ABDUS SALAM,
THE ELECTROWEAK FORCES,
ICTP AND BEYOND
Antonino Zichichi
University of Bologna and INFN, Italy
CERN, Geneva, Switzerland
Enrico Fermi Centre, Rome, Italy
Pontifical Academy of Sciences, Vatican City
World Federation of Scientists, Beijing, Geneva, Moscow, New York
Ettore Majorana Foundation and Centre for Scientific Culture, Erice, Italy
A few episodes about Abdus Salam as physicist and friend will be my contribution to the Memorial Meeting for the 90th Birthday of a physicist whose life has been devoted to the progress of Science the world over.
Our scientific careers started with the strong support of the same great man: Lord Patrick M.S. Blackett [1].
Our physics interests – in spite of the fact that experimental and theoretical approaches do appear different – often converged.
Let me start with a few memories of the fine times with our tutor: P.M.S. Blackett. I joined his cosmic ray group when the production of “heavy mesons” (first called V, then q and finally K), with positive and negative “strangeness” quantum number, was needed in order to overcome the Fermi criticism on the existence of this “new” charge called “strangeness”. The discovery of the simultaneous production of “heavy mesons” with positive and negative strangeness allowed me to become the “pupil” of Blackett.
Professor Blackett was very proud of Abdus. Once he told me that this young Pakistani physicist was really extraordinary. I remember his lectures about the unification of the Weak and the Electromagnetic Interactions at Imperial College, at the end of the fifties of last century, when no one was speaking about these topics. When he knew that he had been awarded the Nobel Prize, for the electroweak unification, he asked me if I remembered what I am now going to recall. Let me start quoting what he said at his Nobel Lecture [2]:
«When I was discussing the final version of the SU(2)´U(1) theory and its possible renormalizability in Autumn 1967 during a post-doctoral course of lectures at Imperial College, Nino Zichichi from CERN happened to be present. I was delighted because Zichichi had been badgering me since 1958 with persistent questioning of what theoretical avail his precise measurements on (g–2) for the muon as well as those of the muon lifetime were, when not only the magnitude of the electromagnetic corrections to weak decays was uncertain, but also conversely the effect of non-renormalizable weak interactions on “renormalized” electromagnetism was so unclear».
Thanks to his friendship I had the privilege to learn new theoretical concepts before anyone else. When I went to work with the first European accelerator, the CERN SC, to attempt the measurement of the anomalous magnetic moment of the muon, Abdus was the only theorist interested in understanding why this quantity was not infinite as it should have been, if the muon was coupled to the Fermi weak interactions.
The goal was to measure with high accuracy the anomalous magnetic moment of the muon. The muon was (and still is) 200 times heavier than the electron, but it does not show any other difference: its weak and electromagnetic properties were (and are) apparently identical to those of the electron. To measure with high accuracy the value of the muon magnetic “anomaly” was a very difficult experimental task. Let me recall the reason. It was necessary to “store” an intense muon beam in a magnetic field in order to “rotate” its magnetic moment as many times as possible. It was necessary to invent a new technology in order to build high precision magnetic fields, two orders of magnitudes faster for construction and two orders of magnitudes less expensive than all known technologies. I started to work to solve this problem and this is how the “flat” 6-metres-long magnet become “real”. I was spending days and nights inside this big magnet in order to build the very high-precision fields needed to capture, store and eject the muons. One day Abdus passed by at CERN and found me inside the magnet. He was very interested to know the experimental value of the magnetic “anomaly” of the muon. The theoretical problem of the weak and electromagnetic interactions needed to be solved. Abdus was on the way to visit the “Pope” of theoretical physics: Wolfgang Pauli in Zurich. Abdus was very enthusiastic on the way towards Zurich, but when he came back he was very depressed. Pauli didn’t encourage him to spend his time thinking about the reasons why the muon magnetic “anomaly” should not diverge: to think about the unification of the electromagnetic and the weak interactions was simply a waste of time, according to the “Pope” of theoretical physics. In spite of this discouragement, he went on and gave a series of seminars exactly on this “waste of time” topic. Nowadays we speak about Grand Unification as taken for granted. In the late fifties, the idea that the fundamental forces of nature had to be unified was in the mind of a very few [3]. Abdus was the leader in the field.
When I first attempted to measure the proton stability in GenevaatCERN – not in an underground laboratory – using a powerfulnewelectronic-logic circuit able to select the forbidden process p→π→μ→e, Abdus was the only theoretical physicist interested in the experiment. Baryon number conservation was – at that time – sacred. The first limit obtained at CERN on the proton lifetime, τp , and the interest of Abdus in this new frontier of physics, were the starting points of the Gran Sasso project [4].
And now it is probably appropriate to recall the time when with Abdus we were listening to Professor Blackett and his friend Bertrand Russell discussing strategic plans for the future of Science, not only in the industrialized countries but also in the forgotten areas of our planet. Abdus was coming from Pakistan, I was coming from Sicily, and we both hoped, to be able – one day – to contribute to helping those fellows from forgotten areas to take part in the fascinating challenge of understanding the fundamental Laws of Nature. When the International Centre for Theoretical Physics (ICTP) was finally established he called me to express his great happiness and satisfaction. It was one of the major objectives of his life.
Professor Blackett and his friend Bertrand Russell were interested in identifying the real motor for progress in technological inventions that has allowed the quality of life to be at the level it is today. This motor is scientific discovery.
When I had the privilege of being in Professor Blackett’s Physics group I learned a lot about these problems, essentially as Professor Blackett was engaged not only in the frontiers of Physics but also with problems concerning the role of science in the culture of our time. This is how the young fellows of the Blackett group learnt about the great technological achievements obtained thanks to the existence of the Manhattan Project.
The Manhattan Project was the result of the collaboration of very many brilliant physicists working together. According to Blackett and Russell, this project was the example of how the new frontiers of science and technology should be implemented in the future. The Manhattan Project was the proof that a new bridge is not only possible but also needed in order to fill the gap between traditional university teachingand the big projects for the future of science and technology. CERN did not exist, nor other institutions such as the Ettore Majorana Foundation and Centre for Scientific Culture (EMFCSC) in Erice and the ICTP in Trieste[5].
Blackett and Russell were discussing the following point.
More than 900 years ago the first university was founded in one of Europe’s most developed areas, Bologna, in order to avoid waiting ten years before books were available. Medicine, astronomy and law were topics being investigated by just a few specialists.
Instead of waiting for the specialists to write a book (printing had yet to be invented), why not invite them to give lectures? Now we have instant books but the primary role of the universities has changed, because human knowledge has exploded during the last four hundred years. The starting point of this cultural explosion was the time when Galilei discovered the first Fundamental Laws of Nature [6]. This produced an exponential growth in human knowledge. Nowadays, the task of the universities is mainly pedagogical and therefore there is a gap between universities and research laboratories which needs to be filled.
During many years this gap has been filled only for military technologies. In fact, starting with the Uranium (Hiroshima) and Plutonium (Nagasaki) bombs, both based on nuclear-fission, nuclear-fusion bombs (called H-bombs) were realized in 1952 by the USA and in 1953 by USSR.
This sequence has as its basis the logic of the Manhattan Project. No institutions devoted to non-military technologies at that point existed. New institutions entirely devoted to non-military technology were needed, one for the industrialized Countries and one for the so-called “developing Countries”. Both institutions were to fulfil the role of the university, established nearly a millennium earlier. Abdus Salam, the theoretical pupil of the Blackett group, was enthusiastic about this strategy, which had Blackett and Russell as its strongest supporters. This is the origin of the two now well-known centres for advanced studies in Erice (EMFCSC) and in Trieste (ICTP).
When I think of life and of its challenges, of the physics community and of its achievements, Abdus Salam is a formidable example of how all of us should be: the young generations of physicists should follow his devotion to physics and to society, and his extraordinary sense for human solidarity.
References
[1] A Lesson for the Future of Our Science. My Testimony on Lord Patrick M.S. Blackett,
A. Zichichi, World Scientific (2016).
[2] Gauge Unification of Fundamental Forces
Abdus Salam, Nobel Lecture, 8 December 1979, from Nobel Lectures, Physics 1971-1980, Stig Lundqvist (ed), World Scientific (1992).
[3] Some Lessons from Sixty Years of Theorizing
M. Gell-Mann, in Proceedings Conference in Honor of Murray Gell-Mann’s 80th Birthday, NTU, Singapore (2010), Int. J. Mod. Phys. A25 (2010); in the same Proceedings Murray Gell-Mann and the last frontier of LHC Physics: the QGCW Project, A. Zichichi; see also Some Reminiscences of Research Leading to QCD and Beyond, M. Gell-Mann, in What We Would like LHC to Give Us, Proceedings of the 2012–Erice Subnuclear Physics School, Vol. 50, A. Zichichi (ed), World Scientific (2014).
[4] The Gran Sasso Project
A. Zichichi, INFN/AE-82/l, 28 February 1982;
The Gran Sasso Project
A. Zichichi, Proceedings of the Workshop on Science Underground, Los Alamos, NM, USA, 27 September-1 October 1982, AIP, New York, 52 (1983);
Perspectives of Underground Physics: The Gran Sasso Project
A. Zichichi, Invited Plenary Lecture at the Symposium on Present Trends, Concepts and Instruments of Particle Physics, in honour of Marcello Conversi’s 70th birthday, Rome, Italy, 3-4 November 1987, G. Baroni, L. Maiani and G. Salvini (eds), Conference Proceedings, SIF, Bologna, Italy, Vol. 15, 107 (1988).
[5] The Abdus Salam Dream
A. Zichichi, CERN/LAA/93-32/a, 21 October 1993. Invited Lecture given at the
Salamfest, in honour of Abdus Salam, ICTP, Trieste, Italy, 8-12 March 1993.
[6] Galilei, Divine Man
A. Zichichi, Italian Physical Society, two editions (2009–2010).
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