Part of what attracted Mara Prentiss ’80 to physics was that it was “the Marine Corps of the sciences,” she says. “It was the toughest, ugliest, and hardest, and I was determined to prove I could do it.”

Prentiss did prove she could do it—and a lot more. In 1995, she became the second woman to receive tenure from the physics department at Harvard, just four years after she started teaching there. Now the university’s Mallinckrodt Professor of Physics, Prentiss has founded a new field in physics: atom lithography. She has received several teaching prizes, has been named a fellow of the American Physical Society, and supervised the work of a student who won the society’s prestigious Apker Award.

She also runs the Prentiss Research Lab, where much of her current research focuses on DNA and the principles of self-assembly, specifically proteins that play a role in DNA recombination and repair. Some of her former students now work in her lab; as she explains it, she really tries to help people get what they want from science.

Beyond her work advancing the fundamentals of physics and science, Prentiss is deeply committed to its practical applications. She has tackled some of the world’s greatest challenges using her perspective as a scientist, becoming a leading source of information on the most effective ways to conserve energy as the world deals with a climate crisis. She has long advised the U.S. government on energy and, along with former students, made one of the first calculations proving that SARS-CoV-2, the virus that causes COVID-19, is airborne.

At Wellesley, she built her foundation in physics with Ted Ducas, now professor emeritus of physics, who became her thesis advisor, and she honed her problem-solving skills and ability to work across disciplines as a triple major in physics, math, and philosophy. Those departments were very different, she says, but each made a deep impression. Mathematics professor Alan Shuchat, for example, didn’t like his students to take notes—a lesson, Prentiss says, in the importance of paying attention and mastering the material well enough to incorporate it into the rest of their lives. She marveled at the natural world around Wellesley, going for long walks on campus, while also enjoying peaceful corners of the library. Those pieces of campus, she says, gave her something “outside of school and outside of stress and pressure.”

Ducas encouraged Prentiss to pursue a graduate degree in physics at MIT. Working from a list of professors he gave her, she typed out letters, one by one, and shoved them under doors until one of those doors opened—belonging to Professor Shaoul Ezekiel. He would later become her graduate thesis advisor, but her first job in his lab was to label a couple of hundred mirrors, each with different properties. She spent her spring break meticulously making an outline of all the mirrors and their properties, only to have the professor come in, rub a label off with acetone, and ask her to redo all her work using the correct pen. A first test in resilience and commitment.

That resiliency and commitment have stayed with her throughout her career as she has addressed seemingly unsolvable problems, including climate change and COVID-19. Though she researches the world’s more perplexing issues, she describes herself as a fundamentally “extremely optimistic” person. “I believe it’s helpful to think about all the things we can do,” she says, “it’s paralyzing to do otherwise. You have to start somewhere.”

She’s applied that principle to energy conservation, the focus of her book Energy Revolution: The Physics and the Promise of Efficient Technology. In it, she makes the case that the world is capable of an energy revolution to stave off climate change, if only we have the courage and the motivation to enact change.

Her goal is to provide information so that people can “think about how to make energy decisions in a reasonable way,” she says. Wind turbines, for example, are incredibly effective when they are put in windy places and the energy is distributed; installing a little one on your roof “is not anything but decorative,” she says. She has put forth a bold suggestion—that wind and solar power alone could generate 100% of the United States’ average total energy demand now. And energy changes, she argues, don’t necessarily have to sacrifice people’s quality of life—Iowa, for example, embraces wind power now because it is helpful to farmers.

She has also advised the government on energy use, as the military has long been interested in how to use energy well. “To get a gallon of gas to Afghanistan costs about $120,” she says. Her work involved analyzing scenarios in which it was best to use solar or diesel instead of gas.

Recent sky-high oil prices, she says, have forced more people to think about energy and where it comes from. The key to encouraging change on a broader scale and within a scientific framework, Prentiss says, “is finding things that fit into the culture people already have, rather than ordering them to change the culture.”

In October 2020, she again put her knowledge to practical use, working with a former student to publish a paper that examined five COVID-19 superspreader events and concluding that the virus spreads when airborne. Her lab is currently working on antibacterial applications of her DNA and RNA work—testing whether it’s working and whether it works better than anything that is commercially available.

Prentiss, her wife says, is someone who “really likes to see things happen in the world.”

Prentiss agrees with that assessment. “I want to see that growth happens in the world,” she says, “to see that something I have thought about comes to exist in the world or to have an impact on the way the world is.”