Hello again

News from ICTP, No. 100, Spring 2002

Patricio Cordero recently returned to the Centre after a 20 year absence to recall a part of his past that has meant so much to his career ever since.

When Patricio Cordero, professor of physics at the University of Chile in Santiago, Chile, returned to the Main Building on the International Centre for Theoretical Physics (ICTP) campus this January, one of the first things he did was to stroll the corridors of the second floor to try to determine where Abdus Salam's office had been. "I couldn't visualise its location," he said. "So much has changed."

Cordero was attempting to reach back more than 20 years in time. In fact, the last time that he had visited ICTP was in 1981 as a senior associate. His broad research agenda since then has taken him to Princeton University and the University of California, Los Angeles (UCLA), in the United States, as well as to the University of Bordeaux and the European Centre for Atomic and Molecular Physics (CECAM) in Lyon, France. But for the better part of the past two decades, he has remained at the University of Chile, where he has taught physics and conducted research in a wide variety of fields related to quantum physics, statistical physics and cosmology.

"Returning to ICTP after such a long absence," he notes, "made me feel like Rip Van Winkle, having gone to sleep and reawakened 20 years later." The only difference--and it's a big difference--is that Cordero had been anything but asleep. In fact, during his 20-year absence from the Centre, he has worked hard to become one of the most respected physicists in his country. ICTP likes to pride itself on being a close-knit community--indeed an extended multicultural family--of scientists. And there is a good deal of truth to this perception. Many of the Centre's visitors first arrive at ICTP as young researchers eager to learn from their senior colleagues who serve as lecturers in the courses and workshops that they attend.

These young scholars often continue their ties with ICTP as they move up their career ladders--returning time and again to the Centre as Regular Associates and then Senior Associates. Because each of these appointments permits three visits to ICTP over a 6-year period (and because appointments are sometimes renewed), it is not unusual for a researcher to have close ties to the Centre for several decades. Those who become Honorary Associates continue to visit ICTP for even longer periods, often coming to view the Centre as 'their home away from home.' Cordero's experience with the Centre, however, took another route. In 1968, with a freshly minted doctorate from the University of London in the UK, he became one of the first postdoctorates at ICTP, thanks largely to the encouragement of his former advisor, Igor Saavedra, who was a close friend of Abdus Salam. Cordero's major field of study at the time was quantum field theory.

"The Main Building on the Miramare campus was not yet completed," he recalls. "When I arrived at ICTP, the Centre's administrative offices and classrooms were still located in ICTP's first home in an office building at 6 Piazza Oberdan in downtown Trieste. I remember that within a few weeks after my arrival I was asked to help move books from the library in Piazza Oberdan to the new library in the Main Building at Miramare, lugging the bags onto a van that would take them to their new home on Strada Costiera. It was a tiring but rewarding experience, one that reflected the close-knit family atmosphere that characterised the early years at the Centre." "Cordero was not only one of the Centre's first postdocs," says GianCarlo Ghirardi, a long-time consultant to ICTP and currently head of the Centre's Associateship Programme. "He was also one of ICTP's first Associates." In fact, Cordero was appointed an Associate in 1972 and Senior Associate 1978-1982, working closely with Ghirardi on a number of different research projects that resulted in several publications. Cordero and Ghirardi first worked with Assim Barut on a theory for a heavy electron. Later, Cordero and Ghirardi worked on spectrum generating algebras. These efforts led to publications in Physical Review, Il Nuovo Cimento, Fortschritte der Physik and Journal of Mathematical Physics.

"During those early years," Cordero recalls, "ICTP had no more than 50 researchers involved in the Centre's training and research activities at any one time. That gave participants an opportunity to receive close personal attention from the scientists who were working as consultants with the Centre." While Salam's leadership ensured that the Centre pursued permanent high energy research activities from its inception in 1964, permanent research groups in other fields were created later on--for example, in condensed matter physics in 1977 and in mathematics in 1986.

"ICTP was so small back then," says Cordero, "that it was not uncommon for even young researchers to discuss physics directly with Abdus Salam, an opportunity I took advantage of on several different occasions." Beyond the friendships and the personal attention he received while conducting his research, what Cordero remembers most about the Centre are the major conferences attended by some of the most prominent scientists in their fields, including many Nobel Laureates. "In particular, I remember the symposium on Contemporary Physics, held in 1968, which included talks by Hans Bethe, Paul Dirac and Werner Heisenberg. It was exhilarating," he says, "to listen to lectures and even exchange ideas with world-renowned physicists whose articles and books I had recently read as an eager student." That experience, along with the excellent training he received at the Centre, has had a lasting impact on his career. "It's something that I have carried with me for the past two decades," he recalled, "and it was the major reason why I wanted to return to Trieste--to see again the place that meant so much to me." Cordero last visited the Centre in 1981. His career since then has taken several twists and turns both in terms of his travels to the United States and Europe and in terms of his wide-ranging research agenda, which has moved from quantum field theory to electron theory to spectrum generating algebra.

Today his research focusses on the physics of granular materials, which involves the study of large conglomerations of discrete macroscopic particles. While such materials may seem to be simple at first, they often behave differently than solids, liquids or gases. In fact, some researchers view granular materials as an additional state of matter.

Cordero's initial effort to return to ICTP after his two-decade-long absence took place last year when, in line with his current research interests, he inquired about participating in ICTP's Research Workshop on Challenges in Granular Physics, which was scheduled to take place from 7 to 11 August 2001. "I contacted Silvio Franz, a staff scientist with the Condensed Matter Physics group, who was serving as the local organiser, to express my interest in coming," Cordero says. "I must admit I had been looking for an excuse to come to Trieste for some time and the conference seemed like an excellent opportunity to satisfy my curiosity while learning something that could contribute to my current research. However, a scheduling conflict made it impossible to arrange the visit. The exchange of e-mails, however, put me back in touch with GianCarlo Ghirardi for the first time in some five years."

Ghirardi was as anxious to have his old friend Patricio Cordero come to Trieste as Patricio was to return. So when he heard that his friend was to travel from Chile to CECAM in France, in January, for a month-long stay, Ghirardi arranged for Cordero to make a side visit to Trieste to present a seminar on the "Dynamics of Granular Gases," which Cordero did on 28 January. "My 36-hour stay in Trieste, which included a two-hour seminar, certainly stirred my memory," says Cordero. "I not only spoke to Ghirardi but also had an opportunity to have brief chats with Maria Fasanella, ICTP's head librarian, and André-Marie Hamende, who had served as ICTP's senior administrator and scientific information officer for many years. It was nice to see that they remembered me. After all, my training here ended some 20 years ago and thousands of other researchers have passed through the corridors of ICTP ever since."

And maybe that's the point of Cordero's experience here in Trieste. While we celebrate the presence of Nobel Laureates and Fields Medal winners who come to the Centre in numbers that make their presence seem commonplace, we should not forget that the heart and soul of the Centre resides in the experience of scientists like Cordero and what they take with them from Trieste to their home countries as both researchers and teachers. Indeed there may be no greater tribute to the impact of ICTP on the development of science in the developing world than Cordero's work as a professor of physics at the University of Chile where, in addition to his research, he teaches a variety of courses in statistical physics, kinetic theory and basic physics courses, while supervising the work of some doctoral students in physics. The big idea embodied in ICTP's mandate often finds itself on quiet display in places that never receive a great deal of attention. Cordero's recent visit to ICTP reminds us just how important these places can be.