Spartak Timofeevich Belyaev, who made outstanding achievements in many-body physics and nuclear theory, died in Moscow on 5 January 2017 after a short fight with pneumonia.
Spartak was born on 27 October 1923 in Moscow. His unusual first name combined with a traditional Russian patronym and family name is typical for the generation born after the 1917 revolution. Spartak graduated from high school in June 1941, at the start of World War II. In August he volunteered for the army and served as an operator of the field-intelligence radio complex. After the Russians captured the Reichstag in Berlin in 1945, he was one of many soldiers who left his signature on the walls.
In 1946 Spartak entered the physics department of Moscow University. When the new physical–technical department, known as Fiztech, was established one year later, he moved there with some classmates. In 1949 he started his research work at the famous laboratory #2, led by Igor Kurchatov; the lab became the core of the Atomic Energy Institute, now the Kurchatov Institute. The lab had an unusual concentration of extremely bright physicists with dramatically different personalities; they included Gersh Budker, Victor Galitsky, and Arkady Migdal.
After graduating in 1952, Spartak demonstrated his outstanding theoretical ability in his 1955 PhD: With Budker as his adviser, he presented the first consistent theory of relativistic kinetic equations with applications to plasma physics and relativistic electron beams. His next achievement was using Green’s functions and diagram techniques to develop the theory of the nonideal Bose gas in 1958. His fundamental result, the existence of a condensate even in an interacting system, required what was later called spontaneously broken symmetry, an idea that Spartak broadly applied. In the same spirit, a few weeks later, Lev Gor’kov published his theory of superconductivity.
In 1957–58 Spartak spent a year at the Niels Bohr Institute in Copenhagen, at that time the mecca for nuclear physics. Nuclear structure and dynamics became a main subject of Spartak’s interest. Aage Bohr, Ben Mottelson, and David Pines conjectured that the phenomenologically known nucleon pairing in complex nuclei is of the same type as the mechanism behind macroscopic superconductivity. Spartak worked out a full theory of nuclear pairing correlations and showed that they influence not only binding energies but all observable properties of complex nuclei, including vibrational and rotational excitations and transition probabilities. His many years of studying nuclear collective motion are summarized in his lectures published by the International Atomic Energy Agency and in the book Collective Excitations of Nuclei (Gordon and Breach, 1968). Niels Bohr, with his philosophy of science and scientific truth in contradistinction to clarity, greatly influenced Spartak’s worldview, as can be seen in Spartak’s publications devoted to Bohr’s 100th anniversary.
In 1962 Spartak and Galitsky joined Budker at the Novosibirsk Scientific Center, established in 1958. Its Institute of Nuclear Physics, now the Budker Institute, was the cradle of new methods in high-energy and particle physics. Galitsky and Spartak assembled the theory department, and Spartak became its head after Galitsky returned to Moscow.
Overlapping scientific interests and the youthfulness of the department members created an extremely friendly atmosphere, which was supported by Spartak’s personal style of paying attention to everyone and encouraging and openly criticizing ideas and individual achievements and by the general “disordered democracy” that was a way of life at the institute. Spartak also was extensively involved in discussions and evaluations of the institute’s experimental program. He worked hard to manage the constantly growing weight of public duties. One of us (Zelevinsky) remembers how we frequently spent Sundays (the only nonworking day of the week at that time) from early morning to late evening in his home, doing parallel calculations at opposite sides of a large desk.
Encouraged by Budker, Spartak agreed to serve as rector of the young Novosibirsk State University. From 1965 to 1978, he put much effort into its development and growth, including searching for gifted young students all over Siberia and the Far East and connecting them to the research institutions of the Novosibirsk Scientific Center.
Spartak returned to Moscow in 1978 and became director of the Kurchatov Institute’s large division for nuclear and general physics. He chaired the theoretical physics department at his alma mater of Fiztech and chaired the Nuclear Physics Council of the Russian Academy of Sciences. In the aftermath of the Chernobyl catastrophe in 1986, he led the investigating commission of the Russian Academy of Sciences and repeatedly visited the contaminated areas. His participation was critical for the development of the synchrotron light source at the Kurchatov Institute. His expanding scientific studies included the problems of interaction of ultracold neutrons with condensed matter, and he participated in various experimental activities, such as the Moscow–Heidelberg collaboration on double beta decay.
Former students from Spartak’s time in Novosibirsk and Moscow are spread over the globe; they gratefully remember his lessons and influence on their lives. Among the scientific awards he received were the 1998 L. D. Landau Gold Medal, the 2004 Eugene Feenberg Memorial Medal, and the 2012 Pomeranchuk Prize.
Neither years nor prizes changed Spartak’s unique personality. Even into his nineties, the routine of his everyday life involved a daily half-hour walk from home to the office and back. While visiting Lake Michigan in 2004, he taught several younger people the correct dune-climbing technique. He never took medicine, which was not good during his fatal illness. He will stay in our memory as a great scientist and a superb human being.
