LÉO RAMOSSilvio Salinas likes a good conversation, and if it is on his specialty, better still. Even for those with little familiarity with statistical physics, a complicated sub-field of theoretical physics for the uninitiated, he tries to communicate the gist of the field in which he has worked for 45 years. Enthusiastic, he walks to the white board and writes down concepts and formulas. After some time, the full professor at the University of São Paulo Institute of Physics (IF-USP) sits and utters a lament: “If we had another hour, I could get you to understand a little of what I have studied.” His objective as a theoretical physicist is to simplify complex statistical physics models in order to make them more accessible.
Physics is far from his only interest. He also holds forth on policy and education. His academic career has been unique. Seven days after the 1964 military coup, Salinas was arrested and expelled from the Technological Institute of Aeronautics (ITA) in São José dos Campos along with other students and professors accused of subversion. “We were young activists on the left, active in the student center, but no one was thinking of blowing up bridges, which is what they accused us of,” he recounts. Released four months later, he applied for two undergraduate programs: engineering at the Polytechnic school (Poli/USP) and physics at what was then the School of Philosophy, Sciences, Languages and Literature (FFCL-USP, now FFLCH). He passed the entrance exam for both and enrolled in both concurrently.
Born in Araraquara, in the São Paulo state countryside, Salinas chose to continue in physics. He completed his masters at USP (1967-8) and his doctorate in the United States (1969-73). When he returned to Brazil, he participated in the debates on the Brazil-Germany nuclear agreement and plunged into research on statistical physics, interacting with experimental condensed matter physicists. An assault he suffered 12 years ago left him blind in his right eye, but has not reduced his enthusiasm.
Restless at 72, he advises students, writes articles and addresses domestic and universal questions. He reveals his frustration at not being able to attract historians to study the history of IF-USP, which was established in the 1930s and represents the origins of teaching and research in physics in Brazil. And he tries to envisage a future for physics, which is suffering through a phase of uncertainty. Married, with twins—one a lawyer and the other a biochemist—Salinas granted Pesquisa FAPESP the following interview.
| Age: |
| 72 |
| Specialty: |
| Statistical physics |
| Education: |
| Bachelor’s degree in Electrical Engineering (Poli/USP) and Physics (FFLCH-USP), Master’s (FFLCH-USP), and doctorate (Carnegie Mellon University) |
| Institution: |
| USP Institute of Physics |
| Scientific Production: |
| 118 scientific articles and seven books. Advised 27 master’s students and 17 doctoral students |
Your imprisonment and expulsion from ITA took place seven days after the 1964 military coup. Were you a member of a leftist group?
I was in the fourth year of my electrical engineering degree and was active in the student center. Before the coup, there was a strong student movement at ITA, despite it being run by the military. Cultural life was intense and the student center was supported by the school and by the CTA [now the DCTA, Department of Aerospace Science and Technology, linked to the Aeronautical Command], from where part of the budget came. We were allowed to use that money without interference. I learned to like cinema at ITA, which had a weekly session of art films, in addition to presentations of good plays and concerts. For someone from Araraquara, it was fantastic. Together with culture, there were student movements, divided into the right and the left. On the left were those influenced by the Communist Party, or linked to the Catholic Church’s social movements.
Was your activism restricted to the student movement?
Yes, it was the same as in São Paulo. The strong groups were in engineering and the humanities. It was only after the coup that it hit us that we were studying on a military base. On April 7 two professors and 12 students were arrested, myself included, and we were held for four months at the Santos Air Force Base, to answer to a Military Police Inquiry. We were expelled from the Institute. In 2005, I was given amnesty with others expelled for political reasons in 1964, 1965 and 1975. The initiative came from a recent Institute president, Michal Gartenkraut, who passed away in 2013. He promoted the reconciliation of ITA with its past and thought the pre-1964 environment needed to be redeemed, from an intellectual point of view and in relation to people’s behavior.
Behavior?
Yes, ITA had an interesting cultural and academic environment. The foundation courses were excellent and allowed me to switch to physics, years later, painlessly. At ITA, I discovered a practice called conscious discipline. It was a concept in which the social rules at the institution and punishment for transgressions were administered by the students themselves. One example: a professor distributed exams and left the classroom. No one cheated. Where else does this happen today?
What was it like at USP?
When I got out of prison I took the entrance exam for the Polytechnic School and for physics at FFCL. I passed, and started in 1965. I was able to obtain both degrees in two years because I transferred my credits from ITA. I don’t think that this would be possible today. I attended classes at Poli in the morning and went to the laboratories in the afternoon. My physics classes were at night. All classes were at the Butantã Campus and, living in on-campus student housing, I was able to handle it.
What led you to lean towards physics?
First, some interesting courses and the intellectual challenges proposed. Second, I was not excited about working as an engineer. I decided to do a master’s degree in physics and, fortunately, I discovered FAPESP. I obtained a scholarship in 1967, when I finished my undergraduate degree. I defended my master’s degree in 1969, but before that I had already been hired as a professor at Poli.
That quickly?
That was how it was back then. José Goldemberg, who didn’t know me, hired me to teach part-time in March, 1968. Poli had a physics position that had been almost abandoned because no one was doing research in the field. Goldemberg was promoted to a full professor position and wanted to remedy this. That was before the university reforms. The Physics group at Poli was different than the Physics group at FFCL. He [Goldemberg] was associated with FFCL, but the position at Poli was the one that opened up. No one seemed to be interested, with the exception of Roberto Salmeron, who was abroad and did not come back for the official examination for the position. Goldemberg was hired and needed young assistants to teach and do research. He thought it was great that I wanted to work with him.
What was your line of research?
Condensed matter. Initially, I worked on semiconductors with Professor Luiz Guimarães Ferreira. He suggested that I do an internship in the Low-Temperature Laboratory and I completed my master’s degree there.
Is that the laboratory that was created by Mario Schenberg in the 1960s?
Yes. At some point, Schenberg realized that he needed to expand the research lines in the FFCL Department of Physics. The USP Physics Department had enjoyed great success with cosmic ray studies beginning in 1936, when it began physics research. Later, those physicists worked on nuclear physics. In the 1950s and 1960s, new areas emerged and solid state physics, now known as condensed matter, seemed promising. Schenberg arranged for the construction of a solid state physics laboratory, completed in 1961.
Personal archiveSilvio Salinas, John Nagle and Carlos Yokoi in Rio de Janeiro (undated)Personal archive
That was not his field.
No. His interest was theoretical physics. Schenberg was already in the most abstract phase of his career and a bit isolated. Since that was not his field, he needed to bring in researchers for the laboratory. The first were Newton Bernardes and Carlos Quadros, who worked in the United States. The laboratory was designed by a professor who came in from the United States.
What did you study there?
Ambient temperature, around 20 degrees Celsius, is not the temperature used in this kind of research. We use Kelvin. Zero Celsius is equivalent to 273 Kelvin. Low temperature means going below that, but the second law of thermodynamics imposes a limit: zero Kelvin. You cannot go below that, except in special situations. There are some important milestones. One of these is the liquefaction of nitrogen, at 90 Kelvin. It is not too difficult to reach this temperature. But, for some studies, you must cool things further. The only liquid substance at very low temperatures is helium. Its liquefaction temperature is 4 Kelvin and this was achieved here shortly before I joined the laboratory, in 1967. With liquid helium, you can take precise electric and magnetic measurements and characterize materials.
What did you do?
I participated in characterizing magnetic materials. There are other materials, such as superconductors, for which one must work at still lower temperatures for characterization. At 4 Kelvin, helium liquefies; at 1.2 Kelvin, the liquid becomes superfluid and has remarkable characteristics, such as the absence of viscosity. Helium was liquefied for the first time in 1906 by the Dutch researcher Heike Kamerlingh Onnes, who discovered sensational properties. The most interesting was superconductivity. Some materials, below certain temperatures, turned into perfect conductors, with no energy dissipation. A lot of work had been done to characterize superconductors. During my master’s degree, I worked with a superconducting coil, supervised by Professor Nei Oliveira, who was a little older than I was. I think that it was the first coil of its kind in Brazil, donated by a laboratory in Grenoble, France.
What are the possible applications of this research?
Although superconductivity does not dissipate energy, it only works at temperatures up to 10 Kelvin. For example, to build a train that could float under these conditions, you would need to maintain everything at that temperature, which is impossible. About 20 years ago they discovered materials that are superconducting at 100 Kelvin. That is better, but this is still a problem that cannot be solved with technology. We can explain superconductivity at low temperatures, up to 15 Kelvin. There is a theory known as BCS, proposed by [John] Bardeen, [Leon] Cooper and [Robert] Schrieffer, that is the foundation of superconductivity. They won the Nobel Prize in Physics thanks to that theory.
John Bardeen, one of the inventors of the transistor?
Exactly, the only person to win the Nobel Prize in Physics twice. Once for the transistor, with William Shockley and Walter Brattain, in 1956, and a second time for the BCS theory. Newton Bernardes did his master’s under Bardeen, who proposed a problem to him. Bernardes solved it very well and published it. But, that same year, Schrieffer solved another that worked better to explain what Bardeen wanted. Together with Cooper, they won the Nobel Prize in 1972. Bernardes had horrible luck. Today everyone is searching for a new superconductor theory and some physicists say that the BCS theory is incomplete.
If your career was going so well, why did you leave Brazil in 1969?
That year, 1969, was a horrible year, with a lot of oppression. In physics, Schenberg and Jayme Tiomno left. The repression became brutal, and my political past did not help me at all. I decided to try to go abroad. My situation was good at the time. I’d gotten married in 1968, I had a Volkswagen and lived in a rented apartment. My friends used this infrastructure for actions against the dictatorship, and even though I didn’t do anything, I was indirectly involved.
How did you manage to leave?
Professor Fernando de Souza Barros, today in Rio de Janeiro, was at Carnegie Mellon University, in Pittsburgh, and arranged a teaching assistant position for me without my having to take an exam or even an English test. I was also accepted into the doctoral program. The invitation was arranged with the help of physicist friends, such as Amélia and Ernst Hamburger, who were at the University of Pittsburgh. My intention was to continue what I had been studying here, but after taking courses and meeting people I switched to theoretical physics. There were strong people in the field there, such as Robert Griffiths, James Langer and John Nagle.
Personal archiveWith his wife, Cristina, and their twins in Pittsburgh, in the early 1970sPersonal archive
Was your advisor American?
Yes, it was John Nagle. Initially I had intended to work with Fernando de Souza Barros, but he planned on returning to Rio. Then this opportunity opened up in theoretical physics, and working with Nagle broadened my perspectives to include work on crystal models with nitrogen bonds, which I continued, later, at USP. To earn my keep at Carnegie Mellon, I had a university assistantship that required that I teach classes. I did that for two years. In the beginning, they protected me a lot, because I spoke poor English. I had to prepare classes carefully, and that took time. Until I discovered that, with a FAPESP grant, I could do research full-time and choose my advisor. I applied for and received a grant. It was better, in financial terms, than what I earned there.
Why didn’t you stay in the United States?
At the time, all my friends planned to return to Brazil. It was not an easy decision. I had problems here, I was involved in the CRUSP Military Police Inquiry when they discovered that I had been expelled from ITA. When I was leaving Brazil, I asked Goldemberg to lay me off, but he suggested that I ask for an indefinite leave of absence. That way, when I wanted to return, I would have a job. He held my position and renewed my contract for four years. During that time, the university underwent a reform, the lead professor system was eliminated and the Poli and FFCL posts became one, at the Physics Institute. I remained in the United States until I received an ultimatum from the Institute. If I didn’t return, they would not renew my contract. I returned in 1974.
Weren’t you worried about returning during the dictatorship?
An uncle, who was a retired prosecutor, said that nothing would happen. The CRUSP Military Police Inquiry had already been closed and I was absolved, the same as with the ITA inquiry. I returned and assumed my position as an instructor. It was only a part-time job, and I could not live off it. Fortunately, there was the BNDE [now the BNDES, the Brazilian Development Bank], which began a funding program later continued by FINEP [Brazilian Innovation Agency]. At the time, the bank had a large project that helped supplement my salary and that of many USP staff. Later I became full-time at the university.
Did you continue working with low temperatures in the United States?
Yes, but in statistical physics. The physics of solids is an application of quantum mechanics and statistical physics. You work with a very large number of particles, which makes treating them individually impossible. That is why a statistical approach is necessary. I worked on ferroelectricity and learned statistical mechanics techniques during my doctorate. When I returned, I interacted with colleagues working with low temperatures. At the time physicists were interested in understanding physical phenomena known as critical and multicritical phase transitions.
What was your most important contribution?
Some of my contributions were towards better understanding how these systems function and the theories existing at the time. There is a book by a friend, Mario Oliveira, commemorating USP’s 80th anniversary, with articles on research that is considered important. He included a study that I did with a student who is now a professor here, Carlos Yokoi, and another professor from Pernambuco, Mauricio Coutinho, related to something that arose in conversations with experimental physicists. It is the model of a phase diagram [graph showing equilibrium conditions between the solid, liquid and gas phases] in which one can make connections and measurements. It was a relatively influential statistical physics result. One of the consequences was that we were able to make a connection with an idea that had arisen at the time—in the theory of dynamic systems—on chaos and fractals. That was in the early 1980s.
Has your work focused on statistical models since your doctorate?
My dissertation was on a statistical model to explain phase transitions in a ferroelectric crystal. I published some articles while in the United States. The article related to my dissertation was published in the journal Physical Review B in 1974.
You followed Brazilian nuclear policy closely. From what can be understood from that period, some Brazilian physicists had reservations about the agreement with Germany, but did not oppose it openly, even though Brazil had a huge potential for hydropower generation. What were the reasons for this reaction?
It wasn’t quite like that. I was very involved with the Brazilian Physics Society (SBF) at the time and the agreement with Germany was a surprise. When it was announced, in July 1975, we were at a meeting of the Brazilian Society for the Advancement of Science (SBPC) in Belo Horizonte. Many physicists supported the agreement and some even participated in it behind the scenes, like José Israel Vargas. Others were stunned, like Goldemberg. He supported the use of nuclear energy, but wanted conditions that would ensure Brazil’s independence and was against methods based on uranium enrichment. There were physicists in favor of an independent Brazilian nuclear program, and resistant to the features of the German program. It was an important debate. Physicists began to discuss the energy question as a whole. Brazil’s hydroelectric potential was not well known to those in our field. Goldemberg began researching energy after these debates and is now critical of the use of nuclear energy. Some also suspected that the military wanted to produce an atomic bomb.
And what do you think now?
I am in favor of a multipurpose reactor, for producing radioisotopes and doing research in that area. But I do not support building nuclear plants to generate electricity. There are unresolved safety problems. In addition to water power, we could exploit wind and biomass energy. Brazil can be cleaner without so much risk.
You once said that physics was at an impasse. Why?
One example: recently, the Higgs boson was discovered, which confirms the standard model, an important theoretical model in physics. What comes next? There are advances in astronomy and astrophysics. Twenty years ago, cosmology was a bit metaphysical. Now its status has changed. Now we study dark matter and dark energy. What is the standard model for cosmology? How will it adjust to modern field theory?
Isn’t this exciting?
On the one hand, yes, but what is there to explain? One of the most interesting areas is string theory. But it is very complicated, because there is no way to test it experimentally, nor build increasingly larger and more expensive particle accelerators. I don’t see anyway out.
And what do you think the future holds for Brazilian physics?
It had a rocky start, without personnel or funding, but it did well, thanks to the work of the initial group formed by Gleb Wataghin in the 1930s and 1940s. Today, the Brazilian physics community is a good size. We need to make sure that our research is high quality and influential.
Recently, you have been concerned with preserving the archives of the Physics Institute. Is it true that you even gave up your office so that historical documents could be stored there?
When I was director of the Institute, from 1993 to 2002, they asked to use my former office. After my term as director, I was assigned another, larger office. I retired in 2012 and continued to do research, but I felt that I did not need all that space. At the time there was a project to create an Institute Archive, and those responsible were desperate for a room. I left my office so that they could use it for documentation. When Amélia Hamburger passed away, I moved into her small office. Plus, I am a theoretical physicist and can work at home. There is some funding to digitize the collection. Part has already been done. It is difficult: science historians are not that interested and there is not enough money. We would like to have two or three young researchers focusing on the history of physics in São Paulo.
You worked at the University of the ABC (UFABC) in 2006-7. Why did this new university impress you?
In early 2006 I ran into Hermano Tavares, a classmate at ITA and former President of Unicamp. He had just been appointed temporary president of UFABC, in Santo André, and said that he needed my help. I visited it and thought that it was an innovative experiment. All incoming undergraduate students study for an interdisciplinary degree, in science and technology, for three years. Half of the courses are electives with a common foundation: physics, chemistry, mathematics, computer science and social sciences. The student chooses what to study. After three years, she can graduate with a degree in technology. Or, if she is interested, and her performance is above a certain level and she chose appropriate electives, she can continue on to obtain a bachelor’s degree (in engineering, physics, chemistry, mathematics or computer science) after another one or two years. The idea was to have a strong conceptual foundation and reduce the distinctions between scientists and engineers or between the different specializations. The university is the only one in the country where 100% of professors have doctorates. It was a strange period, because UFABC recruited a large number of professionals who had completed graduate work and even post-doctoral research at USP, but could not find positions in São Paulo. UFABC does not have departments, but rather common centers, which is good because it brings people together. I was the director of the Center for Natural and Human Sciences. I thought it was a bit strange when they created a bachelor’s degree in the humanities. UFABC does not need to offer degrees in all areas, like many Brazilian universities prefer. Courses in the humanities are important to support the training of engineers, who need this. The United States has had incredible results with what they call general studies, even at Harvard.
