On the verge of a eureka moment

In an underground bunker in Switzerland scientists are edging closer to finding a particle that is fundamental to our understanding of physics, writes Martin Rees

THE excitement from Europe earlier this month was palpable. Experiments had hinted at the discovery of a new fundamental ingredient of nature — a particle called the Higgs boson. This wasn’t just any particle, but one that could tell us that the theory physicists have been using to understand matter’s fundamental building blocks for the past 50 years is premised on a secure foundation.

Even non-scientists — those for whom terms like Higgs field, gigaelectronvolt, and hadron are almost a foreign language — were thrilled, inspired by the notion that we are on the verge of unravelling mysteries previously beyond our grasp.

“Hadron”, in fact, refers to particles that interact through one of the four forces of nature known as the strong nuclear force. The Higgs boson experiments are taking place at the Large Hadron Collider, an enormous particle accelerator crossing the French-Swiss border.

In the Large Hadron Collider’s underground labyrinth, scientists can observe the collision of protons — a type of hadron — that have been accelerated to nearly the speed of light. These protons collide a billion times a second in a region smaller than a human hair. When they do, they can turn into energy, as predicted by Einstein’s theory, and that energy can then create new types of matter, never before seen.

On the afternoon of December 13, in Geneva, spokespeople from the two major Large Hadron Collider experiments, called ATLAS and CMS, announced the status of their searches for the Higgs boson.

Named for the British physicist Peter Higgs, the particle — if it exists — will tell us if the Higgs mechanism, the half-century-old idea for understanding how elementary particles acquire their masses, is correct.

Those masses are essential to much of the structure we see in the world. If electrons didn’t have mass, atoms wouldn’t form. Then neither would galaxies, planets, or life. There’s a lot more to all this structure than the Higgs mechanism alone, so the name “God particle”, coined by the Nobel Prize-winning physicist Leon Lederman and relished by the popular media, might be a bit misleading.

Nonetheless, the Higgs mechanism is critical to today’s theory of the basic elements of matter. Higgs and his colleagues theorised that space itself contains a sort of charge. Elementary particles acquire mass through their interaction with the charge. Space isn’t filled with Higgs-boson particles — you need technology such as the Large Hadron Collider to make those — but the Higgs boson is the telltale sign that there really is such a “charge” in space.

But here’s the catch: The Higgs mechanism hasn’t yet been vindicated by experiments. The reason the news from Geneva was so momentous was that scientists at the Large Hadron Collider might have come one step closer to proving it.

Such a discovery won’t turn our world around tomorrow. But basic science is like that. For all the deep and fundamental truths we learn about nature, it’s rarely clear right away what the implications will be. When electricity was discovered, nobody knew the globe would fairly quickly be blanketed with lightbulbs.

It’s unclear what a discovery of the Higgs boson will mean in 10 or 20 or 100 years, but cultures where people learn more about their world, and science is valued, seem to fare well in the end.

I listened to the Higgs announcements over a choppy internet connection. The first talk was by Fabiola Gianotti, the remarkable leader of the ATLAS experiment, who presented evidence of a Higgs boson decaying into photons and also into other particles. She kept advising caution, which she would belie by periodically breaking into a smile as she spoke. Listening to her, I felt the excitement too. For a moment I even believed the Higgs boson might really have been found.

However, my hope might have been premature, as I learned in the CMS talk that followed. Alas, the CMS evidence for a particle was much weaker. Its researchers couldn’t rule out the Higgs boson — but they couldn’t say they’d seen it, either.

The good news is that with four times the data coming next year even the most sceptical among us are confident we’ll know the answer by next year. If the hints at discovery prove false, it won’t mean the whole story is wrong — it will more likely mean a more subtle theory is responsible for the “charge” in space that gives particles mass.

The great irony is that for physicists, not finding a Higgs boson would be spectacular, pointing to something potentially more interesting. Future investigations might demonstrate either that an exotic Higgs boson-like particle has other ways to decay than those in the standard model, or that the Higgs boson might be a more complex object made up of smaller ingredients, much as a proton is made up of smaller fundamental particles called quarks.

Galileo first realised the value of experiments: Artificial situations a scientist sets up to study a phenomenon. He said they went far beyond making new discoveries or proving an idea correct; just as important was ruling out ideas. Knowing what is and isn’t realised in nature will guide us on our searches, and will help us address still deeper questions about space and the matter of which the universe is composed.

* (c) 2011 Newsweek/Daily Beast

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