Crazy for Lag-Time

This story originally appeared in the 2006 issue of Vassar Views in celebration of URSI’s 20th anniversary.

Peter Pappas, professor of mathematics and the current director of the URSI program, has been a constant in URSI’s 20-year history, having worked with nearly 100 students. One reason for his constancy is that his groups get results. “Each summer takes on a special significance, and sometimes something crazy occurs.”

 One of Pappas’s recent URSI results is a brand new theory he developed with the “Lag-Time Ladies,”—Rachel Betz ’05 and Sandy Eckel ’04. Building on the work from  previous summers (Crystal Bertoncini ’05, Alex Stein ’05, Jen Uyanik ’05, and Sandy Eckel), Pappas and the Lag-Time Ladies discovered and developed a theory of “telling time in higher dimensions,” using a new class of objects called lag-time torus knots which they have completely classified.

During their work, Pappas and his group developed a conjecture on the behavior of these objects, and he told them that he’d give them anything they wanted if they could prove this conjecture. “What I had in mind was a nice dinner, or a ‘free-food event’ as they used to call it.” Early one evening at his apartment, the doorbell rang, and “there were Sandy and Rachel with huge grins on their faces, looking very tired, holding this box of purple hair dye. They handed me their proof of the conjecture, and told me that I had to dye my hair purple and give a talk in front of all of URSI the following week. So I did it—their proof was correct and ingenious. And after the talk, I had my hair bleached out, and it turned red. So with red hair, I took these wonderful students to a very nice dinner at Le Pavilion.”

Betz and Eckel are now in grad school—Betz at Brandeis in the mathematics PhD program, and Eckel at Johns Hopkins in the biostatistics PhD program. And when Pappas speaks on lag-time torus knots at conferences, mathematicians always ask for “The Frequency Result” by its popular name, “The Purple-Hair Theorem.”

And so what does the future hold for Pappas? “I will always be a part of URSI. How could I not be?” And what of his new theory? “It turns out that lag-time sequences may be related to quantum theory. Some interesting summers certainly lie ahead!”