or cosmology. Nobel laureates are again prominently featured, which gives the impression that, in the eyes of the authors, the histories of these fields are largely fueled by the efforts of this select group of prize winners—a thesis I don’t believe stands up to scrutiny.
The Mystery of the Missing Antimatter had all the makings of greatness. Yet somewhere along the line, the authors tried to serve too many masters and failed to serve any well.
