Yuri Nikolaevich Smirnov Unforgettable Yakov Zeldovich

Yuri Smirnov is a Leading Research Scientist at the Russian Research Center "Kurchatov Institute," Moscow. He is coauthor (in collaboration with Victor Adamskii, Yuri Babaev, Andrei Sakharov, and Yuri Trutnev) of the 100-megaton thermonuclear bomb; he took part in the test of its half-power version on October 30, 1961. He was one of the initiators and participants of the program for deep seismic sounding of Earth's crust with the help of underground nuclear explosions for the accelerated revealing of the prospective regions containing oil, gas, and other minerals. He participated in the preparation of 14 "peaceful" explosions; in 11 of them (for deep seismic sounding) he was State Commission Vice-Chairman. His research interests include atomic energy and the history of the Soviet atomic project.

There is a deep analogy between physical processes which take place inside nuclear bombs (especially thermonuclear bombs) and stars. It was soon realized by the designers of nuclear weapons. That is why the newcomers who just came to Sarov, the Russian nuclear center, were sometimes told, "we research astrophysics here." There were good reasons for that.

For instance, the thermonuclear reaction inside a ball-shaped hydrogen medium can be characterized by the mass and radius. Variation of these parameters over a wide range of values changes the process out of recognition: from an explosion in the case of a bomb to stationary burning in the case of a star.

At the same time, the comparison of a "bomb" and a "star" is relative. Thus, for example, the principal reaction inside stars is p+p (the interaction of protons) whereas in a thermonuclear bomb reactions with deuterium and tritium, d + d and d +1, dominate. Or again, in the case of nuclear burning in a star the retentive force is gravity, while in a bomb it is the compression produced by explosives or radiation.

This is why theorists who participated in the Soviet atomic project commonly became experts in astrophysics or cosmology. Thus it was natural that David Frank-Kamenetskii (1959), who left Sarov as long ago as 1956, published his well-known monograph Physical Processes in Stars and a series of papers on the origin of elements in the universe as early as 1959. He was one of the most brilliant theorists to collaborate with Yakov Zel'dovich.

Nevertheless it was Ya. Zel'dovich, who, as a chairman of the physics seminars, performed a quick turn from elementary particle physics to relativity theory and cosmology in 1961-1962. Andrei Sakharov, Nikolay Dmitriev, Andrei Doroshkevich, Michail Podurets, Sergey Kholin, Valery Yakubov, and others were influenced by nobody but him in their studies of astrophysics and cosmology in Sarov. I didn't escape the common lot as well.

For me, a 24-year-old colleague of Sakharov, who had just returned from the test of a 50-megaton superbomb on October 30, 1961, it was extremely interesting to join that renewed seminar. That was especially because Zel'dovich equalized starting positions of all participants and definitely carried young people by the choice of subjects. Along with the chief we synchronously began to study chapters on general relativity in the book The Theory of Field, by Landau and Lifshitz (1960), and, following Zel'dovich's proposal, reported on them in the seminar.

Discussions gave rise to questions which turned into tasks. Soon publications of the participants of the seminar began to appear. And as the chairman accelerated the pace he shortly became an authoritative leader in this branch of physics that was new for him.

Professional discussions with Yakov Zel'dovich were remarkable for their dynamism and expressiveness. Having familiarized myself with his paper The Initial Stages of the Evolution of the Universe (Zel'dovich 1963a), which was just published in the journal Atomic Energy, I discovered some inaccuracies and dropped in at his office. Right off the bat we found ourselves in front of the blackboard, and I barely followed the dance of a piece of chalk in the hand of the master. Remark ... calculation ... another remark ... rejoinder ... another one. And suddenly he said with satisfied smile: "You beat the academician!" Then he walked up to the desk, opened a notebook, and asked me to read a manuscript of his latest work to check whether I was interested in it. I was interested.

When he was leaving for Moscow for the traditional two weeks in February 1963, we failed to meet, and he left the note shown in Figure 4.4 with an assignment for me. He watched over me patiently and with curiosity until the task was completed.

When the work was done, I proposed to publish it as joint authors. Yakov Zel'dovich strongly objected: "No! This is your paper!" He knew the manuscript and he criticized it (in black and white!) and gave several suggestions how to improve the text. It was an objective, impressive, and unforgettable lesson for me.

The paper I published (Smirnov 1964) differs from others, since the calculations were performed in the framework of the Gamow-Alpher-Herman-Hayashi theory. The nuclear reactions in question were as follows:

n + p ^ d + y, d + t ^ He4 + n, d + d ^ He3 + n, He3 + n ^ t + p, (4.1)

The seventh reaction took into account the decay of a neutron into a proton, electron, and antineutrino.

Fig. 4.4. An assignment from Ya. Zel'dovich: "For Smirnov. Calculate the ratio n:p in the (high-temperature) scheme of Hayashi precisely, taking into account the Fermi statistics of v and v."

Table 4.2. Prestellar abundances

Pi

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