October 8, 2013

Two physicists who developed a theory explaining what gives particles mass have won the 2013 Nobel Prize in physics. Mass is a property related to weight. Peter Higgs of the University of Edinburgh in Scotland and Francois Englert of the University Libre de Bruxelles in Belgium were recognized for setting off a 40-year search for a particle, later known as the Higgs boson, which gives mass to the subatomic particles that have that property. The discovery of the Higgs boson—a landmark in scientific research—was announced in 2012 by scientists at the Large Hadron Collider (LHC), the world’s most powerful particle accelerator, at the CERN research center in Switzerland. The Higgs is so fundamental to the nature of matter that it has been called the “god particle.”

A giant detector records the particles produced during the collisions between two circulating beams of high-energy particles that takes place in the Large Hadron Collider (LHC). Using this process, physicists were able to discover the existence of the Higgs boson (© CERN).

Physicists had greeted the discovery of the Higgs boson with excitement because it allowed them to complete the Standard Model, the theory that describes the particles that make up matter and how they interact through forces. The Standard Model has had enormous success in accounting for the interactions between and behavior of elementary particles. However, physicists still could not explain how particles attained mass.

Higgs and Englert were among several physicists who proposed that a missing particle was the source of the mass found in subatomic particles. However, many physicists argued that things could not be so simple, and they proposed models with many additional particles. But the simplest model—proposed by Higgs and his colleagues—became the favorite among physicists.

One property of the Higgs is that it undergoes extremely rapid decay—breaking down into photons and other subatomic particles soon after it appears. A particle accelerator with very high energy is needed to pick out the elusive Higgs among the debris of particle collisions. In the LHC, scientists finally had a particle accelerator powerful enough to reveal the Higgs.

Additional World Book articles:

• Boson
• Nobel, Alfred
• Supersymmetry
• Physics 2012 (a Back in Time article)
• Found—The Top Quark (a special report)