Particle physics shines in 2012 top discoveries
December 25, 2012By Faye Flam
Tis the season for the journal Science to name a "breakthrough of the year" and a list of runners up. The winners were chosen by a panel of scientists, and their selection made 2012 a banner year for particle physics. Not one but three of the top breakthroughs consisted of invisible entities and their surprisingly orderly and predictable behavior and properties. The predictions-come-true made for a sharp contrast to the chaos and randomness of the world on a human-scale, with its weird, destructive weather and random violence.
Bosons and fermions
The top finding for Science was the Higgs boson — a long-predicted but hitherto never observed constituent of the universe. It was detected with an enormous consortium of physicists working at a lab near Geneva. The Higgs made big front-page headlines in the popular press as well, but two lesser-known discoveries made the top 10 list — neutrino mixing angles and the Majorana fermion.
I wondered if there might be a unifying theme connecting the findings. I've been writing about the search for the Higgs since 1991, when I worked as physics correspondent for Science. They even sent me on a field trip to the European lab, CERN, to write about plans to build the multi-billion dollar apparatus that would be needed to create and detect Higgs Bosons. When scientists announced the discovery of the Higgs last summer, I delegated the explaining to a cat named Higgs, who got a lot of help from physicists. Read his account.
Physicists predicted the existence of the Higgs boson back in the 1960s. The Majorana fermion came from a prediction by Italian physicist Ettore Majorana in 1937. Bosons and fermions are just two categories into which physicists place particles. Fermions include the constituents of matter – quarks and electrons. Bosons include particles that are associated with forces, including not only the Higgs but two other very expensive particles called W and Z bosons produced at the same European lab.
Higgs the cat is currently working on an explanation of the Majorana fermion, though he may have to wait till some of his physicist friends finish opening their Christmas presents. We'll try to return to the other winner, the neutrino mixing angle, as well.
In the meantime, one graspable theme that's emerging from the verification of all these long-ago predictions is the surprise that the universe at this level is so predictable. Last fall, I went to a fascinating talk at the Institute for Advanced Study in Princeton. Physicist Nima Arkani-Hamed attempted to explain the Higgs, the whole time unable to shake his own gut-level astonishment that denizens of this sub-atomic realm behaves so predictably. We humans discern certain rules and the universe follows them to the letter.
To return to the story of this Majorana fermion, we'll hark back to the 1930s, when physicists were coming to realize that their picture of the nature of matter required that every particle would have a corresponding antiparticle — opposite in electric charge and another property called spin. Every quark had its own antiquark, electrons had positrons, and so on. When matter meets antimatter they annihilate and give off a blast of energy.
Dr. Majorana proposed that some particles were their own antiparticles. He predicted the possibility that particles called neutrinos were their own antiparticles, though that doesn't appear to be the case so far. But he was vindicated this year when the Majorana fermion was discovered by physicists at Delft University of Technology in the Netherlands.
One intriguing aspect of the finding of the Majorana fermion is that it wasn't a particle but a group of electrons that mirrored the behavior of Majorana's theoretical entity. The physicists use the term quasiparticle to explain this kind of phenomenon in which groups of coordinated electrons mimic behavior of fundamental particles. Higgs and I are looking forward to investigating this matter further.
If predictability was the theme for the top physics findings named by Science, unpredictability was the theme for Skeptic Magazine founder Michael Shermer, who spoke about his top science stories of the year for a public radio station in the Los Angeles area (which is where I'm staying over Christmas.)
Just as physicists are awestruck by the predictable choreography of our sub-atomic world, the rest of us are horrified at the disorder that brought us Adam Lanza, Hurricane Sandy and Arctic ice melting even faster than scientists expected. Shermer brought up another shocking story of 2012 in which six scientists in Italy were sent to prison for failing to warn people of a deadly 2009 earthquake.
It's tempting to think this is all a matter of misplaced priorities – with scientists working too hard to predict the dances of electrons and neutrinos and not hard enough predicting important things like earthquakes and outbreaks of violence. But Shermer correctly identified the latter as complex systems, with an inherent unpredictability. This is not about us humans so much as about the way the world happens to work. The jailed earthquake scientists show just how hard it can be for us to come to grips with this reality.
Science was just one of many publications to name a top 10 list of breakthroughs/findings/stories. The Knight Science Journalism Tracker has collected them. (Disclosure: I'm a paid blogger for the Tracker as well as for NewsWorks. Someone has to shell out for the kibble around here.)
The Guardian, for one, got a very different list by taking the top ten most popular environmental stories, among them, "10 Things You Should Never Flush Down Your Toilet."