Massive: The Missing Particle That Sparked the Greatest Hunt in Science


Massive: The Missing Particle That Sparked the Greatest Hunt in Science
, 
Ian 
 
 Sample
 Basic Books, New York, 2010. $25.95 (272 pp.). ISBN 978-0-465-01947-2



In 2009 the Large Hadron Collider at CERN recorded its first particle collisions. In 2010 LHC experiments rediscovered all of the known elementary particles, from the neutrino to the top quark. In 2011 we plunge into the unknown. Thus it is a good time to bring out an entertaining book for the general public that explains where the LHC came from and what it is trying to accomplish.

With Massive: the Missing Particle That Sparked the Greatest Hunt in Science, Ian Sample, a reporter for the Guardian, seizes this opportunity. Sample’s book is not massive; at 260 pages of text, it’s a quick and enticing read.

Massive is hardly complete or balanced, but Sample knows how to tell a story. Gerald Guralnik is called to Germany to explain the idea now called the Higgs mechanism and is savaged by the aging Werner Heisenberg. Donald Perkins and Helmut Faissner huddle in a bar at Heathrow Airport to examine a bubble chamber photograph that proves the existence of the Z boson. Patrick Janot exhorts his troops in the control room at CERN while the Large Electron–Positron Collider (LEP) runs unstably at beam energies beyond its design. This is a scientific tale with heroes and villains, one that will entertain you and your neighbors.

What is the purpose of the LHC? The well-established theory of weak interactions requires that empty space be an ordered medium, a system with spontaneous symmetry breaking like a magnet or a superconductor. However, we have no idea why this ordering occurs or even what it is that is ordered. There is a wall that we have not been able to see over. All of the necessary concepts—the analogs of the Fermi surface, phonons, and pairing—lie behind it. The LHC will give us enough energy in particle collisions to jump over that wall.

There are many ideas for what we will find. The simplest theory contains just one new field, called the Higgs field, and one new particle, the Higgs boson. It is often said that the purpose of the LHC is to find the Higgs boson, the last undiscovered piece of a complete theory of fundamental physics. Sample takes this statement and makes it personal. On page 1 of Massive, the eponymous Peter Higgs is on his way to Princeton University to explain his new theory of mass to Freeman Dyson.

I was initially skeptical of Sample’s strategy to make Higgs a major character in the story. A professor at the University of Edinburgh in the UK, Higgs is mainly known for one 1964 contribution to the theory of spontaneous symmetry breaking. His idea, formulated at the same time by Robert Brout and François Englert and by Guralnik, Carl Hagen, and Thomas Kibble, is now part of the fabric of theoretical physics, known to every graduate student. It was not itself a great breakthrough, but it made great theoretical breakthroughs possible. Sample explains this in a fair and evenhanded way. His charming interviews with Higgs guide us through the later developments.

In writing about experimental physics, Sample is less balanced. He begins with the work of James Clerk Maxwell and Ernest Rutherford, but then lurches forward toward the current era. The discovery of the W and Z bosons at CERN is featured prominently, but other weak-interaction discoveries are omitted. The sad history of the Superconducting Super Collider receives an unsatisfactory chapter; the political and technical struggles of the LHC are passed over completely. The search for the Higgs boson at Fermilab’s Tevatron is slighted to make room for the story of John Conway’s near discovery of a more unconventional particle. I cannot blame Sample for that last choice. Conway’s story is wonderfully illustrative and has a great scene on the ski slopes of Aspen.

It vexed me that Sample hardly mentions the work of electron accelerator laboratories, though their achievements, including the first matter–antimatter colliding beam experiments and the discovery of quarks and gluons, are central to the story. Every 50 pages or so, someone from Stanford University’s SLAC or Russia’s Novosibirsk laboratory comes on stage, says something important, and then disappears behind the curtain. Sample also omits the critical role played by Benjamin Lee in building the theory of weak interactions. Lee was killed in an auto accident in 1977; if he had lived, he would have shared the 1999 Physics Nobel Prize with Gerard ‘t Hooft and Martinus Veltman.

But the most serious problem is one that presents a true challenge for the popular-science author. Sample yields to the temptation of describing particle discoveries in terms of individual events. I mentioned earlier that single bubble chamber photograph. At another point, Sample talks about a LEP detector that “flickered in a way that it had never done before.” In fact, it was the statistics of these events that was unconvincing; all of the LEP experiments observed events that looked exactly like those expected for Higgs bosons.

At the LHC, this problem of perception will be even more challenging. Signals of the Higgs boson, or any of the more fanciful particles that are predicted, will occur at one trillionth of the rate for ordinary proton–proton collisions. That is the key difficulty of the LHC program. Physicists who are students or postdocs today will have brilliant ideas that will solve this problem. Their results will be published in massively collaborative papers with thousands of authors. But I hope that we will know the names of those people and that they will be the heroes of popular books written in the next decade.

Until then, Massive provides an accessible introduction to the physics of this, the LHC era.