Professor of physics uncovers rarely discussed aspect of magnetic theory

Assistant Professor of Physics Dr. David Pigg recently uncovered a rarely discussed aspect of magnetic theory.

Photo by John David Clark, Photography Editor

Editor's note: This article has been updated to clarify the physics behind Pigg's concepts surrounding magnetic theory.

Science teachers have explained how opposites attract, but they probably never clarified why that is true in the first place.

Lee University Assistant Professor of Physics David Pigg recently uncovered a foundational concept in magnetic theory, explaining that very phenomenon.

During a lecture, a student asked about where the theory of magnetism came from, which left Pigg stumped.

“While I had always prided myself in knowing the answers to such questions, in that moment, I drew from my mind nothing but blanks,” Pigg said. “I had spent over ten years studying physics and had never really considered why a force could be felt by a charge simply because a nearby charge was moving.”

Perplexed by the question the student raised, Pigg set out to uncover where the theory of magnetism came from.

Prior to teaching at Lee, Pigg received his Ph.D. in physics from Vanderbilt and served as a post-doctoral physicist at Oak Ridge National Laboratory. The first step in his search for answers was to reach out to former advisers and contacts at Vanderbilt and Mississippi State University.

However, much to Pigg’s surprise, they did not know the answer either. One of his contacts suggested he begin with analyzing relativity to find his answer, according to Pigg.

With this direction in mind, Pigg started from the ground up and began to analyze relativity’s role in how magnetism worked through the example of a wire.

Within the wire, there’s an equal number of protons and electrons, meaning the wire has neither a negative or positive charge and is therefore neutral, according to Pigg.

“Since like charges repel each other and the wire is neutral, if a proton enters the vicinity of this wire, nothing will happen,” said Pigg. “However, if electricity starts to go through the wire, the proton in the vicinity will be pushed away from the wire even though the wire should still have an equal amount of protons and electrons.”

Essentially, Pigg discovered why this proton is pushed away from a seemingly neutral wire.

“In a live wire, electrons are moving through it, causing a nearby, free proton moving in the same direction to be pushed away,” Pigg said. “Now, let’s ride along with the proton. What do we see? Since we are moving in the same direction and at the same speed as the electrons in the wire, we do not see them move at all.”

"However, still moving forward aboard the lone proton, relative to us, the protons in the wire are moving backward; and, since they are moving relative to us, the distance between them must be contracted by an amount predicted in the framework of Einstein’s special relativity," Pigg said. "Due to this contraction, if we count the number of protons and the number of electrons within a specific length of the wire, we find that there are more protons than electrons; thus, to us, the wire is electrically positive, which explains—at least in the context of electric, Coulomb repulsion—why the proton on which we are riding is pushed away from the wire."

"Thus what we call the magnetic force is actually a manifestation of the electric force requisite to special relativity," Pigg continued. "So, when you stick a magnet to your refrigerator, you can be assured that Einstein was onto something."

With this realization, Pigg has helped shine light on a topic that previously his students and peers in academia were not able to understand.

Senior mathematics education major Julia Qualls said the theory illustrates Pigg’s commitment to providing students with answers to their questions.

“You can really tell he cares about his students and the subject he is teaching,” Qualls said. “His consistency in being able to explain things and wanting you to understand [sets him apart] as a professor.”

For additional information on magnetic theory, contact Dr. Pigg at dpigg@leeuniversity.edu.