Brennan Klein is an Assistant Teaching Professor in the Department of Physics and core faculty at the Network Science Institute, where he also leads the Complexity & Society Lab (aka the “&-Lab”). He studies complex systems using tools from network science and statistics, with a special focus on 1) characterizing dynamics, structure, and scale in networks, and 2) documenting emergent or systemic inequalities in society, from public health to mass incarceration. In addition to his role at NetSI, Brennan is the Data for Justice Fellow at the Institute on Policing, Incarceration, and Public Safety in the Hutchins Center for African and African American Studies at Harvard University.
We caught up with him as he is embarking on a new role as Director of the upcoming Master’s degree program in Complex Network Analysis at Northeastern.
Q.1 Brennan, your career trajectory is truly remarkable—from being part of one of the first cohorts of the PhD program at NetSI in 2015, to becoming a postdoc, then a research scientist and director of the &-Lab, and recently becoming an Assistant Teaching Professor and Director of the new MS in Complex Network Analysis. What key moments or inspirations have driven your professional growth over the past decade?
A. It’s tough to pinpoint specifics, what I know is that, when I reflect on the moments that have inspired and sustained me during my career, I was never alone. I was surrounded by an institution of support and mentors and colleagues and friends who gave me space to learn and grow and, importantly, play. Einstein’s quote “Play is the highest form of research” resonates with me because I have a job that requires me to play with ideas, explore new thoughts, and share that experience with people in my life. During the PhD program in Network Science, almost 10 years ago, my classmates and I would often discuss how strange it was to get a PhD in a field that none of our professors had their PhDs in. We recognized early on that about as much learning would come from discussions outside the classroom as it would inside. This realization—together with the classmates alongside me and the connections we form in this field—led to some of the most inspiring years of my life.
Q.2 You have played a key role in developing the new Master’s program in Complex Network Analysis at Northeastern, ultimately stepping into the role of its first Director. What motivated the launch of this program and what would you say to the students about the importance of studying complex networks?
A. One thing our PhD program has made clear over the past decade is the huge demand for education in network science. Students from around the world want to study complex networks, and they want to do it at Northeastern. But beyond sheer interest, we’re seeing how this training gives our graduates a competitive edge in the job market, both in academia and industry. About 50% of our PhD alumni have transitioned into industry roles; ultimately, this was a strong signal that we could—and should—expand our network science offerings beyond the PhD level. The Master in Complex Network Analysis is designed to fill that gap, providing rigorous training that is both conceptually rich, interdisciplinary, and highly applied. It was designed by a team of core NetSI members, guided by Kate Coronges, and features about a dozen new “CNET” courses. Through coursework and hands-on projects, students in our new MS program will choose one of four concentrations—complex social systems, financial and technological networks, complex biological networks, or population health dynamics—all built on a curriculum that provides a strong computational and mathematical foundation.
The ability to work across disciplines is central to this field, and we've intentionally designed our program to reflect that. As part of the MS curriculum, we’re also introducing a research rotation class where students can work with NetSI labs on short research projects that could translate into a thesis or capstone project. If we’ve learned anything from NetSI’s growth over the last 10 years, it’s that network science thrives when it’s collaborative. That’s the ethos we hope to embed in this program—training a generation of network scientists in a way that is rigorous, applied, and connected to our broader research community.
Q.3 What led you towards establishing your own lab and what are some of the most exciting projects currently underway?
A. This is what I’ve always wanted to do. Throughout my career, I’ve been fortunate to be surrounded by fantastic mentors, from my undergraduate research advisor to the mentors at NetSI throughout my PhD, to the many colleagues outside of Northeastern who advise me in ways large and small. Every step of the way, I’ve had someone to share ideas with, expand perspectives, critique my work, and ultimately help me grow as a scientist. Because I’ve had such strong mentorship in my own career, it’s set quite a high bar for me as I grow the Complexity& Society Lab. My goal with the "&-Lab" — originally a tongue-in-cheek joke shorthand for The “We Study This, and This, andThis, and…” Lab— is to collaboratively build a scientific environment that is full of great people and great scientists, in that order.
As for projects that have be enexciting me recently, there are several. The &-Lab team, and the questions we’re asking, are a massive source of inspiration in my life right now. Some intriguing recent projects deal with representation, uncertainty, and scale in networks, from modeling uncertain and noisy dynamics, to reconstructing networks from non-network data, to defining optimal functional areas in spatial or urban networks. The students— Moritz Laber, Lochan Chaudhari, and Erik Weis are real experts on these projects and always eager to talk about their work.
Q.4 In your spare time, your love for networks and complex structures takes you into a personal artistic space to make visual art with links and nodes. It seems that science inspires your art. Does your artistic creativity also influence your scientific research?
A. My interest in art began in Palo Alto, California, the year before my PhD, but it was truly during my PhD program that I started exploring more and more ways to turn networks—these mathematical objects that had captivated me for so long—into artwork.
Drawing soothes me. Usually, I start drawing without an explicit goal in mind; I first draw some nodes, connecting them with links, andI try to let an unconscious mind uncover the rest. This, I believe, has intangible benefits for me and my process of doing science. The best art, like the best science, tells a rich and vivid story—never the whole story, but enough to inspire the viewer along their own pursuit of knowledge and growth.
For years, art was a core part of my identity. During my PhD, I made over 200 individual pieces of network-inspired artwork. Some wound up in various books, was featured at scientific conferences, or made its way onto lab merch. A few pieces were the focus of a scholarly article, and I exhibited at a gallery in Somerville in 2018 and Los Angeles in 2019. Since the pandemic, this pace has dramatically slowed. Today, it takes months to complete a single piece. I’m slower and more meticulous in planning out the design prior to drawing. This may be a function of age, or a busier schedule, or a changing world, but throughout, I still—and always will—love to make art.
