23/12/2013
Higgs brings physicists a Nobel.
In 1964, two scientists separately proposed the existence of a novel, invisible field. If it existed, this field would permeate the entire universe and provide mass to the matter in it. Last year, scientists confirmed a critical indicator of the field: the existence of a long-sought particle known as the Higgs boson. Anticipating this so-called “god particle” — and its critical role in explaining mass — captured the 2013 Nobel Prize in physics.
On Oct. 8 in Stockholm, the Royal Swedish Academy of Sciences announced it had selected Peter Higgs of the University of Edinburgh, Scotland, and François Englert of the Free University of Brussels, in Belgium, to receive the award. At a ceremony on Dec. 10, the two physicists will receive medals and share a cash prize equal to slightly more than $1.24 million.
The Higgs particle was the final piece of what scientists have referred to as the “standard model” of particle physics. With great accuracy, it describes the interaction of particles and forces in our universe.
The Nobel to Higgs and Englert comes just 15 months after the headline-grabbing discovery of the Higgs boson. The particle turned up in experiments at CERN, site of the world's most powerful particle accelerator near Geneva, Switzerland. This boson’s discovery had been a long time coming for Englert, 80, and Higgs, 84.
As young physicists in the early 1960s, they studied energy and matter. Both had focused on the same perplexing problem. Since the 1930s, physicists had been discovering a zoo of subatomic particles and fine details of the forces acting on them. Still, those scientists could not explain why some particles (such as protons and neutrons) have mass and others (such as photons of light) do not.
In started 49 years ago
In 1964 — within two months of each other — Englert and Higgs came up with an explanation for that mass. Each proposed the existence of a field that influences our universe. They said it should have emerged just a split second after the Big Bang. (The Big Bang was a rapid expansion of dense matter that marked the start of the universe.)
Photons, which carry what’s known as an electromagnetic force, would not be affected by the field, the scientists noted. As a result, photons would have no mass. But particles of matter would be slowed by the field, they said. From this, particles would get mass.
Englert and a colleague (Robert Brout, who died in 2011) wrote a three-page paper describing this. A few weeks later, Higgs wrote a page-and-a-half paper that introduced the idea of the Higgs boson. If found, that boson would confirm the new theory to explain mass. (A few months later, three more physicists would independently propose the same idea.)
Over the next several decades, physicists began using the Higgs field — and Higgs boson — in their mathematical explanations of their standard model. But there remained a sticky problem: No proof yet existed that the Higgs boson was real. Without the particle, the otherwise successful standard model falls apart.
This eventually prompted many physicists, often working together, to begin scouting for the elusive Higgs boson. In 2010, many years into this quest, CERN’s $10 billion Large Hadron Collider began smashing protons into each other. Protons are a type of subatomic particle. Slowly but surely, an army of more than 6,000 Higgs hunters began seeing little blips in the collision data.
These blips suggested the existence of the particle. But it wasn’t until July 4, 2012, that scientists announced they had enough data to conclude the Higgs boson was real.
Since then, researchers have determined that particle is the one predicted by the standard model. It looks and behaves exactly the way theory predicted it should. The one hiccup: It possesses much-lower-than-expected mass. That "tells us that our standard model is incomplete," explains Don Lincoln, a member of one of the teams at CERN that made the Higgs discovery. "There must be undiscovered physics to correct this."
Scientists are also probing other shortcomings of the standard model. One of those: the lack of a particle that could make up dark matter. It outweighs regular matter 5-to-1 in the universe. Whoever solves that mystery will likely join Englert and Higgs as Nobel laureates.
Award quickly follows boson’s discovery
In many cases, it has taken decades for the Nobel committee to judge some research worthy of an award. For instance, Ernst Ruska’s pivotal work toward the development of an electron microscope in 1934 would not pay off in a physics Nobel for another 52 years.
Other times, the Nobel committee appreciated the importance of some achievement right away. One example: the development of “artificial radioactivity.” Irène Curie-Joliot and her husband Frédéric Joliot won the 1935 Nobel in chemistry for this. They had announced the feat only one year earlier. Similarly, Henry Dale shared the Nobel for medicine a mere two years after reporting his 1934 work on acetylcholine and its role in the chemical transmission of nerve signals.
Many people had predicted last year’s Higgs boson discovery would bring a Nobel to people who had worked in this field. But no one was sure just who might get it. The Nobel committee restricts awards to no more than three people (all of whom must be living). Yet six theorists and thousands of experimenters had worked on the quest over the decades. In the end, the committee settled on giving the award just to the first two theorists to predict the Higgs field (presumably Brout would have won if he were alive).
But others may still be in the Nobel game. "Every year is a new year," says Lars Bergström, secretary of the Nobel physics committee. "Nominations that come in next year,” he says, “may well propose the experimentalists who actually made the discovery."
