Following a last-minute delay, physicists Francois Englert and Peter Higgs were today jointly awarded the 2013 Nobel Prize in Physics for their independent formulation of the Higgs mechanism, which supplies fundamental particles with mass. Their theory was recently validated by the discovery of a Higgs boson at CERN's Large Hadron Collider.

In 1964, Englert (with his now-deceased colleague Robert Brout) and Higgs independently proposed a mechanism through which fundamental particles could gain mass.

Professors Francois Englert (left) and Peter Higgs (right) share the 2013 Nobel Prize in Physics (Photos: P. Nicolet and Gert-Martin Greuel)

The Standard Model at that time had a serious problem, in that fundamental particles (meaning particles not made of combinations of other particles) were predicted to have no mass. This prediction was in direct conflict with the observation that the weak and strong interactions only occur at extremely short range (femtometers and below). Short-range interactions require that the particles which carry the force are massive, but there was no mechanism at the time for them to gain mass.

Englert, Brout, Higgs, and others proposed what is commonly called the Higgs mechanism, which is mediated by a new fundamental particle, the Higgs boson. A Higgs boson was finally detected in 2012 (and the main properties confirmed in 2013) by the ATLAS and CMS experiments carried out at CERN's Large Hadron Collider. Often called "the God particle" in the popular media, this unfortunate phrase was born when physicist Leon Lederman wanted to call his popular book on particle physics "the goddamn particle," but his publishers demurred.

Basically, fundamental particles that feel the Higgs field are slowed by their interactions with it, and relativity tells us that particles that travel slower than the speed of light have mass.

There are two points that should be made, however. First is that all mass is not the result of the Higgs mechanism. The human body contains around 20 grams of electrons, and their mass does indeed come from the Higgs field. But neutrons and protons, which make up most of the mass of everyday matter, are composite particles, being made up of combinations of up and down quarks that interact with each other by exchanging gluons. Because E=mc2, the energy binding the quarks together gives protons and neutrons most of their mass. Roughly 99 percent of the mass of common everyday matter is from the binding energy of quarks, and only about one percent is from the interaction of the Higgs field with the quarks making up the protons and neutrons.

The second point is that the Higgs boson has mass: about 130 times the mass of a proton or neutron. This mass is the result of interaction between the Higgs boson and the Higgs field, a point shown in the video below, but not clearly stated.

Explaining how particles gain mass from the Higgs mechanism was a remarkable step into the mystery of existence. Now that the Higgs boson has been found, showing us that the Higgs mechanism actually occurs, this is fully deserving of a Nobel Prize.

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