Beyond the God Particle, Leon Lederman and Christopher Hill, Prometheus Books, 2013. $24.95 (325 pp.). ISBN 978-1-61614-801-0
Cracking the Particle Code of the Universe: The Hunt for the Higgs Boson, John W. Moffat, Oxford U. Press, 2014. $29.95 (232 pp.). ISBN 978-0-19-991552-1
The announcement of the discovery of the Higgs boson at the Large Hadron Collider (LHC) on 4 July 2012 was viewed in real time by physicists all over the world, was reported on the front pages of all major newspapers, and persuaded the Royal Swedish Academy of Sciences to award last year’s Nobel Prize in Physics to Peter Higgs and François Englert. Our nonscientist neighbors recognized and cheered for the Higgs boson—or, as some of them refer to it, “the God particle.” However, they cannot easily explain what the Higgs boson is or why its discovery is important.
A number of books have appeared recently that, however well written, do not answer those questions clearly. Physics Today has already reviewed three such books: Ian Sample’s Massive: The Missing Particle That Sparked the Greatest Hunt in Science (Basic Books, 2010), which I reviewed in May 2011 (page 47); Sean Carroll’s The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World (Dutton, 2012); and Jim Baggott’s Higgs: The Invention and Discovery of the “God Particle” (Oxford University Press, 2012). The latter two were reviewed together in July 2013 (page 50). Now Leon Lederman and Christopher Hill, with Beyond the God Particle, and John Moffat, with Cracking the Particle Code of the Universe: The Hunt for the Higgs Boson, make their attempts at a popular explanation of the Higgs boson.
Lederman, writing with Dick Teresi, started the promotion of the Higgs boson in the first place with his 1993 book The God Particle: If the Universe Is the Answer, What Is the Question? (Houghton Mifflin). That book was a joy to read. Lederman is a Nobel Prize recipient who served as a visionary director of Fermilab and later as a science educator of great influence in the Chicago area. He is also a comic, not above hyphenating his name (“Lede-rman”) to tweak the ears of theorists. In his new book, one sees a more sober side of his personality. Lederman and Hill, a Fermilab theorist, have definite points to communicate. They do it with care and attention to the level of their intended audience—as instructors rather than entertainers.
The key fact about the Higgs boson is that it is the origin of the masses of all known massive elementary particles, including the quarks, leptons, and W and Z bosons. That raises the following question: Why is a new particle needed to give other particles mass? An audience of physicists can understand the answer: Detailed experiments on the weak interactions establish that the Hamiltonian governing elementary particles has exact symmetries that forbid quark, lepton, and boson mass terms. Thus those symmetries must be spontaneously broken. That, in turn, requires a new field to provide the order parameter for the symmetry breaking. Those familiar with contemporary physics will recognize each step in the above argument. But for nonscientists, every step brings in new, technical, and difficult concepts. It is an unsolved problem to present this argument in popular language.
Lederman and Hill set that as their main goal. They begin well, with a wonderful chapter that introduces the notion of parity violation in the weak interactions and extols the virtues of the muon. They assemble all the needed ingredients. But the final stage in their narrative falls short: The muon “marches through space-time oscillating between L and R like the drone of a military marching drill.” The metaphor, which implies a constantly switching rotational motion, is jarring. Laymen will be puzzled, though scientists may find good ideas in the presentation that might animate their own attempts at explanation.
The latter parts of the book turn to other issues. Lederman and Hill plead for increased funding for particle physics, reflecting the degree of its economic benefit for society, and they plead for their favorite future projects at Fermilab. The first issue merits a detailed presentation to the public, but readers will not find it here. The second ignores the nature of the current ferment associated with the Higgs discovery. Although the data were gathered at CERN, the discovery really took place in cyberspace, as young analysts from all over the world found characteristic events buried in a mountain of globally shared data. This discovery illustrates a new, 21st-century mode of science, with collaboration on a scale that dwarfs any individual laboratory.
For a picture of the global nature and excitement of the Higgs discovery, we turn to Cracking the Particle Code of the Universe. Moffat does not hold back his engagement. He writes, “The LHC is a killing machine.” It kills theories, and the theories it could kill are his own. Moffat is a particle theorist who has made substantial contributions to the quantum theory of gravity and supergravity. More recently he has trekked as far from the mainstream as one can go and still be serious. In the introduction, he recalls a 2008 seminar he gave at CERN in which he presented his theory that the Higgs boson does not exist. If such a theory is false, he said, it should be excluded by experiment. That is what science demands, and Moffat insists on seeing the proof.
Moffat’s attempt at a popular explanation of the Higgs is the weakest segment. The contrast to Lederman and Hill’s careful structuring of the argument is striking. But the verve is there. At meeting after meeting, Moffat collars junior members of the LHC experiments ATLAS and CMS and grills them on the exact implications of the data they are presenting. Face to face, Moffat must have made them very uncomfortable, but in the book, he portrays them warmly. Those often invisible analysts shine in his narration.
It is a thrill to see the Higgs data come into focus. It is now clear that the new particle is a scalar (spinless) boson and, at the very least, an important part of the mystery of elementary particle masses. Both books state clearly many questions that remain open. Future detailed measurements of the Higgs boson’s properties will give us new information to address those questions. The saga of the Higgs boson is just beginning.
Michael E. Peskin is an elementary particle theorist at SLAC in Menlo Park, California.
