Oral History Transcript — S. Chandrasekhar
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Interview with S. Chandrasekhar
S. Chandrasekhar; May 17, 1977
ABSTRACT: A thorough, reflective survey of the life and work of this theoretical astrophysicist. Early life and education in India (1910-1930) and experiences at Trinity College, Cambridge (1930-1937), with comments on E.A. Milne and A.S. Eddington; debate with the latter over collapse of white dwarf stars. Move to U.S. in 1937, with comments on the situation at Harvard and Princeton since the 1930s, and especially on H.N. Russell, J. von Neumann and Martin Schwarzschild. Social context at Chicago University and Yerkes Observatory since 1937, with remarks on G. Kuiper, O. Struve, B. Strömgren, etc. Work as teacher there, and as editor of Astrophysical Journal from 1951 until it was given to the American Astr nomical Society in 1971. Scientific work resulting in Introduction to the Study of Stellar Structure (1939) and publications on stochastic processes in galaxy and in general, radiative transfer, interstellar polarization, hydrodynamics and hydromagnetics (including experimental checks). Recent work on general relativity and Kerr metric; comments on cosmology. General remarks on the social structure of astronomy and its cultural role. Extended discussion of his way of functioning as a theorist.
Weart:First of all, we're quite interested in how people become scientists in the first place. That's the logical place to start. I know you were born at Lahore, India in 1910, and that nearly 20 years later you came out of Presidency College in Madras, already writing significant physics and astrophysics papers. I'm very curious as to how that came about. In the first place, I don't know anything about your family — who were your parents, what did they do?
Chandrasekhar:My father was an Accountant-General in the Indian Audits and Accounts Service, in India — a kind of a civil service. He was in the railways. He was stationed in Lahore at the time I was born. But actually, my father and my grandfather and the entire family came from southern India. Sometimes I'm considered (from Pakistan), having been born in Lahore, which is now a part of Pakistan. But actually my family and I belong to the south. In 1918 we returned to Madras, and I stayed in Madras for my high school and college education. In 1930 July, I left India to go to Cambridge.
Weart:Did you have brothers or sisters?
Chandrasekhar:Yes. I come from a very large family. In fact, I am third in a family of ten. The two elder members of the family were sisters. We are four brothers and six sisters.
Weart:So you were the oldest son.
Chandrasekhar:Yes! The oldest son. My other brothers are quite distinguished in their own ways. My brother next to me was the general manager of the Tata Steel Works till recently. He just retired. Another brother is a distinguished doctor. In fact, he was the private physician of Shastri, when he was Prime Minister. My last brother is a radio astronomer working in the space program, in the south of India now. One of my sisters is quite a well-known musician in Madras, and continues to be. And so are the others in various other ways.
Weart:I see. What sort of education did your parents have?
Chandrasekhar:My father was graduated from the University of Madras.
Chandrasekhar:Yes, Presidency College, in fact. And he passed the Indian Civil Service examination and got into the Indian Civil Service. It was an English Civil Service at that time.
Weart:Did you read a lot in your childhood, particularly science books? Were there any that influenced you? Were you taught at home partly?
Chandrasekhar:We (my brothers and sisters) were taught at home, partly, but from mid-high school, what would you call probably sophomore, I went to school. I didn't go to kindergarten or things like that. I mean, I studied all at home. My father and private tutors and so on. But I started going to high school in 1922, when I was 12 years old. I went to the University in '25. I was at the University for five years. But my interest in science was something that was not unnatural, because my grandfather was a professor of mathematics, and his books were all at home. I started using them. In fact, I still have one or two books from his library.
Weart:This is your father's father?
Chandrasekhar:My father's father was a professor of mathematics in what is now Madhya Pradesh, in Vizagabatanan.
Weart:What about your mother? Was she educated?
Chandrasekhar:She was educated, but not beyond high school; though she did learn sufficient English later on. In fact, she translated some of Ibsen's plays into Tamil. One of the books she translated, which had quite a wide sale, was her translation Of Ibsen's DOLL'S HOUSE.
Weart:Oh, how interesting.
Chandrasekhar:Ibsen has always been one of my favorite writers since that time.
Weart:Is that where your interest in literature comes from — from your mother's side?
Chandrasekhar:Well, I suppose it could be said that way, but my own pursuit of literature — it's rather difficult to say. I was interested in Ibsen, and later when I came to Cambridge, I got very much interested in Russian writers, Chekhov, Doestoevski, Tolstoy; and later in Hardy, Virginia Woolf, and others.
Weart:I see. What sort of feeling did people have in your home towards science? Your grandfather had been a professor of mathematics.
Chandrasekhar:Well, there was always an atmosphere of science. You know, my father's brother is the famous Indian physicist (Chandrasekhara Vankat ) Raman, who got the Nobel Prize.
Weart:Oh, I didn't know that.
Chandrasekhar:Yes. So, I mean, Raman's discovery of the Raman effect when I was still a student in India made a big impact on me, just as on anybody else. So the atmosphere of science was always at home. But actually, I would say that my really serious interest in the kind of things I did later on originated when I was in College, in Presidency College in the late twenties. Sommerfeld visited India in 1928, and I went and talked to him quite a bit. He gave me the copy of his papers on the electron theory of metals, which were then in press,* and his papers were clear enough for me to understand the Fermi statistics. At about the same time, I read Eddington's INTERNAL CONSTITUTION OF THE STARS. It's quite readable. And it was the simultaneous knowledge of Eddington's INTERNAL CONSTITUTION OF THE STARS, together with modern statistics, at least modern as of then, through Sommerfeld, that turned my interest into the theory of white dwarfs and related matters.
(*Zeitschrift FÃ¼r Physik 47 (1928))
Weart:I see. How did it happen that you spoke to Sommerfeld?
Chandrasekhar:He came to Madras in 1928. I saw in the newspapers that he was going to be there, and so I went and saw him in the hotel.
Weart:Oh, is that so? What gave you the boldness to do that?
Chandrasekhar:Well, thinking back, it was terribly bold of an undergraduate student to go and talk to the great man. But I had read his ATOMIC STRUCTURE AND SPECTRAL LINES by myself, and had thought that was the end of physics. So when I went to Sommerfeld, I told him proudly that I had read his ATOMIC STRUCTURE AND SPECTRAL LINES, and he promptly told me that physics had changed considerably. He told me about wave mechanics.
Weart:That was the first you heard of the new wave mechanics?
Weart:Oh, that must have been very exciting.
Chandrasekhar:Just about the time it was going on.
Weart:Did Raman play a role in any of this? You must have known him fairly well.
Chandrasekhar:Oh, I knew him moderately well, but not really as well as one would think. His role essentially was to bring my attention to science. Of course, you see, the general sentiment in India at that time was quite curious. I mean, of course, it was the time when Nehru and Gandhi and others were active in politics; and like all young men, I was also very involved in that. And it was also a time when India was very proud of its men. For example, I knew about (Srinivasa) Ramanujan and his life, and that he became the first Indian to become a Fellow of the Royal Society (in 1918).
It was all very much in the air, and of course, we were - i.e., all young students - all very proud of men like Nehru and Gandhi. It was a part of the patriotism of those times to try and see what Indians could accomplish with respect to the external world. Accomplishment in science was one way of expressing what Indians could do, you see. And I would say that this motive was present. Patriotism is a word which is not a very popular one to use these days; but Patriotism, as it was understood in India in the twenties, was one in which it was a part of everyone's wish to show that Indians could be accomplished, in a way which the outside world can recognize. To accomplish in science, to show what one could do in science, was a part of my feeling. And certainly that was one of the early motives that I had. But of course, motives in science change as you grow older. I mean, that attitude towards science is not present in me at the present time, but it was present in those days.
Weart:This brings up some other questions that I wanted to ask you. You mentioned that you moved to Madras in 1918. I wondered—of course you were quite young at the time—how you were affected by the events at the time — the Influenza epidemic, the Famine, the Home Rule movement was going on, I suppose, still in Madras at the time, and there were the uprisings — did all of these things affect you?
Chandrasekhar:It all affected me, in a sense. My father was very very ill, during the influenza epidemic in the twenties, and we almost thought he would die; but fortunately he didn't. But the national movement was one in which every educated person was a part.
Weart:Did you go to a nationalist school?
Chandrasekhar:No, the Presidency College was actually a government school.
Weart:And when you went to high school?
Chandrasekhar:I had four years in high school. The school was called the Hindu High School, which was an Indian high school in the sense that we learned Indian history, we learned Indian languages, we learned Sanskrit. So we were a part of that class of intellectual elite which was growing up at that time.
Weart:Did you join Congress?
Chandrasekhar:I didn't officially join Congress, but I remember very well when Nehru came to Madras in 1928, as the president of the Indian National Congress. He was in his thirties, and the first time he became known in the Indian movement. I went and attended it, just like anybody else. And there was the Simon Commission sent by England to visit the colleges; when the Simon Commission came, all the students went on strike, and I along with all the others went on strike and didn't go to school during those days. So the Indian movement was something which absored everybody of my particular upbringing.
Weart:Was this upbringing largely secular, or was there also a strong Hindu religious component?
Chandrasekhar:No, it was secular.
Weart:Your parents were deliberately secular?
Chandrasekhar:No, one can't say that they were secular; but on the other hand, in Hindu society, religious instruction is not a part of one's upbringing. It's a way of life; it naturally grows on you as time goes along. It isn't something which you get baptized in; attending churches is not a regular custom. Religious instruction per se is not undertaken as such. At least, it was not undertaken in my time.
Weart:Your parents didn't have a particular attitude towards it, different from the other people?
Chandrasekhar:No, it was not very different. But there is a very wide spectrum in Indian observances. I never had any religious instruction myself.
Weart:It was simply in the atmosphere, so to speak.
Weart:I see. Now, I gather from what you said that from a fairly early age, you expected to go to college, and I suppose you expected to go to Presidency, would that be correct?
Chandrasekhar:Not expected. We did it. It was natural that that we should have expected to follow those lines.
Weart:Or was it a struggle?
Chandrasekhar:Not for me, because — well, my father was in financially satisfactory circumstances. We were not particularly affluent. We had a moderately comfortable living, but we had adequate means by Indian standards; but I won't say affluent in any way.
Weart:But in terms of your expectations you were in a class where you expected to become an educated person?
Chandrasekhar:Oh yes. That was standard. I mean, the south Indian culture at that time was one in which to become educated, to become a graduate, to go into various work requiring an intellectual background was the normal thing.
Weart:I see. Tell me a little about Presidency College at that time. It had just been recognized in 1923. They were trying to make the central universities stronger. I wonder, was there still and over-emphasis on examinations?
Weart:What was the nature of the instruction?
Chandrasekhar:It was largely an examination oriented. But the Presidency College in Madras was the college to which all the bright students wanted to go, because the instruction was very good — in fact, in the 1900's I mean up to 1910 or 1920, most of the professors were British. I say that not in any superior sense; but it is true that these English men who taught had higher standards, and they did encourage the students to learn, not merely to memorize. In fact the students who came out of Presidency College in the 1910's and getting probably into the twenties, i.e. my time, provided much of the educated, well-known people of India. I mean, many of the students went up into the civil service. Many went into education. Many went into National movement. Many went into the legal profession. And I think, if one looks at the history of India during the fifties and sixties, you will find that many of well-known names one finds from the South came from the Presidency College.
Weart:It was the chief university, one of the three chief, suppose, in —
Chandrasekhar:— in India at that time. Yes.
Weart:Were there any of your fellow students that were particularly noted, or perhaps that you kept up contact with later as colleagues?
Chandrasekhar:Some of them went into the Indian Civil Service.
Weart:Were there any particular fellow-students that were important to you?
Chandrasekhar:Not especially. I left India too soon. I left when I was not quite 20.
Weart:Were there any teachers, either in secondary school, for that matter, or at Presidency, that made a particularly strong impression on you?
Chandrasekhar:Well, actually, I won't say that any of them made a strong impression; but I would say the following: At Presidency College, physics was taught by H. Parameswaran, who was a PhD of Cambridge and a D.Sc. of London, and quite a competent experimental physicist. His interests were different (from mine) but — understood what research was.
Weart:What kind of teaching did you have, if you can reconstruct it? Did you have any laboratory instruction, or was it problem solving?
Chandrasekhar:Largely problem solving. I am afraid that the education which one could obtain in those days was, from any point of view, not at all satisfactory for the understanding science as science. But it did provide a basis on which, if one had sufficient interest, one could build. It didn't make you more ignorant because the examinations were the stuff of things.
Weart:Was it sort of like the Cambridge system in that sense, very complicated problems and so forth?
Chandrasekhar:They weren't as complicated, but they tried to imitate it, yes; and a bad imitation.
Weart:It was modeled on that.
Chandrasekhar:It was their version of the English examining system.
Weart:I see. Let me ask, did you decide at that point already to go into physics or astronomy?
Chandrasekhar:I don't think I ever felt I wanted to go into astronomy, as astronomy, when I was young. To go into mathematics or physics was my intention. Indeed, when I started I thought I would become a physicist.
Weart:I see. At what point did that decision — ?
Chandrasekhar:Well, it gradually changed because my first work was related to astrophysics, and so when I went to England, I got to know people like Milne and R.H. Fowler. And largely left to myself, as I was in England in the early years, I had to shift to problems in which I as able to be productive. And to go into astrophysics seemed to be natural.
Weart:You mentioned that already at Presidency, you'd read Eddington's INTERNAL CONSTITUTION OF THE STARS, and I noticed in something Struve wrote,* he mentioned that you had gotten this as an essay prize.
(*O. Struve, "Award of the Bruce Gold Medal to S.C.," Publ. Astron. Soc. Pacific 64 (1952), 55)
Weart:How did this happen, that they should give you this as an essay prize?
Chandrasekhar:Well, actually, there was a prize competition to be written on quantum theory; and I could easily write on quantum theory, because I had read Sommerfeld's book; also Compton's X-RAYS AND ELECTRONS was also a book which I studied with great enthusiasm. And when I got the prize I was asked whether I wanted any particular book. And I said, "Yes I would like to get Eddington's INTERNAL CONSTITUTION OF THE STARS," because I had seen it in the library. Of course, it was written in a marvelous language, and the early chapters are very easy to read, even for someone whose knowledge was as inadequate as mine was. It was a book I could start reading and go through.
Weart:Did you have a particular interest in the stars, or was it simply that this seemed like an interesting —?
Chandrasekhar:It was a book which I could read and understand. You see, after all, I wasn't taught quantum theory in school. I learned it from Sommerfeld's book, and Sommerfeld's book is one from which one could read and learn oneself. On the other hand,there were other books which if I started on my own I couldn't read and directly learn. So I started learning from books which I could understand. Eddington's was one of the books which I could understand.
Weart:I see. I wonder, while you were still at Presidency or perhaps even before, when you began to see yourself as being a mathematician or a physicist, did you have any picture of what sort of a life you expected to lead, or was it simply the idea of making an achievement?
Well, the principal motive which urges a young man to do science is first of all, to accomplish results which will be recognized; up to a point, I suppose, one hopes that one's work will become well known. And these motives were present.
And when I went to England, I had a shattering experience; to suddenly find myself in an environment where there were people like Dirac and Eddington and Rutherford and Hardy, not to mention all the other well known names, is a very very strong sobering experience. I was extremely optimistic in India, before I left India; but once I came to England I became very sobered if not humiliated. I didn't really know whether there was any possibility for me to accomplish in the world I found myself.
Weart:Because you were in the presence of these tremendous figures?
Chandrasekhar:Yes. I felt that I had to simply try to work hard and try to learn and try to do the best I can, and my future prospect of becoming well known or not was irrelevant to what I had to do day by day.
Weart:I understand. Tell me, when you left for England or even before, what was the attitude of your family towards this choice of career?
Chandrasekhar:Oh, they were all very much behind.
Weart:They supported your —
Weart:I see. Let's see, now. Even before you left Presidency, you had already published. You published two papers on Fermi-Dirac statistics.*
(*Proc. Roy. Soc. 125 (1929), 231-37; Phil. Nag, IX (1930), 292-99, 621-24.)
Weart:Was there anybody at Presidency who was able to check these things with you, or did you simply send them in on your own?
Chandrasekhar:No, I sent them all to R.H. Fowler. That was how I got to know him. He communicated one of my papers (to the Royal Society), which was an encouragement.
Weart:I see. And how did you pick R. H. Fowler?
Chandrasekhar:Because his monumental book STATISTICAL MECHANICS had just come out. And as I told you, when I met Sommerfeld, he gave me his papers on the electron theory of matter, which continued the Fermi statistics. And glancing through the monthly notices (of the R.A.S.) I found Fowler's paper on dense matter, in which Fermi statistics was used. So it seemed to me that there was an area in which one could go right in. I could understand the Fermi statistics; I knew the theory of polytropes; I had read Fowler's paper; I could understand it. Right there, there was something which I could do. So that is that is how I started, you see.
Weart:I see. Reading publications certainly played a much stronger role in your beginning than in most people's.
Weart:Beginning essentially from the library.
Chandrasekhar:And to a very large extent the fact that there were available to me at that time books which someone like me could read and understand by himself — Sommerfeld's ATOMIC STRUCTURE AND SPECTRAL LINES is not known now, but if one goes back —
Weart:It's well-known to historians.
Chandrasekhar:— if one goes back and reads that English edition, it's a marvelous book, which anyone with an interest in science could read, and verify every single step, and understand it. So is Compton's X-RAYS AND ELECTRONS — in fact, I still have the original copy.
Weart:Your original copy?
Chandrasekhar:The original book which I read in those days. still have them, you see. (Bringing it from the bookshelf.)
Weart:I see. It's in very good condition, too. My goodness, for a book of that date, it's in one of the best conditions I've seen. You took very good care of your books.
Chandrasekhar:Yes. I was very fond of that book, and you see, it was available to me. And that book also (Eddington) both extremely well-written books.
Weart:I see. Interesting. (Reading inscription in Sommerfeld)
Chandrasekhar:— that is a gift to my girl friend, who later became my wife.
Weart:Oh, she was D. Lalithambika. And you already knew her back then?
Chandrasekhar:Yes. She was in college at the same time. She was one year junior to me in college.
Weart:Ah, I see, so you'd already met her then.
Chandrasekhar:Yes. And we later married in '36, when I returned to India after 6 years in Cambridge.
Weart:Yes. I was going to ask you about it when we got to 1936.
Chandrasekhar:This book also had a great influence on me —
Weart:The Compton book? (Looking at the books).
Weart:In fact, during your last couple of years at Presidency you must have been working very hard at mastering these things, and reading the MONTHLY NOTICES and so forth.
Chandrasekhar:Yes, I worked very hard at it.
Weart:Were there any other students there who shared these interests?
Weart:So already you had a feeling of working in isolation. suppose it may have had something to do with your originality.
Chandrasekhar:Well, I would say that when I was young I had a driving ambition to accomplish in science. But my whole attitude changed drastically when I came to England. I mean, not that I lost any of the ambition or the interest to work, but rather that I felt that hard work is needed, something which one has to do, and that fanciful imagination does not help very much in accomplishing in science.
Weart:I see. You had to discipline it.
Weart:I see. About your first impressions of England — we'll get back later to your work on white dwarfs and so forth, but in the first place, your choice to go to Cambridge, was that inevitable? Was anything else considered?
Weart:And you already had corresponded with Fowler?
Weart:And how was this supported? This was supported by your family?
Chandrasekhar:No, actually I was able to get a Government of India Scholarship to go to England for three years, on the strength of what I had published.
Weart:I see. When you arrived in Cambridge and went around to see people and so forth, you were impressed by the character of these people, their scientific character. I wonder what else you saw in Cambridge? You came in and had a completely fresh view of Cambridge and the physicists there and so on.
Chandrasekhar:Well, I remember meeting R. H. Fowler for the first time. I met him in his rooms in Trinity. He had asked me to come and see him. That must have been September, 1930. I went up to see him, and in fact gave him the manuscript of my paper on the white dwarf limit (which I had worked on aboard the streamer coming to England) and one other paper, where I had applied the polytropic theory of that Theory of White Dwarfs. I gave these two papers to him, and he talked for a while. Of course, I was enormously impressed by these men, and sobered.
Of course, another person I got to know very well during that year was E. A. Milne. In fact, he came to Cambridge. I have there a little piece I wrote for his grand-daughter, (Miranda Weston Smith) which you might take, that contains references to Milne.
Weart:Oh, very good, I see, "Edward Arthur Milne, Recollections and Reflections."* Very good, that will help. Maybe I should ask you before we get into that about your voyage to England and so forth — this long sea voyage where in fact you got the limiting mass for white dwarfs. I'm curious where you got the idea of bringing relativity into this problem?
(*Deposited in Niels Bohr Library/BBA-Milne)
Chandrasekhar:Well, that was largely because, you know, had read Lorentz's transformation in Compton's X-Rays and electrons and I knew that the velocities (of electrons) are important. And it wasn't very difficult to see it with increasing mass the velocities were approaching the speed of light. I extended Fowler's work first, for the 3/2 polytrope, and I knew what the central density was, and therefore I knew the velocities at the top of the Fermi level were getting close to the velocity of light when the Mass of the Star was increasing.
Weart:You just noticed that?
Chandrasekhar:Yes. And so I said, "What would be the equation of state?" I could easily write down the limiting formula of the equation state. The little formula which I published in the ApJ later* was the one which I derived on board the steamer. And of course, I had Eddington's book on polytropes, so it was very easy to compute what the limiting mass was.
(* Ap.J. 74 (1931), 81-82.)
Weart:I see, you simply followed the model, so to speak.
Chandrasekhar:Yes. So there was very little else — I mean, it is something which is so simple and elementary that anyone could do it, you see.
Weart:But you had to be able to bring together the different pieces from the different books you had read.
Chandrasekhar:But it just happened, those were the only two or three books which I had read! And it was right there.
Weart:Well, it's probably not a bad way to do astrophysics, as a matter of fact, at least in those days. You mentioned in one of your addresses* that you hadn't understood it at that time, but by October you understood that one you go past this limit, then you go to r equals zero. But you didn't understand the implications of that?
(* "The Richtmyer Memorial Lecture — Some Historical Notes," AM.J. Phys. 37 (1969), 577)
Chandrasekhar:Not right away. But I did very soon after that.
Weart:While you were on you voyage to England, you came up with the limiting mass.
Weart:— but it didn't particularly —
Chandrasekhar:I didn't understand what this limit meant, and I didn't know how it would end, and how it related to the 3/2 low-mass polytropes. But all that I did when I was in England; and wrote my second paper on it.*
(*MNRAS 91 (1931), 456-66.)
Weart:I see. Did you already discuss it with Fowler on your first meeting with him?
Chandrasekhar:Well, I did. But it is very curious that neither Fowler nor Milne thought of the result as very important.
Weart:At what point did you begin to see it as important? When did you realize you had something?
Chandrasekhar:I would say that I fully understood its implications by the end of 1930.
Weart:But when you arrived in Cambridge, you still didn't know whether it was anything significant or not.
Chandrasekhar:I knew it must be significant, because Milne was working on the 3/2 polytropes at that time. He thought that every star must have a white dwarf core. And I couldn't see how that could be true. Because the maximum mass must be — I thought it was 9/10/ (solar-mass) because I was working with 2.5 molecular weight, so I couldn't see how Milne could be right. But I couldn't fully resolve myself. The real implications I knew, that massive stars could not become white dwarfs. But how was it going to be connected with gaseous stars? It was something which I gradually resolved to myself. I think in a paper published in 1932, in the ZEITSCHRIFT FUR ASTROPHYSIK,* I was completely clear as to what the situation was at time.
(*ZS.F.AP. 5 (1932), 321-27.)
Weart:Well, even in the MONTHLY NOTICES in March, 1931, in the beginning of 1931 —
Chandrasekhar:— that's right —
Weart:You come out with the radius going to zero, the density going to infinity — what you said was that you just don't know what the next equation of state would be, that this is physically inconceivable, and therefore something else has to happen.
Weart:Did you feel that this was leading towards a new physics, a new contribution to physics?
Chandrasekhar:The idea occurred to me several times. But I kept away from it. Because somehow, the fact that this was going to play a very fundamental role — I was not willing to draw that conclusion. I was, in a sense, too diffident to draw such a conclusion, even though the thought insistently occurred to me.
Weart:Yes. Well, after all, you were in Cambridge. This was 1931. The positron had just come out. Things were moving very rapidly (these happened in 1933) in physics. You couldn't have avoided a feeling, perhaps, that things were ready for changes, in physics?
Chandrasekhar:Well, it could have. But the fact is that I was really on the sidelines, you know. Very few people were interested in what I was doing.
Chandrasekhar:In fact, Fowler did not have an office those days. He used to meet his students in the library in the old Cavendish. And I used to stand outside the library, sometimes for an hour or two, hoping I could chance to see Fowler; and most often I did not. Somehow or other, I felt I didn't belong there. It seemed to me that there were far too many big people, far too many people doing important things, and what I was doing was insignificant in comparison. I suppose I was afraid. It's rather difficult to put myself back in those days; though I do recollect well. I know exactly how I felt, standing there, even now. But to unravel it in precise terms is not easy.
Weart:Did you discuss your work with other students? Did you have relations with the English students?
Weart:Were there other Indian students perhaps that you knew?
Weart:So you had rooms and worked by yourself.
Weart:I see. What about — there were clubs that met, Kapitza club, Journal clubs and so on.
Chandrasekhar:All that I became part of only later on after I became a Fellow of Trinity, I became a fellow of Trinity in 1933, and my life changed at that time, because I was then a part of 'Cambridge': I could sit at the same table with all these others. Gradually, I could find people with whom I could talk, discuss, and indeed become friends.
Weart:I see. It was the first two or three years there, then, that you were in isolation.
There's a couple of other questions about these first years. You submitted this paper to the ASTROPHYSICAL JOURNAL, and Struve remarks that your first paper was rejected, until you produced the detailed proof.
Weart:To Struve, I suppose?
Chandrasekhar:No — To Edwin Frost who was then, the Managing Editor. (Pause while looking through files.)
Weart:Ah, here's the letter.
Chandrasekhar:Here's the letter I wrote, you see, enclosing it with a short note, and the reason I sent it was because Fowler and others were not doing anything about the paper I gave them in September.
Weart:Ah, you just gave it to them and they said "Very interesting."
Chandrasekhar:And they. left it at that. And then —
Weart:How do you happen to have your own letter?
Chandrasekhar:That is because I was editor of the JOURNAL.
Weart:I see, you retrieved it later on.
Chandrasekhar:Yes. And this is from Frost to Gale an Associate Editor. "Will you please decide whether we should print in the JOURNAL the enclosed article? You and some of your colleagues are doubtless acquainted with the subject," you see —
Weart:And then, Frost replied to me after he had received an adverse report from the referee.
Chandrasekhar:"I beg to thank you .... The subject is an interesting one. The paper is referred to competent critics, and I have been advised that it would not be desirable to print it in the ASTROPHYSICAL JOURNAL. You might like to know the critics find that the fundamental idea is sound, but he has obviously used the ordinary formula (for pressure). This formula is not valid in relativistic statistics. And then I wrote back a letter, of which I have a copy — usually I don't keep copies, but this one I happen to have, and this is the proof which Carl Eckart (who was the referee) had written.
Weart:Carl Eckart was the referee of your paper.
Weart:I see, and he sent you — ?
Chandrasekhar:He didn't send me. But I have a copy of it here. In fact, this one, I picked up from the kJ files. He quotes it here, you see, Frost quotes it. And then —
Weart:I see, he quotes it, and then you found Eckart's in the file.
Chandrasekhar:I wrote a letter to Frost: "The referee's comments which you are kind enough to enclose objects to the paper on the grounds... I am sorry, however, that the value for the pressure I give can be derived from first principles, and does not involve any assumptions except that the relativistic effects predominate. I am enclosing separately a proof. Even if my proof satisfies the referee, I am not sure that the paper will even then be acceptable for publication, and I would like to assure the referee that my formula is correct. If however the matter is intrinsically not worth publishing, I should not press at all. In any case, as it appeared from your letter that the main cause for the rejection of the paper was a supposed invalidity which unfortunately does not seem to be justified, I thought it as well to bring that to your notice..." and so on.
Weart:Uh huh, and there was the proof.
Chandrasekhar:And I gave the proof. And then, you see —
Weart:— This had gone on to Eckart, I suppose —
Chandrasekhar:And then Eckart wrote back a letter — "I am returning Mr. C's paper and think it will be suitable for publication. I have looked through his proof of his equation 2, and it convinces me that the equation is correct. I am sorry that I was in error in critizing his equation, but it seems to me a rather remarkable thing that this equation is true. I should not have expected it at the first glance."
Weart:I see. Very interesting.
Chandrasekhar:And so, they published it, you see.
Weart:And you're going to put these with the rest of your papers in the (University of Chicago Library) Archives eventually, I trust?
Weart:That's a very interesting exchange.
Chandrasekhar:Yes. As you see, I was very difficult. I said, "maybe it is not worth publishing, if it is not worth publishing, it is all right — but don't say it is wrong."
Weart:Why did you happen to submit this to ApJ?
Chandrasekhar:As I told you, I had written this paper in July; and I gave it to Fowler in September and he never did anything with it, whereas he sent my other paper to the PHILOSOPHICAL MAGAZINE.* And fundamentally it is because neither Milne nor Fowler wanted to accept the fact that there was a maximum mass.
(* PHIL. G. 9 (1931), 592-96.)
Weart:Because Milne wanted to use the white dwarf core within his model, is that it?
Chandrasekhar:Yes, right. Of course, all the controversy which I had with him later in '34 was a manifestation of that —
Weart:— right, we'll have to get back to that, I want to ask you about that. But maybe first, we get to the point where you are a Fellow of Trinity and you become more integrated into the way things went. Oh, first of all, in '33 you went to the Bohr Institute, I believe?
Chandrasekhar:Yes: 1932 September to May 1933.
Weart:Oh, it was in '32. How did that come about?
Chandrasekhar:Well, largely because I'd been two years in Cambridge, and done all this work, and hadn't made any impression, to the extent that I could judge myself, on the environment. I mean, Fowler was there, and I saw him once in six months, and I was just by myself, and I did not know whether I was making any headway or not. I used to know Dirac moderately well, so I asked Dirac what I should do as I was getting rather discouraged.
He suggested, "Why don't you go to Copenhagen?" Because that was the time everybody was going to Copenhagen, you know. So I went to Copenhagen, and while scientifically it wasn't a particularly a great opportunity for me, because very few people were interested in the kind of work I was doing - I did make some very good friends. Viki Weisskopf was there, so was Leon Rosenfeld, George Placzek, and all the people with whom I maintained friendships to the present at least until they died. (Both Rosenfeld and Placzek are now dead). Max DelbrÃ¼ck was also there; and we all lived in the same pension. So I had, personally, a very happy life in Copenhagen.
Weart:What was it about Copenhagen that made it so different from Cambridge?
Chandrasekhar:Well, largely because I had friends with whom I could talk.
Weart:But I mean — how would it be that you could make friends in Copenhagen and not in Cambridge? There must have been something very different about the atmosphere there.
Chandrasekhar:Well, largely because I was staying in a pension in Copenhagen; and in the pension, these other people were also living. Not like Cambridge, where you stay in a room of your own, and the only place where you can meet people is when you go to lectures, or colloquia. I didn't mix with people very well. As I told you, I felt shattered in their presence, and essentially sort of recoiled within myself. That's the way I look at it at the present time.
Weart:And also, the other students who where there —
Chandrasekhar:They were all doing quantum theory, you know, and other glamorous things.
Weart:They seemed very far advanced.
Chandrasekhar:Yes, and — whereas when I went to Copenhagen, people like Weisskopf and Placzek —
Weart:Would it have made any difference that these people were Germans rather than English?
Weart:I wondered whether Bohr's personality or the arrangements at the Institute might have —
Chandrasekhar:No, for example, I didn't belong to the scientific community any more in Copenhagen than in Cambridge. For example, I remember that every Friday in Bohr's house there used to be a tea, and I used to partake of the tea; and after the tea Rosenfeld, Weisskopff and others would go with Bohr to his study to work. I used to stay behind and play with the boys. In fact, I used to play with Aage Bohr when he was still a young boy. When I wrote to him when he got the Nobel Prize and he wrote back a very nice letter recalling the time when he used to play with me, as a tiny boy.
But the personal atmosphere was better. And I made so many lasting friendships. I'm rather pleased that in Weisskipf's recent book, he refers to the fact that I was there in Copenhagen, because most often I was so outside the main stream of things, I was never a part of the scene.
Weart:In a way I'm surprised, considering what was going on in Copenhagen at the time. They were just finishing up the quantum mechanics, moving on to nuclear physics and so on, and in a way, I'm surprised that you weren't drawn into these fields. Did you ever feel any attraction for leaving the astrophysics that you were getting into?
Chandrasekhar:Well, that is what one would expect, and that is what I wanted, but I came to England without really very much prearranged preparation, without any real training in mathematics. Everything I had learned, I had learned by myself. During my years in Cambridge, of course, I went to a great number of lectures, and improved my general background, learned analysis and complex functions, all such matters. But I really had two choices — either to be venturesome, and go into some new area like nuclear physics or, continue with the kind of things in which I had, by myself, done some original work. And since I did not know that I was going to be in Europe for more than three years, I had to consider the possibility of returning to India in '34 at the latest. I could not have afforded to return to India without some record of scientific work. And the question — was I to do the kinds of things which I had learned to do on my own, in which to some extent I was able to see I was making progress, go into something more glamorous and fail totally.
For example, the work which I did on my own did provide me a fellowship in Trinity, whereas if I'd gone into some of these other things, I would have learned something new, but I wouldn't have been able to get a fellowship in Trinity. So it was a question of trying to look into the future for myself, as to what kind of a future I could have.
In 1933, after I'd finished my work for the Ph.D., I went to ask Fowler whether I had any further scope in England. He said, "Well, you can apply for a fellowship in Trinity, but I don't think you have much of a chance." I applied anyway; but I was so sure that I would not get the fellowship in Trinity that I had arranged to leave Cambridge on the day the fellowship was to be announced. And I was going to spend one term at Oxford with Milne before returning to India. And on the way to the station, I stopped at the college to find out who were the people that had got elected. I was astonished to find my name among the people who were elected.
I remember well telling myself: "Well, this has changed my life." And in fact, it did, because if I hadn't gotten the fellowship in Trinity, I would have returned to India by the end of '33, and I do not know what my future would have been, except to say that it would have been very very different.
Weart:That raises so many questions. I guess one that particularly comes to me is the question of whether you chose something like theoretical astrophysics because if you did have to go back to India, it would be something that could be practiced there, whereas something like nuclear physics would I suppose have been much more difficult?
Chandrasekhar:I didn't think in those specific terms, but it was all a question as to what I could do myself. It seemed to me that here was an area in which I had broken in, and it was going. Even though I was not getting that kind of external recognition which I hall hoped and thought I would get, I was still doing things which were useful. And it seemed to me that the alternative of not doing anything useful by being over-ambitious, and failing even in what I was able to do was not a satisfactory one.
Weart:I see. The fellowship at Trinity — did you hear afterwards how it happened that you got that?
Chandrasekhar:Well, actually, E.A. Milne was one of my referees. In fact, I have a very nice letter from him, saying that he as -he-had one of the referees, recommended it; he thought my work was very good, and so on. It encouraged me an awful lot, because I hadn't known that my work would merit it, you see, so it was quite a surprise.
Weart:Fowler was at Trinity. He must have played a role?
Chandrasekhar:Yes. Fowler was also one of the electors and he must have been influenced. But you must remember Dirac as one of his students and he was in the center of all the exciting things that were going on in the Cavendish...
Weart:How did you feel about not going back to India?
Chandrasekhar:It never occurred to me that I would never go back to India, in those years.
Weart:It was simply a matter of staying another three years —
Chandrasekhar:— in England, before my fellowship in Trinity expired. And then I had an offer from this country.
Weart:There's many questions one could ask about Cambridge. It was such an important place, and there aren't many people who still remember what it was like. We have some books and so forth. But I'm curious, during your years at Trinity, what you particularly remember about the way people exchanged ideas? Seminars, journals, clubs, informal places that people met to discuss physics and astronomy?
Chandrasekhar:There was the Observatory Club, that Eddington used to run. Of course, I only got into the astronomical environment during the last few years in Cambridge.
Weart:You were saying you were getting into the astronomical community there.
Chandrasekhar:The astronomical community was a very small one in Cambridge back in those days. There was Eddington, Stratton, Redman (who was the associate director), and a few others. We used to have meetings every two weeks. Eddington was very accessible, one could talk to him. At least I found him accessible once I got to know him. In fact I used to discuss quite a lot with Eddington. He was a very modest person, socially, but extremely strong-minded with respect to his own view scientifically. I used to know R. O. Redman quite well.
Weart:What sort of person was Redman?
Chandrasekhar:A very modest person, but very anxious to do the kinds of things he was doing. He was interested in galactic rotation and early type stars. He had been to Victoria before, with J. S. Plaskett.
I used to talk to them, somewhat, about my work. It was a very small community. Eddington used to tell quite often about his conversations with Rutherford, how Rutherford was very excited about all the things. In fact I remember one marvelous occasion, a few weeks after the Cockcroft — Walton experiment had been performed, when Rutherford told Eddington, "I'm sure that what we are doing at the present has more to do with the stars than what you are doing at the observatory."
Weart:Is that so?
Weart:And Eddington repeated this?
Chandrasekhar:Yes. Eddington said, "I'm sure Rutherford is right."
Weart:How did people feel about this idea? By people I guess I mean the astronomers, Stratton, Eddington, and so forth, about this idea of astrophysics as distinct from astronomy?
Chandrasekhar:They were all very much in the front. Stratton was, and so was Eddington.
Weart:In fact Stratton's title was professor of astrophysics, I believe. How did you get together? You mentioned that there was a meeting every two weeks. Was this a journal club or seminar?
Chandrasekhar:Something like that. It used to be called the Observatory Club, which Eddington use to run. There used to be teas which Eddington's sister used to serve.
Weart:Was this in his house?
Chandrasekhar:His house was adjoining the observatory, so it used to be just outside.
Chandrasekhar:We used to have tea there.
Weart:Would the physicists come?
Chandrasekhar:Not many. Occasionally. Hugh Newall was still alive in my time and he used to come. The same way with the Cavendish Club which Rutherford used to preside over on every occasion.
Weart:You would go to that?
Chandrasekhar:Yes, I used to go to that. J.J. Thomson was still around, so was Aston, Chadwick, Blackett, Oliphant, Kapitza, Dirac and a whole lot of others.
Weart:Were there informal places that you used to get together with astronomers or physicists?
Chandrasekhar:In Cambridge in those days the people with whom you got together informally were the people who belonged to your college. For example, I was in Trinity so I used to see a good deal of people who were in Trinity. Rutherford used to dine every Sunday, so I used to see him on Sundays. Eddington used to dine four to five times a week, so I used to see him, I used to know J.C. Littlewood as well as, Hardy, Aston, J.J. Thomson, Gowland and Hopkins (who was a biologist). All these people one met either at tea — there was a common parlor that you could go to for tea and you'd see them — or at dinner you'd talk to them.
Weart:What sort of things were talked about? Did you, for example, talk about philosophy and politics, that sort of thing?
Chandrasekhar:Usually one doesn't talk shop at the high table. Rutherford used to, though. He was an exception to everything. Usually after dinner one goes into the parlor for coffee and people usually sit around in groups. I remember particularly during the Christmas recess, people used to sit around the fire and talk a good deal.
Weart:I know, as you mentioned, you were getting interested in literature at that time. Were there other outside interests, with your general education?
Chandrasekhar:I belonged to a group of young students in my Trinity fellowship years, who were what I suppose one might call avant-garde. People who were friends of F. R. Leavis, who was still a young man in those days. (Now he's retired.) In fact the wife of one of my friends was a literature graduate of Cambridge. She was blind. She was a strongly sensitive woman and she influenced me to read Virginia Woolf. I started reading her in those days, and have consistently read everything she wrote since that time. And James Joyce.
Weart:You must have had some interesting conversations with Jesse Greenstein.
Chandrasekhar:Yes. I also read most of Chekov, Tolstoy and Turgenev, I read all of them in those days.
Weart:I suppose this was very much in the Cambridge spirit to do this sort of thing.
Weart:In your own field, it's always interesting to know what books or journals in particular you read that impressed you. What journals would you read regularly? What books came out that were important?
Chandrasekhar:I used to read the MONTHLY NOTICES [of the Royal Astronomical Society] quite regularly, and the ApJ. The books I read were largely astrophysics books. Milne's books and Milne's articles. But as far as astrophysics went, I learned most of it from periodicals. For example, I remember starting with MONTHLY NOTICES in 1920. I tried to read all the articles on astrophysics.
Weart:Reading straight through?
Weart:And afterwards, when you were in the middle '30s and you were a little more established, did you read it straight through every time it came out?
Chandrasekhar:I certainly used to read all the articles on stellar structure and stellar atmospheres.
Weart:And the ZEITSCHRIFT FUR ASTROPHYSIK?
Chandrasekhar:Some. The ZEITSCHRIFT FUR ASTROPHYSIK was founded only in the '30s—'31 or '32 it came out. I used to look at it regularly and read the papers —
Weart:And read the ones that were of particular interest to you. I see. Were there any other journals you would look at?
Chandrasekhar:Well, the standard physics journals. But I wasn't very much involved in it.
Weart:Did you read NATURE?
Chandrasekhar:Oh yes, NATURE, quite regularly.
Chandrasekhar:— The Royal Society PROCEEDINGS. I used to look at them but not read them. I use to read books in physics. I mean when books on nuclear physics came, like Rasetti's,* I used to read them.
(* Franco Rasetti, ELEMENTS OF NUCLEAR PHYSICS (1936))
Weart:Bethe's REVIEWS OF MODERN PHYSICS articles (1936-7)?
Chandrasekhar:Yes, those articles. I used to learn physics from books. But astrophysics, I don't think I ever learned from any book. I think the only book in astrophysics I read completely was Eddington's INTERNAL CONSTITUTION. But most of it I learned as I went along.
Weart:You would select the pieces you needed at that particular time?
Weart:Who were the people that you looked up to? You mentioned Fowler of course, and Milne, but in particular in your field, stellar structure and so forth, who were the people whose articles may have impressed you?
Chandrasekhar:Russell, of course, came in a little later — I would say I was largely brought up on Eddington, Milne, Jeans, Russell, and among the other people, Stromgren, Biermann, and Cowling. Beside I also read Ambartsumian paper in the PULKOVA BULLETINS.
Weart:It was published in French, wasn't it?
Chandrasekhar:From Pulkova — it used to be published in English in those days, the PULKOVA BULLETINS.
Weart:I see. While you were at Trinity as a fellow, did you visit other places also?
Chandrasekhar:Some. For example, in 1931 I visited Gottingen.
Weart:Oh, I didn't know that. How did that come about?
Chandrasekhar:Well, you know, I always wanted to be a physicist, and so I wrote to Born and asked him if I could come and spend the three months of the summer there. So the first summer I spent in Gottingen.
I went to Russia in 1934 and saw Ambartsumian — that was how I got to learn about him. And Gerasimovich.
Weart:What was Ambartsumian like at that time? What was Russia like at that time?
Chandrasekhar:When I went, it was before the great Purge; Stalin's Purge of '34. It was very free when I went. Ambartsumian was very free and very open. He was extremely critical of his seniors. Ambartsumian, Landau and I went for a walking trip outside Leningrad, we went into the Forest outside Pulkova. It was in August. It was nearly the "white nights." I visited the hermitage with them.
Weart:What was the Russian astrophysics or astronomical community like at that time?
Chandrasekhar:Ambartsumian and Kosirev - (later spent decades in Stalins prison camps). They were the people whom I knew best; I knew also Gerasimovich and Shajin — there was a man called Kratt. I knew of their work a little before, because they published in the ZEITSCHRIFT FUR ASTROPHYSIK. I got to know Ambartsumian and Kosirev and followed their work consistently afterwards; Ambartsumian particularly.
Weart:That's a very important community. We knew very little about it. I wanted to interview Ambartsumian at the last IAU but he couldn't come, and I wonder if you saw them at work — did they get together in seminars, for example? How would it compare to a place like Gottingen or Cambridge.
Chandrasekhar:I think Ambartsumian mixed with the physicists. He was a great friend of Landau. So I rather imagine that he, Landau and the younger people formed a group by themselves. And certainly they were right there on the top at that time.
Weart:Was Ambartsumian already the acknowledged leader?
Chandrasekhar:I thought he was marvelous. My own impression has always been that he was, when he was in his prime, one of the most perceptive and elegant of astronomers. But it seems to me that after the middle forties, he's been much more of a politician than an astronomer.
Weart:But at that time, he had a magnetism?
Chandrasekhar:He certainly was very sharp, and very precise, and his papers were beautifully written.
Weart:Of course, I suppose you must have traveled around England and gone to various conferences and so forth?
Chandrasekhar:Not very much. I used to go to the RAS meetings regularly.
Weart:OK, back to Cambridge, then. We haven't talked much about the people. You said a little about Eddington and Fowler, but I still don't have too much of a picture. Eddington, for example, you say was not too social, he was a retiring person?
Chandrasekhar:That was the general impression he gave. But once you got to know him, he was really very sociable, in the sense that I had no difficulty talking with him. We talked for a very long time. But of course, you know if I start talking about Eddington, I could talk for a whole hour about him.
Weart:Well, maybe we shouldn't talk for an hour about him but one would like to know more about him. What was he like?
Chandrasekhar:Let me see. He was a man who was very distinguished, in the sense that one felt when one talked to him that one was talking to someone really substantial. The British, particularly in earlier times, can be very nice and kind, but at the same time, an element in their behavior makes it very clear that they're on a different level. There's no snobbery involved in it. It sort of comes naturally to them. Eddington was a man of that kind. Scientifically, he was an extraordinarily self-contained man. I don't think he was ever inspired by other people along directions which he did not believe in. One characteristic of him which was extremely typical is manifest in one of my controversies with him. Eddington said, "You look at it from the point of the star. I look at it from the point of view of nature."
I asked him, "Aren't they both the same?"
He said, "No."
Well, you see, that sort of shows his attitude. Somehow, he felt that nature must conform to what he thought was right.
Weart:Almost a philosophical —
Chandrasekhar:Yes. And he was of course very devout. In fact the Royal Society, during the time I was in England, sent a circular to all their fellows, whether they believed in a Divine Presence, and Eddington was among the very few people who replied, in the positive.
I heard his very famous lecture, "Science and the Unseen World," which is very well known, in which he made some marvelous remarks. "There's a kind of sureness that is not cocksureness" — much marvelous, beautiful statements.
Weart:And he communicated this also in his personal relations?
Weart:. How was he regarded by the other people around the observatory or around Cambridge?
Chandrasekhar:Oh, his position in astronomy was dominant, what Eddington said, was right. I don't think there was any doubt in anybody's mind that Eddington was always right. For example — well, I shouldn't call it famous — the meeting at which Eddington and I disagreed. I gave a paper and then —
Weart:In '33 —
Weart:Oh, in '34, this was an RAS —-
Chandrasekhar:— meeting, and I gave a paper. Eddington came up and said, "The paper which has just been presented is all wrong."
He then made a lot of jokes and at the end of the meeting, everybody came and said to me, "Too bad. Too bad." The other astronomers were certain that my work was wrong because Eddington had said so.
Weart:"Too bad" meaning, "Too bad that you had got it wrong"?
Weart:What did this do to your personal relations with Eddington?
Chandrasekhar:It did not affect our personal relations: that is not the Cambridge Style! We remained very good friends. But even now, when I think of him outside of the context of my controversy with him, I have the nicest feelings about him. But he was very, very obstinate. Very obstinate, right up to the end.
Weart:Did other people at Cambridge have similar difficulties with him?
Chandrasekhar:Nobody (except Milne beside myself) crossed any swords with him; and Milne lost grievously. So far as I know, I was the only one who crossed swords with him, and history has shown that he was wrong. But in every other case ... But I don't think Eddington ever conceded. Oh no, he was convinced of this correctness right to the end.
Weart:People would generally be careful of him.
Chandrasekhar:No, I mean — just consider the fact that in the early years, when people were talking about white dwarfs, and when some of these objects were not white any more, I asked then, "Why don't you call them degenerate stars," and they said, "No, because that would imply that I'm accepting your theory."
I think Eddington's influence on this matter remained right up to the end.
Weart:Not just on the Cambridge people but outside also?
Chandrasekhar:Take Russell. The following incident illustrative of Russell's attitude. At the IAU meeting in 1935 — Eddington was the President of the commission on the "internal constitution." Russell was the secretary and presiding. With Russell presiding, Eddington gave an hour's talk, criticizing my work extensively and making it into a joke. I sent a note to Russell, telling that I would wish to reply. Russell sent back a note saying, "I prefer that you don't." And so I had no chance even to reply; and accept the pitiful glances of the audience.
Chandrasekhar:No, I don't think that there was any doubt in anybody's mind in those days that Eddington was right, by virtue of Eddington's extraordinary dominance.
Weart:I suppose other people hadn't thought about it very deeply or hadn't tried to look into it.
Weart:Eddington said it was so, and it was so. I see.
Chandrasekhar:Eddington had an absolutely dominating influence.
Weart:I would think this would have suppressed some other developments, in that case.
Chandrasekhar:Well, if you read my article on Milne, you will find that he effectively destroyed Milne.
Weart:I was going to ask you about that the next. You said you had good relations with Milne quite early, but he wasn't at Cambridge?
Chandrasekhar:No he was not at Cambridge. He was at Oxford. But my work was related to his. And so I corresponded with him. But very soon I found that Milne wanted to just develop his ideas along his own method. All these people — Eddington, Milne and others — knew perfectly well how nature was built. Their work was to confirm that their own ideas of nature were correct. I don't think they ever tried to explore nature with the intent of unraveling it as time went along - never allowing the investigations to reveal nature.
Weart:They began with the accepted laws of physics — or, in Eddington's case, what he expected the laws of physics to be?
Chandrasekhar:Well, in the case of Milne, he refused to accept the physics. He just said that degeneracy must be wrong because it contradicts his ideas, meaning 'common-sense.'
Weart:Getting back to the origins of these things, I was struck when I looked again at this 1931 paper of yours, when you first came out with the fact that it would have to go to zero radius and so forth — that it immediately follows in the journal a paper were Eddington is arguing with Milne.* Eddington gives a theorem here which he says "May be of use in curbing riotous speculations which go beyond the temperature of 109 degrees and a density of 106." Which of course was Milne's speculations. And then, you give a paper which supported Milne.
(* MONTHLY NOTICES 91 (1931), 440, 444.)
Chandrasekhar:That's right. But Milne, again, for different reasons wouldn't accept mine.
Weart:Yes, I'm curious about that. Do you suppose the fact that you began by supporting Milne may have influenced Eddington's view of your work?
Chandrasekhar:No — you see, if you want to take this controversy, the situation as far as Eddington's part in the problem was the following: First, it ought to be said that Eddington did not read anybody's else's papers. For example, he refers to Fowler's work as having applied the Einstein-Bose statistics.
Weart:Not the Fermi-Dirac?
Chandrasekhar:Not the Fermi-Dirac. In his first edition of his THE NATURE OF THE PHYSICAL WORLD, you will find that he says Einstein-Bose. And his account of Fowler's work at the RAS used Einstein-Bose. So, you see, Eddington had an idea that every star, when it cooled, must have a finite state in which it can exist. On the 5/3 law of degeneracy every star can become a white dwarf. So for Eddington that is the way it must be. On the other had, if there's a maximum mass for degenerate state that is not permitted And as Eddington stated, in his own writings — I've quoted many of these in my papers — he said that the only possibility is that " a star must go on radiating and radiating and contracting and contracting, till at last it finds its peace as it recedes into its gravitational radius." Now, that clearly shows that in 1934, Eddington realized that the existence of a limiting mass implies that black holes must occur in nature. But he did not accept that conclusion. He said that must be a reduction ad absurdem. Eddington's enormous physical insight clearly showed that black holes must occur once one accepted physics. If he had accepted that, he would have been 40 years ahead of anybody else. In a way it is too bad.
Chandrasekhar:Eddington wouldn't accept the maximum limit for his own reasons. And Milne would not accept it, because he thought that every star must have a degenerate core for different reason.
Weart:And this was simply because they were stuck on the way that they had first approached the problem?
Chandrasekhar:Just about that, yes. It's because they had preconceived ideas. This is effectively what Milne wrote to me.
Weart:You have this paper that you loaned me on Milne.
Chandrasekhar:Yes, I quote it in other places. [Looking through the paper on Milne.]
Here. Milne wrote me: "If the consequences of quantum mechanics contradict very obvious much more immediate considerations, then something must be wrong either the principles underlying the equation -of- state derivation or with the aforesaid general principles. Kelvin's gravitational -age-of-the-sun calculation was perfectly sound; but it contradicted other considerations which had not been realized. To me it is clear that matter cannot behave as you predict." And he continued, "Your marshaling of authorities such as Bohr, Pauli, Fowler, Wilson, etc., very impressive as it is, leaves me cold."
[Reading from the paper on Milne:] "From the vantage point of today, it is clear that Milne's negative attitude prevented him from realizing that the incorporation positively, of the consequences of Fermi degeneracy leading to an upper limit to the mass of white dwarfs, leads one directly to conclude that massive stars, after they have exhausted their sources of energy, must collapse to black holes — a conclusion which Eddington drew but which neither Eddington nor Milne would accept."
Weart:Right. I understand. I'm curious, you mention the fact that Eddington drew this conclusion — was it in conversation with you?
Chandrasekhar:Actually, he has written that.
Weart:Where did you see it?
Chandrasekhar:It is published in THE OBSERVATORY*
(* "THE OBSERVATORY" Vol. 58 (1935), 38.)
Weart:Right, but I'm interested — did he reach this conclusion while he was talking with you?
Chandrasekhar:Well, the history of this is approximately as follows. I found the limit in 1930, it was published in '31. And then, I resolved the nature of the problem in my own mind in 32. But all this time, I had not worked out a complete theory of white dwarfs, in which I used the exact equations. I did that for the first time in the fall of 1934.
Weart:Right, published in '34*
(* "OBSERVATORY" 57 (1934), 373-77; see MNRAS 95 (1935), 207-25, 226-60, 676-93.)
Chandrasekhar:And during the time I was working on this, was a fellow of Trinity, and Eddington used to come to my rooms in Trinity, every so often, after dinner, to see how my calculations were progressing. How my mass-radius relation was coming out. And indeed in its general progress.
Weart:I see, he was very interested in this. Anxious.
Chandrasekhar:He was very interested, and anxious to know. And then, I was scheduled to give an account of this paper at the January '34 meeting of the Royal Astronomical Society. The meeting is generally on the second Friday of each month. On the Thursday before, I was dining in college and I saw Eddington. Now, the assistant secretary used to send me the program for the meetings.
Weart:The secretary used to send you the program?
Chandrasekhar:Actually, the programs are not sent out before the meeting, but I happened to know the assistant secretary, Miss K. Williams and she sent it to me privately, because I was on the program.
Chandrasekhar:And when I got the program, Thursday evening, I noticed that after my paper, Eddington was to give a paper on the relativistic degeneracy. And I was really annoyed, because here was Eddington coming and talking to me, week after week, about my work while he was writing a paper himself and he never told me about it.
Weart:Never told you about his views, just came to look at your calculations.
Chandrasekhar:Yes. And talking to me all the time about the work. And I was telling him, "How can a star evolve? Massive stars must behave differently," and so on — all this was being talked about.
And then I went to dinner, and Eddington was there, and I was still annoyed, because he had never told me. After dinner, I didn't try to go to see him. But he came up to me. And even then he wouldn't tell me. He only said, "You know, your paper is so long that I asked W.M. Smart who has the secretary with RAS at that time to give you half an hour instead of the normal 15 minutes, so that you can explain your work properly."
And the following day, at the Burlington House where the RAS meetings use to be held, I was standing together with W.H. McCrae. Eddington came by, and McCrae asked Eddington, "Professor Eddington, what are we to understand about relativistic degeneracy?"
Eddington turned to me and said, "That's a surprise for you." Then at the meeting, I gave my paper, and Eddington got up soon after that and said, "I do not know if I shall leave this meeting alive, because the paper which you have just heard, the foundations of it are completely wrong."
Weart:And this was the first you have heard of those views of his?
Chandrasekhar:And then he went on to make some remarks which were mainly if you read the OBSERVATORY you will find, "laughter" interposed in many places. And that was that. And at the end of if, everybody came by and said, "Too bad." "Too bad." And of course, you know, Milne on the other side did not want to accept my work because it contradicted his work in other ways. I had Milne come and visit me in Cambridge during the fall of '34, to talk to him about my work, and to get him prepared to accept my work. And he had pretty well accepted it, but when Eddington said that the formula was wrong, Milne was all aglow.
I remember going to Paddington Station before going to Liverpool St., that evening, and Milne came to me and said, "I feel in my bones that Eddington is right." I told Milne, "I wish you felt it elsewhere." I was so angry. So that was the way it sort of ended.
In many ways, thinking back over those times, I am sort of astonished that I was never completely crushed by these Stalwarts. You know, none of these people would accept my work, astronomers wouldn't accept it and finally in 1938, I decided that there was no good my fighting all the time, that I am right and that the others were all wrong. I would write a book. I would state my views. And I would leave the subject. That's exactly what I did.
Weart:Now, in 1938 there was an IAU symposium. I remember, the first feeling I had about any of this was some time ago, when I happened to read Eddington's report, the 1938 IAU Section report, and he puts in completely gratuitously in his report his feelings about degeneracy and so forth, and I looked at this and I said, "What is going on with Eddington?" Eddington clearly was upset about something. And this was before I even knew that there was a controversy.
Chandrasekhar:There was a discussion after that. I don't know if you have read that. Eddington and I really talked to each other in strong language.
Weart:No, I didn't read the discussion, I just saw Eddington's summary report.
Chandrasekhar:Well, I think the PROCEEDINGS have been published. If you happen to look in it, I won't go through that in detail, but there's a long discussion. I remember, at the discussion, Kuiper asked Eddington, "Well, Professor Eddington, there are two theories of white dwarfs. How can an observational astronomer distinguish them?" And Eddington said, "There are no two theories." I got really angry. I got up and said, "Well, Eddington, how can you say that there are no two theories? Because we were in Cambridge just the other day, in a discussion with Dirac and Peierls and Maurice H. Price, and all three did not agree with your work on degeneracy. And to the extent that these distinguished physicists think that my formula is right, an observational astronomer must conclude that there are two theories." At this point, Russell got up and said, "The discussion is closed." That was the last of that.
Well, that afternoon you asked me about the personal relations — that was the last part of the meeting where there was a big reception and lunch at the City Hall. All of the Paris great were there; Langluis, Joliot, de Broglie, Curie and all the others they were all at the high table, and I was way off in the corner somewhere. At the end of the meeting, I was standing by myself when quite suddenly I found Eddington next to me. He said, "I hope I did not hurt you this morning."
I asked him, "You haven't changed your mind, have you?"
Eddington said, "No."
And I asked, "What are you then sorry about?"
Eddington just looked at me and walked away. That was my last conversation with Eddington, because he died a few years later, you know, during the war.
Weart:So the personal relations maintained a correctness.
Chandrasekhar:Yes. And actually, after the war began I wrote him several times; in fact, I had a letter from him dated two days before he died. He said that he's going to the hospital because he's not feeling well, and so on, but "when I came back, I'd do these things." And when I got the letter, he had already died.
So we kept our personal friendships till the end. I have very warm personal feeling towards him.
Weart:Now, about Milne's role in all this, you mentioned the problems Milne had with Eddington. In a way, I'm surprised Milne should have supported Eddington. What were Milne's feelings towards Eddington?
Chandrasekhar:I think I explain all that pretty well in that article I gave you.
Chandrasekhar:But one thing is certain in my mind: Milne's enormous originality was frustrated by his attitude of trying to do science which would contradict Eddington all the time. In this one respect he went along, because in this respect his arguments in a different context makes his ideas contradicting Eddington right. It's one of those inverted things,you see.
Weart:Would this have happened to Milne, do you suppose, if someone else had been the recognized great authority? Or was it specifically Eddington?
Chandrasekhar:It is hard for people to realize what an incredibly dominating position Eddington had during his life. For example, Shapley told me this: in 1936, they had a tricentennial at Harvard, and, Shapley said, they sent a circular around to American astronomers, to rank astronomers so they could give honorary degrees. And he said that Eddington was the first in every single list he received! And in one of them, Eddington [at the top], 30 dots and then Jeans. [Laughter]
I think that is most unfair, as far as Jeans was concerned, but the fact is that there was not a single astronomer in the thirties who would not with unanimity have said that Eddington is the greatest living astronomer. He had an absolutely dominating position.
Weart:Was it this position, do you think, that attracted Milne's attention?
Chandrasekhar:That is one. But Eddington in science can be most aggressive and abrasive. I mean, he will do things which are quite often terribly rude.
For example, Jeans sent a paper on radiative viscosity. The program contained it. Eddington sent a postcard to Jeans, deriving the formula for radiative viscosity. Because once the concept is stated, anybody can write the formula down.
Weart:Right. Once you see that word, "radiative viscosity."
Chandrasekhar:But isn't it insulting that after seeing the title, you send the formula to somebody else to show "I'm as good as you." It's childish.
Weart:It's funny, in some ways what you're saying about Eddington, particularly in the English scene, reminds me of Russell in some ways in the American scene.
Weart:I'll have to ask you later about Russell, when you came to the United States. I want to ask you also about your personal relations with Milne. After all, Milne had introduced your early papers and so forth, you even credit him with helping you, with conversations on your first papers.
Chandrasekhar:He remained a personal friend all through his life. Look, [pointing to wall of office], that's his picture there. The first one, on the top, is E.A. Milne. He visited us in this country in 1939, and that photograph was taken when he was visiting us.
He remained a personal friend, and I'm deeply attached to him. You know, Milne had a marvelous intellect. He was the first scientist who really encouraged me. When I was at Cambridge in 1930, the first year, I told you that I done this work on the white dwarfs and that Fowler had sent it on to Milne. Milne visited me in my rooms in Cambridge, by himself, came unannounced one afternoon to see me. I was most touched by it. For example, in my book on stellar structure, I refer to Milne at every place where I agree with him. But I never refer to any of our disagreements. Because I knew that it would hurt him enormously, and so I preferred not to refer to our disagreements. I state my own views correctly, and whenever my work impinges on his and he's right, I mention him in those places. He noticed it, and in fact, in one of my last conversations with him, he told me that he had noticed that fact and greatly appreciated my personal courtesy.
My correspondence with him extended right up to his death. In fact, I got a letter from him aboard the steamer going to Belfast, the morning after which he died. He was a very great personal friend of mine: the first and the best.
Weart:Who else were your friends in England? You mentioned Dirac.
Chandrasekhar:Scientifically, McCrae and I became rather good friends. We have continued to be good friends. McVittie was another. And George Cowling. These were my contemporaries in Cambridge at that time. And among the physicists in Cambridge, there was a low-temperature physicist, David Schoenberg. I knew the mathematicians very well, Harold Davenport, (most particularly) Hans Heilbron, Donald Coxeter, Patrix Duval, and A. Besicovitch.
Weart:Speaking again of the physicists, you mentioned, the letter of Milne that you quoted, speaks of the physicists whose support you could marshall on degeneracy, and again at the IAU meeting, Dirac and so forth, supporting you. Did you get a real feeling of support from the physicists at Cambridge?
Weart:So when you say "it was not accepted," it was strictly the astronomers and astrophysicists.
Chandrasekhar:R.H. Fowler accepted me. In fact, he told me, "Don't worry about Eddington." And Pauli, wrote pretty nearly the same thing.
Weart:How did the physicists relate to the astronomers there? And the astrophysicists?
Chandrasekhar:Well, you know, astronomy was never an integral part. In fact, I just got recently a book of scientific quotations, in which Rutherford said, "Don't talk about the universe here." And there's also another quotation of Rutherford, when someone asked him about Einstein — "Oh, that stuff, we don't bother about it." Of course, Rutherford was an extrovert, very open, and very often he would say things merely for the effect; so one couldn't really go deep into it. But I think it sort of gives you the overtones.
Weart:What about some of the others, Dirac and people like that? How much interest did you feel that the physicists had in what you were doing, or in general, what was going on in your field?
Chandrasekhar:Not at all. For example, during the first year in Cambridge, I used to know Dirac very well, because Fowler was away, and Dirac told me, "Well if I were you, I would be interested in relativity, rather than astrophysics."
I asked him, "At one time you did write a paper on astrophysics." Dirac said, "Oh, that was before quantum mechanics." No, I am afraid that astrophysics was considered inferior by most physicists. In fact all physicists.
Weart:Did the astrophysicists react to this?
Chandrasekhar:In a curious way.
I remember Wigner telling me, during the war, "Well, astronomers are very, very clever — they have thought of 1 percent of the possibilities."
That's typical. I think the rather high position which astronomy and astrophysics occupy now is a consequence of the sixties. Then a whole sequence of new discoveries was made, and the relationship with relativity became very important — gravitational collapse, black holes and so on. And the situation has changed.
Weart:So the feeling was at the time, if one discovers something in nuclear physics, that might be applied to astrophysics, but not the other way around?
Chandrasekhar:That's right. For example, I am sure that if you ever have a chance to talk to Bethe, Bethe could tell you if he still remembers, that the attitude of the physicists toward the astronomers was one bordering on contempt. Maybe "contempt" is a little too strong.
Weart:Did you get this everywhere?
Chandrasekhar:Yes, I'm afraid so.
Weart:Not just at Cambridge, but Gottingen, Copenhagen?
Chandrasekhar:There were exceptions. Men like Eddington had enormous personal prestige. But Eddington was the sole exception. Jeans, for example, had very little — I mean, whatever respect people had for Jeans, in England, derived from his very successful ten-year tenure as the Secretary of the Royal Society.
lifted(* PROC. AM. PHILOSOPHICAL SOC. 108 (1964),)
Chandrasekhar:Ok, yes, to the extent nuclear physics was involved.
Weart:But just as an application of nuclear physics.
Chandrasekhar:Well, I'll tell you an interesting conversation I had with Bohr, when I was in Copenhagen 1932-33. I was working on rotating stars at that time. Bohr said, "Well, I was interested in astrophysics when I was young," and he recalled the fact that the helium lines (the Brackett spectrum,) lifted Balmer's formula for half integral quantum number. And then he said, "more lines must be due to the ionized helium lines," and one should be able to detect the difference in the wave lengths because of the mass effect. A. Fowler had found that, you see. [Distinguished spectroscopist who was a Professor in Imperial College in London. He also led some eclipse expeditions.]
But then he said, "Well, I've always been interested in astrophysics, but the first question I should like to know about the sun is: where does the energy come from? And since I can't answer that question, I do not think a rational theory of the stellar structure is possible."
Well, great as Bohr is, that remark of Bohr's is invalid. Later on, if one found the right nuclear reactions, it was because one had found out earlier the right temperatures and physical conditions by their ingenuity.
Weart:Right. They didn't realize that at the time.
Chandrasekhar:You know, it was the standard thing to say. "I look at the sun. Can you tell me how it radiates? You don't. So why should I believe anything else you say?" It looks childish — an attempt that one cannot explore a question like that.
So, I am afraid that the physicists did not think much of astrophysicists. And in a way, it is understandable. So many things were happening in physics. And astrophysics was trying to get an insight into a subject the fundamental of which one did not understand; and that is not a particularly rewarding job for a person who is finding new laws of nature at every other turn.
Weart:This brings me very directly to the next thing I wanted to ask you, the next subject — the rotating stars you were mentioning about discussing with Bohr, is what came out in this series, starting 1933, "The Equilibrium of Distorted Polytropes." In fact, we've done some citation counts, and this seems to be one of your most celebrated papers from the 1930s. I'm curious about this, and how you came to this particular problem?
Chandrasekhar:If you want to know the truth, there is nothing exciting at all. January, 1933 came along, and I knew that my scholarship expired that August, and I knew that I had to get my PhD, write a PhD thesis, and I looked around and asked, what it is I could do? And I saw an old paper of Milne's, 1924, on rotating stars, I wasn't too satisfied with what he had done, so I thought, well here is an area in which I could work up a whole new subject; and that is how it started.
Weart:So to you it was simply like a tripos problem, so to speak, a mathematical problem?
Chandrasekhar:Yes. That is how it started, yes. To call it a 'tripos problem is perhaps not quite fair!
Weart:Did you do this under anyone in particular?
Chandrasekhar:No, I just did it on my own.
Weart:I'm interested, because this looks to me like one of the first of your papers which really is what's become well known as a Chandrasekhar type of paper — it has a lot of mathematics, it takes a particular kind of problem and really works it through, and so forth. I wonder where you got this sort of feeling? This was to produce a thesis, but it seems to be part of a larger feeling that you should do this kind of thing.
Chandrasekhar:Well, I think I tried to state the underlying motive, but on the other hand, what fascinated me about the subject was, here was an area in which one can do some definitive work.
I think that it probably was the first time that I began to build up this feeling, which I have maintained all along; namely, that in astrophysics, if one wanted to do some work which would have some degree of permanence, it ought to be well-defined, complete, rigorous, and relevant — in the long run, not necessarily in the short run. That has been my principal motivation in my work all along.
When I started this work, even though I had to write a thesis, I felt very enthusiastic about it, because I said, "Well, this work which I do now will be a permanent contribution, to the extent I can see, because it will be done and finished and that will be right, so long as people want to use it."
Weart:There will always be rotating polytropes.
Chandrasekhar:Yes. No matter where one goes. And history has shown that, more or less, my idea is right. Similarly when I wrote my book on the ellipsoidal equilibrium,* it was the same feeling, because I said, "Well, people may not 'think much about this subject, but it is a well-defined subject, lots of people have worked on it, it is in a terrible mess, I will straighten it all out and write a book, and leave it; it will be there, if people care about it." Actually, it has turned out that that book is now used quite extensively, and provides the models for lots of things people are doing these days.
(*ELLIPSOIDAL FIGURES OF EQUILIBRIUM (Yale Univ. Press, 1969).)
That has in fact been my primary motive in astronomy. In fact, I said somewhere that my attitude, which first is exemplified in this work on rotating stars, is that theoretical astronomy must provide for astronomy what experiments provide for physics. In other words, you must provide a basis of calculation which is so right that nobody can argue about that. So you can integrate it into your observations, as something that is valid.
Weart:Given the initial assumptions.
Chandrasekhar:And the assumptions are relevant. I mean, it may be a model, but it illustrates the problem, and it provides a basis, so that on this assumption, this conclusion is right. There's no argument about that.
Weart:I see. This style, this program, which has been very successful, does not, however, seem to be a style or program which is too common. I wonder, why did you pick it up? Is it something that you picked up at Cambridge? Is it something in your personality? Something from Madras, even?
Chandrasekhar:No... One moment. [Gets article.] Here is an article in NATURE* which I —
(* "Development of General Relativity," Nature 252 (1974), 15-17.)
Weart:Ah, no, I didn't see that one.
Chandrasekhar:You can have this. I say here,"By saying that astronomy is a natural home for the general theory of relativity, and I am suggesting a role for theory in astronomy which is not generally accepted; in my judgement theory has a double role to play in astronomy; the common one of providing interpretations for observed phenomena, and the uncommon one of providing for astronomy the kind of basis which experiments provide for physics. The latter role is largely unrecognized, and largely not practiced, but one would certainly recognize this role, if one would only stop and realize that unless one can be certain of what one might observe in well-defined astronomical contexts — that is, under such well-defined conditions — one could never be sure of any inference that one may draw from observations. Although I do not wish to go so far, there is an element of truth in an aphorism of Eddington's: "You cannot believe in astronomical observations before they are confirmed by theory." On the other hand, I agree that this is not practiced. And to some extent I am disappointed, at this stage in my life, that having practiced it for nearly 45 years now, it hasn't influenced others. To me, that's a kind of disappointment that my attitude to science seems to be so little accepted, in the practice of other people.
On the other hand, if you ask me, "Why have I practiced it myself?" Let me illustrate it in a different way. You have read Hardy's APOLOGY OF A MATHEMATICIAN? It's a marvelous little book. There's a reference in the end to a conversation which Hardy had with a friend of his, going by the Nelson/Column in Trafalgar Square. "If I had a statue on a column in London, would I prefer the column to be so high that the statue was invisible or low enough for the features to be recognizable? I would choose the first alternative."
The same motive works in science. I think one of the motives of science is to leave some kind of memorial behind oneself. And people can do that in a variety of ways. They can make discoveries and be remembered for that. But there is also a more modest role a scientist can play, and that is to assemble information and material which, in the long run, will be helpful to others, and be of some permanent value — permanent in a relative sense.
I have chosen the later approach. All, I think, as a consequence of my first shattering experience in Cambridge. The idea that one's scientific life has to be motivated by the off-chance that one may make a great discovery, and be remembered for that, was too risky, too much of a gamble. I preferred the more modest approach of trying to do something— and I think, on the whole, it has worked to my advantage. Because if one is not stupid, then in the course of such effort you are bound to find a few things which people might even count as important discoveries. But the main emphasis in your life is to concentrate on producing as permanent a body of knowledge as you are capable of.
Weart:I wonder, did you discuss this with anyone? Here you are, you're working on Equilibrium of Distorted Polytropes — Bohr sort of yawns at it — you must have discussed it with the other people round Cambridge at the time. Did you express it this way? Did you discuss it with people at the time, "Here I am doing something which will be a real thing, which is solid?"
Chandrasekhar:I could not have made it at that time. But what I tell you now is a gradual realization, as time has gone along.
Weart:Somehow it's natural for you and you've gradually been able to articulate what you've been doing?
Chandrasekhar:That's right. I don't think I could have said it in this way, at that time.
Weart:I see. This was rather different from, for example, in 1929 Milne gave a famous lecture,* where he said the aim of mathematical physics was to build up a system, rather than to attack particular problems. What you say seems to me almost directly opposed to that. And of course, Eddington also was a system builder.
(* Oxford Inaugural Lecture. See G.J. Whitnow, "Milne", DSB.)
Chandrasekhar:Yes. I may be wrong to say this, but I think — somebody said, "A person who says he is modest, is not modest." But I don't know how one wants to characterize it. My attitude to my work has always been motivated, not by any intent to make a discovery or produce a paper which will be considered important by my contemporaries — that, somehow, has never been a part of my mature scientific life. After I was 30 my idea has always been trying to find a place in science where I can do work which would not be trivial, which would in time become a permanent body of knowledge.
Weart:Don't you think there are other mathematical physicists and astrophysicists also who have some of this same feeling?
Chandrasekhar:The only person, in the past, who seems to have been motivated in a similar way, as I can judge by reading his work, is Rayleigh.
Weart:Ah, yes. But among the contemporary people, they seem to not take this attitude?
Chandrasekhar:It doesn't seem to be. At least I'm not aware of anyone conspicuously following it.
Weart:I have still a number of particular questions but I notice it's noon.
[Break for Lunch]
Weart:Why don't we talk a little bit about theory and observation at Cambridge? So far, we haven't said anything about observations. Did you ever have any opportunity to do observations? Did you ever interact with the people who were doing observations?
Chandrasekhar:No, I don't think I ever had anything to do with observations. But Eddington, of course, was very conversant with and sympathetic towards observational work. In fact, he told me one very amusing story which I just remembered. He told me that one of the conditions for the Plumian chair in his time was that the candidate must have looked through a telescope at least 100 feet long. And he said that he had worked with Lord Ross's telescope in Ireland, and so was qualified at least on that account. Of course, he also told me that when he was chief assistant at Greenwich, one of his weekly chores was to wind all the clocks at Greenwich every Sunday morning. Well, having been through such chores, and having done his early work on proper motions and star-streaming, he was very sympathetic to observational work. But I myself have done no observational work, and indeed, I never thought that my professional career would be in the astronomical community, till I was appointed to an astronomical position in Chicago, in 1936.
Chandrasekhar:I received my appointment in 1936; but I joined the University in January 1937. I was visiting this country for three months in the winter of 35-36, from December 1935 till March 1936 and during the time I was there, Gerard Kuiper was a fellow at Harvard, and I believe that it was Kuiper who must have recommended me to Struve. And Struve invited me to come to Chicago in March of '36, and I came here. And before I left, Robert Hutchins had offered me the position at Chicago, as a research associate.
Weart:Before that you had supposed that you would be doing what? You would go back to India?
Chandrasekhar:I was a fellow at Cambridge, and the fellowship was to have run through till 1937. I fully excepted that at the end of that, I would go to India.
Weart:So there was no point in learning about large telescopes and so forth.
Chandrasekhar:Yes. That was one of the reasons. And also, by that time, I had really decided that I would do theoretical work. But coming to Chicago, of course, changed my career, in the sense that Struve essentially made me in charge of graduate instruction at the campus here, and so I began to teach subjects like stellar dynamics and stellar atmospheres.
Weart:We'll have to get back to that. I still am not entirely clear whether your case was exceptional at Cambridge, or whether in general the theorists did not talk very much with the observationalists. For example, Stratton. What was Stratton's attitude toward people who did only theory?
Chandrasekhar:Somehow, the implicit felling there was — it's very difficult for me to say. I did know Stratton quite well, I used to see a good deal of him. He used to be particularly excited about his work on Nova Herculis, which came out in December of '35, I believe; and when that appeared he was very excited about the various stages of its development and he used to show the spectra to everyone; not only would he show it to me personally, he would also show it to me in company with other people, including Eddington. And there always used to be excitement as to what spectral lines were coming up in strength and what spectral lines were going down in strength, how the radial velocities were changing. But there is no gain saying, I was in an atmosphere of people who were far more interested in theory. My own social contacts, during my latter years in Trinity, were with the mathematicians. I used to see a good deal of them personally. And my contacts with Eddington and Milne were strong. At Oxford, I used to see Harry Plaskett, who was an observational astronomer and a solar physicist. Indeed, some of the problems I worked on in '35 and '36, when I was still in England, were related to some of Plaskett's interests. For example, Plaskett was interested in the blanketing problem in the solar atmosphere, and I wrote a paper on that in which he was interested.* He was also interested in Wolf-Rayet stars.
(* "The radiative equilibrium of the outer layers of a star with special references to the blanketing effects of the reversing layer," on the distribution of the absorbing atoms in the re-revising layers of stars and the formation of blended absorption lines" (with P. Swings) MNRAS 97 (1936), 24-37.)
Weart:Yes, I wanted to ask you about Wolf-Rayet stars. There's a paper you wrote in 1934, and you thank him for the hypothesis that it's ultraviolet light [that ejects atoms from their atmospheres].
Weart:Is that how you got interested in Wolf-Rayet stars?
Chandrasekhar:That was the origin of my interest. My personal friendship with Harry Plaskett got me also interested in the Zanstra theory; planetary nebulae; stellar atmospheres — in which I was already interested, but certain special problems; and particularly, I got interested already at that time in the discrepancy between Russell's extreme) hydrogen hypothesis and UnsÃ¶ld's lower abundance color temperatures of stars— things which were to occupy me in the later forties. My initial interest came from talking to Harry Plaskett. The one observational astronomer with whom I had much contact was Harry Plaskett.
Weart:What was he like?
Chandrasekhar:Well, he's still living, you know. In fact, I met him during my last visit to England. We have retained a personal friendship during all these years.
I found him extremely pleasant personally, and very sympathetic to theoretical work. He was a great admirer of Milne, rather overly so, I though — beyond reason. I believe in having friendships which are honest; just because he's a friend, you must not exaggerate his knowledge and ability; I believe in being a Nationalist about my friends.
Weart:— you want to separate that from scientific questions.
Chandrasekhar:Yes. And I thought that Harry Plaskett went too far in accepting everything that Milne said, in those days. Retrospectively, I must say that he has not shown that degree of wisdom in astronomy as I thought he might have.
Weart:I'm curious, you seem to have known the people at Oxford fairly well. I don't know very much about what astronomy was like at Oxford. You've given me a pretty good picture of Cambridge. Perhaps you could tell me things about Oxford also?
Chandrasekhar:Well, my knowledge of Oxford largely derives from my personal friendship with Milne. I used to go to Oxford certainly once a term, and sometimes more often. Indeed, during summer of 1936 I spent three months in Oxford, with Plaskett and Zanstra in addition to spending three months with Milne during the fall of 1933 (Oct. - Dec.). I must have spent a total of six months at Oxford during my years in England.
I knew Knot Shaw, an active observer, who later went to Pretoriain South Africa, I think. The Southern Radcliffe telescope was there. The principal interest in Oxford was solar research. Harry Plaskett was interested in solar research, and so I got interested in the problems of the sun on that account. And Herman Zanstra used to come to Oxford quite frequently (he later became a professor in Amsterdam) and Zanstra and I became rather good friends. So I used to know the Oxford community more on the personal level, in the sense that I considered Harry Plaskett as a friend with whom I could go and talk at a level of equality. The same way with Milne. He was much younger, of course, than Eddington. We became personal friends very soon. Whereas in Cambridge, you see, Eddington, even though I knew him very well and would talk to him in an extremely natural way — he was always on Olympus as far as I was concerned. And Stratton was a very ebullient man. I remember very well, he was taking around a Spanish astronomer, trying to speak French, and talking about "Fe deux", (iron II) in the spectrum of Nova Herculis that he had found — and finally this man asked him, "What was the spark by which you got that spectrum? And that sort of collapsed Stratton, because Stratton was talking about iron II lines in the spectrum of Nova Herculis! And (the visitor) thought it was a laboratory spectrum!
Weart:In Oxford did you have any feeling about how the astronomers interacted with the physicists, about the balance or the separation between theory and observation?
Chandrasekhar:I think it is safe to say that in England at that time, the relationship between astronomy as astronomy, and physics as physics was not very much — except through persons. Take Eddington, as a theoretical astronomer. In his book on the INTERNAL CONSTITUTION he says that R.H. Fowler was his referee for theoretical physics, and that C.D. Ellis was for experimental physics. C.D. Ellis was working on photoelectric effect, X-ray spectroscopy and so forth; and Eddington could learn from him about Kramers' opacity, and so, from the point of view of learning about sources of opacity, he had to go to Charles Ellis. So it's quite clear that Eddington personally had contact both with experimental physicists, and with theoretical physicists, not to mention the experimental physicist, in Rutherford.
But of course, they were all Trinity College men.
Chandrasekhar:You see, so he got to know them that way.
Weart:They all sat at High Table.
Chandrasekhar:Yes. And then, take a man like Jeans. You know, Jeans became an entirely private person. Do you happen to know about Jeans?
Weart:Not very much, no.
Chandrasekhar:He was a professor in Princeton during the time when Woodrow Wilson was the president [of Princeton]. Woodrow Wilson somehow had the feeling that the best intellects were in England, and so he appointed a lot of Englishmen to the staff. Jeans was a professor and so was O.W. Richardson, so was Hugh Taylor.
In 1907 Jeans married Charlotte Tiffany Mitchell, daughter of Alfred Mitchell, explorer and traveler of New London, Connecticut. She was connected with the well known Tiffany family of New York and apparently very wealthy.
Jeans remained in Princeton until 1909 and then returned to England presumably because he had elected to the Royal Society in 1907 and George Darwins retirement from the Plumian Chair. On his return to England, Jeans was appointed Stokes Lecturer in Applied Mathematics in the University of Cambridge. When George Darwin died in 1912, Jeans must have considered himself his logical successor - as indeed he was in many ways. But the electors chose instead. Eddington, Jean's junior by 5 years. Jeans apparently felt that he had no place in Cambridge and retired to a country villa (Cleveland Lodge)in Dorkins Surrey.
Weart:Oh, I didn't know that story.
Chandrasekhar:Jeans did. Some of his very best work — his Adams Prize, his stellar dynamics and cosmogony — were written in the (period 1912-1919) in his private home: Cleveland Lodge, Dorking, Surrey.
Weart:Did he come in also to Cambridge to talk with people?
Weart:You had no interaction with him?
Chandrasekhar:No, I had no interaction with him. But he used to attend the meetings of the RAS in the thirties, and I used to see him at the RAS, regularly at a distance. He once invited me to his home in Surrey. I had a marvelous time. He was a marvelous host. He met me in the car at the station, and took me to his house. He had an organ built in his house, and is known to be able to play most of Bach. You know, sometimes people are sarcastic about Jeans, and I always say, "Anyone who can play all of Bach's organ compositions cannot be a trivial person." Jeans was quite an aristocrat. I admired him then, and as time has gone along, my personal regard and respect for his work has, if anything, increased.
Jeans, of course, was entirely by himself. He had no contact with observational astronomy — except through his friendship with Hale. He was a research associate of Mt. Wilson. And he used to come to Pasadena and talk to Hubble and talk to Hale; that is why his book on astronomy and cosmogony is filled with pictures from Mt. Wilson. Because as a research associate, he could do that.
Weart:Did you or the people at Trinity or Cambridge have much connection with the people at Mt. Wilson, or in general, with the big American telescopes?
Chandrasekhar:Eddington, of course, was quite a good friend of the American people. Eddington was admired enormously in the United States. He was a foreign member of the Academy* — which Jeans was not. He had the Draper Medal and the Bruce Medal, from this country, and honorary degrees from a host of universities, including Chicago.
(* National Academy of Sciences)
Weart:Did you people feel that you were quite up to date and in with things that were going on, with Hubble, and the pictures of galaxies and so forth? One doesn't see much cosmology or concern with galaxies in England.
Chandrasekhar:Eddington worked on the universe.
Weart:That's true. Among other people?
Chandrasekhar:When Hubble came to England, I remember, Eddington accepted the expanding universe.
The fact that the expansion didn't quite agree with the age of the earth Eddington simply ignored and said, "Well, it'll all straighten itself out in time.
Weart:Were these questions much discussed, for example, the age problem?
Chandrasekhar:Oh yes. Eddington was very much interested in that.
Weart:Were other people also?
Chandrasekhar:Well, Jeans was. Of course, Eddington always set the standard. Whenever he gave a public lecture, the London TIMES used to report it fully. A controversy will ensure in which Jeans) Oliver Lodge, Larnor and others will take part. But Eddington always used to pride himself that, "I have never written to the London TIMES."
Weart:They came to him. I see. Speaking of cosmology, this may be the right point chronologically to ask about the Letter you published in NATURE in 1937,* responding to Dirac's "Large Numbers" hypothesis. You come up with something of the dimensions of a mass, and you mention that you had noticed this some years ago but had been hesitating to publish — I'm quoting — "hesitating to publish from the conviction that purely dimensional arguments will not lead one very far." Clearly there was a point at which you found this exciting.
(* NATURE 139 (1937), 757-58.)
Chandrasekhar:Well, actually that Letter has a very curious history. I sent it as a personal letter to Dirac, and Dirac forwarded it to NATURE. He modified one or two sentences, to make it, suitable for publication. When I wrote to Dirac, it wasn't intended for publication.
Weart:I see. I trust he let you know that he was going to publish it?
Chandrasekhar:Oh yes, he asked me first it I would mind, and I said, no, if he thinks it is worth putting on record, it's all right with me.
Weart:But there were ideas that you had had before?
Chandrasekhar:Yes. But there is one fact, you know, which is mentioned there, which has never been seriously written about. I have myself written recently on it, recapturing some of my old ideas.
Namely that the combination of natural constants which gives one the white dwarf limit, provides the dimensions of a stellar mass and the fact that this is so is precisely the reason why modern theories of stellar structure are valid. This is in exactly the same way that the fact that the Bohr radius gives the correct dimensions of the size of an atom, provides also the reason for the validity of modern theory of atomic structure.
The principal point I wanted to make there was the significance of the combination of natural constants which appears in the white dwarf limit. That was my principal reason. But the other coincidences, combinations of constants with dimensions of mass, well, I think those coincidences are still there.
Weart:I see; as you say, if it has a significance in one case, it may have a significance in the other also.
Weart:One is really struck by this idea of Dirac's. I think ever since he came out with it, people have been somehow fascinated with it, even though they can't do anything with it. Where did this come from? Did it come from Eddington? Was he already talking about these things in the middle thirties?
Chandrasekhar:Oh yes. He was talking about natural constants, yes.
Weart:Is this where it comes from, do you suppose? Was it Eddington who began this, or did it go farther back?
Chandrasekhar:Well, I would say that Eddington was the originator of these group of ideas. In fact, he was the first person, wasn't he, to point out that the ratio of the radius of the electron to its gravitational mass = 3 X 10 and he added" It's difficult to account for the occurrence of a pure number (of order greatly different from units)in a scheme of things; but this difficulty would be removed if one would connect it with the number of particles in the world" (Mathematical Theory of Relativity, p. 167 (First Edition 1923). So far as I know, the isolation of this very large number was first done by Eddington, and largely under his influence, other people started to go beyond him. Indeed, I think Dirac has stated that his interest in this arose from Eddington's ideas.
Weart:It would be interesting to know, did Eddington ever talk about these ideas, the things that were coming to his "Fundamental Theory," in terms of where it came from, how he got into doing this type of physics or astrophysics, whatever it is?
Chandrasekhar:Well, you know, all these men were playing for very high stakes. Eddington was. You must know the story, that when he was a young boy he was left alone at home, and when the family came back they asked him, "I suppose you found it very hard to be alone all this time." Eddington replied "Oh no, I counted all the words in the Bible." He quotes it himself. It is interesting that when he was young, he counted the number of words in the Bible; when he became a serious scientist he counted the number of particles in the universe!
Weart:I see. I suppose perhaps the religious motivation may be found in those stories, also.
Weart:To get back to some of your own work — well, where are we? We're approximately to '35, and I think the new thing here that interests me is that you did the Wolf-Rayet business, and then in 1935, you come out with the idea that all stars may become dwarfs, if necessary by ejecting matter.*
(* MONTHLY NOTICES 94 (1934), 522; 95 (1935), 226.)
Weart:And you mention Wolf-Rayets. You mention that in some cases it would be novae: you mention that Milne had this idea. Is there more background to this?
Chandrasekhar:Well, actually, the two were related. In fact, I was not only interested in the Wolf-Rayet stars, but also in a related work by N.A. Kosirev in which he suggested that high-temperature stars continuously eject matter. At that time, particularly in '35 - '36, I was really wondering very hard how a massive star was going to find a stable state. And somehow,the fact that very luminous and massive stars were ejecting matter seemed to me that perhaps one may seek a solution along these lines. And I was attracted to these problems also on that account.
Weart:Is this why you wrote the paper on the Wolf-Rayet stars? Or did that come first?
Chandrasekhar:Well, it came about the same time, because I wrote on the Wolf-Rayet stars in '35; I was also working on the white dwarfs problems at the same time. I was in Oxford and Plaskett told me about all these things about Wolf-Rayet Stars. I immediately said to myself, "My God, here we have probably nature telling us what is happening." So it was largely my contact with Plaskett which brought to my attention some of these things. And he told me about C.S. Beal's Wolf-Rayet stars having work flat-top contours. I got interested in these problems as an aside, in connection with my work on stellar structure at that time.
Weart:I see. In a way, your work on stellar structure was still being oriented around the white dwarf problem.
Weart:Was it this idea that white dwarfs must be the end point, and therefore it's fundamental to everything?
Chandrasekhar:I did a lot of work on white dwarfs at that time, which, because of the controversy with Eddington, I did not publish. I did some work on rotating white dwarfs; I did a fair amount of work on pulsating white dwarfs.
Weart:Is this work that you later published?
Chandrasekhar:No. The rotation part I published a short note on, but pulsation, I never did.
Weart:Because you thought it was enough just to get the first thing accepted, without going on?
Chandrasekhar:It was a very strange situation, because here I was convinced in my own mind that my work was right; but surrounded by a lot of people who thought that the work was all wrong. And after all, you must remember, I was in my middle twenties in those days, and I had to think about my scientific future. Was I going to be the one repeatedly telling others that I was right, knowing full well that the whole community against me? It seemed to me that even if I was right, as I never doubled myself, one's scientific future is not built on one discovery, no matter how important it may turn out to be. And I thought it was important for me to widen my knowledge. And so when I came to Yerkes, I started giving lectures on various other subjects.
Weart:Right. And even at Cambridge you were publishing papers in various other areas.
Weart:We've said a lot about Cambridge. There's one other question I wanted to ask you, and I wondered, what sort of difficulties did you encounter because you were from India. Among the scientists, or perhaps in the larger community?
Chandrasekhar:Well, in England, I had no problems.
Weart:Because one does hear that some of the English adopted a racist attitude toward people from India.
Chandrasekhar:Well, the English had a very interesting attitude to Indians. I'll tell you one very interesting story. I told you already the fact about Raman having been my uncle. He (Raman) told me once, when I was still in India, that during one of his visits to Cambridge in the twenties he visited Rutherford. Rutherford was talking Raman around and Raman told him, "Well, I see all the young are playing in tennis courts and so on — when do they work?
Rutherford told him, "My dear Professor Raman, we don't want bookworms. We want governors for our empire." [laughter].On the other hand, the British scientists were enormously interested in creating an Indian science. After all, Ramanjan would have died unknown, but for Hardy.
Weart:Of course, some of them did go out and teach in Indian universities.
Chandrasekhar:Yes. I am sure that during my time when I was in Cambridge, [H.J.] Bhabha was there, I was there, and Bhabha's experience was the same as mine: we were treated, if anything, with more consideration that we thought we deserved. I had racial problems later in this country. But not in England.
Weart:I see. About your move to the United States, then — you've told me briefly how you came over, but I'm curious as to how American astronomy seemed to you, both when you were still in England, before you had come over, and also when you came here. You first visited Harvard. How did it seem to you, from Cambridge, both in terms of observation and in terms of theory and so of?
Chandrasekhar:Well, I would say that in Cambridge, it did not seem to me at that time (but that was in part due to my own ignorance) that theory was very well prosecuted in America. I do know that when Struve appointed me to Chicago, he told me,"We have no one here in this country in the tradition of Eddington, Milne, and theoreticians of that kind. And that is why I want to have you here."
I do know that when my appointment was announced, I understood later, there was considerable consternation the part of many people, as to why someone like me should have been appointed to an observatory.
Weart:People at Yerkes or people in general?
Chandrasekhar:People in general. Struve was very farsighted in these things. I suppose that isn't proper for me to say: it looks self-serving. But Struve did encourage theoretical work. He had personally as enormous admiration for the English astrophysicists, R.H. Fowler, E.A. Milne and Eddington; and he ranked those men higher than Henry Norris Russell. He has told me that. He probably thought that I was in their tradition, and he wanted to have something here of the same kind.
But when I came here, first of all, I was completely and totally astonished that I would be considered a member of the observatory. I took that as a kind of requirement that I should get to learn more astronomical things — that is to say, to study stellar atmospheres more deeply, to study problems of dynamics more deeply. And so during my first three years at Chicago, I gave lectures on all these aspects of theoretical astronomy.
Weart:Was this because you felt deliberately that you should be sort of a theorist at the service of these people?
Chandrasekhar:I don't think I felt that I was needed to serve anybody; but I did feel that these subjects might give me scope for my own work. Particularly, I was anxious to give up stellar structure and go into something else. It came sort of naturally to me. I said, "If I can do things in stellar structure, why shouldn't I be able to do things in other branches of theoretical astronomy?"
Weart:I see. You said you were very struck that you should be invited to Yerkes. From England, had Yerkes and also the other big telescopes seemed like very important places?
Chandrasekhar:Sorry to say, I was not wise enough to think so. I knew that my time in Cambridge was coming up. I had only one more year. And when I got this offer from Chicago, I consulted my friends, particularly Eddington, and Eddington told me that so far as he could see, there was not much scope for my getting a position in England. And he thought that going to America would be useful to me. I took his advice.
Weart:Did people in Cambridge consider Cambridge to be the center of the astronomical world? Or did they regard the American observatories as extremely important?
Chandrasekhar:I think by the time I was through my six years in Cambridge, I had developed a great deal of respect for American astronomy. There was Hubble, of course, whose work I had got to know; and Shapley, J.S. Plaskett, Adams, Bowen, Russell of course. All this seemed to me astronomy of a different kind, but astronomy certainly worth pursuing.
Weart:OK. When you came over, you also married Lalitha Doraiswamy. You knew that you weren't going back to India at that point?
Chandrasekhar:Yes. We knew each other already in the late twenties when we were students together. While we were not officially engaged, we knew more or less that we wanted to get married, and we sort of kept up a correspondence most of the time I was in England. And in 1936 when I had received this offer from Chicago, and knew that I had to come to this country in January, '37, I went to India in '36, for the summer; and while there we met again, and we agreed to get married and come over to this country.
Weart:I see. You mentioned that she had been a physics student.
Chandrasekhar:She was a physics student, yes.
Weart:Which is why this book is inscribed to her. Then you got it back when you married her. That's the Sommerfeld?
Chandrasekhar:That's right, ATOMIC STRUCTURE AND SPECTRAL LINES.
Weart:Meanwhile had she been continuing in physics?
Chandrasekhar:Yes, she was continuing in physics. First of all she was a teacher for some time. Then later, she had joined the Institute of Science in Bangalore, hoping to do some research in physics.
Weart:I see. We have these questions that we ask everybody — we're always curious: how do you think the fact that you're a scientist has affected your marriage?
Chandrasekhar:I'll make one very broad, general statement. I am afraid that by giving to the pursuit of science the highest priority, one necessarily distorts one's personal life. That includes my marriage, in the sense that life has been very hard for my wife.
On the other hand, I do not by any means suggest that we have been unhappy with each other. No. I think I can say I've been as happily married as I could ever imagine having been married. And she has been of course an enormous source of personal strength to me. But still, you know, to devote one's time exclusively to science, and give everything else a second place, does not contribute to one's personal growth. In other things it's the same, particularly after I took the editorship of the ASTROPHYSICAL JOURNAL in 1952. The JOURNAL took a lot of my time. But if you look at my scientific record, for what it is — I don't say it's good or bad or anything of the kind — if people did not know that I was an editor, I don't think they would conclude from my scientific record that I was an editor for 19 years because I don't think that people would find in my published record any difference, either before or after my editorship.
Weart:It's very striking, in fact.
Chandrasekhar:It doesn't happen by itself. It was a conscious decision. When I took over the editorship I said, "My editorship is not going to affect my science." which means that in addition to my editorship and science, there was going to be nothing else. I had in fact time for anything else. When I was young, and when I was in Cambridge, I thought it would be marvelous to be able to read and memorize all the plays of Shakespeare. I still think so, but I still haven't done that. Well, was it worthwhile, to have pursued science in this single-minded way? I don't know the answer.
Weart:Do you think that other scientists you've known have had similar effects on their personal lives?
Chandrasekhar:I don't know. I'm afraid that by and large, have been a scientist entirely in myself. Of course, I have collaborated with my students; a number of students. The close association with my students has been the most valuable thing in life.
I may just make one remark, incidentally, that I worked with Fermi, and I worked with John von Neumann. People sometimes ask me: "Wasn't it marvelous?" And my answer is: "my association with my students personally has meant more to me than my association with these two people and the papers I wrote with them." It was nice, of course, to have known these great men, nice to have worked with them. But if you ask me, in the long range, who has influenced me more, I would say my students have influenced me more. That is one thing which is a different thing.
But I don't know, you see. I don't know enough about other scientists, my contemporaries, to make any judgement. And to the extent that I have read in the biographies of others, I've been unable to drawn any conclusions about what their personal lives have been.
Weart:It's often very difficult to find these things out, unless one happens to have, as with Karl Schwarzschild, we have his letters to his parents, where he tells sort of week by week what is going on with him. But unless you have something like that — and even then, what can one learn? And so, your wife and you were married in England?
Chandrasekhar:No, we were married in India. I went to India in July 1936 and we were married in September.
Weart:Oh, you were married in India.
Chandrasekhar:Yes. We came over to England in October, '36, and we stayed in England for the following three months. By the end of December, we came over to this country.
Weart:Did you go straight to Yerkes or did you stop at Harvard?
Chandrasekhar:No. Well, we stopped for a few days at Harvard.
Weart:When you were at Harvard before, how long were you there?
Weart:Three months. I see. What was your impression of Harvard? You were there during its busy years.
Chandrasekhar:I got to know a few of the people there. I got to know Gerard Kuiper very well, who later was my colleague at Chicago for many years, and a good personal friend. I got to know Fred Whipple (who has retired). I got to know Jerry Mulders, who was a fellow, postdoctoral fellow. I got to know Shapley, Menzel, Bok and Cecilia Payne Gaposchkin. But I'm afraid that there was a tremendous lot of sniping between different centers of astronomy at that time. For example, when I was offered the position at Chicago, I had a competing offer from Harvard.
Weart:Oh, you did?
Chandrasekhar:Yes. They wanted me to become a member of the Society of Fellows.
Weart:Why was that? How did that happen?
Chandrasekhar:I don't know. I was not involved with the politics. But I do know that the moment I was being considered for a position in Chicago, immediately there was a counter-offer from Harvard.
Weart:It was because they knew that you had an offer from Chicago?
Chandrasekhar:It might have been that. It might have been independent, I don't know. But anyhow, there was a counter-offer. Before I left the United States to go back to England in late March of '36, Henry Norris Russell invited me to stay as his house guest —
Weart:— in Princeton
Chandrasekhar:In Princeton. And he tried to persuade me that I should not go to Chicago, but go to Harvard. But when I went to England and I consulted my English friends, Eddington very strongly advised me to go to Chicago. And effectively, I took his advice.
Weart:Why was that, I wonder? What reasons did he give for your going to Chicago?
Chandrasekhar:Well, Eddington probably thought that Struve was somebody that he knew, and he thought the fact that Kuiper was being invited at the same time and that Stromgren was also being invited meant that I would be with a relatively younger group.
Weart:So it wasn't so much anything about Chicago itself.
Chandrasekhar:Well, he knew [the University's President], Hutchins, and Eddington told me that Hutchins was a very strong and upright man.
Weart:I see. Were there any negative feelings about Harvard? Or did you perhaps get any while you were there?
Chandrasekhar:I had a feeling that there was a — nothing very specific, but I sensed in a way, that the general attitude towards Harvard was not wholly one of admiration.
Weart:And while you were there, what sort of feeling did you get about it as a place? Especially coming right from Cambridge [England].
[Tape # 4 (Side 7)]
Weart:A newspaper clipping: "Hutchins finds professors no moral lights worse than most people, he says."
Chandrasekhar:Look at this.
Weart:FROM THE NEW YORK TIMES (Ca. 1968) "Hutchins cited incidents that occurred during his term as UC chancellor. He headed the university from 1929. The medical school of the university 'violently resisted admitting Negro students,' Hutchins asserted. On another occasion, he said, the chairman of a scientific department told him the university could not appoint a leading theoretical astronomer to its faculty because he was an Indian and black."
Weart:Indeed! Did you hear about that at the time?
Chandrasekhar:No. I didn't hear about it at the time, but I was a little surprised that when I came to Chicago in the March of 1936 and when Struve wanted to offer me the job, he took me to see Hutchins. The President of the university, does not normally see an assistant professor who is to be appointed. Then Struve later went to see the dean. But I stayed outside, while he went to see the Dean.
Weart:At the time you were just puzzled by it?
Chandrasekhar:Somehow, it made no special impression — I remembered the fact, but I did not draw any conclusion. But later on, I had reason to suspect that something of that sort was going on. In fact I learned later it is not connected with this story but it is interesting any way. Zachariasen told me this story (he was the chairman of the physics department): Dean Gale who was a professor of physics particularly interested in optics, was familiar with Raman's work, and Raman visited Chicago as Compton's guest in the late twenties. Compton knew Gale's interest in Raman's work, and so he had suggested to Gale to join himself and a guest of his at lunch at the club. When Compton and Raman were sitting in the club, Gale came in, saw the complexion of the man sitting next to Compton, turned around and walked away. Apparently Gale's predilection in this matter was known to others, but I did not know. In fact, I never met and talked to Gale, even though we overlapped in the physical sciences division, for several years. It's a remarkable story.
Somebody called me from the NEW YORK TIMES and asked me what I thought of this. I said, "Well, it simply shows that the University of Chicago was 30 years ahead of its time." I met Hutchins last summer when I was in Santa Barbara, and he recalled this remark of mine and said he was very pleased.
Weart:I see. Did you encounter racism already when you came over to Harvard?
Chandrasekhar:Not during the first three months I was there. But when I told my friends in India, particularly my father, they were all against my accepting the position in the United States, because they all felt that I would confront racial prejudice in this country. In fact, one of the arguments that was used by Russell to persuade me to accept Harvard, in preference to Chicago, was that in Chicago I would meet racial prejudice, whereas. in Harvard I won't. That's what he told me. I did not meet it at the university. But a year or two later, when my wife and I went to Columbia, we went from hotel to hotel, couldn't get any admission, and the only way we could finally find one was to call the astronomy department at Columbia and talk to an astronomer there. He met us at Grand Central Station, and found a place for us to stay. And several times later, I had similar difficulties.
Weart:Did you encounter further difficulties inside the university community?
Weart:It was strictly difficulties —
Weart:In the community outside. I see.
Chandrasekhar:I mean, not only did I not find anything in the university, or universities in general — I would say that the treatment I have personally received from various universities in this country, including most of all Chicago, is beyond all praise. Indeed, I was offered professorship in Princeton in 1946, when Russell retired, but I declined.
Weart:I see. Princeton is not noted as a place where —
Chandrasekhar:— no, but I was offered a position at Princeton University, when Russell retired, and I declined it. It was because I declined it that Lyman Spitzer and Martin Schwarzschild were appointed there at that time. So I don't think that I can point at anything prejudicial against any of the universities I have been acquainted with, in all my 40 years in this country.
Weart:I see. I wanted to ask you a little about Henry Norris Russell, and there's a particular reason for that. David DeVorkin is very interested in him, and in fact he's interested in doing a biography, possibly, of Russell (but maybe I shouldn't say this, it's still something he's considering). Anyway he'd like to know anything you know about Russell — how you encountered him, how he seemed to you, what his reputation was in various places.
Chandrasekhar:Well, let me say this — Russell was one of the most enthusiastic astronomers I've known. Enthusiastic about everything in astronomy. Intensely interested in what other people were doing and interested in encouraging young people. In some ways, it it surprising that a person with so much interest in others should have had so few students in his life. I remember his once describing his former students, how Harlow Shapley came to him. In fact, he said, "God sent me to him, when I had all that work to be done."
Then, Theodore Dunham, Donald Menzel, and Lyman Spitzer — I think that about covers all his students.
Weart:Not a bad list, even so.
Chandrasekhar:But still, for a person who was a professor in Princeton for 40 years?
Weart:Yes. That's quite striking. Why do you suppose that was?
Chandrasekhar:Well, astronomers as a rule don't take students. Shapley — who are his students? Hubble, Merrill, Campbell, Eddington, Jeans? Or take some modern people: Sandage has had no students. Somehow the idea of developing a school is simply not known among the astronomical community. There may be a variety of reasons for that.
This is perhaps a story which illustrates Russell's character: I was spending one quarter in Princeton, in 1941, the fall when Pearl Harbor happened. Russell used to give lectures, usually with three or four people. Gradually the people would disappear one by one and I would be the only person left; Russell would then come sit next to me, and talk to me.
At first it was astronomy; after a while, it used to turn to other matters. And then he started talking about his admiration of Eddington, and the fact that he didn't think so well of Jeans. It came out in a curious way. He was praising Eddington, for his having received the Order of Merit, and suddenly, "Well, I notice Jeans has now an Order of Merit. That must have taken a lot of pleasure out of Eddington."
He sat quietly for a long time; and then he said, "Well, I suppose it is not a crime for a person to live on his wife's wealth." — meaning Jeans retiring to Dorking Surrey (presumably on his wife's wealth).
Weart:Interesting. The lectures were such that the other students had trouble keeping up?
Chandrasekhar:Well, he started at 10 and used to go on till 12:30.
Chandrasekhar:So people simply couldn't stay there all the time. They had other things to do.
Weart:I see. Did he ever talk about personal things?
Chandrasekhar:Oh, he has talked about personal things. I mean, he talked about his disappointment — I remember very well, I don't know in what connection, we were talking about something about Coupling, and he said he had the Pauli Principle right in his hand and let it go, you see.
Incidentally, Russell made a tape, when I was at Princeton, which Lyman Spitzer had arranged: a tape of Henry Norris Russell reminiscing. It must be in their files.
Weart:Oh, is that so? At Princeton? We'll have to look for it.
Chandrasekhar:Yes. There is a tape which Martin Schwarzschild and Lyman Spitzer arranged to have made; Russell talks about his relations with Pickering, and how, when Pickering retired, he was offered the directorship at Harvard but wouldn't take it. And how he was extremely glad that Shapley took it.
I had a fair amount of contact with Russell. But at my time already he was interested only in analyzing spectra and things like that. But he was also tremendously interested in what other people were doing.
Weart:How did people regard him? How was he considered by people in the United States?
Chandrasekhar:All the people whom take for example Struve — Struve had the highest, highest regard for Henry Norris Russell. In fact, the University of Chicago gave him an honorary degree in 1941, at its 50th anniversary.
But I have a faint suspicion that he was not so well received on the West Coast. I heard a marvelous story Redman told me, about one occasion, when Adams was the director [of Mt. Wilson]. Russell was a great friend of Adams — there's the famous Russell-Adams calibration — and Redman told me that Russell came to see Adams, and went inside Adams' office, and for nearly two and a half hours, he heard Russell haranguing him. And finally they both emerged Adams looking very low, and Russell telling Adams, "Adams, you are too narrow."
Russell was tremendously enthusiastic. He used to talk non-stop. Tremendously interested in things.
Weart:Must have had a very strong personality.
Chandrasekhar:Of course, for him, ICS meant the Bible. (ICS is the INTERNAL CONSTITUTION OF THE STARS).
Weart:So he didn't have a particular interest in your white dwarfs either?
Chandrasekhar:Well, he was very dubious about it. For example, he never included it in any of his accounts on the subject.
Weart:Was it accepted at Yerkes, or I should say at Chicago?
Chandrasekhar:Oh, very well. Because Struve set the style, in my time.
Weart:In terms of your work on degeneracy and so forth, did you discuss it in the thirties?
Chandrasekhar:I discussed it with Russell but he was very non-committal.
Weart:And with Struve and so forth, did you discuss it with these people?
Chandrasekhar:They never knew anything about
Chandrasekhar:I'll tell you something — I don't know to what extent it ought to be on public record —
Weart:— you can always cut it out later on.
Chandrasekhar:One of my colleagues, in the middle sixties, was giving lectures on under graduate astronomy; and Jean Hopkins, who was a copy editor on the JOURNAL, (and still is) attended those lectures. And after the lectures she went up to the professor and asked, "What is Chandra's Limit, I hear about all the time?" "Oh, I don't know anything about it."
And A. Trautman, who is a very distinguished relativist was visiting me in 1971. He was invited with a group of astronomers, and members of the faculty were there. Trautman asked one of them, who was interested in galactic structure, "What do you think that the existence of this limit for white dwarfs implies for stellar populations and galactic evolution?" The man said, "I've never been able to understand Chandra's limit."
And I remember asking one of my younger colleagues, "Do you know about it?" He hemmed and hawed, "Well, I haven't read it properly." I said, "Do you really mean to say that what was accessible to an undergraduate student in 1930 is not accessible to you today?
And take Struve. In one of his early books on popular astronomy, he mixes up the white dwarf limit with the other one which is connected with the maximum mass of the isothermal core. When a star burns its hydrogen.*
(* The "Schonberg - Chandrasekhar" limit, as put forth in 1942. See APJ 96 (1942) p. 161.)
Weart:Yes. I remember when I was studying astrophysics, I had trouble knowing which limit was —
Chandrasekhar:— was which.
Weart:There are various limiting masses that people talk about, and I never could figure out which was —
Chandrasekhar:Well, after all, the fact is that astronomers — this is not a reflection on the persons involved, it's simply a reflection on the kind of education the astronomical community has — the fact simply is that the professional astronomer is not acquainted with these things. And indeed, not so long ago, I asked one of the graduate students coming up for his Ph.D. oral a question on the white dwarfs. And I was asked to shut up by one of my colleagues, because I was asking questions in which I was interested. What does come out is, really, that the astronomical community somehow was not receptive to theoretical ideas derived from theoretical physics.
The situation has drastically changed, during the sixties. Particularly with the development of X-ray astronomy, and the theory of pulsars. Now people realize that all this is not so far-fetched. But right up to the early sixties, I don't think they accepted it.
To come back to your question as to how I was treated — I think the answer is the following: As far as I am concerned, if I ask myself: was I appreciated? How do I judge it? Do I judge it from the awards I have received? Certainly, the Bruce Medal came to me when I was 40. The RAS gave me the Gold Medal. I was elected to the Academy, and so on. There is clearly nothing in the record which suggests that I was not appreciated. And personally, certainly, if I consider appreciation from that point of view, I certainly was. As I have said, very much more than would have ever thought I deserved. But on the other hand, if you ask me if my particular work was understood, as a relevant part. I'm afraid there was an enormous time lag, between when the work was done and — when it got absorbed in common knowledge. But that itself is not surprising. Sometimes a work of this kind takes some time to get into the main stream.
So everything I've said simply adds up to the following, that the problems or astronomy, during the time I was active, excluding the last 10 or 15 years — theoretical work never became a integral part of astronomical development and astronomical appreciation (in a genuine sense, not in terms of personalities).
Weart:Specifically, at Chicago and Yerkes, in the late thirties and after, for a long time you were the only theorist? You regarded yourself as the only person doing theoretical — ?
Chandrasekhar:— because Stromgren left very soon afterwards. But he came back later. I was the only person.
Weart:When Stromgren was there — ?
Chandrasekhar:Stromgren came in '36, fall, and he left in '38, spring. So we overlapped for a year and a half.
Weart:So did you feel that you had some support? Was this when you first met him?
Chandrasekhar:No, I had met him in Copenhagen.
Weart:Already in Copenhagen, I see.
Chandrasekhar:I had considerable contact with Stromgren that year and a half when we were together at Yerkes. My contact with him was very slight afterwards. But during that year and a half, we had constant relationship.
Weart:What sort of other relations did you have, whom did you talk with about theory? Physicists?
Chandrasekhar:Kuiper was very interested in the theory of white dwarfs, because he was working white dwarfs. He was one of the few astronomers who wanted to integrate theory and observations. So I had considerable contact with Kuiper. I think I would say that Kuiper was about the only person on the faculty with whom I had contact during that period. On the other hand, starting in the early forties, I went on into other areas, where the contact was not very great in astronomical terms.
Of course, the whole character of my work changed in 1950 or so, because at that time I changed my field of interest to hydrodynamics, hydromagnetic stability and I got into contact with the physicists on the campus.
Weart:And the mathematicians?
Chandrasekhar:Well, the physicists, Fermi, and Wentzel were the principal persons; and then I came in contact with the geophysicists like Dave Fultz who did experiments for me, in some of these convection predictions.
Weart:But up until that point, had people in the astronomy department in general had much contact with the physicists?
Weart:They were sort of off by themselves.
Weart:I'm not sure what kind of working conditions you had. Where were you located physically?
Chandrasekhar:I was located at Yerkes till 1964. However, after 1946, I used to come down to the campus once a week to give lectures here on the campus. In the middle fifties, we had an apartment in the city here, so that I could come and stay over night. So we used to spend part of the week here, Chicago, and then the rest of the week at Williams Bay. Then by the early sixties it became clear that there was no point making this tremendously exhausting drive back and forth every week, and so we came over to Chicago permanently.
Weart:I see. During the thirties and the early forties, did you get down much or did people at Yerkes in general get down much to Chicago, to lecture, to talk?
Weart:So in fact, there wasn't much opportunity even to interact with the physics department?
Chandrasekhar:That's right. I had some contacts, in spite of it. I used to know Carl Eckart quite well. Particularly during the war, when Wigner was here, I used to come down once a week to Chicago to talk to Wigner.
Weart:Just to talk to Wigner?
Chandrasekhar:Yes. He had a lot of influence on me. I was interested in the theory of H minus and at that time, and I could talk to him about it. He is very knowledgeable, even though it was sometimes difficult to draw him out. I used to persist, and I got a lot of encouragement stimulation, from talking to Wigner here in Chicago during the war.
Weart:I see. One thing I never quite understood about Yerkes and that is, how it maintained a teaching program? How did it teach the undergraduate level?
Chandrasekhar:We didn't teach undergraduates.
Weart:There were separate people here [in Chicago] teaching.
Chandrasekhar:No, there was no undergraduate teaching.
Weart:There was no undergraduate teaching in astronomy?
Chandrasekhar:Except when Bartky when he was here, he might have lectured. Walter Bartky was in the mathematics department and also in the astronomy department. He was a pupil of Macmillan. And he used to teach some undergraduate astronomy. In fact, he has a book on astronomy (Highlights of Astronomy?) an elementary textbook on astronomy which Bartky published and from he used to teach. But he stopped doing that in 1940-45, during the war and later.
Weart:Now, you were doing graduate instruction. In fact, you were put in charge of graduate instruction.
Chandrasekhar:I was in charge, and if you look at the old catalogs of the university, you'll find that I taught anywhere between one-third to half of all the courses that were taught at that time.
Weart:How did it happen that you were put in charge of that in the first place?
Chandrasekhar:Well, Struve put me in charge. In the middle fifties the department decided that the kind of things I was teaching was too theoretical, and they changed the style of teaching. But up to that time, the faculty was small, and I was the only person willing to do the teaching, and I did so pretty well most of the teaching. And of course, you know, my students of those times — three of them are in the National Academy: Don Osterbrock, Arthur Code and Guido Munch. Jerry Ostriker was a student of mine over the protest of the Department in early sixties; and he is also in the National Academy.
Weart:I see. You must have been spending quite a lot of your time in teaching then?
Chandrasekhar:But I integrated my teaching with my own research.
Weart:You would be teaching theory, and then you would be working out?
Chandrasekhar:For example, I started teaching stellar atmospheres. I went on into working on radiative transfer and then on to the problems relating to Hydrogen.
Weart:I see. Would it be possible to say how much time you were spending on teaching, how much on research, how much on administration and other matters?
Chandrasekhar:I would say that during the first ten years of my stay in Chicago, I did not consider my teaching and research separate. I was doing graduate teaching, and since I was not a trained astronomer before, I started teaching astrophysical courses like stellar atmospheres, stellar dynamics, interstellar space, galactic structure and all these things, and my research was integrated into my teaching. So that many of my students used to attend the lectures year after year, because each year it was different; I was doing different things. For example, during the middle forties, when I was lecturing on stellar atmospheres, Lawrence Aller, who used to be in Michigan, used to come down to Yerkes to hear my lectures. Because I was teaching many things that were never taught elsewhere. So, while I gave a lot of lectures in those days, on everything I lectured, I was doing research.
Weart:You practically published what you'd been lecturing —
Chandrasekhar:Lecturing and doing research in those years were the same activity. But then, the only administrative thing I ever did was during the year when Struve left Chicago and went to Berkeley, and Stromgren was yet to come: I was acting chairman that year (1950). But apart from that, I have add no administrative responsibility of any kind.
Weart:I would think that being in charge of the graduate program would have a lot of administrative responsibility.
Chandrasekhar:But graduate students are not very many. Practically all the students that came there worked with me. So I had effectively no administrative problem. On the other hand, in 1950-51, I expected the character of my life to change discontinuously.
Weart:Was it because of the chairmanship?
Chandrasekhar:No. Because I was changing my field of interest into hydrodynamics and hydromagnetics
Weart:We'll have to come back to that — What about your colleagues at Yerkes? What kind of hours did people keep? Did they spend much time teaching?
Chandrasekhar:On the whole my colleagues spent very little time on teaching. They did some, but very little. They never gave what I would consider systematic courses. But during the forties, some of the best things connected with the university were done. Struve was at the height of his career, doing marvelous work on peculiar stars; Morgan's best work on the spiral structure was done during those years; Kuiper in the course of one year discovered the inner satellite of Uranus, the outer satellite of Neptune, carbon dioxide on Mars and the atmosphere on Titan. Hiltner's discovery of inter stellar polarization was also at that same time and we had visitors from Europe. Minnaert spent a year with us, Oort spent six months with us, and UnsÃ¶ld was there for some time. And Van de Hulst was a postdoctoral fellow working with me. Actually I would say, from 1946 to about 1949 was the period in which, certainly retrospectively, the department reached its heights. I'm afraid it eventually declined, for a number of years, but I think it's back again on the top now.
Weart:We'll have to talk about that too when we come to it. Particularly, sort of your early impressions-you must have compared it with Cambridge. Did it seem to you a place where people worked very hard, where things were organized differently from Cambridge, where professors and students had a different kind of relationship from what they had in England?
Chandrasekhar:Well, you have asked this question several times. But I want to explain my state of mind in those days. I always felt that I was in Cambridge and also here in the United States on sufferance. In other words, to me, the external circumstances did not play any role on my life. For example, I was a fellow of Trinity for four years, and the fellows meet and vote on various things. At meetings of the college council, the college foundation. And in all my years in Trinity, I never voted once, even though I attended all the meetings. Somehow, I thought that it was not proper for me to contribute to the decision by voting.
I did not feel differently when I came to Yerkes. It did not seem to me that I was there for any other purpose except for doing my work. To take an example [telephone rings] — when I came to Chicago and joined Yerkes, all my colleagues had full-time assistants. I never had any, till 1944; and the thought that I was discriminated never even occurred to me.
Weart:I see, and you hadn't even asked.
Chandrasekhar:I wrote all my —
Weart:— I hope I'm not getting in the way of your phone calls.
Chandrasekhar:No, no that's all right, it's not very important anyway. I was saying that, for example, till 1943, every manuscript I wrote, I wrote longhand. And my first two books were written and sent for publication on longhand; my entire STELLAR STRUCTURE and STELLAR DYNAMICS, and the article in the REVIEWS of MODERN PHYSICS to mention three — they were written longhand and sent to the publishers longhand.
Weart:— in longhand, I see.
Chandrasekhar:In fact, the archives that you saw in the Requisitions Library contains the handwritten manuscripts of my STELLAR STRUCTURE AND STELLAR DYNAMICS. I did not have any assistants, and all my letters I wrote longhand. And it never occurred to me that some discrimination or something was made. I do not know whether it was discrimination or not, but the fact is. Now, these things sometimes puzzle me but then I never asked myself the question, "Is this functioning the way it ought to function?" I never did. So, looking back on those times, the thing which surprises me is how little I considered as relevant to my career what was going on around me. I got something positive — well and good. If I did not get anything — well, it made no impression on me. So this is an essential fact.
Weart:I can understand this. And particularly, being a theorist, you don't have the same interest in the institutions that an instrument man would.
Chandrasekhar:So long as I was allowed to do my work, and nobody interfered with me, and I had full access to publishing what I wanted to publish then I had all I wanted. Struve in fact made me an associate editor of the ASTROPHYSICS JOURNAL in 1944, and so I could essentially publish whatever I wanted the ASTROPHYSICAL JOURNAL — so, I thought I had everything I wanted. The rest didn't matter to me.
Weart:Tell me, what was Struve's style as a leader?
Chandrasekhar:Struve was a very extraordinary man. He was autocratic in many ways, but I never had any personal difficulties with him myself. He had only one interest and one concern, namely, that astronomy should be developed and pushed to the maximum that was possible.
When I first saw him, he was a very distinguished man, already in his mature period, and the staff which he built was all in their twenties, and all of us looked up to him and never questioned his authority or his judgement.
But when the middle 1940's came along, even though as far as I can remember my attitude to him hadn't changed — he must have felt that the difference between him and his colleagues was diminishing; and he used to sometimes behave in a very funny way. For example, I remember we used to give him our annual reports. He had assembled them all and after one year, (it must have been '46 or '47) he called a meeting of the faculty, in which he had the reports of all the people in front of him, and he said he wasn't satisfied with the progress that each of us had done. Then he passed around the SCIENTIFIC MONTHLY, in which there were pictures of some natives in Africa with elephantiasis, with enlarged legs and limbs. He passed the picture around and said, "I have to deal with a faculty in which each member has elephantiasis of his own capabilities." That was a very rude thing to say and you should remember that the faculty at time included Herzberg, Hiltner, Morgan, Kuiper, Greenstein, Henyey and myself.
Weart:So long as he said it to everybody at once —
Chandrasekhar:He was tremendously interested in the development of astronomy, very anxious to serve it the best way he can. His ideal was Hale.
Weart:Is that so?
Chandrasekhar:Yes, his ideal was Hale, and he imitated his life, I think even consciously. You know, Struve was responsible for building the MacDonald Observatory at Texas.
Weart:Yes, I was going to say, it sounds like this must have something to do with the origins of McDonald [Observatory].
Chandrasekhar:Yes. And he wanted very much to be treated the way Hale was treated in the latter part of his life. It was his great disappointment to him that he felt that he was not so treated. Struve was a man given to great moods of depression, but in his happier times, a marvelous colleague and certainly, he ignored all irrelevancies and concentrated on what he cared for) namely astronomy. I don't see how one could have a better director. He was intensely interested in astronomy. That was the only thing which mattered to him. And he looked at all his colleagues in terms of what they were doing for astronomy. And he was sensitive to his own place in astronomy, perhaps even in a morbid way.
Weart:I suppose that could be in part because of his ancestors and so forth. That must have had a powerful effect on him.
Weart:You know, speaking of Struve, Stromgren, yourself and so forth, all people coming over as foreigners, and then of course there were the refugee physicists, we mentioned Wigner, and others. I wonder what effect you think this may have had on the development of American astrophysics and astronomy, in the thirties and after?
Chandrasekhar:I think obviously the effect has been very profound. Bethe's carbon cycle of 1939 — the nuclear reactions that he postulated at that time — has become a central part of astronomy. And —
Weart:— but in terms of what it may have done to the American approach to astrophysics and American institutions.
Chandrasekhar:I don't want to say "American." Because the difference between scientists in one country and another is less than the difference between scientists and the rest of the community in any country. You understand that. So I don't want to use the word "American" either in the chauvinistic sense or in the derogatory sense.
Weart:Let me put it in this way. Bethe presumably could have done the carbon cycle had everybody stayed in Germany. And so forth. But what difference may it have made to the development of modern astrophysics, that so many people came over to this country?
Chandrasekhar:I think, purely in an objective way, I'd say the following. The development of astronomy during the 19th century, made a very big change. First they measured the parallaxes and proper motions; then they started to measure radial velocities; then they began taking spectra. Well, clearly, one had accumulated an enormous amount of information. And so astronomy centered on accumulating data.
While this is an essential component in the progress of astronomy, it also meant that astronomers got separated from the rest of the scientific community. Take a man like Aitken. He goes to Mt. Hamilton, spends his whole life measuring orbits of binary stars. Or take someone like Campbell, who said that everybody in his observatory had to measure radial velocities. Or people who look at variable stars — everybody has to draw light curves, thousands of them, and they take pride in the fact that a millionth setting has been made. One can be sarcastic about all his but one shouldn't be, because the core of astronomy depended upon getting these observations. But it also meant a change in the character of their lives. And principally in America, because here they built all these observatories, it meant that the concentration of the astronomical community was in this data-gathering process. A person can start at the beginning of his life to do one thing, and he does the same thing the rest of his life. Whereas the astronomical people who came from Europe were not in this tradition. Like Bethe or me or Martin Schwarzschild. And consequently, this group played a role in the progress of astronomy, in the sense that astronomy now had to change its character, had to go into understanding what the observations meant. And the American astronomical community, up to the thirties, forties and even the early fifties, had been built around the enormous job of gathering data.
It just coincided, historically, that at the time that astronomy needed a change of pace, it was fortunate that people with that appropriate training happened to be here. So I think that to say that these people made American astronomy is false — if it means a chauvinism, then it is wrong. The point is, sometimes important things happen because of historical coincidences. And there was this historical coincidence, in which the progress which could probably have taken place in time on its own initiative was helped by historical circumstances. Therefore, if one writes the history, one would find that people with a different backgrounds and a different training helped the growth of astronomy along directions which astronomy was waiting for, and which probably would have taken place in any case.
It is still true that the fundamental centers of astronomy were devoted to gathering data. But astronomy canon have developed entirely only in that direction; it had to change. The change took place, and it was accelerated perhaps by the kind of people who were here at that time.
Weart:That's interesting. The kind of courses that you taught, for example, must have been quite different from the kinds of courses that had been taught before.
Weart:You must have had some picture of the other teaching. How did the teaching here at Chicago compare with the kind of teaching that had gone on at Trinity, in terms of the content, in terms of the situation?
Chandrasekhar:Well, I would say that the kind of teaching in astronomy which was initiated in the thirties and forties was different from what was in England at that time, and from what was in this country prior to that. Because in England, there was no program in astronomy as such. During the years I was in Cambridge, there was a course on the internal constitution, which Eddington used to give; a course on relativity; a course on combination of observations and Stratton used to give one course every term on astrophysics and occasionally a course in spherical trigonometry.
Whereas, the course which I started to give here, which very soon were repeated in many other places — like a three quarter course in stellar atmospheres, a three quarter course on stellar evolution — these are completely filled-out programs. And now the programs in astronomy which are given in Europe are modeled after what has been done here.
So I think in a sense, due to circumstances, the character of astronomical teaching changed, in this country. Changed first, and later changed also in Europe.
Weart:What was it like before? Of course you weren't here so you wouldn't have had too much contact.
Chandrasekhar:There were no courses in astrophysics given at all.
Weart:None in astrophysics?
Chandrasekhar:Graduate teaching, the way it was given in '37, was started completely anew.
Weart:Did you encounter any resistance?
Chandrasekhar:No. Struve was the boss and Struve said, "You have a free hand."
Weart:I see. What about the students? They must have been a bit stunned by it at first?
Chandrasekhar:Yes, in the first year or two. But they got along.
Weart:Let me ask you a bit more about the social character of Yerkes, because I really don't know much about it. For example, was there a regular seminar that people went to?
Chandrasekhar:Yes. In fact, Struve asked me one of the first things, was "Chandra, we must have a weekly colloquium; and that is your responsibility.
Weart:A theoretical colloquium.
Chandrasekhar:No, a weekly colloquium. I started running it, and gave the first colloquium I organized, the number 1. And I kept it on myself, up to about a thousand. Which it reached in 1962.
Weart:Had there been colloquia before?
Chandrasekhar:Apparently randomly at intervals, but after Struve asked me to do it, we had it every week.
Weart:Why did Struve pick you to do all these things?
Chandrasekhar:Well, according to him, everybody else had real jobs to do — namely, to go to the telescope and observe. I was there sitting in the office, never worrying about whether it was clear at night of not.
Weart:I see. You didn't have to get up in the middle of the night, I suppose.
Weart:So how did you organize this colloquium? How was it run?
Chandrasekhar:First of all, I tried to arrange that all the faculty participate: one week after another. And then I used to get people from the physics department on the Campus and an occasionally when visitors passed through, I used to have them talk.
Weart:I see. But it hadn't actually been done that much before?
Weart:Aside from the colloquium, in general, where and how did the staff exchange ideas about research?
Chandrasekhar:Well, during the first few years, Struve for example used to attend all the other courses that were given.
Weart:You mean, come and sit in?
Chandrasekhar:That's right. And I used to sit in on his courses.
Weart:Were all the courses on this kind of an advanced level, that it would be profitable?
Chandrasekhar:To some extent, yes. And of course, I tried to learn from others, and they tried to learn from me.
Weart:I almost get the impression that the courses, in some sense, were like an ongoing colloquium.
Weart:Would Struve comment perhaps while you were lecturing?
Weart:Were there other places where you would tend to meet people, in the observatory? After hours? Much socializing?
Chandrasekhar:There was some socializing, yes. But the observatory was the center, and most of the people used to work in the evenings. I remember, there was a visitor from Australia who came and I met him some years later. He said that when he first came to Yerkes, ('46 or '47) he arrived at the observatory at 7:30 one evening, and he was shocked to find that all the faculty were in their offices. Struve was there, Kuiper was there, Morgan was there, I was there, and everybody was there.
Weart:That's very different from the British way, isn't it. Isn't Rutherford supposed to have locked up the Cavendish in the evenings or on holidays and so-forth?
Weart:I was just up there yesterday, of course, and I saw the "battleship" dormitory where the graduate students lived and so on. I almost get the impression of a semi-monastic existence, everybody very concentrated on astronomy. Is that the feeling that one got?
Chandrasekhar:That is what it was like in those days. During my years at Yerkes (by which I would mean essentially the late thirties and forties, those 15 years, that's the period I would call my Yerkes period) it was a scientifically and socially integrated community. Struve, as the unquestioned leader of the group, producing stability and balance. All of us were interested in one thing: to do the best work we are able to. And certainly in the late forties, after the war, we had some of the very best students we have had — as I told you, the three or four names already, and besides there were Ann Underhill, Nancy Roman, Frank Edmonds, Marshall Wrubel and then we had visitors like Stromgren and Minnaert and Oort. We never felt we were an isolated community, working in a vacuum. That feeling came to me after the early fifties, when I found I had to come to the campus every week.
Weart:After the decine had set in. I see. Back in this very vital period, was there much discussion of things outside of astronomy? Was there much talk about biology, politics, philosophy?
Weart:What about physics? Did people discuss new physics?
Chandrasekhar:Well, of course, Fermi was on the campus, and his influcence began to be felt. He came to Yerkes once or twice and I became friends with him, and I used to come to the campus to talk to him.
Weart:About the contact with physics, I wanted to ask you some questions about his remarkable 4th Annual Conference on Theoretical Physics at George Washington Univ. in 1938 that you went down to. Do you know, for example, how that was organized?
Chandrasekhar:That was Edward Teller's and Gamow's idea. They were at the University of Washington and they were interested in astro-physics at that time, and they arranged the conference. It was a marvelous conference. Rosseland was there. In fact, have a picture of the group which assembled there, somewhere.
Weart:Do you recall, what was the character of this conference? It must have been one of the first times, I suppose, that these people got together, these different kinds of people.
Chandrasekhar:First of all, there was a talk by Gamow on the nuclear reactions and Weicker cycles, based on Helium-5. Then, I remember, I gave a talk on the theory of white dwarfs, and Strömgren gave a talk on hydrogen abundances and the H-R diagram. Then Bethe got very much interested in the nuclear aspects, and Bethe one morning said that he had thought about Weizsäcker's cycles and that he had alternative ideas, and he gave a talk right at the meeting on his carbon cycle.
Weart:I see — was that the carbon cycle then already?
Chandrasekhar:That's right, he gave the carbon cycle, exactly as he formulated it. And later he wrote the paper, and I read it. He gave me preprints of it and so on.
Weart:I see. Because in that thing you published with Gamow and someone on the conference,* you don't mention the carbon cycle specifically. You simply talk about the idea of helium, and two protons getting together, and the possibility of the proton-proton cycle — * "The Problem of Stellar Energy," with G. Gamow and M. Tuve, NATURE 141 (1938), 982
Chandrasekhar:that was also mentioned by Bethe, you see.
Weart:Oh, that was Bethe who mentioned the proton-proton cycle?
Chandrasekhar:Critchfield was there, and then of course, there was the question of the Gamow-Teller selection rules, or the alternative selection rules. Bethe proposed that hypothesis, then.
Weart:— and the possibility of resonance levels was brought up — even something of the idea of shell burning —
Weart:Were some of these ideas new to you, this nuclear physics? Had you had much contact with nuclear physics before?
Chandrasekhar:It wasn't new to me the sense that I had not read about these things. In fact, I gave at Yerkes that year a course on nuclear physics, based upon Rasetti's book which had just come out. I tried to keep abreast of what was going on at that time.
Weart:What I'm trying to get at is whether this conference had a different character, in that the physicists were listening with great interest to the astrophysicists?
Chandrasekhar:The only physicists who were there, physicists who were in some sense committed to the subject were — Teller and Gamow and Bethe, who was a great friend of theirs Bethe was of course an expert in nuclear physics, and could pass judgement on nuclear physics, and of course you know, his ability to grasp things is so large that once he felt there was an area for nuclear physics there, he just bull-dozed in. And I think among the other physicists, there was Gregory Breit among the group, I remember, and Inglis was there, and Tuve. I think that was about all. Among astronomers, there was Rosseland and my student Mario Schönberg was there.
Weart:I think you give a list in your article, in fact.
Weart:It's extremely interesting. We're still talking about the thirties, and I guess the next thing to ask is about your INTRODUCTION TO THE STUDY OF STELLAR STRUCTURE,* and how you came to it. The book itself is in a way self-explanatory. I was interested that you said in a way you came upon it from the white dwarfs, that you wanted to sort of do the white dwarfs and set them down. Were there other things, other reasons also? * University of Chicago Press, 1939
Chandrasekhar:No, the fundamental reason was essentially that I felt that my future in science depended upon going into other areas, and that there was no point in my harping on topic and I simply decided that I would write a book putting all my ideas together, and extricate myself from the subject in a gradual way.
Weart:Did you work on this over a long period?
Chandrasekhar:No, I wrote the whole book in less than a year. I wrote it almost entirely in '38. I started in spring and finished it by the end of '38.
Weart:I see, and you simply submitted it to the press.
Weart:It's very straightforward. It seems like we ought to say something more about such an important book, and yet I suppose it simply stands there. Did you have any feeling about it at the time it came out?
Chandrasekhar:I was pleased with the way the book came out, but I don't remember any special exhilaration.
Weart:What sort of reaction did you get from your colleagues, to this sort of a book?
Chandrasekhar:Not very much I should say, at that time.
Weart:Also, about this period — I don't know whether you're the right person to ask, but McDonald was founded and so forth. Were you —
Chandrasekhar:I was present at the dedication of it.
Weart:Were you familiar with all that went on?
Chandrasekhar:Not really, no.
Weart:We have the director's files, letters and so forth, on that. Well, let's see, we have to wrap up the thirties. One thing that I wanted to remark, I notice a general absence of interest in general relativity and cosmology, all sorts of cosmology. Do you recall whether you had any strong feelings about general relativity theory and cosmology? Did you feel it was a field in which much progress could be made at that time?
Chandrasekhar:Actually, I had made up my mind at that time general relativity and cosmology are the two areas in which I did not want to write. Because I felt that the involvement of Eddington and Milne, particularly, in general relativity essentially ended their careers After all, Eddington started working on these cosmological things in 1928, and he kept on it till 1944, and I felt it was all wasted. Similarly Milne started his kinematical relativity in 1931, when he was in his late thirties, and he kept on for the next twenty years, and it all evaporated. I told myself that I did not want to go into that region; so I just wanted to settle on safe grounds. I was to return to relativity in the early sixties, and I remember that in 1961, when I had finished my book on stability, I wanted to change my area of interest and I was wondering where I should turn, and I thought I would go into relativity. But I was really skeptical whether I should or not. I remember talking to Gregor Wentzel, who was a great friend of mine, and asked him what he thought of it, and he said, "Well, Chandra, if you want to work on relativity, why don't you go ahead and work on it?" I said, "Well, maybe I won't get anything very much." He said, "They can't fire you." So I gradually got into relativity only in 1961, '62, but even that after very considerable hesitation. Retrospectively, I think I did the right thing, both in not getting into relativity before, and in getting into relativity at that time. It is very difficult to rewrite one's life, but I think I'm able to do relativity at the present time, in spite of so many absolutely first-rate people working also [in it], largely because I have a background which enables me to do work in relativity of a kind which other people won't be doing. Therefore, coming at the stage I did, it was probably the right thing for me. But on the other hand, I doubt very much whether to have worked on relativity at an earlier time would have been as profitable.
Weart:Did other people feel the same way, do you suppose, about general relativity at that time?
Chandrasekhar:I don't know what other people felt. But I do know that it's true, they did not have very much respect for people who worked in cosmology.
Weart:What about even extragalactic problems and so forth?
Chandrasekhar:We were not doing any extragalactic problems at all. Everyone thought extragalactic astronomy consisted of one thing only, namely, the expanding universe. And Hubble was doing that, with the telescope that was available, and there was very little to do outside; that was what people thought.
Weart:Was this Struve's idea or was it generally accepted?
Chandrasekhar:I think it was probably the general feeling. Extragalactic astronomy, as a part of astrophysics, was a much later development in the sixties.
Weart:It was the feeling one couldn't compete with Mt. Wilson and Lick?
Chandrasekhar:Yes. Op the observational side certainly.
Weart:Which is reasonable, I suppose. It's hard to get a picture of the general field at the time. You mentioned in the 1972 Halley Lecture* that the staple of astronomy is the study of stellar energies. You mentioned that earlier, the question of where the energy comes from. Were you interested in evolution? I don't see it too much in your papers, and yet I get a -feeling from what you're saying that you were interested in the problem of stellar evolution?
Chandrasekhar:I was interested in it, but of course, due to historical circumstances, I gradually got out of the area. But on the other hand, the subject became the center in the forties. Martin Schwarzschild started writing on it, and all these evolution calculations started going on. If one looks at the astronomical literature, and certainly from the vantage point of the editor of the APJ, the one thing everybody was doing was drawing zero-age main sequences, and how to interpret the populations, how to interpret element production. Certainly the characteristic of astronomical development after '46, is one in which nucleosynthesis evolution of stars, was both the center of theoretical work, and the center of observational work. But at that time, I had dissociated myself from that line of development and was doing other things.
Weart:I wonder how in general you kept up with what was going on? Of course you had a lot of conversation around the department and so forth, but I wonder also, did you get a lot of information about the general state of what was going on from meetings, from letters?
Chandrasekhar:No, as an editor.
Weart:I'm thinking now again before that, before '46.
Chandrasekhar:Then before that I was going to meetings. I used to be rather regular in attending Astronomical Society meetings.
Weart:Were these important in getting to know what was happening, or did you already get it just by being at Yerkes?
Chandrasekhar:No, half by being at Yerkes and half by going out. Of course there were people like Oort and Stromgren with us, - both extremely knowledged.
Weart:What journals did you read regularly during the forties, let's say,? APJ of course.
Chandrasekhar:APJ, MONTHLY NOTICES, ZETTSCHRIFT FUR ASTROPHYSIK. I was getting interested in hydrodynamics, so I was looking very much into the PROCEEDINGS of the Royal Society, which published much of the literature there. *"The increasing role of general relativity in astronomy," OBSERVATORY 92 (1972), 160-174.
Weart:I see. OK, now we should talk about where you went next. Of course, all this period you were producing many papers on many subjects. I'm just trying to guess what the high points were. I guess the next high point is PRINCIPLES OF STELLAR DYNAMICS.* And your whole work on relaxation times. How did you happen to pick this problem next?
Chandrasekhar:Well, it all started by my having to give some courses at Yerkes on stellar dynamics. I read the books which were available at that time, Smart's STELLAR DYNAMICS in particular, and it seemed to me that the whole subject was in a terrible mess; the simple problem of relaxation hadn't been worked on properly. When I went into a new subject like stellar dynamics or stellar atmospheres, I tried to study what other people had written. And I asked myself, "does it satisfy me?" And I found that in stellar dynamics at that time, one of the major problems was the problem of relaxation through two-body encounters. Nobody had done anything very rigorous about it, so I just said to myself, well, I ought to be able to do that.
Weart:Did it strike you as a serious problem because of the problem of getting the age of the universe and so forth?
Chandrasekhar:It came later.
Weart:That came later?
Chandrasekhar:Yes. I realized the implications of it as soon as I started on the work.
Weart:I see, it was after you had started working on it. That's interesting. I almost get the picure, from this and from other things you've told me before, that you studied a great many things, particularly in connection with yourteaching and so forth —
Weart:And then when you found a field — all through your career, when you found a field which was in mess, then you would go in and straighten it up. Is that a fair — ?
Chandrasekhar:That's the way I went about it. Except in relativity.
Weart:Where there's more of a continuing — ?
Chandrasekhar:— well, in relativity, you see, I went in as an outsider, with diffidence. * Univ. of Chicago Press, (1942.)
Weart:This is in the sixties you're talking about?
Chandrasekhar:Yes. I went in with diffidence. And of course in relativity at the present time, there are enormous numbers of extremely competent people working. But the situation was not that in the other areas.
Weart:They were neglected areas.
Chandrasekhar:Neglected areas in which the people who had done work before, up to a point, had made a mess of it.
Weart:Or just hadn't gotten very far.
Weart:And hadn't done it.
Chandrasekhar:Yes. For example, I took radiative transfer, and I asked myself, "How do you write down the transfer equations of polarized light?" There was nothing on that. Nothing
Weart:— nothing had been done?
Chandrasekhar:Nothing had been done, so one starts right from the beginning. So in many ways, getting into general relativity as late as I did was a most risky thing for somebody like me to have done.
Weart:Yes, I understand.
Chandrasekhar:From my earlier background.
Weart:Though of course you had the mathematical background, or the theoretical background.
Chandrasekhar:Yes. But apart from that, I had no reason to believe that I could make success of it, because I didn't even know what problems to work on. Whereas in other areas, you see, I started reading the subject, I found it in a terrible mess, and thought, "My God, I ought to put this straight," you see.
Weart:In these other fields you didn't really have competition.
Weart:That's very interesting. I hadn't seen that before. That's true, when you were working on these books and so forth, there wasn't anybody else who was working on that thing at the time. Or likely to be. A little technical question on the relaxation times work — a technical sociological question, I should say — in the 1940 paper,* you thank "Mrs. T. Belland, who carried out the entire numerical work *"The dynamics of stellar systems. IX-XIV." APJ. 92 (1940), 441-642. connected with the tables." I'm interested in this because one knows that some time around in this period, numerical methods and powered machines and so forth began to become important. I'm curious about you whole introduction to numerical methods and machines and so forth — at what point did that come in?
Chandrasekhar:Of course, you know, in 1935 when I did my white dwarf work I had to integrate all the white dwarf functions with a hand computer.
Weart:Turning the crank, I suppose?
Chandrasekhar:Yes. And I realized that in order to complete a theoretical problem, one had to have numbers. I was fortunate that at this time, Mrs. Belland was there, and Struve did not have any work for her, and he asked me, "Could you use her?" I said, "Well, I have this problem to work numerically," and so it started that way.
Weart:She used a hand calculator.
Weart:Were there people around Yerkes to do calculations?
Chandrasekhar:There were people; Struve had an assistant who reduced all his spectra, and van Biesbroeck was there with his comet orbits to be computed. So there were computers [i.e. computing assistants] in the observatory, yes.
Weart:This was just the first time that you had had the use of one.
Weart:After that, did you retain one?
Chandrasekhar:Gradually I started out. After the war, I had Mrs. Francis Breen who worked with me for some time. She did a lot of calculations for me on H minus. And of course, in late '49 Donna Elbert started working with me, and she is still with me here.
Weart:It wasn't till after the war that you started to use punched cards and that sort of thing?
Chandrasekhar:I've used very little of it, really.
Weart:Still haven't used much of it. That's true, I see. Now, to get back more specifically to stellar dynamics and relaxation times. At what point was it that you began to get interested in the age problem? Almost immediately after you started working on it?
Chandrasekhar:Yes. Because very soon I started working on the related problems of galactic clusters and the escape of stars from them. That immediately impinged on the age of the universe, and so I got into it. And Kuiper was there, who was very much interested in the age problem.
Weart:It seems to me that the age problem is a problem that runs all through the thirties, this problem of reconciling things with the radioactive ages?
Chandrasekhar:Yes. There was a part of that in it .
Weart:It wasn't till '43 that you had a paper that raised the relaxation times enough so that it was fully consistent with the radioactive rates?
Chandrasekhar:For the clusters, yes.
Weart:Then also at the same time, this is work done in '41, there's your work with Louis Henrich. On the relative abundances of the elements and their isotopes.*
Weart:How did you get into that problem, from Weizsäcker, or?
Chandrasekhar:Weizsäcker, yes. Of course, I was trying to follow the nuclear-physics developments at that time, and the Bethe cycle was one side, the other side was the origin of the elements. So I felt that there was something which one could do, namely redo some of the calculations the people had done at an earlier time, and concentrating on the isotopes in determining the age, rather than on the whole periodic sequence.
Weart:This is one of your more cited papers, by the way, from your earlier period. People are still citing this. I wonder, how did you feel when the results came out and they were quite reasonable?
Chandrasekhar:I was really very pleased. I remember, I gave it at the 50th anniversary celebration at Chicago. I had to give a talk in a session which the first one was given by Russell, I had to give the second, and the last was by Lawrence. It was a symposium here, in connection with the 50th anniversary celebration of Chicago in '41; and I wanted to give a paper which would in some sense be worthy of the occasion. So I worked on this particular problem the previous summer.
Weart:If you can recollect, how did you feel about the Big Bang as an idea? Were you convinced of it through this period? * APJ. 95 (1942), 288-98.
Chandrasekhar:I've always been on the side of the Big Bang all the time. Somehow it seemed to be the simplest solution. Though the present attitude is to go back to the closed universe.
Weart:Back to the — ?
Chandrasekhar:I mean, starting with the Big Bang, but ending also with a Big Bang.
Weart:Well, that idea was certainly around in the thirties also.
Chandrasekhar:Yes, but not very much in vogue. At least, not to the extent I knew. Eddington's famous remark, "I'm an evolutionist not a repetionist."
Weart:How did you feel about that?
Chandrasekhar:I was not committed to it in a particular sense in my work, but I thought that the simplest explanation was in terms of an initial Big Bang.
Weart:— and then of course, your own paper must have —
Weart:But perhaps you didn't need the confirmation?
Chandrasekhar:No, I thought it fitted into that picture. But I didn't draw any overly dogmatic conclusions from it.
Weart:Now, a question I suppose I'm obligated to ask, for the record. Many people have of course compared the oscillating cycle universe with Hindu cosmology and so forth. I wonder whether this ever had any effect on you, or whether you ever thought about these things?
Chandrasekhar:No. In fact, I'm against reading our thoughts in ancient writing. If you believe certain things now, and the English sentences which incorporate that belief happen to coincide with some of the sentences from the old texts, it doesn't mean that the thoughts behind it are the same. If you say certain things now, you say them for certain reasons, and those reasons cannot obviously have been in the minds of the people who wrote the same sentences at the earlier time. I don't go along with people who try to find confirmation of their ideas in the philosophy of the Koran, of the Bible, or any other ancient text.
Weart:OK, fine. Getting back to the paper specifically, we haven't talked much about your work in collaboration. I wonder for example, in this paper as an example, what was the role of Henrich?
Chandrasekhar:He was essentially a person with whom I talked about the problem, and I said, "Well, there's a lot of calculations to be done, let us do them together." The collaboration was not on a level of scientific equality, and it was in later years, particularly during the sixties, and seventies when some of my students have supplied original ideas, and corrected me in some of my work.
Weart:How did these collaborations work in general? Is there any general rule for how you work in collaboration with somebody?
Chandrasekhar:Some students come along - particularly during the sixties - most of the students came from the physics department, and many of them were very good. When I find after a while that I am able to communicate with them and we have compatible ideas, then we start working together. I tell them, "I have these problems; would you like to work with me, because there's a lot of work involved, and I do not know very much about the subject, I have to learn an awful lot, and we'll study it together." For example my last collaborator, John Friedman, was absolutely first rate. We started, and I was going to England, he came along with me to England. He integrated his work with mine. He was very good. I made several mistakes on the way, he corrected them. So it was on a level of scientific equality. That was the way my collaboration with my students developed. But in fact the forties and early fifties, it was essentially one of my having a fairly well-founded idea, which I felt I didn't have the time to work through completely —
Weart:In terms of working through the mathematics?
Chandrasekhar:Or making some particular calculations, checking them, numerical work, these sorts of things — and asking them to go along with me on that.
Weart:So there was a pattern at that time where you set up the framework, and then they would fill it in.
Weart:But now the pattern is somewhat different? Now they sort of come in at the initial — ?
Chandrasekhar:They come in at the early stages. I haven't had a student for the last three or four years.
Weart:But over the past 20 years, you would say.
Chandrasekhar:Most of my collaborators, starting in the middle fifties, come in at the beginning on a subject I'm learning, and we learn together, we discuss it together, and mistakes are made and corrected.
Weart:So they will work out some of the equations, you will work out some of them.
Weart:There's no clear division of labor.
Weart:I see. Now, here's another collaborative paper in the same year. This is Sch8nberg and Chandrasekhar*, I think there is a lot going on in the paper. To me the most interesting thing is that, I believe this is the first place where one sees quite clearly that stars evolve into red giants.
Weart:I wondered how you came to this paper, also.
Chandrasekhar:Well, it all came this way. You see, one of the things which people talked about in those days, for example on which Gamow was writing in this — Gamow took the carbon cycle, and assumed that evoluations was through a series gholomogously contracting stars.
Chandrasekhar:But it didn't seem that could r ght. On the one hand, one assumed that there's a convective core. But the convection takes place only inside the core. And I knew that convection cannot come [bring material] outside. So the hydrogen must be exhausted in the center first.
Weart:How did you know it couldn't come out from the convection?
Chandrasekhar:Well, because there were all these arguments of Eddington, Sweet currents and so on. I knew sufficiently of the earlier work to know that it's matter in the convective core will be mixed. And if the hydrogen in the convective core is exhausted well, it must develop into isothermal core. And I felt the isothermal cores couldn't expand for ever and can grow only to certain maximum size. What will happen then? I had done a similar work earlier. You know, Gamow had some idea about lithium burning, and coming right out to the outside. But I pointed out that in the early stages, the lithium can't be burned beyond a certain point. Then the question arose, what happens to the main constituents? And Mario Schönberg from Brazil was visiting me, and I said, "Let us do these calculations together." At that stage, we were doing hand calculations. There was a lot of work to be done, and he was very much interested in these problems, because he had been with Gamow earlier. So we worked together on that, and we were very surprised at what came out. In a way, you know, I sort of regret that I didn't pursue this matter beyond my work with Mario Schönberg. *APJ. 96 (1942), 161-72. Once we came to this maximum mass, you see, I realized that one ought to continue the integrations forward in a secular way.
Weart:To revolve the star.
Chandrasekhar:Yes. But I was then in the middle of my work with John von Neumann, and the radiative-transfer work was progressing. I suppose it was a missed opportunity.
Weart:But in fact, although I suppose this paper isn't too widely known, it is in fact the first paper to come out in this way. And I'm just wondering, when did you first begin to think — you say you were surprised, but when did you begin to think that this was in fact where red giants came from?
Chandrasekhar:Well, I would say that I probably had the idea in '41, maybe.
Weart:Did it come strictly out of doing the calculations?
Chandrasekhar:No. Gamow was there doing ofthese things, you know, in Washington. He was publishing a lot of papers.
Weart:Oh, you saw his published papers.
Chandrasekhar:Yes. And also I corresponded with him, and I knew him quite well. You know, he was writing extremely speculative things, of how the variable stars come from lithium burning, berylium burning, and I knew that all of that was wrong. So I began to think, and it seemed to me that the direction evolution has to go was along the lines Schoenberg and I had found. It came in, by and large through stimulation by work that Gamow was doing at that time, and my belief that the way he was going about it was not right, and that one had to go in an alternative way. Even though, when I wrote the book, I thought I was done with stellar structure, I kept on thinking about there problem. I had to essentially force myself to relinquish the subject, at a time when my mind was extremely active along these lines. I hated to do it but I had to make a choice.
Weart:But then you were drawn back to it, when you saw this particular problem.
Weart:Before this paper or before 1941, what were your opinions of red giants, of the whole direction of evolution?
Chandrasekhar:Let me put it this way. During those years, after 1939, I was always in stellar structure with a mild protest. I was seeing what was going on, and I was being consulted by people like Bethe and Gamow, and so I was constantly made to think. And so, I felt that some of the things that Gamow was writing were so completely wrong — and since nobody else was working at that time, because of the war, I felt that I had to go in and do something. I really got interested, seriously interested in it, when Mario Schönberg and I were working on the subject, and I wanted very badly to go on. But again when Schönberg left —
Weart:But before this period, did you have in your head some sort of mental picture of the H-R diagram, with some sort of evolutionary track — ?
Chandrasekhar:it was emerging at that time. It was not well formed.
Weart:You didn't have a definite idea that stars start as red giants and go in this direction or whatever?
Chandrasekhar:That was my idea, yes. I mean, I definitely had the idea that once a star moves away from the Main Sequence, it might go into the red giant branch, you see. And I said, "One ought to follow it in a secular way, looking at the evolution." That is something which I wanted to explore. I felt that was the direction to go. But I had no absolute conviction that the answer would come out that way.
Weart:Did you discuss these things with people around Yerkes? Was there much discussion of what sort of tracks one might have in the H-R diagram?
Chandrasekhar:No, I didn't.
Weart:People were not much interested?
Chandrasekhar:I talked with my students. I talked with Henrich, for example, quite a bit, and I talked a little to Martin Schwarzschild.
Weart:He must have been very interested in all these things.
Chandrasekhar:Yes. But of course, you see, we weretogether in the Aberdeen Proving Grounds during the war, and then he went to Italy, and by the time he came back at the end of the war, I had left the area, pretty nearly.
Weart:Well, maybe this would be a good place to stop. Tomorrow morning, we'll talk about the Aberdeen Proving Grounds, and then — when things get too recent, we have to be careful what we talk about —
But I certainly want to talk about things that happened at Yerkes, about your editorship of APJ — about the whole history of APJ — and of course, if we have time, also about your postwar work.