The Aspen Center for Physics started in 1962 as a place for theoretical physicists to spend the summer thinking and talking together. Based at a small campus on the south end of Aspen Meadows, it was originally part of the Aspen Institute before becoming an independent nonprofit in 1968. Several landmark developments in physics have originated there, including the design of the Fermi National Accelerator Laboratory, early work in string theory, and the online scholarly repository arXiv.org. In its six decades in operation, the center has hosted more than sixty Nobel laureates and three Fields Medalists.
The Aspen Center for Physics was the brainchild of George Stranahan. Stranahan came from a wealthy family that began to take ski trips to Aspen starting in 1949. Several years later, when Stranahan was in graduate school at the Carnegie Institute of Technology, he had the idea of coming to Aspen for the summer to fish, hike, and work on his dissertation. Over the course of several summers in the late 1950s, however, he found that he did plenty of hiking and fishing but little physics because he had no colleagues with whom he could discuss his ideas. The solution, he decided, was to get other physicists to come out to Aspen with him.
Soon Stranahan met Robert Craig, the executive director of the Aspen Institute, and suggested starting a summer physics research center devoted to thinking and talking, with no students, no courses, and no high-tech equipment. Stranahan also discussed his idea with Michael Cohen, a physicist at the University of Pennsylvania who had a similar plan for a summer colony of physicists at Los Alamos, New Mexico. Cohen enthusiastically supported Stranahan’s proposal and promised to ensure that if Stranahan built it, physicists would come.
In 1961 Stranahan and Cohen pitched their idea to Aspen Institute chair Robert O. Anderson, who quickly agreed to set aside some Aspen Meadows land for a physics division. Stranahan raised money for a building, including $38,000 from his own family. Designed by Herbert Bayer and later named Stranahan Hall, the center’s first building was a simple cement-block structure with ten shared offices, meant to encourage people from different fields to talk to each other. The building welcomed its first group of physicists in June 1962, when the road leading there was not yet paved. Nevertheless, thanks in part to Cohen’s promotion, more than forty physicists came at staggered intervals that first summer, some of them working in rented houses nearby.
The center soon gained renown in the physics world. Former Manhattan Project physicist Hans Bethe attended in the first few years and went on to receive the 1967 Nobel Prize in Physics for his research on how the sun produces energy (stellar nucleosynthesis). He donated part of his prize money to the Aspen Center for Physics for a second building, Bethe Hall, completed in 1972. Also in the late 1960s, another building was added to house Robert Wilson and his team of physicists working on the Fermi National Accelerator Laboratory, which was designed over the course of two summers in Aspen.
In 1968 the Aspen Institute shifted its priorities, and the Aspen Center for Physics spun off as an independent nonprofit. Since then, the Aspen Center for Physics has been funded largely by grants from the National Science Foundation as well as contributions from the Department of Energy, the Office of Naval Research, and other corporate and academic donors.
The Aspen Center for Physics has largely stuck to Stranahan and Cohen’s original vision of a place for theoretical physicists to discuss their work. Physicists tend to regard the center as a utopia where they can spend time thinking without the usual administrative and teaching demands of academic life. The atmosphere is deliberately informal to encourage questioning; at talks, for example, no slides are allowed and interruptions are welcomed. Even as the campus has expanded, physicists still share offices to encourage collaboration. Starting in 1985, the center began to host weeklong winter “science and ski” conferences in addition to its usual summer program.
The center’s collaborative atmosphere has yielded numerous important ideas. In the 1970s and 1980s, much early work in string theory occurred there, including when two office mates, John Schwarz and Michael Green, did calculations showing that string theory could provide a potential foundation for a unified field theory. In the 1980s and 1990s, the field of particle astrophysics took shape in Aspen workshops.
In 1991 the idea for what is now arXiv.org, a free online archive of scholarly science articles, was conceived at the center when physicists staying there worried about large files filling up their limited e-mail in-boxes while they were away from home. Paul Ginsparg and others realized they could use a central server to host papers that scholars could download on demand. When Ginsparg returned home after his stay in Aspen, he coded the idea and put it online in August. It quickly became the main forum for physicists and scientists in related fields to exchange their research. Ginsparg has cited the free flow of ideas at the Aspen Center for Physics as the model for the open exchange that occurs on arXiv.org.
The outside world intruded on the Aspen Center for Physics in the 1980s, when it realized that it didn’t have clear title to its property. The center was built on land it got from the Aspen Institute, but in 1980 the institute’s leadership was considering moving the institute from Aspen and sold its Aspen Meadows property to a developer. The property then changed hands several times over the next decade. The Aspen Meadows nonprofits—the Aspen Institute, whose leaders had decided to maintain a presence there, as well as the Aspen Center for Physics and the Aspen Music Festival & School—worried that they might be evicted or that their serene surroundings would soon become a busy development. But the city council was in an antigrowth mood, and the developer was sympathetic to the nonprofits, so eventually he gave the nonprofits clear title to their land in 1992 while getting the right to build a handful of houses on the edge of Aspen Meadows. After securing title to its land, the Aspen Center for Physics raised $3 million for a new building designed by local architect Harry Teague, which was completed in 1996.
In 2012 the Aspen Center for Physics was named an American Physical Society Historic Site in recognition of its significance to the field. Today the center continues to foster research and collaboration in physics. More than 1,000 physicists come to Aspen every year for weeklong winter conferences or summer stays of two to five weeks. In addition to their work at the center, participants give public lectures and visit local schools.