A Palette of Particles

by Jeremy Bernstein

Overview

Jeremy Bernstein guides readers through high-energy physics from early twentieth-century atomic models to leptons, mesons, quarks, and the newly discovered Higgs boson, drawing them into the excitement of a universe where 80 percent of all matter has never been identified. From molecules to galaxies, the more we discover, the less we seem to know.

Product Details

ISBN-13:	9780674073647
Publisher:	Harvard University Press
Publication date:	03/11/2013
Sold by:	Barnes & Noble
Format:	eBook
File size:	2 MB

About the Author

Jeremy Bernstein is the author of many books on science for the general reader, including Plutonium: A History of the World’s Most Dangerous Element and Oppenheimer: Portrait of an Enigma. He is a former staff writer for the New Yorker.

Read an Excerpt

Chapter 7: Part III

Secondary Colors B

1. Strange Particles

In prior chapters I have noted that some particles were discovered in cosmic rays. The positron being an example. Someone unfamiliar with the subject might get the idea that there was a kind of back yard treasure hunt in which these particles were unearthed. Since the particles in this chapter were also found initially in cosmic rays I want to explain what this means beginning with a discussion of what a cosmic ray is.

In 1896 the French physicist Henri Becquerel made the accidental discovery that a substance containing uranium emitted charged particles. This was the discovery of radioactivity. Radioactivity was thought then to be the solution to a puzzle. Atmospheric air appeared to be ionized. It carried an electric charge. The assumption was then made that this was caused by the natural radioactivity coming from the Earth. This was tested when in 1912 the Austrian physicist Victor Hess flew in a balloon to an altitude of some 5300 meters carrying an electrometer. He found that the ionization quadrupled at this altitude which meant that it was extra-terrestrial. At first it was thought that it was emanating from the Sun. But Hess ruled this out when he flew in his balloon in a near total solar eclipse and showed that the radiation persisted. But what was it and where did it come from?

In those pre-satellite days one could only study the radiation fairly close to the Earth. There were two schools of thought. One argued that the primary radiation consisted of very high energy photons-gamma rays-and the other argued that it was positively charged particles. The two proposals could be distinguished by measuring the cosmic ray flux at different locations on the Earth. Uncharged particles like gamma rays would not be deflected by the Earth’s magnetic field while charged particles would. Because of the Earth’s magnetic field it was predicted that more positively charged cosmic rays would come from the west than from the east. By the end of the 1930’s measurements made it clear that the charged particle people were right. Now it is agreed that most of the primaries are high energy protons. Some of them are of a higher energy than can be produced in any accelerator. It is also generally agreed that they have their origin in super nova explosions. The ones that we see have been traveling for millennia in the vacuum of outer space. When they crash into our atmosphere they produce a great variety of secondaries which is what is detected. But how to detect them?

Table of Contents

Contents Introduction I. Primary Colors 1. The Neutron 2. The Neutrino 3. The Electron and the Photon II. Secondary Colors 4. The Pion and the Muon 5. The Antiparticle 6. Strange Particles 7. The Quark III. Pastels 8. The Higgs Boson 9. Neutrino Cosmology 10. Squarks, Tachyons, and the Graviton L’Envoi Appendix 1: Accelerators and Detectors Appendix 2: Grand Unification Appendix 3: Neutrino Oscillations Acknowledgments Index

Editorial Reviews

Casting subatomic particles across a metaphorical painter’s palette, Bernstein (Quantum Leaps) blends science, history, and anecdote (including his own work on staff at Harvard University and Princeton’s Institute for Advanced Study) to reveal the lively, often bewildering world of particle physics. The primary colors of Bernstein’s palette are the electron, photon, neutron, proton, and neutrino, “the set that was in play until the 1930s.” Questions about what held the nucleus together (which Edward Teller described in a poem as the “nuclear glue”) and what constituted elementary particles lead to Bernstein’s “secondary colors,” including Hideki Yukawa’s mesons and Murray Gell-Mann’s whimsically named up, down, and strange quarks. At the palette’s outer reaches lie the mysterious “pastels” and the forces that shape our universe. These include the elusive Higgs boson, quantum gravity’s graviton, and the tachyons physicists posit move faster than the speed of light. Bernstein is an unabashed romantic, fondly recalling the tabletop experiments of the mid-20th century (he’s worked in the field for more than 50 years). Later discoveries, especially the Higgs—coaxed to visibility with powerful accelerators and computer analysis—remain, in the author’s estimation, coldly “abstract.” For Bernstein and for readers, the true wonder lies in how each discovery reveals yet another mystery. 11 halftones, 11 line drawings, 3 tables. (Mar.)

Publishers Weekly

Overall, it is a pleasant, short read, and a reminder of the past century-and-a-half crusade at the forefront of modem physics.

Choice - A. M. Saperstein

[Bernstein] brings to this popular history of particle physics the advantage of having been around when some of that history was being made. Bernstein, now in his 80s, knew Wolfgang Pauli, who hypothesized the existence of the neutrino in 1930, a quarter-century before it could be confirmed...Bernstein covers the material in a sprightly manner, with only the occasional equation that will reveal the beauty of it all to the reader who can grasp it...It turns out that Bernstein's sober and lucid introduction to particle physics has an almost mystical quality, even if the author shows no interest in that kind of cosmic thinking.

Inside Higher Ed - Scott McLemee

The real appeal of A Palette of Particles...[is] 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.

Bookslut - Mary Mann

Physicist Jeremy Bernstein pays homage to the subatomic, tinting particles according to era of discovery. So electrons, neutrons and neutrinos are assigned primary colors; the muons through to quarks, secondary colors; and the Higgs boson, neutrino cosmology and squarks, tachyons and the graviton, pastels. The abstractions come alive as Bernstein meshes history and science with anecdotes on everyone from Murray Gell-Mann to Richard Feynman. A colorful chronicle backed by 50 years in the field.

Nature

[Bernstein] pares away most of [the mathematical] complexities, thereby allowing general readers to share in the excitement of epoch-making science without shouldering the burden of rigorous analysis. Not merely lucid, Bernstein's exposition is refreshingly human, sprinkled with anecdotes revealing the piquant personalities of pioneering scientists including Einstein, Pauli, and Gell-Mann. A must-read for armchair physicists.

Booklist (starred review) - Bryce Christensen

This is a superb little book. No one, with the possible exception of Freeman Dyson, writes so gracefully about physics and its recent history, or so effectively inserts himself into the story without self-advertisement.

Kenneth W. Ford

Physicist and prolific author Bernstein (Quantum Leaps, 2009, etc.) applies his fine talents to this short but not simplified overview of subatomic particles. Using an artist's palette as an analogy, the author explains that the visible universe is made up of primary colors: familiar, long-lived particles detectable with simple instruments. J.J. Thomson discovered the electron in 1896 with a magnet and a cathode ray tube. Between 1911 and 1917, Ernest Rutherford's men discovered the proton by aiming radium emissions at various targets. Other primaries include the neutron, the photon and the not-so-easily detectable neutrino. That was how matters stood in the 1930s when technical advances turned up a torrent of odd colors: unstable, short-lived particles. In the 1950s, physicists grumbled at a seemingly endless series of pions, mesons, sigmas and lambdas, but matters improved in 1964 when Murray Gell-Mann and George Zweig theorized that these plus the proton and neutron consisted of fundamental elements called quarks. In the 1970s, experiments confirmed this, resulting in the "standard model," a fairly good explanation of subatomic particles and their interactions. Everyone cheered the 2012 discovery of the Higgs particle, the last undiscovered element in standard model theory, but everyone agreed that the model needs work. It doesn't incorporate gravity into particle interactions and says nothing about dark matter or the accelerating expansion of the universe revealed by dark energy. Bernstein delves into some areas that will flummox beginners, but few will resist his accounts of the history, flamboyant geniuses (many of whom he knew personally), and basics of protons, neutrons and electrons that make up the familiar world.

Kirkus Reviews