Oral History Transcript — Dr. Geoffrey Burbidge
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Geoffrey Burbidge; November 15, 1974
ABSTRACT: Early life in the Cotswolds, England; Bristol University, 1943, and physics program during WWII; teachers include Nevill Mott and Edward Tyndall; effect of WWII; work with Harrie Massey on meson capture; University College, London; meets wife and growing contacts in astronomy, late l940s; thesis, 1952; work in stellar atmosphere; visit to U.S. at Howard and Terkes, 1951-1953; Cavendish group under Martin Ryle, house theoretician; contact with William Fowler and growing interest in nucleosynthesis, 1954; fellowship at Pasadena, 1955; opinions on operation of major observatories, philosophy of cosmological research, reaction to steady state; problem of high energy sources, synchrotron radiation; belief structure in cosmology; Halton Arpís work; Nuclear Processes in Astrophysics - B2FH; Yerkes Observatory, 1957; physics of galaxies, 1959. Also prominently mentioned are: Wilhelm Heinrich Walter Baade, Margaret Burbidge, Subrahmanyan Chandrasekhar, Paul A. M. Dirac, Enrico Fermi, William Alfred Fowler, James Edward Gunn, Fred Hoyle, Martin Ryle, Allan Sandage, Maarten Schmidt, and Arthur Wolfe.
Wright: This is an interview with Dr. Geoffrey Burbidge, in Dr. Burbidge's office on the campus of the University of California at San Diego on November 15, 1974 by Paul Wright on behalf of the Oral History Program at California State University at Fullerton.
Dr. Burbidge, would you tell us at length about your childhood and especially how events influenced you into going into physics?
Burbidge: I got into science quite by accident. My best subjects in school were mathematics and history. I did physics and it did not thrill me, but I suppose I was reasonably good at it. What actually happened, it was during the War, I was at school and there came a possibility that I could go to University. But the situation was that if I went and read history, which was what I thought I wanted to do, I would not be able to stay there any length of time at all. I would get a year maybe and then I would have to do other things. Then it was pointed out to me there was a scheme by which one could take what was called a physics bursary. They were very short of people who were trained in physics and electronics. Thus it was suggested that I go to the University and read physics!
I was fairly open minded about these things, and so I decided that that was what I should do. I was successful and did that and the War went on. It was towards the end of the War, and I obtained a physics degree. I got quite interested in physics. At the end of two years, normally in England to take an honors degree, and two years to take a passed degree. They were still taking me at the end of two years for consideration into various military organizations or government labs. This was very close to the end of the War, they apparently decided that a very small number of people could go on and take a degree in physics and out of a rather large number of people there were six people chosen, as I recall. I was one of them and so I took a degree in physics. It was during that period that I really became interested.
Neville Mott was one of the people who was a professor where I was at Bristol. He got me really interested in physics. I obtained an Honors Degree in Physics. I then went to work in a ballistics lab for a year. At the end of that period the War was over. I decided I really was fascinated by physics and went to graduate school at University College London where my professor was Massey, and I obtained a Ph.D. in Theoretical Physics. While I was a graduate student I met an astronomer and married her and that is how I got into astronomy. So it was not one of those things where from the year one you know what you will do. Thus I donít always take very seriously people who say they have known from the beginning exactly what they wanted to do.
Wright: There seems to be two different types of people that I have run into. One type seems to be interested in astronomy or physics from the cradle.
Burbidge: My wife was interested in astronomy in this way. She is a distant relative of Sir James Jeans. She was involved in astronomy when she was very young.
Wright: There are others like yourself, whoÖ
Burbidge: Purely accidental. The amazing thing is that my daughter, my only daughter, who has just gone to Berkeley this year, her best subjects are history and mathematics. She canít take astronomy at the moment but she may do. She has been surrounded by astronomers. She knows most of the prominent astronomers of the world and doesnít want to face astronomy.
Wright: Just for the record, I had some difficulty in finding some of the basic background of your early life, such as where you were born and where you grew up.
Burbidge: I was born in England in the Cotswolds (Hills). In a little town called Chipping Norton, which is midway between Oxford and Stratford-on-Avon. My father was a builder. He and his brothers were in business as builders. We lived in this small town and I went to a grammar school there. I stayed there until I was about seventeen. Then I went to Bristol University on this bursary and then I went from there to the Graduate School in London. I spent some of the time, while I was in London, up at Cambridge. I would go up quite often because I became interested in Field Theory. There was no one in London in the area where I worked. My advisor, Professor Massey, suggested that I spend some time with the people in Cambridge and I did. I got to know quite a lot of people in that area. In fact, my external examiner in London for my Ph.D. was Nicolas Kemmer who was at that time a Reader in Cambridge. He later held a Chair at Edinburgh. I already had an academic position when I was a graduate student, I think as an Assistant Lecturer. Massey, my professor, was in the Mathematics Department at that time, so that I was actually a graduate student in the Mathematics Department. Massey later moved and became Professor of Physics. However, I was never in the Physics Department as I became an Assistant Lecturer and then a Lecturer in Astronomy which was really a subdivision of the Mathematics Department at that time.
Then, quite soon after I took my Ph.D. we came to the United States. We came first in 1951. I was a Fellow at Harvard, and Margaret was at Chicago at the Yerkes Observatory. Then we spent a second year, both of us, at Yerkes, and then we went back to England to the Cavendish [Laboratory] at Cambridge for a couple of years. I was in Ryleís group at Cambridge. Then we came to Cal Tech. From Cal Tech we went to Chicago where we spent about five years with summers at Cal Tech, and then came here [University of California at San Diego]. We have been here since 1962.
Wright: Going back a little earlier. What was your familyís reaction to your interest in physics?
Burbidge: They did not understand, because they had no background in this field. They didnít know anything about it. My father when he found out I was good in mathematics, wanted me to be an accountant. He was very tolerant and anxious to help when he found that I apparently had some talent. But he didnít have a lot of money. It was difficult because there was no one with any expertise around. The Head Master of my school was an Arts graduate and didnít have the slightest idea about what to do. I had a very good Mathematics teacher in school, Leonard Miles, who has a brother who is a famous British actor, who I happen to know. He had quite an influence on me, I suppose, but it was something quite strange and new to my parents.
Wright: During your education at the University of Bristol, what was your general impression of your courses?
Burbidge: [laugh] Well, as an undergraduate, I ďbeatĒ my way through the courses. The English style is very different from the American style anyway. During the War it was a terribly tough course structure in fact. I think we had some good lectures. I donít remember too much about them now to be quite honest with you.
Wright: Did you ever take a course in astronomy?
Burbidge: C.F. Powell who was a cosmic-ray physicist who later won the Nobel Prize, was at Bristol and he gave some lectures and he must have talked a little bit about astrophysics. I donít remember very well. Somewhere, probably back in England, all my notebooks exist. But that is the only thing that I have the slightest recollection, in my undergraduate life, in which anybody talked about astronomy. I am not the astronomerís astronomer, as I am sure you will find out.
Wright: Could you relate how your wife had influence on you in astronomy?
Burbidge: When I was a graduate student in London, I met her at a graduate course being taught by D.R. Bates. She was coming from the observatory where she was already. I met her at these lectures. I used to go up to the observatory with her. I became a Fellow of the Royal Astronomical Society. I used to go to their meetings and picked up things that way. I have had no courses in astronomy, no regular courses at all. As many of my friends [laugh] will tell you, ďsure Geoff hasnít had any courses in astronomy.Ē I was trying to teach the students today in an undergraduate course in astronomy, as I am teaching now. I kid them about many things. We were describing variable star nomenclature. I told them I didnít know where it came from and that it wasnít important anyway. But I was sure that I couldnít tell them.
Wright: This does not relate to astronomy per se, but could you compare the social and political climates at the University of Bristol and at the University of London?
Burbidge: I was an undergraduate student at Bristol in a bad period during the War. I lived in a Hall of Residence and I donít think that I knew much about the general University goings on. Everything was very austere, everything was shut down and there was very little social activity. When I moved to London I was living in Maida Vale and going to the theatre and ballet a lot, and that was a very different social life. London is a very different kind of university because it is a very large university, and I was at University College, a very large college and there were no residential halls. People lived all over the place and were only together when they were on the ďcampus,Ē as an American calls it, during the day time or even the night time. There is no social life in the sense that there is in some American universities or in Cambridge where I have spent a lot of time since. So they are very different and I find it very hard to compare different times and atmospheres.
Wright: Did your family support your aspirations financially or sympathetically?
Burbidge: Oh yes, my father helped in any way that he could. If you become a graduate student in England and are accepted, you automatically get a grant from the government. It used to be from the Department of Scientific and Industrial Research and it is now the Science Research Council. I lived more or less on such a grant with a little help from my father. My father, after the War, for ten years did quite well. They were very sympathetic without knowing what the hell was going on.
Wright: During your graduate work, I believe you mentioned Massey. Were there any other professors who impressed you?
Burbidge: Oh yes, there were quite a number of people. Kemmer, who encouraged me very much, was in Cambridge, though he wasnít my professor. I used to go up there one or two days a week to see Dirac, who I first met in Cambridge at that time. Then there were people in London, Bates who was with Massey, and Gunn, now a professor in Glasgow, also Burhop who worked actively with Massey. All of these people had some influence, though I suppose I have always been a fairly independent kind of person, at least at that level. Of course, for graduate students in England, at least in those days, it was a ďsink or swim business.Ē You really didnít have to do anything you really didnít want to do. It depended very largely on you and what contacts you have with your professor.
Massey, in retrospect, was really very good, and he was a very busy man. I used to go see him occasionally. Graduate students were treated as adults and are simply thrown in to sink or swim and are not expected to get much advice or help from people. In fact, in many situations, it is actively discouraged, certainly in Cambridge. When I was visiting in Cambridge, it was a difficult situation. Some of the best people in the field, my contemporaries, actually got their problems for theses from each other. There was very little in the way of help and guidance. Some people didnít like it and just wanted to go somewhere else. One man, who is now very famous, an old friend of mine, went to Birmingham. He left Cambridge because he couldnít face this system at all, it was too difficult.
Wright: Do you have any anecdotes you might care to relate about any of your professors?
Burbidge: I donít remember any anecdotes about any of my professors. All the jokes are about astronomers. No, I donít have any anecdotes.
Wright: How about some anecdotes that occurred during your undergraduate lab work?
Burbidge: We had a man called Birch at Bristol. It was a very good Physics Department, with a very good research group. Birch is a famous man in optics and is still alive. His main characteristic is that he used exceedingly filthy language continuously. [laugh] It used to be very entertaining because I used to share labs with a man, now in London, who was a very religious type. I really used to enjoy getting Birch to come down to tell us how to do things and he would really start letting go with every other word a four letter word. My generally nasty behavior! You have probably got me at a bad time, as I have so many things on my mind. There are lots of anecdotes I could probably think of but I donít think of right now.
Wright: About the time you were at London, the Bondi-Gold Theory of the Steady State Universe was proposed. I guess that might have been a little later, that was 1948.
Burbidge: Bondi and Gold on the one hand, and Hoyle on the other, wrote two separate papers published in 1948. I had no contact in those days at all with those people. I first saw them at the Royal Astronomical Society meetings. But when I was going up to Cambridge in those days I was a graduate student. My contacts were with people purely in Field Theory. I had no contact with the cosmologists and I didnít get to know any of them until considerably later, in fact, until we were back in Cambridge in the middle l950s. I didnít know Fred Hoyle although I had seen him at meetings. I didnít get to meet with him or work until much later. I canít remember where I met first Hermann Bondi or Tommy Gold. I certainly remember Gold at a meeting in London in 1949, but I didnít know him particularly well, so there was no personal interaction.
Wright: I was going to ask you if any of your professors had any feelings about the Steady State Theory.
Burbidge: I am sure that everyone had feelings about the Steady State, but I was dealing with physicists who were reasonably normal people. It was the astronomers who got upset. Various kinds of people got terribly upset about this business of the Steady State. Fred Hoyle gave a set of lectures on the BBC that upset everybody.
Wright: About what year was this?
Burbidge: It must have been 1948 or 1949. I vaguely must of heard some of these things on the radio, I think, though it wasnít something that particularly intrigued me in those days. But there has always been antagonism towards the Steady State. Most of it, as far as I can tell, has had little really to do with science. You can read Dingleís Presidential address, when he was President of the Royal Astronomical Society in 1952, I think, in which he essentially castigated them on the ground that it was not a scientific theory. Fred told me later that he got to hear that Dingle was going to attack the Steady State, so he never came to the meeting. But Gold and Bondi had to sit there and listen to him.
Wright: I looked around your library here, I noticed that you have a number of books relating to the history of science, such as the works of Rutherford and Maxwell.
Burbidge: Yes, thatís right. We have books all over. My wife has our astronomy books in the next office.
Wright: You mentioned that you got some advice, when you were at the University of London, from Dirac.
Burbidge: Dirac was in Cambridge. All that happened was that I used to go up there every week and Dirac was in a seminar, but of course he doesnít say very much. I found him a person who always is very reasonable and very straight about things, though he was a very hard person to talk to. I didnít know him well in those days. I have got to know him better more recently.
Wright: How did you perceive the field of astrophysics prior to your decision to concentrate in this field?
Burbidge: What do you mean by that? I didnít perceive it at all. As I told you, I got into astronomy and I started working on some problems related to stars with Margaret. Then when we first came to the United States, I was interested in problems associated with stars and their atmospheres. I worked at Harvard on that and then in Chicago I became more interested in a wider range of problems. I developed some interest, I suppose, in radio astronomy. It was after coming back to England in
1955 and deciding to go the Cavendish, where I was supposed to be working on Radio astronomical problems, that I first worked in the field.
Wright: Would it be ďputting words in your mouthĒ to say that you fell into astrophysics?
Burbidge: I told you, I got into astronomy by accident. I donít precisely remember the details but I used to read, as I always do. I read a tremendous amount. When I get into something, I get into the whole field. I read all manner of things. I make a deliberate attempt to find out what is going on in many areas. Without knowing the background you donít know where you can make progress. What really happens, I think, is that you are very strongly influenced by the atmosphere in which you are put. I went to Harvard knowing about the United States, nothing about American astronomy, knowing, however, the way things were being done in the English scene didnít seem very satisfactory.
Otto Struve, the famous astronomer, first suggested to us that we should come to the States. Then it was simply a question what arrangement could be made and where could we go. When various possibilities opened up, the ones we considered to be most reasonable were at Harvard or Chicago. At Harvard, I was a young Ph.D. I found the social life very pleasant. I wasnít terribly impressed by a lot of things being done -- rightly so in retrospect. But my interests were mostly associated with stars. At Chicago I was exposed to people like Chandrasekhar. Our interests began to broaden, but we had not thought beyond coming back to England after a couple of years. Then it was a question of where we should go. We had two offers, at Manchester and Cambridge. We decided without any real basis in fact to go to Cambridge. There I was very definitely associated with radio astronomy groups. It is not surprising that I started working on problems starting from that point.
Wright: While you were at Harvard, what instrumentation did your wife use?
Burbidge: They have a 60Ē telescope at the Agassiz Station that is 20 or 30 miles from Harvard. But it very really suffers from the same problems as many of the European observatories and the English ones do. It is in a lousy climate. There are no really first class observational astronomers there. I wasnít particularly interested. When my wife first came, they were very anxious that she do something with this telescope. Well, she went out once, and decided immediately that this didnít make any sense at all.
The first observational program we got involved in was done at the McDonald Observatory at the University of Texas which in those days was run by Chicago. We spent our first Christmas in the U.S. in 1951-1952 at McDonald, and that was the first time that Margaret used a large optical telescope in a good climate. I remember then in the following spring back at Harvard, they were very upset because we had chosen to pay no attention to their operation. Of course, we have had long and complex careers since. We have been pushing the Europeans and the British to work in decent facilities. It is all part of the same pattern, you canít do optical astronomy unless you put decent equipment in good observing sites and that is why in the modern world the lead in optical astronomy has come from California and Arizona. There is little of great importance done by optical astronomers east of the Mississippi or east of the Rockies.
Wright: Who were some of the members of the staff at Harvard when you were there?
Burbidge: Shapley was still the Director. He actually retired as an administrator when I was there, he was 67 when I was there in the spring of 1952. Menzel, Bok and Whipple were there. The Gaposchkins were also there. Harvard had a number of senior people and very few younger faculty people, but a number of graduate students, many of whom are now at different places in this country.
Wright: Can you think of any possible anecdotes about any of these individuals?
Burbidge: I am not in an anecdotal mood. You have to get me at a different time to tell stories about people. I am sure there are lots of entertaining and semi-scurrilous things one could say. But I donít have much to say about that period. Shapley was a very entertaining character. We were often away as I said earlier, the first Christmas we were in Texas, and the following summer we left and went to Chicago. I remember various parties at the place and various entertainments; they were very good to young people. But nothing stands out in my mind. There is the strange behavior of Sergie Gaposchkin, and other things like that, but as Chandrasekhar once said to me, ďGeoffrey, the problem with astronomers is that they are not very generous one to another,Ē and thatís true. I prefer not telling stories that are somewhat uncomplimentary.
Wright: I understand. You mentioned that you returned to England in 1953 to the Cavendish Laboratory. I would like to know, as a theoretician, where did you get your data, from the local radio telescopes?
Burbidge: Well, I was working with the radio astronomers there, and also using optical data and other kinds of information that were available in the literature and elsewhere. Margaret and I were also working on problems of the magnetic stars. We had observational material which we had got at McDonald. It was in that period at Cambridge that we first met Fowler, who was a Fulbright Professor visiting from Cal Tech. It was in 1954 that we first started working with Willy on problems of the element synthesis in stars, and it was there that we first got to know Fred Hoyle. We met Fred at the Cavendish at tea. First of all, Margaret and I worked with Willy and wrote some papers with him in that period. Fred had, of course, done things earlier, but most of the work was done later after we went to Cal Tech in 1955.
Wright: You mentioned that Ryle was on the staff there at Cavendish.
Burbidge: Martin Ryle was Head of the Radio Astronomy Group at Cavendish. I had an office near him. I knew Martin very well.
Wright: It would appear from looking through some of your papers of the early l950s, your primary interest was in spectroscopy at that time. Could you comment on how you perceived the importance of that work at that time relative to stellar evolution?
Burbidge: It was clear that stellar evolutionary arguments and various kinds of measurements suggested that there were composition differences between stars associated with their evolution and one of the key problems was sub dwarfs. At that stage very few studies of that kind had been done. Margaret and I started a study based upon material we had taken at McDonald which we later had completed when we were at Mt. Wilson. That was one thing of interest in stellar evolution. In the summer of 1953, before we left the States and went back to England, we went to a Summer School at the University of Michigan at Ann Arbor. That was the most entertaining summer school. Baade was there as one of the lecturers. George Gamow was a lecturer there as well as Ed Salpeter and George Salpeter and George Batchelor among others. It was very much in that period that we became interested in stellar evolution. Allan Sandage, who is a very good friend of ours, and is the same age as me approximately, was there and we first got to know him. Allan was very keenly and actively involved in stellar evolution.
Wright: I wasnít sure if I should mention his name because I know you are on opposite sides.
Burbidge: No, No. Allan and I get along personally extremely well. The problems that have developed only become difficult if you cannot separate scientific beliefs from personal matters. It is true that Allan is certainly very difficult about this. As time has gone by, he may have gotten worse. But Allan and I still get along. I was on the phone talking to him about two days ago. I think it is because I am very tolerant. At the same time he may think it is because he is very tolerant, I donít know. We have all got very uptight about the red shift question. Among astronomers there is a strong personality cult as I am sure that you are going to realize. I certainly would like as far as I can to not associate people with the things that they do, though there is a bad tendency to do that. Anyway, Allan and I get along. When we first met him in 1953 and saw little of him again until we came to Cal Tech in 1955, Allan was not married at that time. He spent much of his time with us. He would eat dinner with us most every night and we went all kinds of places together; we were very close at that period for a very long time. Since then we have never been together in the same institution. We have exchanged houses in the summer between La Jolla and Pasadena [laugh]. But you donít have to worry about talking about Allan.
Wright: I did have an earlier interview with him and I enjoyed that very much.
Burbidge: Allan is very intense, but he is the way he is and I am the way I am.
Wright: In 1954, it appears that your interest shifted slightly to a theory of red shifts as evidenced by work done by Freundlich.
Burbidge: No, that is not true. What happened there was Freundlich came out with this paper. We were in Cambridge at the time. We and others, McCrea, and Ann Underhill, for example, thought that this was an absolutely ridiculous business. We wrote a paper shooting it down, and that was the paper you are talking about. It was purely a matter of trying to deal with something that was absolutely ďup the creek.Ē There was no feeling that there was a problem there the way Freundlich has posed it, in my view anyway. He was just playing games with the observational data. There was no feeling that it was a significant thing. I felt then as I feel now, that it is necessary that if people publish things that donít make any kind of sense, you had better say something. So ours was a very negative paper. I would never have got into that if Freundlichís paper had not appeared and didnít get into it anymore.
Wright: You mentioned earlier that you worked with Fowler on the Synthesis of the Elements.
Burbidge: Thatís right, we started working together. We wrote two papers in the period of 1955-1956 which, I think, were reasonably good papers on different aspects of the subject.
Wright: What motivated your interest in this area?
Burbidge: Well, what motivated interest in that area were the observations. Margaret will say that it started from a meeting at a conference that was held at Yerkes Observatory sometime in the spring of 1953. It was concerned with the abundances of the elements. Urey was present. It was the first meeting of that kind we had been to. We were working at that time on the compositions of magnetic stars. Some of the first analyses of the spectra showing the remarkable compositions were what we were doing in that period, our results were published in 1955. Margaret and I realized in that period that one way of explaining this observational data was to argue that nuclear processes were taking place on the surfaces of these stars. This was not nucleosynthesis in the normal way in which it was later discussed. I talked about our results at one of the two well-known clubs, the Experimental or Theoretical Physics Clubs in Cambridge in 1954. The Kapitza Club is the Experimental Physics Club and the Theoretical Club is called Δ2 v. I think that I gave this talk at the Kapitza Club. It is a seminar held after dinner in one of the Colleges. I talked a little about the results using nuclear physics that I was guessing about.
This man came up to me, I had never met him before, but he was Willy Fowler, and said he was very interested and that he was a nuclear physicist on leave from Cal Tech. So we agreed to get together and we started working together at that time. That has gone on intermittently ever since. We branched out from the magnetic stars to processes in the deep interiors, and neutron sources in stars, all this leading towards work that finally culminated in this very extensive discussion of the synthesis of all the elements in the stars which Hoyle, Willy, Margaret and I published in 1957 after coming to Cal Tech.
Wright: Were there any particular circumstances that made you decide to come to America?
Burbidge: Oh, I donít know. As I say, we originally came to the States never planning to stay and we had gone back to England in 1953. We decided after a couple of years there, it really wasnít sensible to stay in England and we would enjoy coming back to the U.S. Willy was very anxious to get us to come back, and he arranged that we both got some kind of research appointments at Cal Tech and Mt. Wilson. The opportunity was there and inclination was there, so we just did it.
Wright: Well, I will try one more time to see if you might have an anecdote about Fowler.
Burbidge: About Willy? You and your anecdotes. I donít know any anecdotes about Willy. If you came back to me on a different occasionÖ You get in the mood or you donít get in the mood and I am not in the mood.
Wright: Friday afternoons are bad times.
Burbidge: I donít knowÖ I was just not thinking about anecdotes. I can talk chronologically, as you can tell, but I canít think of anecdotes.
Wright: I think you mentioned earlier that you had done work at McDonald -- this is a bit out of the chronology -- on stellar radial velocities. Besides Otto Struve, who were some of the other members of the staff at McDonald?
Burbidge: Struve was not at McDonald. Struve had been the Director there. He was at that point at Berkeley. I believe he was chairman of the department at Berkeley. He later became Director of the National Radio Astronomy Observatory or then went there and then to Berkeley. We were never at an Institution with Struve, though at one point he tried to persuade us to go work at NRAO. He offered us jobs there, that was in the period when we were in Chicago, in the late 1950s. But at McDonald it was the staff of the Yerkes Observatory. The staff was Chandrasekhar, who of course never observed. Stromgren, another theoretician who did observe. The Director when we were first there was Kuiper. Also Morgan, who is still there and retired there, and Hiltner, who is now Chairman of the Department at Michigan, was there. Aden Meinel was there at that time and is now at Arizona. Helmut Abt, who is now at Kitt Peak, was there. Nancy Roman, who is now at NASA, who was a young Ph.D. Don Harris who was there died. Bidelman, who is now at Case, was there. We were contemporary with some of the younger people I have mentioned. People used to go to McDonald regularly for quite long observing runs.
Wright: By 1956 you seemed to have broadened your interests further into studies of extended magnetic fields around our galaxy and M 31.
Burbidge: I had been working on these things in Cambridge, you see, and everything started to come together. At that time I was working extensively on the explanation of nucleosynthesis, which in many ways was the most satisfying things we have ever done. I had also been working on radio sources and non-thermal-radio sources associated with our own galaxy.
You see, the history of this whole subject, our understanding of non-thermal-radio sources, really began in the period, the early l950s when I was in Cambridge. At that point, there was an argument as to the nature of the physical mechanism that produces the radiation from non-thermal sources. We were arguing about whether or not it was synchrotron radiation. I was one of the people pushing the synchrotron theory which, of course, turned out to be right. But it was the Russians, really, unknown to most of us, Ginsburg, Shklovsky, and Pikelner who made the major breakthrough in this area. There was very little communication in those days between the East and the West. In fact, I first heard of this Russian work through Oort in Holland when I was at the Cavendish.
I started doing things that were fairly obvious, I think, and these things were also being done by Ginsburg in the Soviet Union. In 1956 some of the papers I published from Cal Tech were in this area. I suppose those papers were pretty nice. They were the kind of thing that, at that stage, it was fairly clear you should do. I had access to the people who were doing the fundamental work observationally in this field, Baade and Minkowski, for example. So I was in a very good position to work in this field. I did a lot of work and continued to work in that field.
Wright: About this same time you did a study with your wife of five stars which showed characteristics of Population II.
Burbidge: They are the sub dwarfs that I talked about earlier. That was based upon observational material obtained at McDonald and it was finally analyzed and published when we were in Pasadena.
Wright: Did you work at all with Baade on this?
Burbidge: No, no. We, of course, knew Baade. Baade was a great character. Baade, of course, had first discovered population characteristics much earlier, ten years earlier. At that point he was very excited about the radio sources. I had the strongest interaction with Baade in that area. We all used to have tremendous arguments with Walter Baade. He was a most entertaining character. He used to have violent arguments with Allan sometimes along the corridors at Santa Barbara St. At the end of it all he would stick his head in the door and ask, letís go out for a drink.
Baade was one of the most marvelous people with young people. He and his wife lived in the street behind us near Cal Tech. We used to see a lot of them. We used to take our daughter over to them when she was a baby -- she was born in 1956. They used to baby sit for us. We got to know the Baades very well and the Minkowskis. Also Humanson who was first of all, very, very difficult because of the old conservative approach of Mt. Wilson and women on the mountain. There was a terrible row over Margaret and the mountain, which led to Allan Sandage and I making a tremendous fuss and going first to the then Director at Mt. Wilson, Bowen, and the President, then, Lee Du Bridge at Cal Tech over Miltís behavior. But he came around so much so that he offered Margaret some of his material when he retired. That was one of the periods when Allan and I really went to town. We created all kinds of hell around there over issues like that. We were very difficult, I think, to the establishment, at that point. They were a very conservative group -- they still are.
Wright: About this same time you co-authored a paper with Fred Hoyle on Californium 254.
Burbidge: There was a whole group of us involved in that. That was one of the really entertaining ideas that we got in the nucleo-synthesis bit. We discovered what we thought was a connection between the light curves of supernovae and the decay curves of particular transuranic elements which according to the theory are built through rapid neutron capture in a supernova explosion. I think that I was the first one who spotted that relationship. A group of us wrote two papers. One paper was by Baade, Burbidge, Burbidge, Christy, Fowler and Hoyle in the Publications of the Astronomical Society of the Pacific. I remember persuading Bob Christy to put his name on it -- he had certainly worked on it -- because I had an argument with Dick Feynmann, who was fascinated by all of these things. Dick said, ďWe1l, if Bob Christy believes in it, I will believe in it.Ē So I got his name on it since he was involved in it. That was a tremendously exciting period. That part of the theory may not be right, it may be only very partly right. At the time it had a tremendously strong effect on us and everybody else because there did appear to be a very direct connection with the processes we talked about. They could be directly related to the Bikini nuclear explosions, other atomic bomb explosions and tests.
Wright: A little later you wrote a paper with Hoyle on Matter and Anti-Matter and their Implications for Cosmology.
Burbidge: Thatís right. That stemmed from work I had done on M 87. It was in that paper that I said towards the end of it that maybe anti-matter might have something to do with it. Then Fred and I got together and wrote a paper which we published in Nuovo Cimento in which we set limits to the ratio of matter to anti-matter that could exist. That was one of the early papers in that field. Our philosophy was that there was really very little evidence, but we could set limits. It is amusing to me in more recent years that Alfven, who is here, and Teller are back on the anti-matter track. I still donít think there is any good evidence. In one particular context, in M 87, it was a possible way to go, but it had all kinds of problems.
Wright: From your work on cosmic ray particle acceleration among extra galactic nebulae, I would appreciate your comments. Was that work a continuation of your earlier interest in cosmic rays?
Burbidge: That was just an idea. It is still a rather amusing idea and it still may have some relevance. This really came from Fermi who had a theory of cosmic ray acceleration. I had met Fermi through Chandra, in the period when we were in Chicago the first time. Fermi died in 1954 when we were back in England. Fermi, in his last years, worked with Chandra. We were members of the Fermi Institute in Chicago as well as members of the Astronomy Department. We used to go into Chicago every week and Chandra used to let me come sometimes and listen while he and Fermi talked about problems.
I got very interested in cosmic ray problems through Fermi. Fermi had this mechanism for understanding how particles can be accelerated by being scattered by interstellar clouds. It suddenly dawned on me one day that you could extend this whole argument and apply it and instead of using clouds, use a cluster of galaxies, in which each galaxy is like an interstellar cloud. Thatís how that paper came to be written. It is purely an application of the Fermi acceleration mechanism for cosmic ray particles between galaxies.
Wright: By 1958, your interests seem to have continued to broaden into the mechanisms of radio emission from clusters of galaxies and galactic explosions.
Burbidge: This was all part of one theme. There were basically two, or perhaps three themes. On the one hand, following the work we had done on the composition of some stars, I think the most important was obviously nucleosynthesis. But I had also been working quite independent of the people who I had been working with at that time, Margaret, Fred, Willy and so on, and ever since I had been at the Cavendish on the radio source problem.
I was getting better at it and learning more -- maybe I was not -- but I liked to think I was. Then I became quite interested in cosmic ray physics, quite early on through Fermi, so all these things were going on at the same time, and they have gone on all at the same time ever since, plus a few other things. I keep going back to things -- it is easier to go back to things that you know something about to start with.
Wright: In the early 1960s you had some lively debates with A.G.W. Cameron on star formation in Elliptical galaxies and intense radio sources.
Burbidge: No, no, it was not quite like that, you have jumped a lot of the science. Shklovsky had an idea involving many supernovae going off in the center of a galaxy and I published a paper in which I argued it must be due to a triggering mechanism between supernovae. Al Cameron wrote a paper in which he was suggesting that stars could form easily in the centers of galaxies. I was somewhat critical of this suggestion. I certainly thought it wouldnít work under the circumstances.
Wright: You wrote a paper on the origin of He3 on the surface of stars. Did this paper have any bearing on the helium abundance problem?
Burbidge: That was back to the problem of nucleosynthesis on the surface of stars. No, this was on the special question of the mechanism of nucleosynthesis on the surfaces. I have written about the helium problem as a general question, helium in the universe, in fact, I wrote I suppose the first paper published in the modern era, in 1958 in the Pub. A.S.P.
This whole question of understanding the abundance of helium relative to hydrogen in the galaxy the argument is a very simple one. Apart from a small amount of energy emitted as neutrinos, the abundance of helium is directly given by the luminous energy radiated by the stars integrated over time. Thus we can ask how much light has been emitted to give us that amount of helium found in the stars. If we assume that the galaxy has had a constant luminosity, we find that it will not have produced as much helium as we see. Thus you conclude either that the luminosity of the galaxy was very much higher in the past, or that the helium has been produced elsewhere, or possibly that the helium abundance is not uniform, and the value you have taken for the relative abundance is too high. A calculation was made by Fred Hoyle and Roger Taylor in 1964 that is often referred to, but I actually predated that calculation.
Wright: In 1963, in a paper on X-rays from the galactic center, external galaxies and intergalactic media, you indicated that the observed intensity of the isotropic X-rays was incompatible with a Steady State hot universe. What were your perceptions of the importance of this work to cosmology then and now?
Burbidge: I have never been a cosmologist. I did that work with Bob Gould. It was a fairly obvious deduction, again it was very early in the history of X-ray Astronomy. What you could say was that there was an isotropic background. If you simply looked at the flux you could immediately conclude that whatever was generating it was far too much for it to be associated with the decay of neutrons, and that Fred Hoyle and Tommy Gold suggested would be created in a hot universe. This was a very powerful argument against a hot universe of this type. If a hot universe could produce only one percent of what you see then it would have been still a possibility.
Wright: In 1964 you became interested in the recently discovered Quasi-Stellar Objects. Since you have worked a great deal on these objects, would you describe, at length, why and how you became interested in these objects?
Burbidge: Well, you know the old story Ö ďbecause they were there.Ē First of all, back in the late 1950s, when we went to Chicago we became interested in galaxies and the extragalactic field in general. When we went to Chicago we started very extensive sets of observations of galaxies at McDonald, and worked on the basic dynamics and the masses of galaxies. This all stemmed from our interest in the evolution of galaxies. I wanted to work on the evolution of galaxies, but when I looked at the data, they were lousy. There were practically no data. We decided the first thing to do was to get basic data. That is what got us working on the masses of galaxies and so on and so forth. Then on continuously for a period of seven or eight years we did a lot of work on normal galaxies. In fact, we wrote thirty or forty papers with Kevin Pendergast on this subject.
In 1962 the first quasi-stellar were identified jointly by radio astronomers with positions by Allan Sandage and Tom Matthews. The first position they came up with was identified with 3C48. Everybody started looking at it. One of the amusing things about astronomy is that when observers observe something they donít think they understand, they donít want to publish it. Almost all of the leading observers observed 3C48, including Margaret at McDonald with that spectrograph.
She could not understand the spectrum any more than anybody else, no matter how hard she tried. I remember that Allan Sandage was full of these things, but he couldnít understand them. There was nothing published. The only report for some time on 3C48 was in Sky and Telescope.
Then in late 1962, the sequence of events started on 3C273. Cyril Hazard and his friends made a very accurate identification of an object by lunar occultation. Cyril is a very disorganized guy and John Bolton sent a letter about it to Maarten Schmidt. It was Maarten who took some spectra and made the discovery that showed a very large red shift. At that point, we were all vastly intrigued and Margaret started to work in this field. She has been one of the leading people in this field, observationally. She started observing these things as fast as radio astronomers and others generated positions. From that point on her observations went very much away from normal galaxies or abnormal galaxies, very much in the direction of the quasi-stellar. Of course, at that point we were all concerned with the nature of these things. The relationship to the strong radio galaxies, they are radio sources, was obvious. The energetic problems that I have been hammering at for twenty years were obviously present in these.
In that period, just as 3C273 business was getting started, just before that, I got started on one of these schemes of mine on the energetic problem. Willy and Fred didnít like it and then they proposed gravitational collapse, which was taken up by many people. The four of us wrote an extensive paper on this in 1964. I might say in that period when we were puzzling about those damn objects, I wrote a paper in which I proposed that the red shift might have something to do with the gravitational red shift in the neutron stars. Of course, I was wrong. My arguments became quite irrelevant as soon as one assumes that these objects are far away. Collapsed stars exist, so we are told, but not in that context.
Wright: By 1966, along with Hoyle, you began to point out that QSOs might have a non-cosmological interpretation. At what point did you become uncomfortable about a cosmological interpretation?
Burbidge: I can tell you about that. I can tell you precisely, driving down the freeway somewhere in Orange County [Ca.]. What really happened is the following: In 1964 and 1965, people began to find that these objects were variable. Allanís early paper suggested optical variations but none of us paid attention to this. In 1964, I think -- I may have the dates wrong -- there was a report from the Soviet Union that one of the radio sources associated with a quasi-stellar, namely CTA 102, showed radio variability. It was claimed and announced by the Russians that it had something to do with a highly sophisticated civilization, or God knows what! In fact, we first heard about this at Cal Tech at the time. We first learned about this from Walter Sullivan of the New York Times, who got this report. None of us believed what the Russians were saying, not because of what they were saying about little ďgreen men,Ē but because we happened to know it had a large red shift.
Maarten had measured its red shift and it hadnít been published, but the red shift was of the order of one. So we didnít believe that rapidly variable objects could have a red shift of one. We didnít believe the report. The amusing thing is that the following year, 1965, Bill Dent, who was a student of Fred Haddock at the University of Michigan, showed quite conclusively that the radio source 3C273 showed variability. Now that meant that we really had to worry about this question of objects with large red shifts showing variation.
In the summer of 1965 we were in Pasadena. Margaret and I were living in Allan Sandageís house and Allan was staying in our house. He got the best part of that deal that summer, because it was smoggy in Pasadena. Fred Hoyle was there and Fred was actually staying with us in our house, as he frequently does. Maarten Schmidt, among others, was continuously worrying about this problem and trying to get Fred and I worrying about it. So Fred and I spent much of the summer trying to make models explaining the variation of quasi-stellar objects at a great distance. It was in the course of those investigations that we really began to ask ourselves what are the arguments for and against the red shift being distance indicators and so we wrote a paper you are referring to. In the summer of 1965, in Pasadena, we attempted to make the argument with models which Ginzburg criticized. We wrote a paper in which we balanced the arguments pretty well and we gave a case for cosmological effects and a case for non-cosmological effects. Most people who read that paper apparently felt that we argued for non-cosmological red shift but that was not what we thought we had done. We simply said that we didnít know. But we made the arguments both ways.
One of the first times I realized that there would be tremendously strong feelings in this situation was actually when I came back from Europe. We went to Europe in the summer. We returned in September and the paper had been pre-printed before it was published in the Astrophysical Journal. Allan refereed it as a matter of fact -- he told me about it on the phone on Monday.
One of the first things that happened, I remember when I came back here, was I had a phone conversation with Maarten Schmidt. Maarten, as I recalled, said, ďthat is really quite a nice paper.Ē I said, ďyes, thank you very much, Maarten.Ē He said, ďwhat are you going to do with it?Ē I said, ďit has gone to the Journal to be published.Ē Maarten said, ďyou mustnít do that, you will give everyone the wrong idea.Ē I always remember that remark, because I realized that what Maarten really meant in the authoritarian sense, was that now that you and Fred are saying something, people will have to listen. At that point it dawned on me, for the first time, I was perhaps naive, that the authoritarian approach -- I always kid my Dutch friends that they have it strongly -- would enter into the subject. But we didnít decide they had to be close by. We simply weighed the argument. I remember running down this freeway and getting stuck in a bloody traffic jam with Fred somewhere up near Disneyland. We sat and more or less tried to work out the various lines of argument. We were driving down here to spend a weekend in our house with Allan. It got so smoggy, Fred said we must go to Europe, ďI wonít stay here anymore.Ē He wouldnít go out of the house for about three weeks. It was horrible up there.
Wright: How did you perceive your role in questioning the cosmological interpretation as a scientist and as a human being?
Burbidge: I donít know what you mean by that. For me it is purely a matter of observational fact, and how far you can go in interpretation. If you look at the history of our understanding of modern cosmology, you find that what really has happened is that a few people and a few ideas and one or two predictions really have dominated the whole field. In the 1920s it was the prediction that we could live in an expanding universe and the discovery by Hubble and Humason that there was a velocity-distance relation or an apparent brightness-distance relation. I think it made everybody feel that was the way to go. But no one could necessarily rule out some alternatives on observational grounds.
The more you look at the quasi-stellar, the more you realize that the observational data only can be interpreted in the conventional way if you assume continuity between them and all of the other classes of objects -- continuity in the sense of the red shifts having the same origin. Once you wonder about that the whole subject is up in the air. At the beginning in this field it never really crossed my mind that people would do other than look at all of the evidence and worry about it. I am a cynic in general, but I was pretty naive about this business. I have never been involved in cosmology, and I am still not involved in cosmology. I would say that I am an informed critic of cosmology, I wouldnít say I am a cosmologist.
I never realized until this whole business of the quasi-stellar broke just how determined people were to have a universe of their own, the way they want it. I am afraid that a lot of very good people in the field only do it thinking they know the answer. The real difference in outlook, on the large scale, between many people and say, Fred and myself, is that most people would say they understand the skeleton and want to put some flesh on the skeleton. Fred and I think we donít really understand the skeleton yet, we donít know what the pattern really is. The bandwagon runs on very strongly and it is very, very hard to discuss this in a straight forward way. I think you have to look at all the evidence. I think it is unfortunate that sometimes the evidence comes before the theory to explain it all, but I donít think that this difficulty necessarily rules the evidence out. I canít quite put myself back in 1966 and 1967 the same way I feel now.
Wright: By 1967 you were rebutting papers by many people on QSOs.
Burbidge: I didnít know that I was. Whose papers was I rebutting?
Wright: I ran across one by Cannon and Penston on the optical variations of 3C446Ö
Burbidge: What did I write? Cannon and Penston are two young people at Herstmonceux. 3C446 is an object that Margaret studied extensively and measured the red shift, 1.4 as I recall. It shows rapid variability but thatís all. No one is rebutting, I donít understand.
Wright: Maybe I misunderstood the thrust of the paper.
Burbidge: The point is that 3C446 is one of the objects which has shown very large changes in optical luminosity, first discovered by Allan, Maarten and Margaret. Allan observed the thing and measured the colors when it was eighteenth magnitude. Tom Kinman is the key man. Allan measured the thing when it was faint and later on Margaret measured the red shift when it was faint. Later on, what happened was it got very bright, I forgot who discovered it, within a year to eighteen months, it got three magnitudes brighter, and then varied rapidly for a long time. Tom Kinman, who was at Lick at that time, observed it. There was some argument, I donít remember the argument, but I have always given it as a good example, of a rapidly varying QSO. There is no question about the observational data. There may have been some argument, but I donít remember much about Cannon and Penston. There may have been some argument about the lines and the continuum -- Margaret was involved more than I. If you want to go into details, we can read the papers and see what we are arguing about, but it is not a terribly important matter.
Wright: I misunderstood, but it appeared to me that you were having to spend quite a bit of time trying to promote your ideas concerning the QSOs.
Burbidge: I think the basic point is the following: There is a lot of evidence concerning these objects. Most of which was put in our book and much has been found since. People tend to want when there is any ambiguity in an interpretation, to assume, usually without discussion, that they know what the distance to the objects are. They do all the analyses on that basis. All I can say is when you look at all of the evidence together in a fairly systematic way, I think you have to ask yourself whether that is a reasonable approach. I donít know the answer myself, but the last place I put it all down was in that paper in Nature a year ago. I think most people will argue that it is all there. They may not agree with whatever bias I show in that particular article. I think the boot should be on the other foot. I think you should find a protagonist of the cosmological hypothesis who writes an article in which he includes both sides of the question. That is where I would argue quite strongly that I would not take second place to anybody in that type of discussion.
Wright: I do think that having looked through the literature to some small degree, I believe that you have presented your position much more forthrightly than perhaps the cosmological group.
Burbidge: Why sure, people have simply asserted in this field. I donít think it is a closed thing one way or the other, but it is very difficult when you get into a scientific controversy of this kind. I donít particularly want to take a position in which one advocates one point of view, but you are more or less forced into this position by people who very much do it the other way around.
For example, this is not a case involving me right now. There is a very recent result, a comparatively recent result, in which an object which is akin to a quasi-stellar, BL Lacerta, which is a very strange object with very rapid variation. The fuzz around this object was measured by Oke and Gunn with the two hundred inch telescope. It was published in the spring. They asserted in their paper that what we are seeing here was a quasi-stellar surrounded by a galaxy, embedded in a galaxy. They think from the fuzz that they have measured the red shift of the galaxy. They go on and from this they discuss the distance of the object. They reason therefore that this removes many of the objections people might have had to a cosmological interpretation and so on and so forth. A big play was made of this in April. In fact, I wrote a cynical editorial for Nature, ďWhat Does BL Lac?Ē in July. The article is somewhere behind you [pointing at the shelves]. The problem is that extreme publicity was given to this. Walter Sullivan wrote it up for the New York Times.
Wright: I heard about it on the radio.
Burbidge: Well, ok, so you know what I am talking about. The interesting thing is a group at Lick, using what is technically thought to be better equipment, but you can argue the same kind of equipment, have repeated these observations on a lot more nights and can find no trace whatever of the features from which Gunn and Oke deduced it was a galaxy. Now they have submitted this paper. This paper is being published in the January issue of the Astrophysical Journal Letters. It is entirely negative in the sense that you canít deduce anything about this because, in fact, What does BL Lac, BL does lack, if you like.
Now what should the Lick group do? Should they call up Walter Sullivan, should they make as big a fuss about something that isnít there that everybody is hanging onto now? What should they do? Once people make a strong position on something, it is very hard. What are you supposed to do? This is not the normal way you do science, but it seems to me you are duty bound, at some point, to counter this kind of nonsense. I donít know the answer in this case either. What do you say? I sit on a committee with Jim Gunn, and he is a friend of mine, too. I said to him, ďJim, what do you think?Ē He said, ďI think it is a matter of technique, we have a marginal positive result and they have a marginal negative result.Ē ďJim, you didnít say it was a marginal positive result when you put it all over the New York Times.Ē He said, ďthatís the news bureau,Ē but it is not only that because it is the result they wanted to get. This enters into the discussion, unfortunately, I think. A lot of the discussions in these fields raise peopleís blood pressure.
The quasi-stellar problem is associated with the fact that if the objects are not very far away, we donít understand their red shifts, and there is a possibility of new effects that no one understands. Many people would say that is the strongest objection to the whole idea and that may be. That is a point you can take. My point of view is to look at all the evidence and see whether you think on balance you can play this game or not. I donít think I know the answer, but I said in that paper there, my suspicion right now is, there is a hell of a lot more that we donít know than we do know. Maybe there are new things to be learned, but you mustnít censure the system. Arp, because he takes such an extreme view, his colleagues donít want to give him observing time, that has been the problem. Science is not as objective as some people would have us believe.
Wright: Your questioning the cosmological implications of the QSOs has involved several concepts. Since Penzias and Wilsonís work on a residual fireball was based on blackbody radiation, you have tried to determine if anisotropic regions exist. In general, has this been your method of approach?
Burbidge: What is the question?
Wright: You have taken various aspects of the cosmological versus the non- cosmological view.
Burbidge: Just for quasi-stellar.
Wright: You did mention in this paper, I believe, in one of your papers at any rate, the anisotropic regions located near some galaxies.
Burbidge: I donít know what you are talking about, I am sorry. There are several different things you might be talking about. As far as the quasi-stellar are concerned, the question is one of the distances of these objects. If you are going to talk about the question of observational cosmology, that is something quite different. The quasi-stellar, we could talk about the observational data. It is all in that paper somewhere or other.
Wright: The paper has to do with the discrete source models to explain microwave background radiation.
Burbidge: Oh, yeah! Well, they spelled my name wrong -- they are always doing that. That paper has nothing to do with quasi-stellar.
Wright: What I was trying to put across was an indirect relation as buttressing evidence for the ďbig bangĒ theory.
Burbidge: That was nothing to do with the quasi-stellar. Let me try and talk about these things in a systematic way. The quasi-stellar have large red shifts. Now, if these red shifts are associated with the expansion of the universe, there are cosmological implications. There is no question but that what Maarten Schmidt has shown is fairly obvious, and would be shown in a very crude sense using the back of the envelope approach that Hoyle and I have frequently used in problems. It was certainly clear that the universe, in some sense, is evolving with time. It is very hard to avoid this with quasi-stellar if they lie at cosmological distances. This is certainly within the framework of the kind of cosmological models that are normally discussed.
If the quasi-stellar are not at great distances, then they, the quasi-stellar, are irrelevant to cosmology, and we are interested in their physics, but they donít tell us anything about the large scale structure of the universe. Ok, so that is the only way in which the quasi-stellar can enter into cosmology. Now there is a question in cosmology, a basic question. What observational evidence is there, besides that of the quasi-stellar, which is ambiguous, if you are not sure about the red shifts, as to whether or not the universe is evolving? In the simplest and crudest sense, you contrast the simple ďbig bangĒ with the ďsteady state.Ē
I wrote a paper at one time in Nature, ďWas There Really A Big Bang?Ē, in which I attempted to summarize these arguments. Now this again was a cold-blooded look at the literature and I have not been involved in that work at all. Allan was upset by the article, because it was a cold-blooded look at the data, but here there are several kinds of data. There are the quasi-stellar which I say you have to put a question mark against unless you are absolutely sure, unless you are sure where they are. There is the value of the deceleration parameter which Allan struggles to measure which you may or may not think you know. Most people think they are not very sure about it anymore, it keeps changing. Allan is worried about it, others donít agree with him and so on, that is another question.
Now there are the counts of radio sources. Again, the counts of the radio sources depend on where they are. It still remains to be shown that the radio sources, as used by Ryle and others, are really showing us large scale evolution of the universe.
But the strongest argument concerned with observational cosmology is, in my view and many other peopleís view, apart from the apparent magnitude of red shift relation, the nature of the microwave background. The microwave background was discovered by Penzias and Wilson as an isotropic background radiation. It was immediately argued that this was indeed the remnant radiation from a hot big hang. The theory requires that this radiation should have a black body form. Now when I wrote that paper in 1971, the evidence suggested that indeed it was not a black body. In fact, I pointed out towards the end of that paper that this was, I thought, one of the great uncertainties. If it has a black body form, then, in my view, this is very strong evidence in favor of a simple big bang. I speak for myself. Fred doesnít believe in that kind of universe at all, but on the other hand, if the radiation is not of black body form, it has to come from something else. If the universe was not in a condensed state, it cannot have come from a hot fire ball. It has in some sense to come from discrete sources, all the galaxies radiating to give the curve that you observe.
Arthur Wolfe, a young post-doc working with me, and I, in 1970 and 1971, made calculations of various populations of discrete sources to see whether we could explain the observed results as they stood at that time. As I discussed in that paper in 1971, we found you could make such models requiring large numbers of discrete sources and such discrete source models were indeed possible. The observational situation has changed somewhat now and the high points above the peak of the black body curve have disappeared and it looks, as far as it goes, more like a black body curve. Most people, therefore, believe in a hot big bang. The primary evidence is the existence of an expanding universe as predicted, and primordial radiation field predicted in a hot big bang by Gamow and his colleagues and observed by Penzias and Wilson and others. We make life simple by leaving out all the complexities and all the other arguments.
Quasi-stellar, if they are far away, also indicate an evolving universe, but it is a big if! The value of q0 is another question, another question is the counts of radio sources. So thatís the way I see the observational cosmological picture. So the reason behind the paper you are referring to simply was at the time, four or five years ago, it seemed reasonable to see how far you could go with discrete source models. Now it is less reasonable, though there was a paper in the latest issue of Monthly Notices in which a case is still being made for discrete source models the back ground radiation.
Wright: Could you, getting away from quasi-stellar objects, could you comment on the potential data that you believe may be gained from X-ray astronomy in the future?
Burbidge: Every new window in the electromagnetic spectrum has led us to new discoveries. Our predictive ability in astrophysics is very limited, so there is little we can say. Letís look at the electromagnetic throughout the spectrum and see what we can see. The X-ray astronomers have already shown us that binary stars that are apparently very powerful objects. In terms of stellar evolution, they are prolific. The X-ray astronomers will eventually go faint enough to work on problems of cosmology. They hope they can study the X-ray sources for an analysis of the counts. They have the same problems as the radio astronomers, X-rays, if they are thermal, require hot gas, so you look for hot gas all over the universe. Otherwise, X-rays require interaction of microwave background radiation, with high energy electrons. But I canít tell you exactly where it is going.
The major thing that has happened so far is we have realized these are binary stars. When the X-ray astronomers first got into the binary star proposal, in which I was heavily involved, they thought it was not exciting enough, some of them. The history of the X-ray sources, which is modern history, is interesting in the sense that again when the first X-ray sources were discovered in the Galaxy, the first identification involved Allan Sandage. He worked with Ricardo Giacconi and others on this problem.
There was then a group of us at a meeting in Holland. Bruno Rossi, who was one of the senior people involved with a group at M.I.T. told us with great excitement that Scorpius X-1 was an X-ray star. So a small group of people Involving the Russians, Ginsburg, Shklovsky, Lo Woltjer, me and Margaret, George Herbig from Lick, Kevin Pendergast and I forget who else, met with Rossi to talk about this subject. When we heard the star looked like an ex-nova, we realized that it was probably a close binary and thus we began to make a model. I remember that I got up at the black board and everybody helped and we made up the model which now people are using for binary X-ray sources. The amusing thing is that earlier the Japanese had first mentioned in a long list of possible sources, binary stars, and no one paid any attention.
After this episode and this discovery, I actually gave a report at that meeting of what we had concluded. Later on, quite independently, Al Cameron and a student of his, Mook, wrote a paper along the same lines, and Pendergast and I wrote a paper in which we made the first real calculations on the accretion process. Now people are thinking accretion takes place on a neutron star or a black hole, whereas we had used a white dwarf. The subject has gone ďhay wireĒ and everybody is excited about it. But the discovery that X-ray sources in binaries, one of which is a very compact star, is one of the tremendously exciting discoveries. The attraction to me was that one could get the energy for the X-ray emission from the binary system, the X-ray source. Most X-ray astronomers thought that they would discover something exotic and the fact that they were binary stars at first horrified them. Now a black hole in a binary system is making them happy. I kid them about it.
Wright: Your interest seemed to have broadened additionally when you started doing some work on cosmic sources of infrared radiation.
Burbidge: True. Anything that broadens ones outlook is good. We have an infrared astronomy group here. I got involved in this with Wayne Stein, who is one of the faculty here. He works right down the hall from me. You have to utilize everything you can to find out as much as you can.
Wright: You became interested in black holes in connection with elliptical galaxies?
Burbidge: Well, I could see that explosive phenomena in galaxies could at the end give rise to a collapsed configuration. Artie Wolfe, the same man I worked with before, who is still here, studied the problem of whether we could set limits for the masses in the centers of galaxies. Something we worked on and now others are working on.
Wright: Do you believe there is observational evidence for black holes?
Burbidge: The best evidence is in one of these binary systems. I think that within the framework of straight forward theory and with the simplest arguments you can use, there is some evidence. If you can derive the mass of the system, and the mass of one component, you can establish whether or not it is a collapsed configuration. As far as I can tell, although I havenít studied this in great detail, this evidence isnít too bad, in the case of Cygnus Xó1. Now you can immediately do what you can always do in astrophysics, that is, complicate the issue in various ways. You can say, for example, as some people have said, that maybe it isnít a simple binary system, but a triple system, and the dynamics of a triple system are such that you donít have to have a black hole.
You can be more extreme, which most people wonít do, but some people would do, and say that the problem is that you get singular solutions and when this happens it is because you havenít got the physics right. So perhaps this demonstrates that when you go to places where you get to the situation where you consider a strong gravitational field, then Einsteinís theory breaks down. The simplistic argument is that we have Newtonian theory which is a zeros order gravitational theory. Then we have Einsteinís theory and in the limit of a very strong gravitational field, further modifications have to be made. This maybe is what is going on. Now I donít think that most of us would feel that this is a good argument, but the observational problem is always a difficult one. You can get out of any given observational circumstance by complicating the issue in some way and usually in astronomy it is very hard to check up on it. So much depends on what I think is reasonable or you think is reasonable, or Allan or someone else thinks is reasonable and plausible. Judgment and taste enter in and that is where much of the difficulty lies because, of course, it is a personal matter. Not everybody feels the same way.
Wright: Your papers on the apparent associations between bright galaxies and QSOs provide evidence of discrepant red shifts. You have expressed reservations on the data. How conclusive do you feel the evidence is now today for a non-cosmological universe?
Burbidge: I think the evidence is some of the best evidence we have, but it is statistical evidence. If you want to demonstrate the existence of non-cosmological red shifts independent of any theory, what you have got to do is demonstrate that two objects at the same distance have different red shifts. You can only do that by one of two methods. By showing that they are associated by some luminous material, or by showing that this object here with a very different red shift from this object here, statistically speaking, is very likely not to be associated with it. These are the lines of argument which are the most direct.
Now many people, including me, donít much like statistical arguments. But the problem is we have no methods other than these two for deriving distances in astronomy. You either take the red shift of an object (B) and assume it is at a cosmological distance, use the Hubble Constant H, and q0 to derive distance, and you say that since Object A is associated with Object B, I know the distance to Object A. If you are referring to the red shift hypothesis, what you look for are conflicts between those two arguments and in that paper ďThe Problem of the Red Shift,Ē I discussed what I considered, a year ago, was evidence of this kind. I tried to put all of it down, some of it is good and some of it not so good. Arp would put down more than I would.
Fred Hoyleís way of putting this is, Fred feels rather strongly now, you should talk to him. ďThere is something funny going on,Ē Fred essentially says, ďGeoff, if we are wrong about all these things, then we are very unlucky.Ē Fred talks about luck and being unlucky. ďIf the conventional people are right, so that all these things have got to be attributed to accidents, you and I have been misled by all these accidents and everybody else hasnít been. If you believe in cosmological red shifts, every event which is unreasonable must be treated as yet another accident.Ē
These things are next to each other purely by chance and the statistics of what we have done is pretty damn good, I think. There are some people who may not even agree with that, but other people who donít believe in anything done by statistics, and I tend to sympathize in a sense. People have got to clearly understand what the argument is, because frequently some are prepared to use it in one connection and not in the other.
One of the amusing things, or rather irritating things, about this association business is that when Gunn found a galaxy with the same red shift as he thought, though he got it wrong, it was a galaxy next to a quasi-stellar with the same red shift. He only got one case, but he made a tremendous claim that this proved the cosmological red shift hypothesis. Several other cases have been found. There is a paper by Odell who works with me along the corridor, we did the statistical argument both ways around. We found that the statistical weight attached to that kind of argument is lower than the statistical weight associated with the non-cosmological level.
People are so used to the idea of objects with the same red shift are at the same distance. You canít test hypotheses such as red shifts as a measure of distance if you go that route. You can only set up a hypothesis. If you look for objects which are at the same red shift, you are only going to check the hypothesis in the sense that you will only find the results you want. You are not testing it, you are setting up the answer. I think these arguments are ďso up in the air,Ē that they can boil on for years and people can get fed up with these. I sympathize with that too. Many arguments in science donít get resolved, what happens is that the proponents or their opponents die out, and later on the ideas are raised again. I was amazed, going back and reading Hubbleís papers, how Hubble himself began to doubt many of the bases for his papers. I got a paper by Dirac, which just came, he is very doubtful for other reasons of the belief that the universe is expanding. You have probably talked to lots of believers, but there are some doubts. The trouble with doubting is that if you donít have anything in its place, the stakes are very high. [sigh] You may be on the verge of something tremendous or you may be on the verge of nothing.
Wright: The Friedman Universe has been on the scene for about half a century. In the terms of Thomas Kuhn, I think it may be considered something of a paradigm. How do you perceive your work in relation to this paradigm?
Burbidge: That is very difficult, I donít know how to answer that. I have not been involved really. My problem, and I joke about this when I give talks, is that I think that in a sense to be a cosmologist, you have to believe. I donít really believe.
Wright: I donít think there are any cosmologists, Sandage doesnít consider himself a cosmologist.
Burbidge: Well, but Allan has been getting the data, I will not argue about that. I have not done theoretical cosmology, as Fred has, I have not devised a theory. I have not attempted to measure H or q0, in that sense I am not a cosmologist, but skip that. What I think is that in order to do it well, somehow you have got to feel very strongly. Allan feels that ultimately he will find the answer in his lifetime.
He is going to know q0 in five years. There is a plot of H against time, have you ever seen this? Well, this makes most peopleís blood ďboilĒ when we show it in talks. Some people just canít bear the idea that the age of the universe, or the age of the world as it is called, itself has changed as a function of time. I sometimes show it at the beginning of a talk and tell the students, ďlook, if you are twenty-five now you can calculate what it will be when you determine it at the age of fifty,Ē and things like that. I think you have to believe.
Now from a philosophical standpoint, I think many people I know like the big bang, because many people like a beginning. They have a strong feeling of a beginning which I think is religious. Allan has it in a religious sense, and I think Martin Ryle has it in a religious sense. There are others I know who find much more intellectual satisfaction in the concept of the universe as really endless. I think this has something to do with peopleís religious background. Again, I havenít felt strongly.
I am a physicist, and what intrigues me about these problems, about the non-cosmological things and so on, is the nature of the objects themselves. I would like to find the ultimate structure of the universe. But I have a very strong feeling what I would like to do is find something out about the physics from astronomy rather than applying the laws of physics to find something about the universe. It may mean astronomy is going to enable us to turn the problem around.
But I feel like Chandra and many others, that there are so many cosmological theories and Friedmanís was something picked up by Eddington which became very, very popular in a certain period, and everybody likes it still. Whether it has any bearing on reality, I donít know. There are so many classes of theory that have never been discovered. We are terribly naive if we think we really understand the large scale structure of the universe or know basically what went on, but thatís what most people do believe nowadays. If it really is that way, then it doesnít interest me terribly.
Study of the first few microseconds of the universe doesnít appeal to me at all.
I sit on the ďsidelines,Ē and watch the very non-scientific attacks that have been made on the Steady State theory for years. The attacks have been terribly non-scientific. This fight Ryle was having with Fred was awful. The arguments used were most unfair. If you look at the history of Steady State cosmology over twenty-five years, you will find from the beginning people raised objections to it. One after another the objections disappeared. Some of the observations were just plain wrong. The excess reddening of galaxies, which was discovered in the mid l950s and was used as an argument, just disappeared, it just wasnít true. Then the counts of radio sources have got into some difficulty. Now we have the microwave background which looked like a more powerful argument than most.
But as Fred has said in various lectures, looked at from that standpoint, what has really happened, the Steady State has simply survived all the crises except the last one, the latest one, the worst one and maybe it wonít survive it. Most people would say it hasnít survived it. They donít want to talk about the Steady State anymore and it has dropped out of the literature. But I donít have any brief for the Steady State and it may indeed be wrong; on the other hand, I donít have any strong brief for anything else.
People say, Geoff, you canít work anything out unless you believe in something. True, itís a difficult game, but it is a game, I believe. I donít have sleepless nights over it, I can tell you that. If you have to have that intensity of feeling about a belief in something, that is up to you. Martin Ryle has it in the most extreme form. Martin for years didnít believe that the radio sources he was observing were outside the Galaxy. I remember when Tommy Gold first said this in a meeting, Ryle thought it was awful. I found this with Martin, I found that when I argued with Martin he would get very upset. Others said, ďGeoff, you mustnít do that, he will get very upset and go home for a week,Ē and he did. He had tremendous intensity.
Allan finds it very hard to disconnect ideas people have from their personal relationships. He got Arp to Mt. Wilson. He was the great friend of Chip Arp, when I was there he was working tooth and nail to get him there. Chip is a very nice guy and Allan now will just not have anything to do with him personally. It is a very hurtful situation, but it is all because Chip is doing things that Allan thinks are wrong! He cannot give up on that, he canít let go. The problems we have had, have been associated with that. Allan finds it very hard. ďGeoff, you and Fred have ruined cosmology,Ē that is what he says -- Bull! Then he says later on, ďThe fact that I can say that means something, I wouldnít even say it to most people.Ē But that is one of the things, the intensity that some people have over these matters. It is related in an inverse way to the amount of information.
Cosmology is like religion in that sense, as I frequently say. A large amount of belief and a small amount of information.
Wright: I have read a good deal about your professional interests, you have mentioned that you have an interest in the ballet. I would like to know if you have personal interests or hobbies?
Burbidge: I donít have time for much. I do too many things right now. I have been involved in too many societies. I used to play a lot of tennis, and I still play some, but I am in bad shape. I have a daughter, who used to keep me fairly busy and still does. I like reading all kinds of things. I am fascinated by American politics, but I am still a British subject, so I just read about it. But I suppose as an Englishman I like sports as much as anything. I used to play all kinds of games.
But life for us is very complicated, we are always on the chase. Margaret is at Lick, she came down from Kitt Peak the day before yesterday. So just keeping things going, I have to admit, is rough. Well, I think for most people, for most scientists I know, who have made any progress at all, basically it is a seven day a week operation. You do it because you enjoy doing it. You get up and down, but you do it.
There are lots of things about it I donít enjoy. There is a lot of politics, a lot of fund raising and a lot of government committees and so on. I have got involved since I feel that I should take responsibility.
Wright: I really want to thank you for giving me your time.