Georgetown College. Georgetown University.

By Megan Weintraub

Sketching a picture of Dr. James Mattingly, an associate professor in the Department of Philosophy, is a difficult task. Despite the fact that he conveys the vivid details of his work in an engaging and accessible way, his research into the structural features of scientific theories eludes simple description. More importantly, his work raises questions that challenge our deeply held beliefs about the purpose and methods of science, especially in the discipline of physics. Perhaps the most accurate portrait of Dr. Mattingly appears in a drawing by one of his students, sophomore Charlotte Powers, whose depiction of her professor captures his irreverent spirit as it shows him emerging from the Magic School Bus sporting bushy sideburns, a retro dress with a pattern of flower-like atoms, and an affable grin.

A self-described “student of science,” he approaches his field with the goal of changing the way we typically engage in scientific inquiry. Dr. Mattingly’s ultimate concern is in advancing and productively deploying a certain skepticism about the way we reach scientific conclusions and define the nature of property. What other scientists see as certainty, he views as a place to start asking questions, challenging them to understand how their own approach to the field informs their research.

“I have a conviction as a philosopher that the objects described by scientific theories are completely irrelevant,” he explains. “It’s not the business of science to find objects and tell me about their properties. It’s the business of science to find relational structures, to predict new issues, and to investigate and produce relationships that govern our experiences.”

Dr. Mattingly’s work in the philosophy of science involves a deep inquiry of the foundational concepts behind physics, such as quantum gravity, in order to understand how we use theories to explain the forces we observe. Specifically, he looks at a method of constructing physical theories called gauge theory that stands in contrast to our traditional notions of force laws, such as the gravitational and electromagnetic forces. In fact, gauge theory, which relies on an analysis of the symmetries of systems as opposed to an analysis of the behaviors of objects within those systems, turns our notion of science on its head and holds useful applications for scientists in explaining phenomena.

“Gauge theory is a powerful and important technique in physics,” says Dr. Mattingly. “It allows physicists to work on physics problems without knowing anything about force laws. Rather than taking measurements and relying on descriptive claims about the way things are, gauge theorists construct physical theories by asking how physical systems transform under various kinds of operation.”

As students of science in our own right, we have learned about force laws at some point in our education.  For instance, inevitably we all took part in the classic physics experiment in which we pushed a ball down a ramp and studied its progress from the top to the bottom.  One way to understand what happens is by appeal to the notion of force. Through this experiment, many of us learned how force laws govern science and give us a vocabulary to communicate our observations.

Another way to understand the experiment is to note that the ball’s energy remains the same no matter where on the ramp it sits. We can then follow the change in the system as the energy is converted from potential to kinetic. Analogously, when gauge theorists do not know the force laws of a system, they attempt to characterize it by analyzing its symmetries.

Gauge theory comes into play in the analysis of quantum systems, which are processes that are not explicable by traditional force laws. Dr. Mattingly looks at one particularly interesting experiment of electromagnetism, called the Aharonov-Bohm effect. In the experiment, a box shoots out electrons that hit a barrier with two slits cut into it, and scientists observe the diffraction pattern of the electrons hitting a screen placed behind the barrier. Next, scientists place a magnetic whisker between the slits and behind the barrier and find that it affects the diffraction pattern of the electrons.

"Given our standard account of force laws, this result is baffling," says Dr. Mattingly.

Some researchers have found that this experiment is an important demonstration of the tension between using force laws or gauge theory to explain phenomena in physics. Dr. Mattingly looks at places where gauge theory can provide a useful explanation where traditional scientific explanations of electrodynamics have fallen short, but his commitment to critical scientific inquiry remains firm when he draws conclusions about this experiment. In an effort to challenge the ways in which scientists make theoretical claims, he has found a method of describing the influence of the magnetic whisker on the electrons’ diffraction pattern without relying on gauge theory. Instead, he argues for the possibility of explaining the Aharonov-Bohm effect using classical, local, electromagnetic fields rather than gauge fields.

“I don’t have a commitment to the force law of electromagnetism, but I feel the need to defend it,” he explains.

Not surprisingly, his work inspires a range of reactions. While some physicists view his findings simply as a new way to look at the nature of property, other devoted gauge theorists panic at his use of force laws to explain a phenomenon previously understood through the terms of gauge theory. Dr. Mattingly offers a third reaction to the chorus, one that paints a clear picture of a professor and scholar whose healthy dose of skepticism and limitless irreverence serve him well as a “student of science.”

“All of my work is in the service of trying to push a particular line on the nature of scientific inquiry,” he says. “I want to know how we know what we know.”

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