Exploring the Standard Model of particle physics

    At the end of my high school Quantum Mechanics class, our teacher gave each of us a poster of the Standard Model of particle physics. It’s a sweet poster. The diagrams of particle clusters and clouds are pretty, and the charts are fun to read. Particle categories and names (fermion, boson, neutrino, muon, quark, lepton, baryon, meson, gluon…) beg to be used in bad puns or knock-knock jokes. And, in addition to the mass and charge attributes we saw in chemistry class, these particles have “spin” and “flavor.”

    But that’s about as far as my understanding of the Standard Model goes. Assistant Physics Professor Andre de Gouvea, on the other hand, comprehends the Standard Model beyond its sheer grooviness. Inside his office, a bike leans against a bookshelf full of physics texts, and a cascading cluster of lanyard nametags from science gatherings hangs from a file cabinet. When he’s not teaching a physics class or guiding students through research, de Gouvea investigates the results of particle physics experiments, especially those involving neutrinos — they’re quick, light elementary particles.

    With a slight Portuguese accent from his native Brazil, he calls the model an “ad hoc, weird-looking theory” that has never been perfect, as his investigations helped reveal. The model states that neutrinos have no mass, but in 1998, experiments showed that they did. Such contradictions to the Standard Model, de Gouvea says, are cause for celebration rather than consternation. “We’re always on the hunt to find things that violate it so we can get a better idea of what the right picture should be.”

    Nothing excites a particle physicist as much as the device that will present a clearer view of that picture: the Large Hadron Collider (LHC) at CERN, a nuclear-research facility in Geneva, Switzerland. The LHC, which should be ready for operation this summer, will bang together protons and other particles in an underground tunnel 17 miles in circumference. These collisions could produce the heavy Higgs boson, dubbed the “God particle” due to its massive implications for the Standard Model and science as we know it.

    The development of physics’ Standard Model runs along the same lines as the development of chemistry’s periodic table in the 19th century. Scientists seek an ultimate logical organization, but inconsistencies arise. The model can only approach perfection through time and research. Right now, as de Gouvea’s research helps show, the Standard Model remains incomplete.

    One big reason the Standard Model comes up short: It doesn’t explain “dark matter.” The name itself sounds ominous, like some trick of Lord Voldemort. Dark matter, which is invisible, somehow accounts for gravitational force. “Whatever it is, it’s not normal matter,” de Gouvea says. Dark matter is probably made of a new, un-observed fundamental particle, he says: “And whatever that new particle is, it’s not something that belongs in the Standard Model.”

    Why bother perfecting this bear of a model? The Standard Model could give us crucial insight into the universe’s first moments. Initially, the universe was so hot and dense that it looked like a giant bag of fundamental particles, de Gouvea says. “We have to know what their properties are in order to understand why we live in a universe that looks like it does when we observe things.”

    Besides shedding light on the birth of the universe, developing a better Standard Model might contribute to a “Theory of Everything,” the Golden Fleece for scientists. A theory of everything would elegantly explain why nature works the way it does. Could all of these different particles and interactions really be manifestations of one grand, underlying principle?

    While the LHC will provide some answers, some worry that it might also produce tiny black holes that could swallow the earth. But the probability of this happening is so small that it’s not worth being concerned about. Other apocalyptic fears include the production of some strange matter that would react with other matter and transform the earth into a dense ball of sameness (like Kurt Vonnegut’s “ice-nine,” the catalyst of the apocalypse in Cat’s Cradle).

    These scenarios won’t occur, de Gouvea says, because the LHC won’t create a situation that hasn’t already arisen in nature. Particles in cosmic rays, for example, could have transformed Earth — but they haven’t. “It’s sort of science fiction,” he says, and the potential benefits of using the LHC far, far outweigh the risks.

    What did one particle physicist do to the guy who claimed the LHC would destroy the universe?

    He lepton him.


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