Sometimes physics is a slow science: work in particle theory published 45 years ago has led to a major prize for two MIT alumni. Gerald Guralnik and Carl Richard Hagen are among six recipients of the 2010 American Physical Society's J. J. Sakurai Prize for Theoretical Particle Physics.

Guralnik, a physics professor at Brown University, and Hagen, a physics professor at the University of Rochester, share the prize with their friend and collaborator Thomas Kibble, a professor at Imperial College London, and three other scientists for contributing to the identification of what scientists believe is the origin of mass. Nobel laureate Steven Weinberg has called the work an essential precursor of the electroweak theory, which is at the core of the so-called standard model--an attempt to describe the particles and forces that account for all physical phenomena.

"Despite the current significance of our work, to me the most important thing that has come from it is my enduring long friendship with Dick and Tom," Guralnik says.

He and Hagen met as undergraduates at MIT. Originally drawn together by their common academic interests and their midwestern roots-Hagen is from Chicago and Guralnik grew up in Cedar Falls, IA-they quickly went from talking about physics to "talking about everything," Guralnik recalls. "That helps, when you're friends and doing physics, because it's a very high-pressure business. You eat it. You sleep it. You live it. It's just very intense."

Neither remembers when their seminal work began. "It was a seamless transition from one thing to another, so the precise point at which we began discussing this is probably long lost," Hagen says. Guralnik was doing postdoctoral work at Imperial College and Hagen was at the University of Rochester in 1964 when they published their groundbreaking paper "Global Conservation Laws and Massless Particles" in Physical Review Letters.

Guralnik went on to Los Alamos National Laboratory, where he pursued an interest in numerical calculation in quantum field theory, but he has since returned to fundamental theory. Hagen has remained focused on field theory. He and his wife, Suzanne, have three sons, Christian, Jon, and Jason '93, SM '93. Guralnik and his wife, Susan, have one child, Zachary '90, who is also a theoretical physicist.

Guralnik and Hagen were slated to accept their prize from the American Physical Society in Washington in February.