Aaron Sternbach Combines Light and Matter to Push Experimental Boundaries

Aaron Sternbach, a new assistant professor in the Department of Physics at the University of Maryland, is an expert in combining light and material properties to produce unique results. His experiments have allowed him to spy on elusive quantum interactions that play out on extremely small and fast scales.

“I study quantum materials with light,” Sternbach said. “When I encounter something I can’t see with light because of common ‘limits,’ I study the physics behind these limits and try to push them further. That is a really fun part of the job. In some cases, that approach can lead to new opportunities.” 

Since he was a kid, Sternbach enjoyed math and physics. But even as he enrolled to study physics as an undergraduate at Boston University, he wasn’t certain that he wanted to pursue a career in physics. During his freshman and sophomore years, he worked in an astrophysics lab where he spent most of his time helping design measurement devices. But after almost two years of work, his efforts hadn’t produced a physical device. The project wasn’t progressing at a pace he found satisfying, so he considered switching majors to study medicine in his junior year. Aaron SternbachAaron Sternbach

That changed after he spent his summer working in physicist Richard Averitt’s lab. He assisted with an experiment that used light to manipulate the electrical properties of a quantum material. In the project, light drove the material from being a poorly conducting insulator to an electrical conductor. Achieving the transition required focusing the light into a smaller spot than is possible using lenses or other common techniques. Instead, it required taking advantage of the material’s structure. 

A material’s response to light is dictated by its internal structure, and the project was looking at just one of the countless possible materials that scientists can find in nature or deliberately engineer. Sternbach became hooked on physics when he started to explore simulations of materials as part of the project, and he never looked back.

"I found it fascinating that engineering light could totally change the properties of a quantum material," Sternbach said. "I started playing with all sorts of simulations to try to understand how far this approach could go."

He started to wish he could watch the transitions between insulator and conductor in experiments as they played out in real space and real time. In 2013, that desire led him to graduate school at UC San Diego, where he joined the lab of Dimitri Basov. Basov had recently been investigating new techniques that used material properties to focus light into unusually small spots. His early results showed that the approach could be useful for observing and learning about quantum materials. In the middle of his graduate studies, Sternbach moved to Columbia University when Basov relocated his lab there.

Working with Basov, Sternbach helped develop a new observation technique that can observe very quick changes while also getting around a rule in physics called the diffraction limit. The diffraction limit is the inevitable result of the way that waves, including light, spread—diffract—when they pass the edge of an object and then keep spreading as they travel. For devices that use lenses and apertures to manipulate light, the diffraction limit imposes strict constraints both on the smallest spot a beam of light can be focused into and on the smallest features that the device can be used to clearly distinguish. However, by using the structure of a material to continually influence light, researchers can circumvent the diffraction limit and build new tools for manipulating and observing the microscopic world. 

The observation technique that Sternbach helped develop simultaneously uses the material’s structure to herd light along paths that beat the diffraction limit and uses very short flashes of light to accurately capture quickly unfolding events as they play out over time. To get clear snapshots of rapidly changing experiments, the team used extremely short flashes of light, providing a clear view of brief periods instead of capturing a blurry image like an overexposed photograph. 

“Learning to interact with data and gaining an intuition for what you're seeing is like learning a new language,” Sternbach said. “You learn fantastic approaches to see parts of the world that are way beyond a native human scale.”During positive refraction (green) the path of incoming light (blue) will bend, but it will never cross the dotted line perpendicular to the interface of the two materials. In rarer circumstances, called negative refraction (red), the light sharply turns and continues on the same side of the dotted line. (Credit: Bailey Bedford, UMD)During positive refraction (green) the path of incoming light (blue) will bend, but it will never cross the dotted line perpendicular to the interface of the two materials. In rarer circumstances, called negative refraction (red), the light sharply turns and continues on the same side of the dotted line. (Credit: Bailey Bedford, UMD)

As part of his graduate work, Sternbach got to apply the technique he’d developed to observe materials transforming in real space and in real time after light was used to initiate a change.

After completing his degree, he continued to work with Basov as a postdoctoral researcher. In a new project, they incorporated an additional way that light and matter can interact. They studied polaritons—particle-like combinations of light and matter with characteristics of both. Since the matter portion of a polariton contributes mass, polaritons behave more like matter than normal light: They can carry significantly more momentum than light and can be more tightly confined into a beam than freely propagating light. 

Sternbach and his colleagues wanted to observe a particular type of polariton, called a hyperbolic polariton, that travels through the bulk of a material along a specific type of constrained path. In an article published in the journal Science in 2021, the team shared how they created polaritons by hitting a layered material with a pulse of light and then used their new technique to observe polaritons and follow their journey through the material. Their measurements revealed details about quantum states that were crucial to the polaritons’ existence and that only existed in the material for trillionths of a second. 

Following that experiment, Sternbach and his colleagues studied hyperbolic polaritons that moved between two different adjacent materials. They investigated two naturally occurring materials that were known to produce polaritons and revealed that a polariton’s path would bend in an unusual way as it passed across the interface between the two materials. 

Normally when light travels between two materials, such as water and air, its path bends slightly based on the fact that it travels at different speeds in each material. This bending of light—called refraction—is why a straight straw placed in a glass of water looks like it bends at the interface. 

In an article published in the journal Science in 2023, Sternbach and his colleagues showed that when they properly oriented the two materials, the polaritons at the interface didn’t refract normally. 

Most materials produce positive refraction, where light is deflected a bit but is limited in how far it can swerve to either side. Positive refraction is similar to a simple dive into a swimming pool: The diver’s direction will change some when they move into the water, but as they continue down, they also keep moving forward. 

Sternbach and his colleagues observed their polaritons bending in a more drastic way, called negative refraction. During negative refraction, a beam almost does a U-turn. While it continues down into the new material, it also travels backwards, like a diver who instantly makes a sharp turn as they hit the water so that they end up under the diving board instead of in front of it. 

The team’s experiment revealed that producing negative refraction in the experiment depended on getting the top layer turned at just the right orientation to the bottom layer. The team went on to use negative refraction to create a tiny container for trapping light. They demonstrated that when the polaritons were reflected at the exposed surfaces of each material, the negative index of refraction allowed the polaritons to become stuck in a loop that is much smaller than the wavelength of the light outside the materials. 

Now that Sternbach has joined UMD, he plans to continue this line of research in his own lab, where he hopes to create a supportive environment for students. He is currently looking for new students to join him in exploring quantum materials and the complex interactions that can be engineered between light and matter. 

“I always felt that exploring curiosities and doing things that I really enjoyed doing was enough,” Sternbach said. “And I think that was a good rule of thumb. It's allowed me to explore this direction, which is basic research, freely and grow in whatever direction nature allows. I'm very excited to see where this goes in the future at Maryland.”

Story by Bailey Bedford


The Sternbach group is always looking for exceptional graduate and undergraduate students as well as postdoctoral researchers who wish to join the team. Those interested may reach out to him by email at This email address is being protected from spambots. You need JavaScript enabled to view it..

Solving the Mystery of the Stinky Vapor Plumes on Campus

Billowing white columns of vapor rise silently from sidewalks and manholes around the University of Maryland campus when it gets chilly. These mysterious plumes are sometimes accompanied by a strange odor or a lingering warmth. Like ghosts, the hazy wisps seem to come and go without much explanation. But what’s the cause of this foggy, strange smelling campuswide phenomenon and where is it coming from? 

“It’s definitely not intentional or desirable,” said UMD Physics Professor Daniel Lathrop. “You’re not supposed to see or smell it at all. In fact, it’s just one component of a much bigger problem. This visible vapor is a sign that our underground utilities infrastructure is aging and inadvertently helping to cause water and heat waste across our campus.”Dan Lathrop. Credit: Georgia JiangDan Lathrop. Credit: Georgia Jiang

Like a leaky pipe, this leaking vapor can cause serious problems including infrastructure damage, energy waste and pollution to the natural areas surrounding UMD. 

The university’s infrastructure—some of which dates back over 150 years—naturally deteriorated over time. That includes the decades-old tri-generation energy system that the majority of the campus runs on today.

“Our current energy generation system was installed in 1999. It heats, cools and powers over 250 campus buildings,” explained Lathrop, who also holds joint appointments in the Departments of Geology and Physics, the Institute for Physical Science and Technology, and the Institute for Research in Electronics and Applied Physics. “A natural gas-fired turbine generates most of the electricity we use and the heat that this turbine produces is recaptured to produce steam, which produces additional electric power. The steam is then also used to heat and cool our buildings.” 

Gregg Garbesi, assistant director of utilities and energy management at UMD’s Facilities Management, says the visible vapor comes when liquid (like groundwater, city water leaks, stormwater leaks, etc.) physically contacts the underground steam line. He compares the campus’ visible vapor to steam caused by pouring cold water into a hot pan on a stove. He explains that the odd smells accompanying the vapor occur when organic materials come into contact with the leaked vapor, which is generated underground or in a steam manhole. 

According to Garbesi, seeing these vapor plumes signals energy loss. 

“For every pound of vapor generated, a pound of steam is condensed in the steam pipes,” he said. “All the energy that went into making that pound of steam—which could have been used to power campus—is lost, and if 100% of the condensate doesn’t return to the energy plant, that water is also lost.”

“We’re wasting about a million gallons of water a day now,” Lathrop added. “The loss in 2019 alone is estimated to be 700 million gallons, costing us an estimated $4 to $6 million a year. And that’s just the financial price tag that we know about.”

That’s why Lathrop is leading a multidepartment, cross-disciplinary Grand Challenges team that aims to map and pinpoint locations where steam is being lost and get a better look at challenges with energy consumption, water quality, methane emissions and air quality on UMD’s campus. With colleagues and students from the Departments of Geology, Atmospheric and Oceanic Science, Geographical Sciences, and Environmental Science and Technology, Lathrop hopes to tackle these interrelated issues by pinpointing the biggest problems and providing concrete solutions.

“Methane emissions, carbon dioxide emissions and pipeline water loss from our campus play a big role in stream water and air contamination nearby,” he said. “It’s our goal to measure these impacts and figure out how we can remediate these challenges to reduce our campus’ climate footprint and improve the environment here.”

Diagnosing and treating an aging energy system

When Lathrop began this project in spring 2023, his first step was to work with Facilities Management to learn more about the campus’ utilities-related challenges, particularly the steam issues caused by underground pipelines. He soon realized that his ongoing U.S. National Science Foundation-funded research—to develop sensors capable of detecting geophysical anomalies—could play a key part in this new project. 

“My lab was originally developing geophysical sensors to look for landmines and unexploded ordnance, but we recognized that this same system could be used to find buried utilities,” Lathrop explained, referring to a project that was named a UMD Invention of the Year in May 2022

Licensed drone pilot and physics senior Meyer Taffel is test-flying a drone over campus to magnetically map UMD's underground utilities. Credit: Dan LathropLicensed drone pilot and physics senior Meyer Taffel is test-flying a drone over campus to magnetically map UMD's underground utilities. Credit: Dan LathropUsing these sensors and historic infrastructure blueprints provided by Facilities Management, Lathrop and his team sketched out an extensive map of steam-emitting sources on campus. They concluded that UMD’s energy system had at least 55 active steam vents. 

A group of undergraduate physics majors taking Lathrop’s PHYS 499X class added to those findings when they hand-built a calorimeter (an instrument that measures heat from chemical and physical reactions) in fall 2023 as a course project. 

The students used the calorimeter to identify dozens of campus hot spots and learned that some of these accidental vents lost more than 60 kilowatts of heat energy via escaped condensation. For reference, a standard incandescent light bulb uses about 60 watts of electricity on average—meaning that the steam and heat leaking from some of these vents could power approximately 1,000 of those light bulbs. 

Lathrop estimates that this loss alone could equate to approximately $50,000 per year but he believes that identifying and analyzing the factors that led to the hot spots was invaluable.

“This is a team effort and having everyone on the same page can really make a difference when it comes to fixing things on campus and allocating resources appropriately. Our work has already started to help the university identify and patch sites on campus with water leaks,” he said. “We were able to prevent local building damage and protect students, staff and faculty from potential safety hazards.”

Putting together pieces of a bigger puzzle

Other members of the Grand Challenges project team are also on the ground looking for ways to locate and address the campus’ interconnected water and air quality problems.

Geology graduate student Julia Famiglietti and Geology Chair and Professor James Farquhar tracked gas leaks on campus through the sewer system to create a methane inventory (list of methane sources and sinks). They identified a contamination source underground that they suspect is related to the aging steam system.

“We think that the contamination has something to do with steam additives accidentally coming into contact with and reacting to methane,” explained Famiglietti, who sampled the air in campus sewers at least once a month to determine the composition of gases found in emissions. “We’re focusing on understanding the chemistry behind this contamination signature and directly discussing with the steam plant management personnel how to address the problem.” 

Geology Associate Professor Karen Prestegaard and Professor Sujay Kaushal found similar results while working with student groups to monitor the water quality of streams and storm drains. They discovered that water discharging from steam vents into storm drains had noticeably higher pH values and higher salt contamination than natural rainwater—potentially encrusting pipes with buildup and impacting wildlife in the Paint Branch waterways. 

Other efforts to gather and analyze the researchers’ environmental data include Project Greenhouse, in which First-Year Innovation & Research Experience (FIRE) undergraduates are drafting a sustainable methane budget for UMD.

Lathrop hopes that this multiyear campuswide team effort will help UMD reduce water and steam waste (and the associated environmental and fiscal costs) by 30% by the end of the project in June 2026. He believes this project can serve as a model for other research efforts to analyze similar urban environmental impacts for cities or large organizations like universities. 

“Our campus is a microcosm of urban and suburban environmental impacts, so evaluating UMD’s impact on the environment leads to a better understanding of how humans impact climate on a local, national and global level,” Lathrop said. “We’re all doing our part to protect our campus and the people living and working here.” 

Written by Georgia Jiang

 Other UMD faculty members involved in the Remediation of Methane, Water, and Heat Waste Grand Challenges project include Atmospheric and Oceanic Science Professor Russell Dickerson, Environmental Science and Technology Associate Professor Stephanie Yarwood, FIRE Assistant Clinical Professor Danielle Niu, Geographical Sciences Assistant Professor Yiqun Xie, and Geology Professors Michael Evans and Vedran Lekic. 

Determined to Learn, Inspired to Teach

Long before he became a scientist, Brad Conrad (M.S. ’06, Ph.D. ’09, physics) was a curious kid, determined to learn everything he could about the world around him.

“My favorite story is when I was three or four my mom found me in the living room where I had found a screwdriver and I’d taken apart the videocassette recorder,” Conrad explained. “I did that because I had put my peanut butter sandwich in the VCR and was trying to figure out how to get it out. I was always determined to learn about things.”

Conrad’s passion for learning and an interest in science—and maybe one too many questions in a high school chemistry class—helped him find his niche.Brad ConradBrad Conrad

“I was doing well in chemistry, but I kept going to the chemistry teacher asking things like ‘What do orbitals mean?’ and ‘Exactly how do atoms do this?’ and he threw up his hands at some point and said, ‘You just need to go talk to the physicists—you’re a physicist,’” Conrad recalled. “That’s when I decided that I should probably do physics instead of chemistry.”

Conrad’s fascination with physics launched a successful career that’s taken him from state-of-the-art research labs and university classrooms to the American Institute of Physics (AIP) where he supported thousands of undergrads and alums as the national director of the Society of Physics Students (SPS) and Sigma Pi Sigma, the honor society for physics and astronomy. 

In 2023, Conrad took on the role of education and workforce development manager in the Partnerships and Outreach Division at the National Institute of Standards and Technology (NIST). There, he works to build education and workforce development partnerships for NIST’s Office of Advanced Manufacturing to promote awareness and training opportunities for manufacturing jobs in STEM.

“I work across government agencies like the Department of Defense, Department of Energy and NASA—so it’s an all-of-government approach to solving the problems that we have in manufacturing today,” Conrad said. “It’s helping people realize that now when we say manufacturing jobs, it’s programming robots, doing advanced electronics and using lasers to do really cool stuff. My mission is to make the world a better place with science.”

Beyond the “middle of nowhere”

When Conrad was young, his dreams stretched far beyond the “middle of nowhere” Pennsylvania town where he grew up. 

“I went to my high school guidance counselor to figure out what I should do, and they said I should be a truck driver because it paid really well,” Conrad recalled. “That rubbed me the wrong way because I’d already decided I was going to be a scientist.”

Determined to be the first one in his family to go to college, Conrad enrolled at the Rochester Institute of Technology (RIT) as a physics major, but fitting in was harder than he expected. 

“It was definitely a tough major and I didn’t have a support network at all. I had this feeling that I didn’t belong,” he explained. “But, then, the summer before my junior year, one of my undergraduate teachers called me and said ‘Hey, I was wondering if you’d be the president of the Society of Physics Students when you come back in the fall,’ and that made a world of difference to me. It made me feel like somebody cared.”

With SPS activities and events keeping him busy and connected, Conrad stayed at RIT, earned his bachelor’s degree and went on to graduate school at the University of Maryland, where an active, engaging community took his passion for physics to the next level. 

“At Maryland, there was a physics talk or multiple talks every day of the week, different topics, different people coming in, different labs, it was so inspiring,” he recalled. “I felt like I was at the hub of science, and it was great to be in one of the biggest, highest-ranked places in the country for physics.”

After exploring a variety of research opportunities from astrophysics to lasers, Conrad landed in Distinguished University Professor Emerita of Physics Ellen Williams’ surface physics lab conducting cutting-edge semiconductor research.

“When I started, she was doing nano stuff, semiconductors at the smallest level—so, individual molecules and interfaces between semiconductors and metals and graphene and carbon allotropes, and that was all really hot stuff at the time,” Conrad explained. “My Ph.D. ended up being on the interface effects of nanoelectronics. It was a great decision.”

In 2009, Conrad accepted a National Research Council postdoctoral fellowship to conduct organic electronics research at NIST. 

“There was a chemist at the University of Kentucky making new organic semiconducting molecules. Nobody else in the whole universe was looking at them and they were being shipped to me and I was trying to grow single crystals of them and then determining if they were semiconducting or not,” Conrad said. “I was literally on the bleeding edge of organic semiconductor research and that was very exciting.”

Meanwhile, he was also teaching an introductory physics class at UMD. Inspired by the challenge of working with students, Conrad joined Appalachian State University in 2010 and spent the next eight years teaching physics and astronomy, building workforce and outreach opportunities for his students, and enjoying life on the doorstep of the Blue Ridge Mountains.

“Everyone there had four-wheel drive vehicles so they could get up and down the mountains, and I could see the Blue Ridge Parkway from my house,” he recalled. “I could just go off from my backyard and find one of the paths and connect up with the Appalachian Trail, so I definitely became a hiking person.”

Conrad also became a popular teacher and mentor, committed to providing the support and guidance he knew his physics and astronomy students needed. But he was just getting started.

Joining AIP in 2016 allowed him to do even more. As the director of SPS and Sigma Pi Sigma, Conrad impacted thousands of U.S. physics and astronomy students and alumni by building programs and sharing best practices to enhance physics education.

“My job at Appalachian State taught me how important teaching is, then what I loved at AIP was I got to direct the conversation and resources nationally, for 32,000 undergrads in physics and astronomy across the country,” Conrad explained. “It was my dream job, the coolest thing I’ve ever done.”

Thanks to his own experiences as a student and a college professor, Conrad knew that SPS provided support that can be crucial to students’ success.

“It gives students a common mission and it supports fellowship and interest in physics,” Conrad noted. “The reason students don’t stay in physics is because they don’t feel like they fit, but SPS helps every student feel they belong, and that’s the real strength of SPS—belonging.”

Always a physicist, always a teacher

In his current role at NIST, Conrad still supports students interested in science and technology, but he also supports the high-tech employers who need them. He works to build collaborations between manufacturers and government agencies and advance specialized training and apprenticeship programs.

“Within Manufacturing USA there are 17 institutes, each focusing on a specific technology like robotics, optoelectronics, reuse of electronics and biotech—and all these tech areas need really awesome people to fill these jobs,” Conrad explained. “My role is to work with each of those institutes on their education and workforce development strategies, how they can get people access to those skills, and get people interested in these opportunities.”

Whether it’s teaching a class, connecting people, or creating opportunities in physics and beyond, for Conrad it’s a meaningful investment in the future.

“When people ask me who Brad Conrad is, I’m a physicist and I will always be a teacher,” he reflected. “I may do things that aren’t teaching but it’s always in support of people who want to learn and do good things. It’s more than just advancing science—I also know that every day I’m connecting people who are going to go off and make the world a better place.”


Written by Leslie Miller

Philippov Awarded Sloan Research Fellowship

Assistant Professor Sasha Philippov is one of 126 scientists in the United States and Canada to receive a 2024 Sloan Research Fellowship.

Granted by the Alfred P. Sloan Foundation, the $75,000 award recognizes scientists who have made important research contributions and have demonstrated “the potential to revolutionize their fields of study.” The fellowship, introduced in 1955, is considered one of the most competitive and prestigious awards that an early-career scientist can receive. To date, 71 UMD faculty members have earned this distinction, including 14 from UMD’s College of Computer, Mathematical, and Natural Sciences since 2015.

Fellows are nominated by other scientists and selected by independent panels of senior scholars. Philippov was nominated by Eliot Quataert, a theoretical astrophysicist at Princeton University who said that Philippov’s research “stands out” from his peers covering similar topics.

“Sasha has a combination of physical intuition, physics depth, code development skills and computational acumen that is characteristic of the very best computational astrophysicists I have interacted with in my career,” Quataert said.Sasha PhilippovSasha Philippov

Philippov, who holds a Ph.D. in astrophysical sciences from Princeton, was previously named a NASA Einstein and Theoretical Astrophysics Center Fellow at UC Berkeley, where he completed a postdoctoral fellowship from 2017 to 2018.

After his postdoc, Philippov worked as an associate research scientist at the Simons Foundation’s Flatiron Institute, where he constructed the first models capable of explaining the mysterious coherent emission of pulsars—magnetized neutron stars that rapidly rotate.

Since joining UMD in 2022, Philippov has been busy with several research projects. He used simulations to show the production of gamma-ray flares from the black hole in galaxy M87, which was the first black hole to be pictured. He also demonstrated how kinetic effects change the flow of plasma and produced proof-of-concept simulations of radiative plasma turbulence.

Philippov also serves as deputy director of a Simons Foundation project called the Simons Collaboration on Extreme Electrodynamics of Compact Sources that models electrodynamic processes related to neutron stars and black holes.

Looking ahead, the two-year Sloan Research Fellowship will enable Philippov to delve deeper into the study of plasmas—hot, ionized gas that surrounds neutron stars and black holes, which he describes as “some of the most mysterious and exotic objects in the universe.”

Part of Philippov’s research will involve the study of magnetars, which are neutron stars with the strongest magnetic fields in the universe. He plans to use advanced 3D simulations to better understand the powerful magnetic flares that occur when pulsars release magnetic energy, enabling scientists to connect the dots between what is observed through telescopes and what is actually occurring at a magnetar’s surface.

He will also investigate black holes that accrete plasma “very efficiently,” meaning more plasma falls into those black holes than ones that accrete low-density plasma, such as the one in M87.

“Depending on how much falls in, the properties of the plasma are quite different because their temperatures and density are different,” Philippov explained.

For Philippov, more plasma means more opportunities to study neutrinos, which are weakly interacting particles that can be generated in the environment surrounding black holes. Philippov’s ultimate goal is to create models that explain how protons accelerate and end up producing neutrinos.

The timing is ideal, considering that the IceCube Neutrino Observatory at the South Pole recently detected neutrinos from a spiral galaxy called NGC 1068.

“There will be more observations with IceCube and future detectors, so it’s a good time to work on theoretical models,” Philippov said.

Ultimately, Philippov is excited to study the phenomena that help illuminate objects like black holes, which do not emit light on their own. In pictures of black holes, what we sometimes see are accretion disks, or rotating rings of plasma that create a glow.

“We haven’t learned much about black holes themselves yet, but we are able to learn a lot about how they shine,” Philippov said of the study of plasmas surrounding black holes. “Our goal is to understand how all the emission that we see is produced. We can see it, but we cannot really explain why and how, so that’s the underlying question.”


Original story by Emily C. Nunez: https://cmns.umd.edu/news-events/news/umd-astrophysicist-sasha-philippov-awarded-2024-sloan-research-fellowship

Distinguished University Professor Ellen Williams Retires

Ellen D. Williams, a Distinguished University Professor in the Department of Physics and the Institute for Physical Science and Technology at the University of Maryland and director of the university’s Earth System Science Interdisciplinary Center (ESSIC), retired on December 30, 2023, after 42 years at the university. Following her official retirement, Williams is now a research professor of physics and executive director of ESSIC’s Cooperative Institute for Satellite Earth System Studies (CISESS).

“Dr. Ellen D. Williams is an iconic figure at the University of Maryland. Not only was she a trailblazer as one of the first female full professors in physics, but she was a transformational scholar and leader,” said UMD President Darryll J. Pines. “Because of her scholarly excellence, she was recognized with the highest honor that the university bestows on its faculty, which is the title of Distinguished University Professor. I am deeply grateful for Dr. Williams' many contributions to the University of Maryland. I sincerely wish her well in her retirement!”

Williams came to UMD in 1981 for a postdoctoral fellowship and rose to the rank of professor by 1991.Ellen WilliamsEllen Williams

“I have had a wonderful career at the University of Maryland,” Williams said. “It has been my great pleasure to work with talented colleagues in interdisciplinary work that crossed both departmental and college lines. I am happy that I’ll be able to continue engaging with the university as I move into the next stage of my life.”

At Maryland, she established an internationally recognized research program in experimental surface science, exploring fundamental issues in statistical mechanics and nanotechnology. To accomplish this work, she pioneered the use of powerful scanning tunneling microscopy to quantify atomic scale order and disorder on the surface of materials such as silicon. In 1996, Williams founded the National Science Foundation-supported University of Maryland Materials Research Science and Engineering Center, serving as its director until 2009.

“Ellen Williams made fundamental contributions in applying statistical mechanics tools in surface science and nanotechnology,” said Steve Rolston, chair of UMD’s Department of Physics. “In addition, she has provided great insight and tireless effort to finding solutions to immense problems that threaten our entire planet.”

Within the Department of Physics, Williams also championed diversity in hiring and was active in the American Physical Society’s Committee on the Status of Women in Physics. In addition, she was an early proponent of the importance of computational tools in physics education. In 2004, she developed a Python-based course “Introduction to Programming for the Physical Sciences,” which subsequently became a required course in the undergraduate physics curriculum. 

Williams has a distinguished history of professional service both within the university, including serving as chair of the University Senate, and externally. Her external service includes work on national security, including chairing the development of the National Academy of Sciences’ 2012 report on “Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty” and providing extensive technical advice to the U.S. government, primarily through the Departments of Energy and Defense. 

“Ellen Williams contributed immensely to the University of Maryland community and the global scientific community during her 42-year career here,” said Amitabh Varshney, dean of UMD’s College of Computer, Mathematical, and Natural Sciences (CMNS). “She has demonstrated distinction as an innovative scholar and teacher, valued mentor and colleague, and effective leader.”

Williams took a leave of absence from the university and served as the chief scientist for British Petroleum (BP) from 2010 to 2014, where her work included sustainability studies in collaborations including the Carbon Mitigation Initiative at Princeton University and the Energy Biosciences Institute at the University of California, Berkeley and the University of Illinois. In 2014, she was confirmed by the U.S. Senate as the director of the Advanced Research Projects Agency-Energy (ARPA-E). Williams led the agency in its mission to advance high-potential, high-impact clean energy technologies that are too early in development for private-sector investment. One of her goals while at ARPA-E was to establish a documentation process for research outcomes, so that every project, whether it succeeded or failed, would have a record of what worked or didn’t and a clear explanation of why to help guide future explorations in similar areas.

Williams returned to UMD in January 2017 and began work on bridging policy and technology perspectives for clean energy innovation. She established a graduate course to foster interactions between public policy students and students in the natural sciences and engineering called “Intersections of Technology and Policy in Modernizing the Energy System.” In 2018-19, she led a report to the State of Maryland on “The Present Status and Future Potential of Maryland’s Clean Energy Innovation System,” which was instrumental for continuing state support of the Maryland Energy Innovation Institute in UMD’s A. James Clark School of Engineering.  

Most recently, in 2020, she accepted the role of ESSIC director. As the largest research center at UMD, ESSIC serves a unique role as a collaboration hub within the national Earth system science research community by linking research efforts in UMD’s Departments of Atmospheric and Oceanic ScienceGeology, and Geographical Sciences with NASA and the National Oceanic and Atmospheric Administration (NOAA). Under Williams’ leadership, ESSIC was awarded a new five-year, $95 million cooperative agreement with NASA in 2022 to support research, teaching and career training in Earth system science. In 2023, Williams presented the mid-term review of ESSIC’s cooperative institute, CISESS, to a NOAA committee. This resulted in the highest ranking of outstanding and an endorsement for continuing CISESS.

In 2023, a team led by Williams of researchers from ESSIC and the Departments of Atmospheric and Oceanic Science, Geology, and Geographical Sciences received a three-year, $3 million Grand Challenges Institutional Grant from the university to address climate change for a sustainable Earth. The team is working with federal partners as well as regional and state agencies to develop systems capable of providing early warning to communities about climate-related floods, tornadoes and other weather disasters. Using satellite data, ground-based sensors and other tools, the team is also working to deliver information to Maryland farmers and agribusinesses to help shield food production from changing climate.

Williams’ research and service accomplishments have been widely recognized. She has been elected as a member of the National Academy of Sciences, the American Academy of Arts and Sciences, and a foreign member of the Royal Society (London). She is also a fellow of the American Association for the Advancement of Science, the American Physical Society and the American Vacuum Society. She has also been recognized by awards from the American Physical Society and the Materials Research Society, and Distinguished Alumnus Awards from the California Institute of Technology and Michigan State University. 

Williams has also been a very generous donor to the university, creating a legacy of support for future generations of scientists. Her late husband Neil Gehrels, a College Park Professor of Astronomy and chief of the Astroparticle Physics Laboratory at NASA’s Goddard Space Flight Center, was named a 2017 Dan David Prize laureate a few days before he passed away. The prize included a $1 million award, and Williams donated his share to establish the Neil Gehrels Memorial Endowment in Astrophysics to support UMD students and postdocs engaged in research with astrophysicists at NASA Goddard. Five individuals have received Neil Gehrels Prize Postdoctoral Fellowships since 2018 and Williams continues to add to the endowment annually.

“In addition to the Gehrels Fellowship, Ellen has also generously supported diversity efforts within CMNS, undergraduate students with financial need, and the Department of Physics,” Varshney added. “She established renowned scientific and philanthropic legacies here at Maryland.”