March 2013

Mary Mann


A Palette of Particles by Jeremy Bernstein

In college I took a physics course. I walked away from every class feeling just as frustrated and confused as I did in second grade when I stayed after class to confront Mrs. Rollins about the nonsensical nature of subtraction. For us non-physicists, academic physics elicits the same cries of anguish as subtraction does for the average seven-year-old: it's just so much slippery math.

Since those early days of mathematical fury I have developed a spectator's fascination for higher math and science, probably in part because so many of the concepts are over my head and always will be, ensuring an enduring mystery. I'm not alone in this. From A Beautiful Mind to A Wrinkle in Time, NPR's Radiolab podcast to sci-fi, people are hungry for a slice of scientific mystery. Not too big, mind you; just a taste -- it's far too rich for every day.

A Palette of Particles is more like a pu-pu platter than a slice, but the idea is the same: it's an attempt to gently introduce the common reader to the concepts of particles -- from the early days of protons and neutrons to the more recent quantum developments of squarks and tachyons -- in easily digestible bites. The book itself is small and nonthreatening (cute cover, about seven-by-six), and its mere 224 pages encompass the highlights of particle physics from the first time the word isotope was used in 1913 up to the discovery of the Higgs boson in the summer of 2012. Since physics is the study of matter (the building blocks for everything that we touch, see, smell, taste, and hear) physicist and writer Jeremy Bernstein has essentially taken it upon himself to provide the common reader with a loose knowledge of... everything.

In The Hitchhiker's Guide to the Galaxy, a computer named Deep Thought is asked to calculate the answer to the "Ultimate Question of Life, the Universe, and Everything." The answer, forty-two, is about as helpful to the "hyper-intelligent, pan-dimensional beings" who built Deep Thought as E=mc˛ is to the average human. Physics shows that the essence of reality is structural mathematics, rather than stuff (couches, toasters, bodies, trees), but just because an equation is more "real" than a couch, the fact remains that the couch is what we understand and the equation isn't. The difficulty of giving a cogent explanation is further complicated by the fact that even physicists can't fully explain exactly how an equation leads to a couch. Cosmologist Stephen Hawking famously asked, "What is it that breathes fire into the equations and makes a universe for them to describe?" So far, no one has answered him.

All of which is to say that Bernstein has his work cut out for him. How does one explain math-governed particles to a non-physicist?

Bernstein begins gamely by giving us a metaphor of particles as "colors in a palette that can be used to compose the tableau of the universe." This makes them easy to organize: primary colors are the electron, the photon, the neutron, the proton, and the neutrino; secondary colors include pions, muons, and quarks; and pastels are the real oovy-groovy, out-there particles: squarks, tachyons, gravitons (to detect a graviton, says Bernstein, you'd need a device that "would have to be so massive that it would collapse into a black hole of its own making").

The primary colors are introduced in a friendly way, with more history than math, showing the old-fashioned tabletop experiments that introduced us to our old friends the neutrons and photons. The tone is light, conversational, and anecdotal. Then, slowly, inevitably, the math creeps in.

The section on primary colors ends with Planck's constant, h, which becomes part of the measure of a photon's energy: E=hv. This is sort of an amuse-bouche, preparation for the mathematical language to come. As we're introduced to secondary and pastel colors things start to heat up. Charts show numbers that denote the strangeness and spin of each particle. Diagrams are made up entirely of squiggly lines, arrows, and letters with plus or minus signs after them. Equations boast more Greek symbols than frat row. The meson octet is pictured as a hexagon with two dots in the middle and a bevy of equations surrounding it at regular intervals. "You must admit," says Bernstein, "that it is a thing of beauty."

This crescendo of the mathematical language is the introduction of Gell-Mann and Okubo's mass formula for the familiar baryons. Bernstein invites the reader to test this equation, assuring us that we will "find that the agreement is quite good."

These are the moments when A Palette of Particles becomes a bit more than the common reader can chew. Most of us no longer have our Texas Instruments calculators from college, and wouldn't know how to reproduce an equation like Gell-Mann and Okubo's mass formula if our lives depended on it. Most of us do not use any math in our daily lives, beyond figuring out the tip for a waiter, which can be done using the basic calculator on a cell phone. Since particles are made of math, it's understandably difficult to describe them without using, well, math, but more metaphors and analogies would have greatly improved the readability of this book.

However, if the non-mathematically inclined reader is interested in the history of physics and doesn't mind being in the dark while "the pi-mesons are placed in an octet that also includes the strange k-mesons," there are some true gems tucked into this book. Bernstein has been a physicist for over half a decade, and he has great stories to tell about some of the best minds in the business. Einstein, for example, when asked by a student what he would have done if experiments proved his theory of general relativity wrong, answered: "Then I would have been sorry for the dear Lord. The theory is right." Murray Gell-Mann came up with the name "quark" because he was both an avid birder and a fan of James Joyce -- he first thought of the duck's sound, "quack," then he read the line "Three quarks for Muster Mark" in Finnegans Wake, and it morphed into quark. Bernstein himself, while working at the Cosmotron (a particle accelerator in Brookhaven) used to go into the building at night, when the machine was down, to practice his trumpet. "The acoustics were wonderful."

These anecdotes illustrate the real appeal of A Palette of Particles: not comprehensible physics (a tall order, which goes undelivered), but rather Bernstein's infectious love not only for the mysteries of physics but also for the minds behind the magic. The stories and photos of physicists in action -- especially that of Wolfgang Pauli and Niels Bohr, two venerable fathers of physics, bent over to watch the spinning of a child's top -- bring physics to life in a way that equations simply can't.

The answer to the "Ultimate Question of Life, the Universe, and Everything" is probably incomprehensible to those of us who use our cell phones to calculate a tip. It might as well be forty-two. For the common reader, the real mystery and magic is in the mind of the physicist -- someone who may very well be able to look at forty-two and fall back in wonder.

A Palette of Particles by Jeremy Bernstein
Belknap Press
ISBN: 978-0674072510
224 pages