And David McComas, vice president for the Princeton University Plasma Physics Laboratory, said Matthaeus is a “household name” in plasma physics.

“Bill has made seminal discoveries and contributions in so many areas that it is hard to summarize his contributions in a brief letter,” McComas wrote. “Many of these contributions have been paradigm-changing in the field of plasma physics, creating new subfields studied by scientists worldwide … Quite simply, Bill’s breadth and depth of contributions are unparalleled.”

Matthaeus’ ideas about turbulence and its significance for the solar wind weren’t always embraced.

“In the days before the papers I wrote, the prevalent opinion was that there were fluctuations, but they weren’t really doing anything. They weren’t dynamically active. They were just fossils from the sun,” Matthaeus said. “Now turbulence is widely regarded as the reason we have the solar wind and the cascade transfers that energy from a large-scale structure to the kinetic scale, where the plasma gets heated.”

Fostering a thriving research environment

The ripple effects of Matthaeus’ research prowess have been nothing short of transformative for his students, who say they have been energized not only by his expertise but by his collegial warmth and interest in their ideas.

“A wonderful feature of working with Bill is that discussions are always two-way,” wrote Sean Oughton, who was a doctoral student of Matthaeus’ and now is professor of applied mathematics at the University of Waikato in New Zealand. “Bill is totally open to ideas from everyone. As graduate students, our own ideas were taken seriously and explored, even when they were naïve or inchoate.”

Rohit Chhiber, who also was mentored by Matthaeus in his doctoral studies and now works at NASA’s Goddard Space Flight Center, agreed. 

“Instead of rigidly hierarchical relationships with students, working with him is characterized by the values of flexibility, approachability, spontaneity and fun,” he wrote, “fostering a culture in which scientific research thrives.”

Matthaeus is skilled at bringing it down to earth for non-experts, too, giving them a taste of the wonder and curiosity that has driven his studies for more than five decades. He recruits students — from novices to those with demonstrated skills — for grant-supported projects of Delaware Space Grant, which he has buttressed since becoming director in 2016, and the competitive opportunities provided through NASA’s Established Program to Stimulate Competitive Research (EPSCoR).

By his example and mentoring nature, Matthaeus passes the torch to future generations of scientists.

“I would certainly not claim to have Bill’s charisma,” Oughton wrote. “However, in supervising graduate students myself, I have very much based my approach along the same lines he employed with me and other students.”

Except for a couple of years during the COVID-19 pandemic, Matthaeus has made an annual pilgrimage to Arcetri, Italy, the hometown of astronomer Galileo Galilei, to teach at the Arcetri Workshop on Plasma Astrophysics, which he helped to found in 2006.

Kasper said this workshop has become a classical space science meeting for both Europe and the U.S.

“I have sent all of my plasma graduate students and postdoctoral researchers to attend these programs at one or more points in their career, and have been delighted by the impact Bill had on their understanding of challenges in turbulence in plasmas and in major topics,” he said.

In all, Matthaeus has supervised 24 postdoctoral fellows, 17 doctoral students, nine foreign exchange students at the doctoral level and three undergraduate research students.

Since the completion of his doctoral thesis in 1979, Matthaeus has published more than 560 papers, which have been cited about 46,000 times by other researchers, according to Google Scholar.

He has been a primary investigator on multiple grants from NASA, the National Science Foundation and the U.S. Department of Energy, with more than $40 million in previous, current and pending support.

Among the major missions he has been part of are: the Parker Solar Probe, Magnetospheric Multiscale Mission, Interstellar Mapping and Acceleration Probe, Polarimeter to Unify the Corona and Heliosphere (PUNCH), HelioSwarm and Solar Orbiter (a joint mission with the European Space Agency).

A lifetime of curiosity

Matthaeus and his sister, Mary, were the first in his family to graduate from college, but they grew up in a home that valued education, study and excellence. 

His father, an Irish-German Catholic, worked in the library of The Philadelphia Inquirer for almost 40 years, providing research and background information for reporters there. He was demanding and strict.

Matthaeus said if he earned a 98 out of 100 at school, his father had one question for him:

“What happened to the other two points?”

Plenty of science-oriented neurons came from his mother’s side of the family. Her father, Max Chalphon, a Ukrainian Jew who migrated to the U.S., taught himself radio physics and their home had textbooks on equations of electricity, magnetism and the theory of how radios operate.

Those books caught Matthaeus’ interest, before most children are captivated by Winnie the Pooh.

“Before I started first grade, I started reading those books. And when I started first grade I could read and do arithmetic,” he said.

He made the most of that first year of formal schooling. When his mother took him to the library in downtown Philadelphia, he found a high school chemistry book and he started reading about valence electrons (charged particles that orbit around atoms and make chemical bonds and other reactions possible).

He grew up in North Philadelphia and went to St. Joseph’s Preparatory School, where he won the gold medal in biology and the gold medal in chemistry. But in physics, he won the silver medal. He leveraged that into a double major at the University of Pennsylvania — physics and philosophy.

“I finished the philosophy degree first,” he said, “and I looked at The Philadelphia Inquirer’s employment section. I looked for any job in philosophy. But there weren’t any, so I decided I’d better finish physics.”

After Penn, he started graduate school at Northwestern University. A lot of his time, though, was spent playing basketball and partying with his buddies.

“I wasn’t the best student,” he said.

Though he made decent grades in quantum mechanics, he was jolted when one professor gave him an “F” and a withering assessment of his prospects.

“They pay me a lot of money for my professional judgment,” the professor told him. “And in my judgment, you’ll never finish a Ph.D. and if you do, you’ll never be able to do scientific research.”

Matthaeus left Northwestern to get his master’s degree at Old Dominion University, a much smaller program in Norfolk, Virginia, where he aced his exams.

When he was invited back to Northwestern to consider a faculty position a few years later he saw that professor again.

“I think I proved him wrong,” Matthaeus said with a smile.

A series of consequential encounters brought Matthaeus to UD in 1983.

While at Old Dominion, a classmate in the master’s program invited him to visit William & Mary with him to check out its doctoral program. There, they met with Prof. Peter Gary, who had a NASA grant to study plasma physics. Matthaeus, who had been studying particle physics and accelerators, started his doctoral work under Gary’s guidance.

“That was completely new to me,” he said. “I had never worked on any space stuff.”

After Gary left William & Mary for a job at Los Alamos National Laboratory, Matthaeus studied plasma physics and plasma turbulence with his mentor David Montgomery.

NASA asked Montgomery to chair a study panel to investigate how to characterize turbulence in the solar wind. Montgomery wrote a report and as Matthaeus was winding up his doctorate, Montgomery suggested he work on that research with Melvyn Goldstein at NASA’s Goddard Space Center for a few years. The papers he later wrote with Goldstein are among the most cited of Matthaeus’ hundreds of publications.

While he was working at Goddard, Matthaeus attended a conference in New England and two men approached him about the poster he had. One was Dennis Peacock, the head of the solar terrestrial division of the National Science Foundation. The other was Martin A. Pomerantz, a pioneering astronomer from the University of Delaware for whom an observatory is named in Antarctica.

Then Peacock said, “Bill, why don’t you write a proposal for some grant funding?”

“I can’t,” Matthaeus said. “I’m a postdoc. I need a job first.”

Pomerantz, who was director of the Bartol Institute at UD at the time, said “Why don’t you come to Bartol and we’ll give you a job?”

When he arrived for a visit at UD, he met with Pomerantz to learn more.

“When can you start?” Pomerantz asked.

“I have to talk about what you want me to do,” Matthaeus said.

“Don’t worry about that,” Pomerantz said. “Just keep doing what you’re doing.”

Matthaeus said he didn’t even ask about the salary. At the time, he was making around $24,000 a year at Goddard. Pomerantz said he’d give him $30,000.

“I was rich!” Matthaeus said. “I decided to try it out.”

Almost 42 years later, he’s still going strong.