Higgs boson captured
IT WAS without doubt a splitting-the-atom, DNA-double-helix, penicillin-discovering moment, a once-in-a-generation breakthrough that raises scientific understanding to a qualitatively new level.
The announcement by two teams at Geneva’s Cern laboratory that they have demonstrated the existence of the elusive Higgs boson represents a massive vindication for both Higgs and fellow scientists who postulated its existence 50 years ago as a keystone of the “Standard Model”, and for the visionaries – physicists, engineers, and politicians – who built, and run Cern’s €4 billion, 27-kilometre Large Hadron Collider.
The find gives a new certainty to our understanding of the universe and the origin of the masses of fundamental particles. Without the Higgs boson, the Standard Model, the theory that is generally agreed to best describe the basic building blocks of the universe, would be at a loss to explain why some particles are mass-less (such as the photon, the quantum bit for light, and other types of electromagnetic radiation), while other particles have varying degrees of mass. Higgs suggested the problem can be resolved if we imagine the existence of a field, a sort of cosmic soup, permeating all of what we see as empty space, and through which, in the milliseconds after the Big Bang 13.7 billion years ago, a range of ultra-light or mass-less particles travelled with varying degrees of ease. Depending on their characteristics many of these particles would acquire mass from the field’s own special (“Higgs”) bosons. As the universe began to cool, they slowed down and began to bunch up to form composite particles and, eventually, atoms.
Until yesterday nobody had been able to verify his theory, not least because the Higgs boson decays into lighter particles in just one septillionth (1 x 10–24) of a second. To spot it scientists could only look at its effects, essentially its shadow, by scrutinising millions of super-fast proton collisions and their after-trails for statistical aberrations only explainable by such a particle.
Of course, as soon as one question is answered, more are asked. Cern will continue in months ahead to pore over the evidence to move from “overwhelming evidence” of the particle – what Cern calls “sigma 5” or 99.9999 per cent certainty – to “discovery”, and to clarify whether it is the Higgs boson (dubbed “God’s particle” by a canny publisher). Or is it just one of several, opening up yet further theoretical challenges? One theory, “supersymmetry”, calls for more than five Higgs-like particles with completely different properties.
The Higgs boson provides critical answers about the coherence of the Standard Model, but the latter has only yet provided scientists’ desperately sought “unified” explanation of three of the four fundamental forces in nature – gravity remains elusive, perhaps the Higgs challenge for the next generation. Yesterday’s announcement, perhaps one of the greatest triumphs of the human intellect in decades, vindicating one of the greatest theoretical edifices in science, and requiring the construction of the most complicated machine ever made, takes us one step closer.