AS celebrities go, the Higgs boson is an unlikely character. For one thing it is an unimaginably tiny and fleeting speck of matter. For another, its existence is purely theoretical. Yet celebrity it is.
In the mid-1990s, Britain鈥檚 then science minister William Waldegrave offered a bottle of champagne to those who could best explain the Higgs to him. At about the same time, Nobel laureate Leon Lederman immortalised it in the title of his book The God Particle.
The attraction of this elusive beast stems from its role in explaining one of nature鈥檚 deepest mysteries: why subatomic particles have mass. Without mass the components of the Universe would be flying around at the speed of light and there could be no planets, stars or people. The theory goes that it is the way Higgs bosons interact with each fundamental particle that gives it its characteristic mass.
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So it is something of a shock to learn this week that physicists hunting the Higgs are worried that it does not exist (see 鈥淣o sign of the God particle鈥�). Researchers at CERN, the centre for particle physics near Geneva, have ruled out most of the likely energy slots where the particle might lurk and now reckon it more probable that the Higgs is the product of an overactive imagination.
Without wishing to speak ill of the (probably) dead, it鈥檚 worth pointing out that despite its celebrity the Higgs never was the complete answer to the mystery of mass. Before Higgs, there were two key questions: where does mass come from and why do different subatomic particles have different masses? The Higgs answers both but raises another: exactly how does this much vaunted cosmic ingredient endow different particles with different masses? Instead of resolving the mystery, it merely transferred it to itself.
Then there鈥檚 the fact that the Higgs explains only a tiny part of the mass of everyday objects, which comes largely from the force that holds the ingredients of protons and neutrons together. Nor does it describe why particles feel the influence of gravity.
Yet if the Higgs is no more, it will be sorely missed-not least by the physicists who convinced governments around the world to stump up 拢1.5 billion to build the Large Hadron Collider (LHC) at CERN. It was the campaign to drum up political support for this vast particle accelerator that made the Higgs famous. In our sound-bite culture, where messages have to be direct and brief, the prospect of finding the Higgs became a potent marketing tool.
It was an understandable ploy. Unlike other big science projects such as the Human Genome Project, the LHC could not promise great utilitarian benefits. No cancer cures. No gene therapies. Sure, it might spark the birth of some new and useful technology-just as CERN鈥檚 previous accelerator led to the existing World Wide Web-but this would be a spin-off. The primary purpose of the LHC is cultural, to change our view of the Universe and our place within it. Getting hard-pressed governments to find cash for such an intellectual endeavour needed a sharp focus. Enter the God particle.
The downside is that many politicians and members of the public now believe the LHC is being built solely to find the Higgs, when it is not. This is a dangerous perception. If the Higgs turns out not to exist, politicians will be wary of parting with the next 拢1.5 billion, and physicists may rue the day they rallied behind it.
In reality, the LHC is designed not to find the Higgs, but to discover whether or not it exists. We certainly won鈥檛 be able to sign its death certificate without the LHC. What鈥檚 more, not finding the Higgs will, paradoxically, prove even more exciting than finding it.
Physicists will have to rethink not just their theories of where mass comes from but their entire model of the subatomic world. And what better tool to inform that process than the mighty LHC. Smash particles together at energies not seen since the earliest days of the Universe and all sorts of insights into the nature of matter are likely to tumble out of your experiments.
Now that the money for the LHC is assured and construction has begun, it鈥檚 time for particle physicists to modify their message. For too long they have allowed themselves and onlookers to obsess over a particle that may-or may not-exist. All too often they鈥檝e shown religious-like conviction in something they may never find. In so doing they have undersold an exciting experiment that, communicated properly, could enrich all our lives.
