What Are We Made Of?

Alumni6 min. read

With National Science Foundation grant, physicist Hannah Bossi investigates existential questions

Quark gluon plasma
By Laura Meader
April 8, 2020

Physics and philosophy are unlikely bedfellows. But they unite in the existential questions physicist Hannah Bossi ’18 seeks to answer.

What are we made of? How did we get here from the very beginning of the universe?

“These are very appealing questions to anyone that wonders about the universe,” Bossi said. “They’re definitely intriguing and challenging—and almost philosophical—questions.”

Now, Bossi, a Ph.D. student in experimental particle physics at Yale University, has added fuel to continue in her pursuit of answers—she has just won the Holy Grail for graduate students nationwide: a Graduate Student Fellowship from the National Science Foundation (NSF). 

The fellowship frees up funds for Bossi to further her research at the world’s largest experimental facility, the Large Hadron Collider at CERN, the European Organization for Nuclear Research, in Geneva, Switzerland. The fellowship also acknowledges her contributions to the community through outreach programs with middle school girls in Connecticut.

“It’s definitely a very good thing,” said a humble Bossi from her home in Maine, where she’s waiting out the coronavirus. “It’s good for Colby and for Yale, for my advisors—it’s good for everybody.”

The NSF, it seems, agrees.

The Large Hadron Collider, where Hannah Bossi ’18 conducts research on particle physics to help answer questions critical to scientists and philosophers alike.

The strength of Bossi’s fellowship application laid in part in the longevity of her project, which she began in 2017 as a Colby junior after receiving her first NSF fellowship, this one through the foundation’s REU (Research Experiences for Undergraduates) program. That first fellowship took her to CERN and “totally changed my outlook on what I wanted to do and what kind of research I was interested in,” Bossi said. With funds from Colby’s DavisConnects, Bossi returned to CERN a second time for Jan Plan her senior year.

“Hannah is not only extremely bright and motivated, but she also has a terrific can-do attitude,” said Colby’s Sunrise Professor of Physics Robert Bluhm, Bossi’s honors thesis advisor. “She set high goals for herself and then went after them.”

“There are so many things you can do with physics from Colby”

Hannah Bossi ’18

Bossi is part of an international team working on the ALICE (A Large Ion Collider Experiment) project using the Large Hadron Collider, a 27-kilometer, underground ring of superconducting magnets that uses particle beams to hurl two particles—protons or lead ions, for example—in opposite directions until they reach close to the speed of light, at which point they’re directed to collide.

The main goal of ALICE “is to study the state of matter that was present right after the Big Bang,” Bossi said. The smallest particles imaginable existed in this state of matter: quarks, the building blocks of protons and neutrons (and thus everything we know), and gluons, which “glue” everything together, Bossi simplified.

Bossi’s project uses machine learning to study jets, which she described as a shower of particles that traverse through the “soupy medium” of quark-gluon plasma created by particle collisions. It is in this medium, this state of matter, where quarks and gluons move freely and are thus most easily studied. However, the detectors in the collider only see the final product—the jets—Bossi explained, and not the medium, or the collision, itself.

To “see” that collision, Bossi uses machine learning to comb through terabytes and terabytes of data looking for the jets’ weak signal in the background noise in order to trace their path. “It’s like seeing where a dart came from based on how it hits the board,” she said.

Here’s where Bossi has an advantage over some of her peers: formal training in computer science at Colby. As a double major in physics and computer science, she leans heavily on computational problem-solving skills learned in CS to solve physics problems.

Physicist Hannah Bossi ’18 has become a mentor to young women, to both undergraduates and to middle schoolers.

Bossi, a first-generation-to-college student, is quick to give credit to her mentors for her success. Her involvement in Colby’s Women in Physics group provided essential support from and camaraderie among her peers and their professors, including Associate Professor of Physics and Astronomy Elizabeth McGrath.

Together, they traveled to the Conferences for Undergraduate Women in Physics (CUWiP) meetings to present papers and meet new mentors. In 2019 Yale hosted a CUWiP meeting, and Bossi was suddenly the mentor to Colby undergrads. “It was a good chance to show them that it will all be okay, it all works out,” she said. “There are so many things you can do with physics from Colby.”

Bossi’s Colby education imbued her with skills in problem-solving, communication, and critical thinking, providing what she calls a “rare gift” to communicate well in physics and the ability to see the big picture. “I always tell my students that physics isn’t about what you know,”  she said. “It’s about what you can figure out.”

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