Tadić, Dubravko

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ISSN1330–0008CODENFIZAE4IVAN SUPEK AND THEORETICAL PHYSICS IN ZAGREBDUBRAVKO TADIĆDepartment of Theoretical Physics, Faculty of Science, University of Zagreb, 41 000Zagreb, CroatiaTalk at the SymposiumProfessor Supek is father of our contemporary theoretical physics in Zagreb. Itall started through the activity of Professor Supek, who founded the Seminar forTheoretical Physics in 1947 at the Faculty of Science (Prirodoslovno-matematičkifakultet, PMF), which itself was founded in 1946.Professor Supek was the best available person for that job. He studied in Za-greb, under Professors L. Stjepanek, V. Varićak and S. Hondl, and obtained his B.Sc. degree in 1939. Then he began studying physics and philosophy at Europeanuniversities, which resulted in his Ph. D. in 1940 from the Leipzig University, wherehis work was supervised by Professor W. Heisenberg and Professor F. Hund. Therehe was also a member of Heisenberg’s seminar, becoming eventually his assistant.In his research he was very much involved in problems of solid state physics, notablythe electron-phonon interaction in connection with phosphorescence.Together with H. Euler and W. Heisenberg himself, he also worked on problemsin QED and on the theoretical description of cascades. He was dealing with theforemost theoretical physics problems at that time, being one of the first to realizethe importance of the electron-phonon interaction. His good war record gave himreasonable standing with political authorities, although he was no longer partymember.After his return to Zagreb, in the period 1945 – 46 Supek was employed as Profes-sor of physics at the School of Medicine. He became professor of theoretical physicsin 1946 soon as the newly formed School of Science (Prirodoslovno-matematičkifakultet, PMF) was opened by cloning it from the older School of Arts (Filozofskifakultet) which contained sciences and mathematics as a subgroup. At that time theFIZIKA A 1 (1992) 1, 7–10 7tadić: ivan supek and theoretical physics . . .chair for theoretical physics was empty. The former professor, L. Stjepanek (whowas not active during the war), retired in 1946, without leaving a successor. Hehad been the head of the Theoretical Physics Seminar (chair) (Seminar (Zavod) zateoretsku fiziku) since 1920, together with Professor V. Vrkljan. Professor Vrkljanwas the head of chair for Classical Mechanics and Applied Mathematics. He wasactive in modern theoretical physics, meaning relativity, in quantum mechanics andDirac’s equation. Through some imbroglio with students, which contained strongpolitical undertones so important in those years, Vrkljan retired. (In order to givehim some moral statisfaction, in 1950 his colleagues, at the instigation of Prof.Supek, made him a corresponding member of the Academy of Sciences and Artsin 1950 (contemporary acronym being JAZU). When the new PMF was formed,Supek was made the head of both chairs. The only other scientist was assistantZ. Janković at the Chair for Classical Mechanics, etc., who was then preparing hisPh. D. thesis. (Janković became a distinguished professor, who headed this chairuntil his untimely death).In 1947 Professor Supek started a process that changed this very unsatisfactorysituation by activating the Seminar for Theoretical Physics, which met regularilyevery Wednesday, finishing with a tea party. The core, which were Supek (mem-ber of the Academy (JAZU) since 1948) and Janković, was soon reinforced by anoutstanding mathematician, D. Blanuša. (As well as in pure mathematics he wasalso interested in applications and problems connected with special and generalrelativity.) However, the main strength to the Seminar came from young students,some of whom came over from the School of Engineering (Tehnički fakultet). Theybecame founders of various branches of our theoretical physics, starting the growthwhich eventually resulted in about 50 internationally established theoreticians inelementary particle physics, nuclear physics, solid state physics and classical theo-retical physics. It is fit to say a few words about Supek’s pupils, whose educationis his outstanding contribution to the development of Croatian science.The Seminar was concerned with the same problems as those investigated inHeisenberg’s seminar in Leipzig. Various lines of research were divided among stu-dents, very often determining their future scientific orientation. Important membersof the first generation were (in alphabetical order) Gaja Alaga, Ivo Babić-Gjalski,Vladimir Glaser and Borivoj Jakšić.Babić-Gjalski, a very talented descendant of a famous 19th-century Croatiannovelist (Ksaver Šandor Gjalski) of whom much was expected, died prematurely ina mountaineering accident in 1951. With his impeccable social manners and sunnynature he was an important cohesion force in the Seminar. Supek suggested himthe research on the correspondence between classical and quantum electrodynam-ics. Together with Professor Supek he published Korespondencija klasične i kvantneelektrodinamike (RAD 296 (JAZU) 23 (1953)). They also extended the semiclas-sial Weizsäcker-Williams approach, developed for soft photons in QED, to mesonphysics.Alaga was a Croatian from Vojvodina, from a landowning family. Alaga startedworking on nuclear structure and nuclear β-decay. In 1949 he was expelled for atime from the University in one of the purges, being suspect as a son of the “kulak”-8 FIZIKA A 1 (1992) 1, 7–10tadić: ivan supek and theoretical physics . . .father. Alaga was a member of the first group that visited the Bohr Institute inCopenhagen (the others were Z. Janković and S. Kurepa). There he started hisbrilliant career in theoretical physics by writing a joint paper with the future Nobel-prize winners A. Bohr and B. Mottelson. Alaga’s selection rules are still referredto in nuclear physics and he was the author of the most quoted paper among thoseproduced by the Zagreb theory group. He died as the head of the TheoreticalPhysics Department.Glaser was probably the most talented member of the Seminar, exceeding inmathematical brilliance, which made him later, when he was on the CERN staff,an undisputed authority for mathematical problems. Among CERN mathemati-cal physicists he was known as the “pope”, stressing his mathematical infallibility.Supek directed him towards QED and problems connected with field-theory nor-malization. He was sent to Goettingen to spend some time in Heisenberg’s group.After his return to Zagreb he published (1955) the book Kovarijantna kvantna elek-trodinamika (Covariant QED), which still provides a useful reading with many in-teresting insights. He also collaborated with Lehman, Szymanzik and Zimmerman,helping further development of (for some time) the famous LSZ formalism. Whilein Zagreb, he found his much appreciated exact solution of the two-dimensionalThirring model field theory. He left Zagreb for good in the late fifties, and diedwhile serving as a distinguished staff-member at CERN.Jakšić was introduced by Supek to meson physics and sent to work underRosenfeld in Manchester. Later he became the head of the Theory Group at theRud–er Bošković Institute, gathering many talented young people in the field oftheoretical physics, and finding them suitable fellowships abroad. He was expert inmathematical problems, especially nonrelativistic scattering. Together with Glaserhe produced a noted work on electromagnetic form factors, which contained manyrelations which were used by later researchers. He left Zagreb in the sixties.Supek’s Seminar was later jointed by K. Ljolje and A. Grossmann, who grewto be theoretical physicists. Other members, K. Ilakovac, M. Petravić, M. Cerineo,B. Leontić and V. Knapp, were directed and persuaded to become experimen-tal physicists, all being given foreign fellowships. This was dictated by an urgentneed to develop experimental research in Zagreb, connected with the newly builtRud–er Bošković Institute. Same was the fate of even newer Seminar members N.Cindro and I. Šlaus. Most of these scientists were, and still are, the backbone ofthe experimental physics in Zagreb.One of the Seminar members, M. Randić, was offered, by Supek, a fellowshipunder the condition to specialize in theoretical chemistry. He is now a well-knownauthority in that field. Although he left Zagreb a long time ago, his occassionalvisits are useful to the Zagreb theoretical chemistry group.Supek also contributed to the education of undergraduates by writing the firstCroatian theoretical physics textbook Teorijska fizika i struktura materije (1949).This book is important for our science and our culture in general, as it is the firstbook on quantum mechanics ever published in Croatia. Since then it has had manyeditions being enlarged and modernized by his numerous former students (G. Alaga,FIZIKA A 1 (1992) 1, 7–10 9tadić: ivan supek and theoretical physics . . .N. Bilić, B. Jakšić, M. Martinis, M. Randić, V. Šips, M. Šunjić, D. Tadić and M.Tomaš).Supek’s own research stayed in solid state physics. With K. Ljolje, another Semi-nar member, he published Utjecaj termičkog titranja kristalne rešetke na elektrone upobud–enim stanjima metala i fotoluminiscencije metala (1953). After obtaining hisPh. D. under Supek, Ljolje went to Sarajevo, where he is now a leading Universityprofessor.Supek also published another pioneer paper in the Croatian language Kore-spondencija klasične i kvantne elektrodinamike (with Babić-Gjalski 1953), whichis connected with Supek’s early publication Kvantiziranje elektromagnetskog polja(Glasnik matematičko-fizički i astronomski 4 (1949)) (Quantization of the Electro-magnetic Field). These are the first papers on quantum field theory ever publishedin Zagreb.The latest scientific papers by Supek reflect the rapid development and sophisti-cation of theoretical physics in Zagreb. By now he has educated a group of theoret-ical physicists, who are or were members of the international scientific community,producing papers for the leading international scientific journals. In his papersElektrische Leitfähigkeit der Metalle bei tiefen Temperaturen (Z. Phys. 149 (1957)324 and Electrical Conductivity of Metals at Low Temperatures (Nuovo Cimento 12(1959) 290), Supek attacked the same problems on which he had worked during hisyears in Leipzig. His pupils Glaser and Jakšić published an elegant mathematicalformulation (Glasnik mat.-fiz. i astr.) of Supek’s ideas on low-temperature conduc-tivity. In this way Zagreb developed theoretical research of international standingin nuclear physics, quantum field theory, particle physics and solid state physics.That was soon backed by experimental work.Thanks to Supek’s efforts, systematic modern physics research became an im-portant part of Zagreb science, in less than 10 years.10 FIZIKA A 1 (1992) 1, 7–10

Ivan Supek and theoretical physics in Zagreb

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