I am no stranger to Chamberlain’s white walls or garish fluorescent lighting. But until recently, I never noticed the ‘No Bosons Allowed’ sign above the Physics club lounge on the second floor. Until recently, the word boson meant nothing to me at all. Now it represents the heart of all matter.
On July 4, 2012, scientists working at CERN, Europe’s Center for Nuclear Research, announced the discovery of the most sought-after particle of modern science, the Higgs boson.
The missing cornerstone of the Standard Model of particle physics had eluded physicists for nearly 50 years before near-conclusive evidence of its existence was discovered from experiments conducted this year.
So what is a Higgs boson? To put the particle into context, we have to start from the beginning.
The universe was born with the big bang about 14 billion years ago. Fractions of a second after the cosmic explosion, when the universe cooled, energy condensed into many particles. To create matter, particles had to slow down and congregate; they had to be weighted.
Peter Higgs theorized there was a field that was responsible for all masses from electrons to galaxies, what we now know to be the Higgs field, in 1964. The Higgs field would permeate all space. Particles that were once zipping around at the speed of light acquired a mass in the field, slowed down and eventually formed atoms.
The Higgs boson is just an excitation or vibration created by the Higgs field.
“A common misconception is that the Higgs field is made up of Higgs bosons," said Wesley Smith, a professor of physics at the University of Wisconsin-Madison. We have to create a Higgs boson. They are not all around us. Otherwise, why would it be so difficult to find one?”
Think of clapping hands. The motion of bringing hands together and clapping disturbs the air and creates sound waves. The sound waves allow us to perceive the sound of clapping. Protons colliding together are like hands clapping. If we can disturb the field enough, we can detect the Higgs boson.
To prove the Higgs field, scientists had to find the Higgs boson. To find the particle, CERN’s Large Hadron Collider (LHC) was built.
The LHC is the world’s largest and most powerful particle accelerator. Two beams of protons are shot through 17-mile circular underground tunnels. They travel in opposite directions until they barrel headlong into each other causing half a billion collisions per second. The near speed-of-light velocities and colder-than-outerspace temperatures in the LHC mimic the extreme conditions a trillionth of a second after the big bang.
Only about one collision in a trillion will produce a Higgs boson.
To make matters more difficult, the Higgs boson decays almost instantly, in a matter of nanoseconds. Scientists are then responsible for reconstructing its existence from the decayed products. Since there are so few Higgs bosons, to find particular patterns, LHC had to produce a significant amount of data.
Smith played the lead role in helping CERN process all the data from CMS, one of two particle detectors charged with searching for the Higgs boson. From the initial construction of the LHC, Smith and his team had been tasked with designing and overseeing the CMS “trigger,” a filter of sorts to remove unwanted data from the wanted.
“It’s pedobytes of data. It’s a huge amount. Deciding what to keep and what to throw away is a pretty big deal,” Smith said. “Wisconsin is not just a participant. We are leading this experiment.”
UW-Madison professor of physics Sau Lan Wu, who played a significant part deciphering the data from ATLAS, the other particle detector looking for the Higgs boson, said it best.
“We had one million billion collisions with four and quarter billion events," Wu said. "In those events, 240,000 Higgs particles were produced. We were able to observe 350 Higgs events. From those events, we discovered eight cases with similar decayed particles.”
The data from CMS and ATLAS were published together with a standard deviation of five-sigma, meaning there is a 0.00006 percent chance that their matching data was purely coincidental.
“Chances that the events observed were due to random fluctuations are less than one in three million,” Wu said.
Ellen Zweibel, professor of physics and astronomy at UW-Madison, finds this process of discovery the most impressive.
“The discovery of the Higgs will not change my research," Zweibel said. "But what cuts across many fields of science is how these teams analyzed these complicated data sets. These techniques can be applicable anywhere. This is the common language of science.”
But since when is the word “god” in the science language? A PR stunt pulled by a physicist’s book publishers coined the new nickname for the Higgs boson—the god particle.
“Saying the Higgs boson is more important than another undiscovered particle is not right," said fifth-year math and physics major Alex Plunkett. "Why not call the electron the god particle? After the big bang, there would have been nothing without the electron. But if it provided the initial spark for people to start reading into the field of particle physics, then I think it’s totally great.”
“It was clever because indeed people paid attention," Smith said. "This showed them that this was not just another particle.”
So what is next for the god particle?
There is a dark side and light side to the universe. Scientists can see four or five percent of the universe right now, only about half of the light particles. They are hoping the Higgs boson will yield insight into the other half and its super symmetric interactions with existing particles. The 90 percent of our world that is contained in dark matter has also just barely been touched by today’s science.
What may sound like science fiction with a Star Wars twist to most of us non-physicists will most likely end up a significant part of our lives.
“Once upon a time, Rutherford discovered the atom had a nucleus, breaking science. It was hard to tell the public how important the finding was. However, the discovery of the nucleus led to understanding of the electron, which led to electricity and all of its practical applications," Plunkett said. “Time and time again, investments in physics lead to huge growth in technology and power.”
Smith is already planning the next phase of the trigger for the Higgs project. His team hopes to increase the number of collisions by a factor of 10 and have to modify their detectors in order to keep up with that level of data. The experiment is designed until 2035, but he still does not see that as the end for the Higgs boson.
“We have just landed on an island," Smith said. "The act of arriving there was important. But what is more important is what we are going to discover and learn on this island. We are starting a new era of exploration.
"This will rewrite the textbooks.”