The Higgs generates mass, but only a minuscule part of it (Image: Naresh Singh/Millennium images)

After all the excitement surrounding the discovery of the Higgs, a new book called Beyond the God Particle asks where we go next

IN 2012 American Independence Day was a high-water mark for European science: it saw the announcement of the discovery of the Higgs boson at the Large Hadron Collider, near Geneva, Switzerland.

For Leon Lederman, though, it was a low-water mark for American science. The Nobel prizewinning physicist is a former director of Fermilab, the Fermi National Accelerator Laboratory near Chicago. He is also the person who, tongue in cheek, gave the Higgs boson its “God particle” moniker.


In Beyond the God Particle, co-written with fellow particle physicist Christopher Hill, Lederman bemoans the short-sightedness of American politicians who pulled the plug on the Superconducting Supercollider (SSC) in 1993 and signalled the retreat of the US from the high-energy frontier of fundamental physics.

But while the US Congress may well have lacked what Lederman and Hill call “leadership cojones”, it is perhaps unfair to blame Congress entirely. The plan for the SSC was to excavate a vast circular tunnel in Waxahachie, Texas, while the LHC plan proposed reusing an existing subterranean ring. Confining a superfast beam to such a small particle racetrack could be achieved only with superconducting magnets of such power that they were pure science fiction at the time the LHC was proposed.

In short, European scientists displayed the kind of daring, can-do spirit formerly seen in American scientists of the Apollo moon-shot era. As a consequence, and ironically, they presented their collective funding governments with a far lower total bill for the enterprise.

Although Lederman and Hill mourn the SSC, they seem to have accepted that European-style international collaborations with their pooled financial resources are the sensible way forward for particle physics.

Even so, they want to see the US punching its weight in particle physics again. In 2015, the LHC will start operating at even higher energies. Lederman and Hill suggest an American “Project X” to coincide with this, to look for ultra-rare, low-energy processes that may reveal a new fundamental physics.

It’s a bold plan, and well argued, but the real meat of Beyond the God Particle is the Higgs boson itself and its raison d’être. And this is a truly fascinating story, well told.

Mass, in a nutshell, is not what you think it is. Not by a long chalk.According to Lederman and Hill, a subatomic particle such as a muon, which feels the weak nuclear force, flickers back and forth between a right and a left corkscrewing form (the flicker is known as Zitterbewegung).

If, however, the muon could be boosted to the speed of light, its time would slow to a standstill, as predicted by Einstein’s special theory of relativity. A particle that experiences no passage of time is a photon, so the muon would appear like a photon. Since a photon has no rest mass, running with the photon analogy, neither would the superfast muon. Its mass would have been “switched off”. But all that has happened to it is that the flickering between left and right forms has stopped. The inference is that this oscillation is what gives a muon its mass.

So where does the Higgs come in? In switching from the left to the right form, a muon must destroy its “weak charge”, which is as impossible as destroying the ordinary electric charge. Hence the left-right switch must be mediated by another particle that takes away the weak charge.

The particle is not obvious so it must be short-lived, which in quantum theory is synonymous with being massive. It cannot add electric charge, so it must have zero electric charge. And it cannot add quantum “spin”, so it must have zero spin, making it a boson. Hey presto, the recipe for the Higgs.

According to Lederman and Hill, the defining characteristic of bosons is their gregariousness. Just like the photons that make up an electromagnetic field, the bosons of the Higgs field like to be with their mates, crowding the vacuum that fills the universe. And it is the drag exerted on a muon as it continually has to interact with Higgs bosons in the vacuum that endows it with mass.

But while photons are easy to pluck from the electromagnetic field, Higgs bosons are immensely hard to pull from their field. In fact, that takes a whopping 125 gigaelectronvolts to be precise – which is why nothing less than the $9 billion LHC could do it.

All of this is about as far from the standard cocktail party description of how the Higgs generates mass as it is possible to get. And it is worth the price of the book alone. Mind you, three-quarters of the way through, Lederman and Hill do belatedly admit, with a sheepish apology, that the Higgs explains only a minuscule part of mass. The lion’s share – 99 per cent – comes from the strong nuclear force and has nothing whatsoever to do with the weakly interacting Higgs. But then, this fact has been omitted by almost all particle physicists in their eagerness to big up the Higgs to the media.

Lederman and Hill’s book is a great read and a mine of stuff you may not know about the standard model of particle physics and about the Higgs. In places, however, I found the explanations a little baffling: for instance, the description of the unobservable “gauge fields” that underpin our reality left me puzzled – and I have a background in physics. Also, we sometimes have to wait a little too long for an explanation of terms: “wave function”, for instance, is defined nearly five pages after it is introduced.

As for what is beyond the God particle – the title of the book, after all – that turns out to be anyone’s guess. Frustratingly, the Higgs has as yet provided no clues about the deep physics we did not already know. The outstanding question remains: if the Higgs gives other particles mass, what gives the Higgs its mass?

“The outstanding question remains: if the Higgs gives other particles mass, what gives the Higgs its mass?”

It is to answer this kind of question that Lederman advocates building a higher-energy machine in the shape of the International Linear Collider – probably in Japan – plus that American Project X, to look for oddball events at lower energies that do not fit the standard model.

But it’s hard not to think that, as particle physicists make these grandiose plans, the universe looks on and mocks their efforts. After all, we now know that the stuff particle physicists are trying to understand accounts for a mere 4.9 per cent of the mass-energy of the universe. No one has the slightest idea about the true identity of the major components, dark matter and dark energy.

If anything, the discovery of the God particle has shown just how much further we have to go to penetrate the heart of nature. It all makes me think of the words of American poet Stephen Crane in A Man Said to the Universe:

A man said to the universe,

“Sir, I exist!”

“However,” replied the universe,

“The fact has not created in me A sense of obligation.”

Beyond the God Particle Leon Lederman and Christopher Hill Prometheus

This article appeared in print under the headline “Is the universe mocking us”