On the fifth floor of BiHall is a glass-paneled enclosure where many students of physics can often be found, socializing, snacking and collaborating on problem sets. A sign on the exterior of the glass wall serves as a friendly reminder to onlookers: “Please don’t knock on the glass. It scares the physics students.”
“I’m not sure [the sign] casts the students in the best light,” Professor of Physics Anne Goodsell joked as we walk towards her lab, which is further down the same hallway.
The signage here in the lab is considerably more serious. “Danger,” it warns in large text bolded for emphasis. “Visible and/or invisible laser radiation. Avoid eye or skin exposure to direct or scattered radiation.”
Professor Goodsell’s lab works in the cooling of atoms using laser light to study the interaction between highly excited atoms and electric fields. Put simply, the Goodsell lab has been assembling a laser-cooling system: that includes the lasers themselves, a source of atoms (Rubidium, in this case) and the vacuum chamber, optics and electronics for these experiments.
Multiple lasers are shot and intersect at a point, forming a magneto-optical trap where rubidium atoms will cool to 200 microkelvins and launch upward in discrete clouds. This cooling process slows the atoms’ movement in midair. For reference, room temperature is 293 kelvins, or 293,000,000 microkelvin. According to Goodsell, these rubidium atoms are the “coolest atoms in Vermont.”
Why cool atoms in Vermont, of all places, where average temperatures go down to 10ºF in the winter? (That’s 261 kelvins, in case you were wondering). Cooling down atoms slows their movement, which allows the lab to more accurately measure the atoms’ trajectories to investigate their interactions with external electric fields and forces.
Goodsell’s study of the laser-cooling of atoms began as an undergraduate at Bryn Mawr College and continued into her graduate and post-doctoral research at Harvard.
Goodsell’s experience at a liberal arts undergraduate institution allowed her to explore her different academic interests, which was ultimately what had led her to embark on her journey of becoming a physicist.
In fact, her first research experience had been in a laser-cooling lab in between her sophomore and junior year in college.
“Being in a lab made me feel like there were things I could build and feel and see,” Goodsell said.
“It was the first time when I spent some time reading about science work that other people had done. I read a whole bunch of papers — some of it I didn’t understand.”
She showed me a box of papers that she had collected that summer. Each paper was folded neatly in half, organized chronologically and tagged by author, title and date.
“I printed out all these papers that talked about laser cooling. There weren’t PDFs yet at this point,” she said.
“There’s my electron,” Goodsell pointed affectionately to a small diagram in the margins of one of the papers. “It absorbs some energy and spits out some light.” She laughs. “This [box of papers] is, in some ways, just a relic. I feel like I just couldn’t discard them. This was a set of papers that was recommended by a faculty member that I worked with and there’s stuff that’s like the foundations of the field.”
“I think that [summer is] when I started to understand things,” Goodsell reflected.
“That was also the first time where I was really learning a bit more about the community of science and science people,” Goodsell said, commenting on the collaborative nature of research in the sciences.
“For a lot of the topics in science, the work that you do is really connected to the work that other people have done. It’s not just connecting with ideas in a textbook,” Goodsell said.
When new fields of research first begin to materialize, experimental procedures can often encounter various glitches and challenges so that initially only a few people are able to carry out the relevant experiments successfully.
“A lot of work in science starts that way,” Goodsell said. “A few people do something successfully, compare and confirm, argue about it, come out with either one general outcome — or sometimes two — and from there these ideas get picked up by a larger group and then at a later time there may be as many people who have done that experiment as people who have run the Boston Marathon in history or have served as a congressperson or have bought hamburgers.”
After joining the Middlebury faculty in 2010, Goodsell has taught courses from Newtonian Physics to Experimental Physics to a first year seminar called Light: Metaphors and Models.
Goodsell has taught the Experimental Physics course at least once every year since 2015. “I still very much enjoy doing experimental physics, so getting to teach that class is — sort of — like getting to take it again.”
“For me, [teaching and doing research] was a really desirable coexistence,” Goodsell said. Teaching and doing research simultaneously at a liberal arts college, however, comes with its own set of challenges.
Though the process of research and formulating questions works really well during the summers, maintaining that mental connection to research during the school year is harder, Goodsell said. During the school year, Goodsell splits her time between her teaching and research responsibilities, but central to both is her passion for sparking in her students the same joy of experimental physics that she maintains.
“[My undergraduate physics courses] was the experience that I had that helped me decide on doing research, so it feels like one way to offer other people that same kind of opportunity,” Goodsell said. “Not like, ‘You must do physics because I loved it and you will, too,’” Goodsell said, but if you’ve never had the opportunity to explore the field, “how would you know?”
Sasha Clarick ’19, Amanda Kirkeby ’19 and David Cohen ’20 presented on their work in the Goodsell lab in the Spring Symposium two Fridays ago.
Clarick stayed at Middlebury over the summer to do research in the Goodsell lab. “I am modeling atoms as they fly upwards towards a charged wire, visualizing their behavior in different circumstances,” she said.
Visualizing such behavior allows various aspects of the atom cloud, such as its velocity and size, to be measured and characterized.
Though the research initially ran into hiccups over operation of the laser apparatus, Clarick described a “feeling of accomplishment” when they were able to successfully trap the cloud of atoms for the first time, after getting the lasers working and properly aligned — but lasers aside, the entire process was “also just really cool” Clarick said.
“That’s just kind of mind boggling, isn’t it? That you can take lasers, which you’d think would heat things up, and cool it down and physically condense it into this cloud,” Kirkeby said, sharing Clarick’s and Goodsell’s enthusiasm, “…the perplexity and the counter-intuitiveness of it.”