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Extreme Science

What is the Higgs boson and why is it so important?

When UVA physicist Brad Cox says he feels lucky to be alive, he’s not talking about surviving a car wreck or a battle with a deadly disease.

Brad Cox Dan Addison
Instead, he’s talking about having a role in the discovery of what scientists believe could be the particle that explains what holds the universe together and is the basis of matter.

“It’s the discovery of the millennium in particle physics,” says Cox, who was part of a four-person review committee that gave the green light to publish the evidence of the Higgs particle. “It’s tremendously gratifying that I’ve managed to survive long enough to see this become a reality.”

The Higgs particle was first hypothesized in 1962 by Peter Higgs, an English physicist. For decades before, scientists had been slowly but steadily defining the dozen basic building blocks of the universe, which make up more familiar particles such as protons and neutrons, but there was “no mechanism for giving mass to these fundamental particles,” Cox says.

Higgs, however, suggested that there existed an invisible field throughout the universe that acted on these building blocks to give them mass—the quantity of matter that a body contains.

Higgs’ theory postulated that the universe until shortly after the Big Bang was sort of like a snow globe without water, with electrons and quarks zipping about. But as the universe cooled, the invisible field was switched on, and it was as if the snow globe became filled with water. The particles, or the “snow,” now had impedance, or drag, on them. And the more these particles interacted with the field, the more mass they had.

While the theory was a way of giving mass to particles, “it was (just) talk at that point,” Cox said.

Large Hadron Collider Courtesy Maximilien Brice/CERN
In July, scientists decided to put Higgs’ theory to the test inside the Large Hadron Collider, the largest scientific instrument ever built. Located in Geneva, the collider works by smashing protons together and then immediately sifting through the rubble to find their component parts. Theoretically, if scientists looked closely enough and in the right place, those parts would include a Higgs particle, or boson.

It wasn’t long after smashing up a batch of protons that scientists—with Cox’s committee’s OK—announced they had all but found a Higgs particle. Peter Higgs, who was present during the experiment, reportedly wiped tears from his eyes at the discovery.

Cox is careful to say scientists still have work to do before they can confirm that what they have is the real deal. There is a small chance that the particle thought to be a Higgs particle is a fluke.

But it is hard for Cox to hide his excitement.

“There are kinds of profound things that happen once every half-century,” says Cox. “We were there at the time it was done. You can’t beat that. I feel sorry for all those people that didn’t live long enough to see it.”