I. D. Novikov

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ORAL HISTORIES
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Interviewed by
Spencer Weart
Interview date
Location
Montreal, Canada
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Interview of I. D. Novikov by Spencer Weart on 1979 August 21,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/5045

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Transcription of dictation using notes made at a short interview, not tape-recorded, during an IAU meeting. Novikov's early interest in astronomy, and training with Livshitz and Zeldovitch. Functioning of Zeldovitch's group and their outside contacts. Views on evolution of our ideas in cosmology, on current cosmological questions, and on the nature of cosmology.

Transcript

Weart:

I’m at Montreal Airport, dictating from my notes of a conversation I had with Igor D. Novikov earlier today in Montreal. Dr. Novikov preferred that I take notes, rather than speak with him into a microphone.

I asked him how he got started in his astronomical career. He said, “It’s rather a long way for me, to astronomy.” His first contact with astronomy was when he was quite young and read an astronomy book for children. He was very surprised at the great size, the vastness of space and time. Enormous things like solar eruptions spreading out from the sun made a great first impression on him. From the start, he said, he liked strange and puzzling things. He was very young at the time, and it was hard for him to understand the details, but he tried very hard to understand them. Right from that time he knew that he should be an astronomer, in order to try to investigate such things.

In other words, he said, astronomy was his first love, and first loves are the best things, what makes one happiest in life; to stick with things that ore really likes to do.

He was educated in Moscow as a child. There was a very good planetarium there that he used to go to. He alas participated in various children’s clubs for astronomy associated with the planetarium. There were excellent teachers there. He remembers Dr. Shashakov(?). Of course this is all after the Second World War.

About this time, also, he saw a book on special relativity, and he said he was surprised for the second time. It seemed so strange to him that time could flow at different rates in different places and for different objects. Now he understood that he should not only be an astronomer, but should be the sort of astronomer that would investigate relativity — not only a theorist but in fact specifically a theorist in relativity.

In answer to my question, he said that he hadn’t yet encountered general relativity at that time. He couldn’t have really understood it anyway.

He was also an amateur astronomer. Around the age of 14 he built a telescope which was a new kind of amateur telescope — a small one suitable for school — and he had a publication about this, describing how to make this telescope, in a special Russian journal called PHYSICS IN SCHOOL.

Then he started to study variable stars. All this is still before he went to college. There were groups that were interested in amateur variable star work; particularly in this field, he was taught by Dr. Kukarkin(?) and Dr. Parenago(?). Even before college he published papers on variable stars.

I asked him about his parents’ attitude, and he simply said that after reading that first astronomy book, he was sure that he wanted to go into astronomy. Apparently his parents’ attitude did not affect him.

Then he went to Moscow University, took the examinations and entered and so forth, and very quickly he met the relativity theorist, Dr. Zelmanov from Sternberg Astronomical Institute, which was part of the University of Moscow. He worked with Zelmanov even while he was an undergraduate. He worked with him on the energy density of gravitational fields, for example, the energy density of gravitational waves — a very complicated problem. He learned tensor analysis at this time, at the beginning of his university years. After he finished his undergraduate education at Moscow, he met Zeldovich.

And now he wanted to say some things that he felt were important, not only for his own career but for many Soviet Union students, particularly in cosmology and relativistic astrophysics, general matters that he wanted to stress.

He said, “Our country was the cradle of cosmology.” In the early 1920s Alexander Friedmann did the first models, the first basic steps in cosmology, on which all later cosmological work was based. For 20 or 30 years after that, the main problems in cosmology were the geometry and the mechanics of the evolution of the universe, things involving essentially the rate of expansion, the Hubble constant, and q0.

After the Second World War, attention began to turn to physical problems rather than geometry. It became more and more clear at that tire that physicists would play a major role in the future development of the field.

Now, just at this moment, a few Russians turnedd their attention to the field of cosmology, for example Livshitz, the now famous student of Landau. In the mid-1940s Livshitz studied in detail the process of evolution of perturbations in an expanding universe. He did very classical work, showing how perturbations can grow, and how as a result of this some objects can originate. Some perturbations, of course, get smaller, but some can grow. It’s only now that we understand how classical and basic this development was. This of course later became a field in which Novikov himself worked. This work of Livshitz was a first step in the investigation of real physical processes in the early expanding universe. In the United States another step was taken by Gamow, who studied the physics of the Big Bang itself, the early conditions in the Big Bang.

Then this was studied in the Soviet Union also. At that moment Zeldovich began to work in cosmology. This was a time when observational data and progress in theory could both come together and give fundamental things. In particularly things like the theory of particles and plasma physics theory were just getting to the point where they could really be useful. Great physicists with their great intuition began to understand that cosmology was a key to many other processes, and also something that could be investigated, and they turned their attention to it. So Zeldovich began to investigate physical processes in the cosmological context, and indeed he began a school.

I asked how this worked, were there seminars and so forth? Novikov answered, yes, there was a seminar. Then later there was a special astrophysical department within the university. Novikov, when his education was finished at Moscow, met Zeldovich. They were both working on a semi-closed universe, so it was natural that they should get into communication with each other, and Novikov became Zeldovich’s student and his collaborator. Soon after others came, and very strong and active groups were formed, not only dealing with cosmology but also with relativistic astrophysics, that is, high energy astrophysics; astrophysics of objects that are concentrated enough so that general relativity plays an important role. The group studied many aspects of these problems. One point in this came when Novikov with Zeldovich wrote a book, RELATIVISTIC ASTROPHYSICS, published in 1967.

Since then, there have been two main problems studied by the group, both of which are connected with physical problems. Of course mechanics and geometry of the universe remain important and are still studied, but there are two newer very important physical problems that are now being studied. The first is the question of the start of the expansion conditions in the very beginning of the expansion. Zeldovich investigated processes of particle creation in the early Big Bang. The second problem was origins of galaxies.

I asked how the group functioned and how Zeldovich functioned as a leader. Novikov responded that Zeldovich is the absolute leader of this group, because he’s such a strong physicist. There is “some kind of attraction. He’s an extremely strong physicist.” He produced brilliant ideas in lectures and in symposia and so forth. He would talk and so people would be interested in these problems, and smart people would try to solve the problem. They would go and discuss them with Zeldovich and so they would become his collaborators. As this happened, a strong group began to form. He compares it with, “in astrophysics one too can have an unstable situation, a group will collapse, there will be a collapse to a state of high density, so to speak.” He said this was the sort of instability that helped to form such a strong group in relativistic astrophysics and cosmology.

The first problem which Novikov has studied has been the evolution of perturbations as seen from a physical viewpoint, starting with the hot universe and then seeing what happens as it cools. The pressure in the equation of state and its changes can be studied.

The second direction that he has gone in has been the processes near the singularity. Again, this is like the two main problems that we talked about earlier.

For example, he has studied what takes place if you have a very anisotropic universe at the beginning, such as what result this would have on the evolution of the light elements, hydrogen, helium, lithium and so forth. He found that in some cases, one will get a different set of abundances of the elements than one observes, so from this one can exclude certain highly anisotropic and so forth early universes.

Asked where this sort of research program came from, the idea of working in this way, he said that certainly the main ideas were Zeldovich’s but in many cases you cannot attribute an idea to any one person. The ideas came in discussion. The whole group will be talking together and one person will say one thing, one will say another. There’s quite close working in these groups.

A third important problem that he worked on was singularities — Delinsky(?) and others, showed that these singularities can be very complicated. This is not so much really a physical problem as a problem of the equations of general relativity. They can get mathematically quite difficult. But Novikov thinks that the structure of space-time can be very important, for example, inside the event horizon of a Black Hole. This is now a main question for Novikov, and also some colleagues and students of his are very interested in it.

He remarks that in all of this, theorists must confront the observational data. They have to be in close contact with it.

I asked about his contact with observational people. He says he knows many observational people. He has discussions with them. Sometimes they come to the Moscow Seminar and talk there; sometimes theorists will go and give talks at the various observatories. At present Novikov is working at the Space Research Institute. He finds his contacts with observers are much more convenient and simpler now, because space research is a highly observational field.

For example, right now he is trying to calculate the angular variations of the relict radiation from the Big Bang. One can get some kind of idea of processes that took place during the early evolution. For example, certain features relate to galaxy formation. Just recently, he has demonstrated that for an anisotropic universe, one should see a spot of higher intensity in the microwave radiation background, and the size of the spot depends on the curvature of space. Other colleagues of Zeldovich are also working on the physics of galaxy formation and evolution.

I asked him a bit about the situation at Moscow University. He said there is a big physics department there, with the Sternberg Institute within the physics department. Novikov was educated in the Sternberg Institute and so were some other members of Zeldovich’s group, but other people in the group came from other institutes within the physics department — for example, from the technology group.

There’s a great deal of interaction with the physicists. Cosmology is for example related to particle physics. And also because Zeldovich himself is extremely broad. With time of course some people separate from Zeldovich. This is a natural process; they will go away and do their own things. I asked about nuclear physics workers. He says yes, there’s some but not very many.

I asked him questions about the development of his ideas on the Big Bang. He said he was very surprised when he first read about the Big Bang, and indeed, he didn’t really understand it at first, and thought of it as spatial expansion from a point, rather than as we now understand it, geometric expansion of space-time. It took him five or six years to see that his original naive view was incorrect.

He says there’s a certain inertia in our thoughts. Before Friedman, inside all astronomers there was the thought of a stable universe, all the stars in place, the solar system stable. At heart people did not believe in evolution; within them they felt they had a universe without walls but not really an evolving universe. It was very strange for them to imagine stars and galaxies as anything other than stable. He wants to stress that it was in cosmology that the idea of evolution began for astronomy. From cosmology came the idea that everything, stars and so forth, has a history. This was in the 1920s and 1930s.

For example, Einstein mistakenly tried to make a stable universe, which shows how persistent the idea can be. This was a natural view for people to have, and Novikov too had this view when he began to be interested in astronomy.

He also wishes to stress that while certainly the Big Bang is the correct physical view, he doesn’t believe that the Big Bang is the beginning or some sort of a birth — rather, before the Big Bang (if we can say before and have the word “before” have some meaning) there was another form of space-time.

I asked him, is this like John Wheeler’s ideas? He said, “Yes, that’s right.” So the Big Bang is not a beginning, but it’s a change from one form of existence to another form. Maybe space and time have a different meaning. But essentially it’s a change, rather than an absolute beginning.

I asked him whether he had any aesthetic preference for or against the Big Bang and he said, no, not really.

I asked him about the deceleration, q0. He said that it seems quite clear that the universe is open, but that is a question of real observational data, not a philosophical question, whether the universe is open or closed. The matter, density, clearly is much less than would be necessary to close the universe. But he stresses that the topology of three-dimensional space can depend on many factors, not only on the mass density. One can construct many kinds of spaces. For example, one can imagine a plan for closed spaces. You take a table and have the right hand edge be continuous with the left hand edge and the front edge be continuous with the back edge. Then one can have a flat space which nevertheless is closed, by doubling it over. I asked him whether there was any preference for an open or closed universe. He said, “Yes, some people would have preferred a closed universe,” but not he. This is not important to him. He says, “What we must do is study the real universe.”

I asked him whether cosmology was regarded in the same way as other fields in astronomy, and he said, “It’s simply a branch of astrophysics.” Certainly long ago, cosmology was part of philosophy, but now this is not so. “We try to construct a theory of physical processes,” he said, “And then one tries to make some predictions, to calculate some consequences, which can then be compared with experiments. This is a typical way of doing physics.”

I asked him, “Have some people said that cosmology is too impractical, or too philosophical?”

”Yes, sometimes,” he said, “but this is less so recently. Now it is no longer true, what people used to criticize, that one can imagine anything. Now in fact one can make predictions that can be checked with observational data.”

Novikov said, “One should try to do only things which can in fact be checked. You have to be very careful about that.” For example, now Novikov is studying the inside of a Black Hole. He says it’s hard to make predictions. You can talk about someone going inside a Black Hole, but then of course you can’t get messages out, so this is not really making predictions. But he does believe very deeply that the internal structure of the Black Hole can have some effect on the overall structure of the universe, for example, by way of some sort of “worm hole.” He’s impressed by Stephen Hawking’s evaporation of Black Holes.

Incidentally, Novikov predicted the existence of primordial Black Holes in 1966, well before Hawking and others.

I asked him how he learns of new developments, and he says “There are various ways. In particular too, one has personal contacts, for example, at the International Astronomical Union meeting, in seminars, in visits.” And the second way is by letters and by preprints, particularly by preprints. He sees a lot of preprints. Occasionally he may hear things by telephone — not so often by Journal articles, but certainly it’s very important that a Journal article should be published; and the final description in the article is important, and he does read these also.

At that point the interview concluded, and he asked me to mail him the transcript for him to check over.