NOT THE ONION:

Proof surfaced in 1898 that the reals, complex numbers, quaternions and octonions are the only kinds of numbers that can be added, subtracted, multiplied and divided. The first three of these "division algebras" would soon lay the mathematical foundation for 20th-century physics, with real numbers appearing ubiquitously, complex numbers providing the math of quantum mechanics, and quaternions underlying Albert Einstein's special theory of relativity. This has led many researchers to wonder about the last and least-understood division algebra. Might the octonions hold secrets of the universe?

"Octonions are to physics what the Sirens were to Ulysses," Pierre Ramond, a particle physicist and string theorist at the University of Florida, said in an email.

Günaydin, the Penn State professor, was a graduate student at Yale in 1973 when he and his advisor Feza Gürsey found a surprising link between the octonions and the strong force, which binds quarks together inside atomic nuclei. An initial flurry of interest in the finding didn't last. Everyone at the time was puzzling over the Standard Model of particle physics -- the set of equations describing the known elementary particles and their interactions via the strong, weak and electromagnetic forces (all the fundamental forces except gravity). But rather than seek mathematical answers to the Standard Model's mysteries, most physicists placed their hopes in high-energy particle colliders and other experiments, expecting additional particles to show up and lead the way beyond the Standard Model to a deeper description of reality. They "imagined that the next bit of progress will come from some new pieces being dropped onto the table, [rather than] from thinking harder about the pieces we already have," said Latham Boyle, a theoretical physicist at the Perimeter Institute of Theoretical Physics in Waterloo, Canada.

Decades on, no particles beyond those of the Standard Model have been found. Meanwhile, the strange beauty of the octonions has continued to attract the occasional independent-minded researcher, including Furey, the Canadian grad student who visited Günaydin four years ago. Looking like an interplanetary traveler, with choppy silver bangs that taper to a point between piercing blue eyes, Furey scrawled esoteric symbols on a blackboard, trying to explain to Günaydin that she had extended his and Gürsey's work by constructing an octonionic model of both the strong and electromagnetic forces.

"Communicating the details to him turned out to be a bit more of a challenge than I had anticipated, as I struggled to get a word in edgewise," Furey recalled. Günaydin had continued to study the octonions since the '70s by way of their deep connections to string theory, M-theory and supergravity -- related theories that attempt to unify gravity with the other fundamental forces. But his octonionic pursuits had always been outside the mainstream. He advised Furey to find another research project for her Ph.D., since the octonions might close doors for her, as he felt they had for him.

But Furey didn't -- couldn't -- give up. Driven by a profound intuition that the octonions and other division algebras underlie nature's laws, she told a colleague that if she didn't find work in academia she planned to take her accordion to New Orleans and busk on the streets to support her physics habit. Instead, Furey landed a postdoc at the University of Cambridge in the United Kingdom. She has since produced a number of results connecting the octonions to the Standard Model that experts are calling intriguing, curious, elegant and novel. "She has taken significant steps toward solving some really deep physical puzzles," said Shadi Tahvildar-Zadeh, a mathematical physicist at Rutgers University who recently visited Furey in Cambridge after watching an online series of lecture videos she made about her work.

Furey has yet to construct a simple octonionic model of all Standard Model particles and forces in one go, and she hasn't touched on gravity. She stresses that the mathematical possibilities are many, and experts say it's too soon to tell which way of amalgamating the octonions and other division algebras (if any) will lead to success.

"She has found some intriguing links," said Michael Duff, a pioneering string theorist and professor at Imperial College London who has studied octonions' role in string theory. "It's certainly worth pursuing, in my view. Whether it will ultimately be the way the Standard Model is described, it's hard to say. If it were, it would qualify for all the superlatives -- revolutionary, and so on."

Tweet   @brothersjudd