During World War II, Ramsey developed the delivery system for the atomic bomb, a job that included choosing and modifying the allies' airplanes.

His work has also focused on the physics of measuring time. His discovery of the physics behind the atomic clock, an extremely precise time measurement system, won him the Nobel Prize in physics and half of the $469,000 monetary award he shared with two other scientists.

But Ramsey is perhaps best known for his work that contributed to the creation of a technology known as the Global Positioning System (GPS). With vast military and lay applications, GPS allows people to pinpoint their geographic location with a small handheld device.

Although officially a professor emeritus, Ramsey has continued to play an active role at the University. On Saturday he presented a lecture at a symposium celebrating 50 years of proton beams at the Harvard cyclotron laboratory.

Ramsey said he envisions working at the University for an additional 10 years.

"I've still got plenty I want to do here," he said.

Professor of Physics Gerald Gabrielse said Ramsey is a "vigorous" scholar and person despite his age.

"I can tell he's getting older because when I when we walk across campus, I can just about keep up," Gabrielse quipped. "He's a real class act, Norman is."