Notice: We are in the process of migrating Oral History Interview metadata to this new version of our website.
During this migration, the following fields associated with interviews may be incomplete: Institutions, Additional Persons, and Subjects. Our Browse Subjects feature is also affected by this migration.
Please contact [email protected] with any feedback.
This transcript may not be quoted, reproduced or redistributed in whole or in part by any means except with the written permission of the American Institute of Physics.
This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.
Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event. Disclaimer: This transcript was scanned from a typescript, introducing occasional spelling errors. The original typescript is available.
In footnotes or endnotes please cite AIP interviews like this:
Interview of Gerard De Vaucouleurs by Alan Lightman on 1988 November 7,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
Interview discusses Gerard de Vaucouleur's childhood in Paris and family background; early reading; membership in the French Astronomical Society; early work on astronomical catalogues; work at the Paris planetarium in 1937; undergraduate work at the University of Paris; education at the Sorbonne; introduction to Julien Peridier; early work in astronomical photography; discussion of French astronomy in the 1930s; early attitude toward the big bang model; work at the Sorbonne; move to the new Institute of Astrophysics in 1945; work on the r1/4 law for the brightness distribution in galaxies; work on the supercluster of galaxies in the 1950s; influence of Vera Rubin's work; community's reception of de Vaucouleurs's work on the supercluster and his challenge of the assumption of large-scale homogeneity; interaction with Fritz Zwicky; attitude toward the Center for Astrophysics (CfA) redshift surveys by de Lapparent, Margaret Geller, and John Huchra; a hierarchical model for the universe; discussion of the meaning of homogeneity; attitudes toward the horizon problem, the inflationary universe model, dark matter, the flatness problem, work on the very early universe, and the big bang model; relationship of theory and observation; the ideal design of the universe; the question of whether the universe has a point.
I wanted to start by asking you some questions about your childhood and early background. Could you tell me a little bit about your parents?
I was born and educated in Paris, France. My parents were divorced and I was raised by my mother, Raymonde, a talented painter, who gave me strong moral principles. She died in 1987, aged 94. I read my first book in astronomy when I was 12, in 1930. It was “L’ Architecture de l’Univers” by Paul Couderc. That was my first contact with cosmology. It was just a little above my head at the time. It was an excellent book. Couderc was a teacher of mathematics. In fact, he was my professor in high school 1932 and became an astronomer at the Paris Observatory in 1944. He was a superb popularizer of science.
Did you say your mother gave you that book?
No. Her brother, Georges de Vaucouleurs let me read the book. He had been a member of the French Astronomical Society since 1925, and he had bought the book in 1930. On summer vacation I read most of it, but it was only when I was 14, in 1932, that I decided to become first an amateur astronomer and then a professional astronomer.
Was it based on that book? What was the motivation for your decision?
I think there was something in the family. As I said, my uncle was a member of the French Astronomical Society. My mother in the 1920s had bought a book called “le Ciel”, which was one of those big Larousse books about astronomy, and I read it in the late 1920s. The decisive influence was that I read four booklets by French popularize of science and astronomy, Abbé Moreux, who was a professor of mathematics at the Seminary in Bourges. He was a prodigious popular science writer. He must have published a hundred or a hundred and fifty books — booklets on mathematics, on physics, on astronomy especially, because he was interested in astronomy. And he had these four booklets. The titles were something like: “Where Are We?” “Where Are We Going?” “Where Do We Come From?” “Who Are We?” The last one was more about biological evolution and the Catholic point of view. These books attracted my attention. My mother bought me my first ‘spy glass’ in June 1932, and then I started observing. I became interested in galaxies almost immediately — through the observations of some nebulae in 1932 or 1933. And I tried to observe galaxies with the telescopes of the French Astronomical Society, which I joined in 1933. I was not quite 15. So, I’ve been a member of the French Astronomical Society for 55 years.
Were either of your parents scientists?
So it was just your uncle who was the main influence?
No. My mother had an interest. She bought this book. I remember trying to make plots of the paths of the planets when I was in school, about 1930-1932. But the decision to become an astronomer came about 1933, when I began observing.
Did your father also encourage you?
No. As I said my parents were divorced and I was raised by my mother. My father had no influence whatsoever. I saw little of him and he did nothing to encourage my scientific interests. He could not see any future in my ‘scribbling’s.
At this early age, around 14 or 15, when you decided that you wanted to become an astronomer, did you think about the universe as a whole?
No, not too much. I was more interested in looking at the planets, the moon, the sun, and then the stars. Nevertheless, I began to fill five booklets of bibliographic references on nebulae and star clusters, (NGC and IC objects), in 1933 or 1934, which you might say were the first seeds of the reference catalogues. By 1935, I had access to the 6-inch and 7-inch refractors at the observatory of the French Astronomical Society. I used them extensively, sometimes at the expense of my school studies. Trying to observe all night and attend class the next day is a strain. I offered to help the librarian of the French Astronomical Society to straighten out the mess and clean the dusty shelves of the library, so in this way I had access to things like the Harvard Bulletin, the Mt. Wilson Contributions, the Astrophysical Journal, Popular Astronomy, and all the publications that were not usually read by members of the Society, but which I devoured assiduously.
And you read those journals at the age of 15?
No, not 15. Seventeen to 20, in the last few years before the War. Essentially from 1935 to 1939. I was an active member, and I received some early prizes and medals, from the French Astronomical Society. And then I became a lecturer at the Paris planetarium in 1937. We had the Zeiss Planetarium, the full-scale instrument. I was part of a little team of students and amateur astronomers, headed by Reysa Bernson. She was the secretary of the ‘Association Astronomique du Nord’, that is, the North of France. She was Jewish, and she was deported and killed by the Germans during the war. Then there was André Hamon, who was for many years the secretary of the French Astronomical Society; he died just a few years ago. And there was Armand Delsemme, who is now a professor of astronomy at the University of Ohio in Toledo. He is still going very strong. I think he is emeritus too. And then an amateur astronomer named Codry, who remained an amateur all his life and, at 71, is still the driving spirit of an astronomy club in France. So we had a good group of enthusiastic amateur astronomers. We lectured at the planetarium to something like a half million people during that summer. For myself, I gave some 250 lectures, which was a good start.
Good practice for teaching at the university.
Yes, a full-scale planetarium is a wonderful teaching instrument. I hope that someday Austin can get one. That would really be a valuable tool. Then I began observing. I looked at practically all the Messier objects, in the years 1933, 1934, 1935, 1936, first with a 3-inch refractor at home (in Vincennes, a suburb of Paris), then a 7-inch refractor at the French Astronomical Society. I began taking photographs. I remember photographing two supernovae. The famous one in IC 4182 in 1937, and one in NGC 4636 in 1939.
This was after you had finished at the University of Paris?
No, I was then an undergraduate student. I had earned my Bachelor of Science degree — that’s the final degree of high school in France, you know — in 1935 and 1936. It was a two-stage exam at the time. And then I did one year of special mathematics at the St. Louis Lycée in Paris, just across the street from the Sorbonne. But I was fully aware that the Second World War was coming, and it was affecting my schedule of studies. I felt I had to obtain some university degree before the World collapsed. So instead of taking the long and chancy route through one of the ‘Grandes Ecoles’, I crossed the street to the Sorbonne to do a quick ‘Licence’ in mathematics, physics, and astronomy, which I finished in 1939, just before the War. In 1939, I was introduced to Julien Péridier. Today you can see his name on the door of the astronomy department library here. He was a wealthy amateur astronomer. He had been a member of many astronomical societies, since the early part of the century. He was, when I met him, the general director of the Paris transport system — the whole thing: buses, trams, and subway. So he was wealthy, and in the 1930s he had built a very nicely equipped observatory of professional quality in the southwest of France, at Le Houga. ‘He had a superb twin 8-inch refractor and a 12-inch reflector, which are both here in Austin today. He was looking for a young astronomer to work at the observatory, and I was fortunate to be introduced to him by an engineer, Mr. Saget, who was the head of the astrophotography section of the French Astronomical Society. I was very actively interested in photography in those days, and later I wrote several books on photography. And so I began to work for Mr. Péridier in July, 1939. First, I observed the planet Mars, which was in opposition in 1939, and then did some experiments in photographic photometry. I designed some out-of-focus cameras of the style used by King at Harvard in the 1910s and 1920s to do stellar photometry. But the war came and I had to spend a year and a half in the French army, the in-glorious French army of 1939-1940. I was lucky and came out unscathed. I returned to the Péridier Observatory in July 1941.
During your time at the University of Paris, were there any people who were particularly influential besides Péridier?
Yes, my professor of physics, Jean Cabannes, was the leading French physicist in molecular optics. He was the director of the Physics Research Laboratory at the Sorbonne. As soon as I graduated in 1939, I contacted him and asked if I could become a grad student in his lab, and he said yes. This was postponed because the war came. In addition to the credit classes, I took classes from Georges Bruhat, a physicist who was interested in astronomy; he had written an excellent text, a high-level popular book on the sun. He was the associate director of the Ecole Normale Supérieure. In 1939 he gave a one-semester course of lectures on the physics of the sun. I remember taking that. There were very few students taking this class because it was not for credit. Bruhat was also killed by the Germans during the war for helping students to escape deportation.
Were these people influential because of the subjects they were talking about or because of their approach to science?
Well, both, Cabannes was an excellent teacher and a great physicist. The clarity of his lectures was remarkable, and he had a large audience from his students. I took my formal basic astronomy course from Ernest Esclangon, who was then the director of the Paris Observatory and the inventor of the talking clock. By the time I graduated from the Sorbonne with my undergraduate degree, I was living for astronomy 24 hours a day. I had already been given access to the library of the Paris Observatory in 1935, through the good offices of Dr. Paul Baize, who was a physician. He was an active — in fact a world-class — observer of double stars. Through him I met Esclangon, and was given access to the Paris Observatory library. I read books there and translated many research papers from English into French or German into French. So I learned a lot of astronomy on my own.
In your studies of astronomy at this time, in the late 1930s or so, had you studied the big bang model?
I was aware of it because I read books and the review articles that were published. There were excellent review articles in those days, high-level review articles — in l’Astronomie, the French bulletin — which we don’t often find today in popular magazines. We had excellent articles about stellar astronomy, including articles on extragalactic astronomy by Henri Mineur, who was a young and very active promoter of the new astronomy in France. I must say that French astronomy had been revived after the Franco-Prussian War of the 1870’s. Surprisingly, after the victory of the First World War, it [astronomy] was neglected by the state and reached its minimum around 1932. At that time, from a statistic that stuck in my mind, the French papers represented only 5 per cent of the world production in astronomy. Then with the access to power of the ‘Popular Front’ socialist government of Lé on Blum in 1936, there was a revival. Blum created an under secretariat for science, within the Popular Front government, which was headed by Jean Perrin, the French physical chemist, one of the promoters of the atomic theory He made studies of the Brownian motion, et cetera. What was then called the fund (‘la caisse’) for scientific research became the ‘Centre National de la Recherché Scientifique’ (CNRS), the French NSF [National Science Foundation]. Among the projects that had been discussed by astronomers for more than a decade before was the creation of an Institute of Astrophysics in Paris, and of a national observatory in the lower Alps for the observations. This was started with a program of fellowships for would-be astronomers. Then the war came and remarkably, [this program] continued, although at a low level; it was never interrupted by the war. This was directed from Paris even during the period of the Vichy government. So after I had spent about a year and a half at Péridier Observatory, I received a state fellowship to come as a graduate student to the Physics Research Laboratory in Paris. [This happened] through my mother, in fact, when my professor of physics [Cabannes] asked what had happened to me and where I was. I was well entrenched at the Péridier Observatory, being fed and housed, with nothing to do but astronomy. I was putting in 15- or 18-hour days of observing and studying. At that time, I was more and more involved with photography and stellar photometry. In fact, several papers were published after the war, based on the work I did during those years.
Let me ask you before you go on if you can possibly remember what your early impressions were of the big bang model. I know it’s hard to remember back that far.
Well, there was great excitement with the discovery of the redshift and the Hubble law. When Couderc wrote his book in 1930, the Hubble law was one year old, and it was the first book that brought the subject to the French reading public. I must say that I did not spend too much time speculating about beginnings and philosophical implications of the big bang. [The expansion of the universe] was an observed fact. It was not called the big bang, then, of course. It was the primeval atom of Georges Lemaitre. I didn’t have a strong reaction one way or the other. I was interested in what is today inside the universe, not in speculating about origins, although I was aware of some of the implications.
Did you accept the interpretation of Hubble’s measurements, as indicating an expansion?
Yes. Yes. I had no question at that time. I accepted it. Why? It was what the authorities were saying. I started like an innocent, believing what the authorities are saying. Only later you begin to question the dogmas. Yes, I accepted it, that it was valid, that it was reasonable. But I was more interested in the planets, especially in Mars, and then the stars. I did a lot of stellar photometry, observed variable stars. It was not for a lack of interest in galaxies, because I was continuing my bibliography [catalogue of galaxies]. But I had no telescopes suited to such studies. I did photograph a few nebulae, a few supernovae. But I realized I did not have the tools. So our effort at the Péridier Observatory was first to equip the observatory with a micro photometer, [allowing] the plates to be measured. We bought a recording micro photometer, which is very unusual for an amateur observatory, and then I built some simple spot photometers to measure photographic plates. I still have somewhere the tracing of one axis of the Andromeda nebula, which I measured with that recording micro photometer. It showed the extension of the envelope well beyond the visual edge. It was around 1942 or 1943. I could not go to the Péridier Observatory, of course, in 1944. But I went back in 1945. I was keeping up my interest, by reading and collecting data. I put a lot of effort in photographic stellar photometry in those days. Few astronomers have gone through boot camp in photography. They often bad mouth it because they don’t know how to use it, simply because of lack of organized teaching of the subject. After the war I was asked to organize lab classes in scientific photography for the CNRS and taught them for 5 years. Let me go back to the early years in my career. After I received a fellowship from the CNRS in 1942, I went back to Paris in the spring of 1943. Then I started the research work for my dissertation, which was in molecular physics — Rayleigh scattering of light in gases and liquids. At the Sorbonne, needless to say, the funds were very limited. Everything was moving very very slowly. But my professor gave me freedom to do as much astronomy as I wanted. He knew that I was working, and he did not insist that it [my work] should be strictly physics as done by others in his laboratory. I had a two-room lab in those days — a dark room and an office. To show you how ancient those things were, in the drawers of a [cabinet] in one room I found some of the small-angle prisms that had been used by G. Lippmann at the turn of the century, for his interference technique of color photography (for which he received the Nobel Prize in 1908). I soon made good use of these prisms in a set up designed to measure the thickness of photographic emulsions by interference techniques.
It was almost a museum. We used to joke that we were using equipment made of ‘optical wood’. It was ‘string and wax’ physics. But I learned a lot about optics and about photography in those days. It was very helpful later.
Let me move to the late 1940s and early 1950s.
Can I finish this?
Yes, please. I’m sorry.
The decisive step occurred as a result of a mishap. After the liberation of Paris, the following winter, we were still at war, and it was very cold. There was no heating at the Sorbonne, so the lab was closed for a couple of weeks at one time. As usual, someone forgets to turn off the water when this happens. So when the thaw came, there were burst pipes. One day I arrived at the lab, and the assistant said “Oh, Monsieur de Vaucouleurs, it’s terrible. Your office is flooded.” And there were several inches of water on the floor. Unfortunately, some of my plate collections had been ruined. I turned around and immediately went to the telephone, and I called Daniel Chalonge, a leading astrophysicist in those days. He was the acting director of the Institute of Astrophysics. I said “Monsieur Chalonge, here is what’s happening. I’m fed up with the old Sorbonne. Can you give me a lab at the brand new Institute of Astrophysics?” I had hardly finished, and he said, “Why, of course. When do you want to come?” That was my admission test, to enter the Institute of Astrophysics as a grad student. [Laughs]
You just asked.
Yes. Of course, he had known me for about two years. He was the developer of one of the first French micro photometers. He built the prototype in 1926 at the Sorbonne, in the lab where I was working. For my first job, my professor said “Take this old piece of equipment and make it work.” (I did). [Since 1926], Chalonge had developed more modern types of recording micro photometers, which were very nice, state-of-the art at that time. I had used them when the Institute was housed in just two rooms at the Ecole Normale Supérieure nearby. So I had been in touch with these people, and they knew what I was doing. On April 1, 1945 (no joke) I moved to an underground lab at the institute where I had a brand new, beautiful darkroom and an office. I was the first and only graduate student at the Institute.
Will you forgive me if I skip ahead to the early 1950s?
I want to add another thing of interest: I was the only graduate student in France and probably in the world to have an assigned, full-time assistant. I was doing astronomy and was very productive already while working for my dissertation. After the war, Mineur resumed his position as director of the Institute of Astrophysics. I said to him one day in 1947, “I’m working on all this and that and I need an assistant.” He said, “All right, I will hire one and you can use him full time.” I even had a candidate for the job, Paul Griboval, who 20 years later came to the University of Texas to build a fine electronographic camera for McDonald Observatory.
Every graduate student wishes that he had an assistant.
That was unique, but it didn’t seem strange to me. I was working — very hard, full time doing what was regarded as good work. It seemed to be natural. But in retrospect it seems incredible. Then, after the war, toward the end of 1945 Evry Schatzman came to the Institute, then Jean-Claude Pecker, who just retired last year after a distinguished career, then Raymond Michard who was later director of the Paris Observatory. So we had this small group, but all have made their mark in astronomy. This showed that the first few grad students were well picked. I finished my dissertation and graduated in the spring of 1949, which I think is the year when I published more papers than at any other time.
I’ll ask you for a copy of your vita and bibliography.
[Consulting his bibliography.] I published something like 25 papers, including popular articles, in 1949.
Yes. It really was. My wife, Antoinette (whom I had met in 1944), and I were busy with various projects. Then we moved to London, because with the background of having been an amateur astronomer interested in Mars, and a physicist interested in galaxies, there was little future in French Astronomy. As Chalonge, sadly remarked to me one day “Il faut faire ce qui est a la mode” (one must do what is in fashion). You had to have a powerful patron, or otherwise you were lost.
You needed a powerful patron to get time on a telescope?
No, but to be promoted. To be protected. Also, the salary scale was pitiful in those days. It was just after the war. And then the instruments available were very limited. There was a 32-inch reflector in Haute-Provence, and a 50-inch, which had a glass so old and full of stresses, that one day it exploded. We used them after the war. I had met [Harlow] Shapley in 1949 also, and I wanted to come to this country because that’s where galaxies [were being well studied]. But at the time he was looking for solar astronomers.
I wanted to ask you some questions that possibly related to your meeting with Shapley, although I’m not sure.
Oh, it was very simple. I had read his books. I had written to him.
Which of his books?
All of his books, especially Galaxies. I had long ago read Hubble’s The Realm of the Nebulae, I still have them. [De Vaucouleurs gets the two books off his shelf.] I was very familiar with all that had been published in The Astrophysical Journal, Astronomical Journal, Astronomische Nachrichten, Harvard Bulletin, and Harvard Annals. I still have a good collection of Harvard Annals myself; I bought it before the war. I started building a sizable astronomy library as soon as I could afford it.
May I ask you some questions about your work at this time?
I wanted to know your motivation in the early 1950s when you began working on the local Super cluster.
That was later. I had done work on galaxies a little earlier, as soon as I could. Yes, my first work on galaxies was done in France, at the Haute Provence Observatory. I did photographic photometry, and that’s where I introduced the r1/4 law that expresses the brightness distribution in elliptical galaxies.
Could you remind me what year that was?
Yes. I published this in 1948. My concern at the time was this: I realized fully that there was no point, to compete with Hubble when you had only small sized telescopes. Studying his [Hubble’s] work in detail, I discovered that he had made some technical mistakes in photographic photometry. Also, having been trained as a physicist, I was not impressed by this eyeballing of photographs to decide the Hubble type of a galaxy. I thought “to be scientific, we must be quantitative. What are we doing when we look at a photograph? Well, we look at the distribution of surface brightness, or specific intensity. Therefore we must do photographic surface photometry to be able to classify galaxies and measure things quantitatively.” So, my training in photography and photometry was very helpful, and I started a program of photographic photometry of galaxies in 1945-46 at the Haute Provence Observatory. By 1948, I had some preliminary results, which were published in the “Comptes-Rendus” of the Academy of Sciences and in the ‘Annales d’Astrophysique’. That’s where I defined a number of quantitative parameters to measure the size, brightness, and so on, of galaxies, which are still used today. And I stumbled on to the r1/4 law, which for 20 years was denied as being impossible. Now everybody is making hay out of it. Apart from that, I see some papers on the “Principle of a Method of Detecting the Nearer Side of the Andromeda Nebula,” to find the sign of the inclination. A paper with some cosmological implications: “The Contribution of the Extragalactic Nebulae to the Light of the Night Sky.” Using the Hubble counts of faint galaxies, I calculated that the total light of the galaxies, including those fainter than the counted ones, would be only 0.3% which is not detectable. I also worked on the sense of rotation of spiral galaxies. The subject was widely debated at the time. Hubble wanted them to have trailing arms, as most astronomers did, but B. Lindblad and his school in Sweden wanted them to have leading arms. I made a special study of one galaxy that seemed to me to be especially critical for this, and the arms were trailing. Then we spent a year and a half in London. I was in charge there of the science program for the French section of the BBC. I also had a good opportunity to visit laboratories and observatories, and meet British scientists. To keep in touch with astronomy, my wife and I worked on a paper, a follow-up to our photometry, which was to build a model of elliptical galaxies. Isothermal spheres or truncated isothermal spheres do not fit well. So I introduced a mass function. It turned out that this is not appropriate, as we know today, but at least I tried. That was done while we were in London.
When was it that you were doing your work that ultimately questioned the assumption of homogeneity in cosmology? Wasn’t that around this time?
That was in the 1950s. After a year and a half in London, we went to Australia. The Australian National University had been created in 1948. They had an astronomy department, in which there was just one professor, Richard Woolley. Having seen the 74-inch reflector for Mt. Stromlo in the ‘Dome of Discovery’ in London in 1951, I wrote to Woolley, to explain what I wanted to do in the south. Initially, a redshift survey. It was badly needed. Things moved very slowly in Australia in those days, and I could just barely start that survey in 1956, as I was getting ready to leave. Instead, I did a photographic survey of the southern galaxies, which has been useful because there was [no other work done in this region of the sky]. In 1949, I had already started a revision of the Shapley-Ames catalogue [of galaxies]. I had measured the diameters of galaxies on as many plates as I could use, including those of Isaac Roberts, a wealthy British amateur at the turn of the century. He had made the first large collection of photographs of galaxies, using a 20-inch reflector. It was in the course of this work on revising the Shapley-Ames catalogue — providing better [galaxy] types, sizes, and so on — that I began realizing that there was a stream of galaxies across the northern galactic hemisphere. It was either a very rare chance alignment, or, more likely, it was a physical association of galaxies, on a scale much larger than clusters or clouds of galaxies. Of course, I was aware of the work of Shapley on very large-scale density gradients [in homogeneities] across the universe. I didn’t have much to say about that, but I was aware of it. I was [also] aware, of the work of Fritz Zwicky, claiming that clusters [of galaxies], not galaxies, are the building blocks of the universe. It occurred to me that this belt of galaxies had to be a real physical association. This I reported in The Astronomical Journal in 1953. I was given the incentive, or the courage, to publish this because Vera Rubin had just published an abstract of her master’s thesis, where she tried to detect a “universal rotation” of the world. She had used a hundred redshifts that were available from Humason in 1936, and she did a regular Oort-type, first-order, differential rotation analysis.
And she found anomalous velocity fields?
Yes. She found a solution [to her equations and data]. Through a misunderstanding of mine, I thought that the direction of the pole of the ‘universal equator’, as she called it, had been found from the kinematics. When, later, she sent me her full master’s thesis, I realized that her ‘universal equator’ was nothing more than the local super duster equator. As you know, probably, she was so poorly received when she presented her paper at a meeting of the American Astronomical Society in 1951 that she never touched the subject again for 25 years. They really scared her away, and for about 10 years I was the only astronomer who was corresponding [with her on this subject.]
How did people receive your work when you reported it in 1953?
Very badly, very badly. But I am more pugnacious, probably, and if it’s there, damn it, I’m going to say it’s there. Now, trying to be very conservative, I said this line [of galaxies] must be the edge-on view of a flat system, analogous to our Milky Way. So I realized two things. If it is a disk with a center near the Virgo cluster [of galaxies], because it’s flat it must be rotating — (that was the kind of reasoning I was making; of course it’s absurd today). And we know it is expanding because there is a redshift at Virgo. Therefore, I built a disk model in differential rotation and expansion that was published in The Astronomical Journal in 1958 and which fit the data very well, at the time. Also, to support the little paper I had published in The Astronomical Journal in 1953, I wrote a lengthy review paper in ‘Vistas in Astronomy’, volume II, which was published in 1956 to honor Professor Stratton [de Vaucouleurs gets the Stratton book from his bookshelf.] Professor (Colonel) Stratton was the grand old man of British astronomy in those days. They listened to him in government circles; he had been interested in military affairs since the First World War. Stratton was the man who had interviewed me in London. Effectively, he gave me the job at Mt. Stromlo. The job was created for me. I did not answer an ad in the paper. On several occasions people have created jobs for me. It’s much nicer than having to apply for them.
It certainly is. If you just ask and they know your work. Were you aware that your work here and the results were challenging some of the assumptions of the big bang model?
Yes. Not the big bang model [in general]. What I was challenging was the assumption of uniformity. [That assumption] is obviously incorrect, and what puzzles me is that it took 20 years before [my view] became accepted. Because it’s absolutely obvious.
Why do you think people resisted so much in 1953?
Longer than that. First, for several years, there was complete silence. Then there were denials. I still love those denials so much [I’ve written them] on my blackboard here. You can read them. For example, [Walter] Baade, in 1956, said to someone who came to interview him: “We have no evidence for the existence of a local super galaxy [Super cluster].” And then in 1959, Zwicky said: “Super clustering is nonexistent.” It’s surprising because Zwicky was open to new ideas. These are good quotations.
So you have all of these quotations on your blackboard from people who have not believed in super clustering.
In fact, Gart Westerhout, who is now the scientific director at the U.S. Naval Observatory, told me that when he was a student in the 1950s, at Leiden, the students were interested in this concept [of super clusters] and wanted to make some studies. But the great professor there, Jan Oort, told his students “It’s complete nonsense. You shouldn’t pay any attention.”
And that was in the 1950s?
Yes. In fact, in 1957, at the Solvay Conference, Oort had something very negative to say about the hypothesis of the super cluster. But in 1983, at the Trieste meeting, he was one of the defenders of the super cluster. Well, people learn.
Why do you think that people resisted? What’s your opinion?
Number one, because it did not come from a member of the establishment. As one of them told me years later; “if it doesn’t come from us, I don’t believe it.” There is only one true church.
Do you think that if Oort had been saying that there was a super cluster people would have believed it?
Yes, of course. They would have acclaimed it as something great. The greatest discovery of the great man. That was very clear for many years. I think it took a new generation and just the overwhelming accumulation of evidence [to gain acceptance for the concept of super clusters]. Also, I must say, the inhomogeneous structure complicates life to those who try to determine H0 [the expansion rate of the universe] and q0 [the rate of deceleration of the universe]. The homogeneous model is necessary to do calculations. No one knows how to handle [the mathematics] in an inhomogeneous universe except by numerical simulations. So that [the existence of Super clusters and large-scale inhomogeneity’s] made life difficult. I remember a discussion I had with Allan Sandage about this in 1957. He was very upset because he could see this would complicate his life. He said to me, “If what you say is true, what would you do to measure H0?” I said “I would try to find a rich Coma-type cluster [of galaxies] near the south galactic pole, at about the same distance as the Coma cluster in the north, and then measure the relative redshift and their distances. Then you would have an approximation of the Hubble constant.” Of course measuring distances was the catch, but [you could not do such a measurement] from nearby galaxies, as was done at the time, because, I insisted, excess density in groups [of galaxies] and obviously in clusters would [locally] reduce the expansion rate. There was nothing revolutionary about it. I even double-checked with some theoretical cosmologists. My statement was perfectly Newtonian and Einsteinian. There was nothing wrong with saying that an excess density must slow down the expansion rate. Why this was resisted has always been a puzzle to me. I think there is a combination of reasons. It complicates life for those who want to [determine] H0 and q0 in their own lifetimes. [And] it was not from the establishment.
I remember that in some of your later papers you also pointed out the problem that there may not be any average density in the universe.
One of the early supports for the concept came from George Abell’s catalogue of clusters, where he found some weak correlation indicating that clusters tend to be associated. But here I have repeatedly stressed, in vain, that Super clusters are not made up of clusters. Rich clusters are rare. You cannot map Super clusters very well by means of rich clusters only. For example, the local Super cluster has not one rich cluster. Super clusters are populated by groups and clouds of galaxies. They are not clusters of clusters. That’s what I think Zwicky had in mind when he said that super clustering was nonexistent. [One should not] think in terms of big globular clusters [of galaxies] of the Coma type. What I was speaking about was plane groupings, populated mainly by poor groups [of galaxies], rich groups, and what I call clouds of galaxies, not by rich clusters. Of course, rich clusters do show associativity, and participate in super clustering, but super clusters are not made of rich clusters. This has confused some of the discussion. Another thing was purely a question of nomenclature. I remember having Zwicky for lunch in 1957 or 1958, when we were at Lowell Observatory, Flagstaff [Arizona] where we had a house on ‘Mars Hill’. Although we had this disagreement, Zwicky was always extremely generous towards me. One could discuss freely with him. I said, “How big can a cluster be in your nomenclature?” He said, “Oh, 30 or 50 megaparsecs.” I said, “But that’s the size of a Super cluster.” And I pointed out that we could say that New York City and Johnson City, Texas are both ‘cities’, that is agglomerations of houses, but surely there is a structural difference, a very deep difference between a megapolis and a little village. Even for classification, we need different terms. And this he would not recognize. He had in mind that the clusters were in the centers of “cluster cells,” which were their spheres of influence. Today, we know it is just the opposite. The cells are empty, and the galaxies are on the faces of the cells. So this took some time to develop. In 1961, we had the Santa Barbara conference on clusters of galaxies, and I proposed a classification. In the 1953 paper, I had already pointed out the existence of the ‘southern supergalaxy’, which has just been finally studied in some detail by one of my students, Shyamal Mitra. This is the nearest super cluster outside our own. And it has been completely neglected up until now, in part because it is in the south. It’s about the same distance from us as the Virgo cluster. And, again, it’s a stream of galaxies. Then, I was also aware of the Perseus-Andromeda stream, which had been noticed by John Herschel. In the early 1960s, I became suspicious that there were just too many linear formations. If they were disks edge on, there were just too many of them to be due to random orientations. So I began to worry that they were perhaps streams of galaxies in space.
I was going to ask you about your reactions to the recent work by Haynes and Giovanelli on the Perseus-Pisces super cluster, and the work of Geller, de Lapparent, and Huchra. Is this all consistent with your earlier thinking?
Oh yes. Absolutely. I make the point that what we are discovering now at intermediate and even great distances — on the Lick maps for example — is entirely consistent with the structure we see nearby. But because of the instrumental limitations, I’ve never attempted to study great distances. I’ve never been given access to very large telescopes. I’ve always had small or medium telescopes. The biggest I’ve used regularly is the 2-meter at McDonald. [I’ve been limited] to nearby space, where we can see better and know what we are doing. But these [newly discovered] structures are entirely consistent.
[These inhomogeneous structures] disturb some people, shakes their confidence in the big bang model, in the assumption of uniformity.
Well, this is something I’ve discussed repeatedly, beginning in 1960. In 1960, I made studies of the viral theorem in nearby groups of various sizes, and then clusters. I found that the mean density of the groups decreases as the size increases. Then I realized that this was the same thing that Ed Carpenter, the former director of the Steward Observatory in Tucson, had said all along in the 1930s. Nobody understood what he was talking about because he gave a funny title to his paper, which was “A Density Restriction in the Metagalaxy.” What he had done was to take counts of 25 clusters of galaxies published by [Harlow] Shapley. [Carpenter] found that the number density, of galaxies decreases as the cluster becomes bigger, which he derived from the redshift. He discussed the meaning of this relation. It’s a very profound paper. It’s a pity it was completely missed by everybody in the 1930s. [Carpenter] realized this was some kind of balance between the total kinetic energy and potential energy of these groups. And the question is: why is it that nature cannot pack more matter in a given volume? In other words, the Carpenter relation, as I call it, is not a relation; it’s an upper limit, an envelope. There are loose systems of a given size. Most of them we don’t see because they are lost in the [noise]. If a loose open [star] cluster were a thousand light years away, we would hardly see it because it would be too poor. It would be lost among the field stars. But we don’t miss dense clusters. At any given radius, there is a maximum density that can be packed in that volume of space. This density is several orders of magnitude less than the Schwarzschild limit. There is no reason in the world why we could not see a denser object. If there was in the sky an object the same size as the Coma cluster but 10 times denser, it would have been the first cluster to be discovered. So it’s not observational selection. It’s not a black hole type of exclusion. There’s plenty of room. To my knowledge, this point has not been addressed by cosmologists. Why is it that we don’t see denser clusters? And this relation extends from the nuclei of the densest elliptical galaxies, which have a density of the order of 10-20 grams per cubic centimeter, down to the volume of the space probed by the Lick counts which has a mean density of perhaps 10-30 grams per cubic centimeter. In other words, over this range, we don’t see anywhere a constant density.
[The density] hasn’t leveled off. [A constant density] is certainly required by the [assumptions] of the big bang model.
That’s right. At first, I said that maybe we have a hierarchical universe of the type discussed by Charlier in which the density of increasing volumes decreases indefinitely, and at the limit [of very large volumes] it could be zero. Also, the slope [of log density versus log radius] was -1.8, and that is the slope of the covariance function. That’s well established now, but it took twenty years before this became generally accepted, mainly through the work of [James] Peebles. It seems to me that that is a basic cosmological datum that has not been taken into consideration. Why cannot nature pack more matter into a given volume? As you know, from the viral theorem, we find masses that are one and a half orders of magnitude greater than those from classical rotation. But whichever measure you take, the visible part or the dark matter, the range of radii covered is so large that you cannot miss the trend. The fact that the same mean density for the universe was found repeatedly from the 1930s until now — except for distance scale corrections — proves simply that we are just probing always roughly a hundred million light years, give or take a factor of two or three. Over that small range, within the errors of distance scales and of mass estimates, you always get about the same numbers, 10-30 to 10-31 grams per cubic centimeter. I believe today that the deep radio source counts show that on scales of thousands of megaparsecs, we do have homogeneity, with the proviso that these deep radio source counts do not cover the sky, but are just narrow strips that have been explored at great depth. There is another battle that still has to be won, but it’s making progress rapidly. In the 1960s and the 1970s, Kiang in Ireland and Saslaw working with him in England, Kalinkov in Bulgaria — nobody ever tells you about the work of Kalinkov in Bulgaria, but he’s done good work — [all found that] on scales of hundreds of megaparsecs, there is still positive correlation [inhomogeneity’s]. Recently, Neta Bahcall has found the same thing, not knowing the previous work. Karachentsev and Ozernoy, about 15 or 20 years ago, showed that the density contrast between one order of the hierarchy and the surroundings decreases as you increase the size. In other words, there is a varying contrast between stars and galaxies, between a galaxy and a group [and so on]. By the time you reach a super cluster and the surrounding volume, the mean density ratio is down to about three. I think that on the hyper cluster, or “super-duper-cluster,” scale, that is on scales of hundreds of millions of light years, there is still a density contrast. I think the work of Kiang and Saslaw, based on the Abell clusters, the work of Kalinkov on general galaxy counts, [and the work of] Neta Bahcall, again on the Abell clusters, proves there is still a weak positive correlation, an association, on scales of hundreds of megaparsecs. So it means that we have to go out to a radius of about a thousand megaparsecs before we define a fair sample of the universe.
And that’s within a factor of a few of the [scale of the] cosmic microwave background radiation.
That’s what worried me for a while. I thought that perhaps the only fair sample of the universe is the universe itself. In which case, what does the concept of homogeneity mean? Homogeneity means that if you take equal disjoint volumes, they have the same mean density, within statistical fluctuations, as molecules in a glass of water. But if the only fair sample of the universe is the whole universe, where can you take another sample? I believe now, fortunately for theoretical cosmologists, and if the faint radio source counts are correct, that if we take a volume a thousand or two thousand megaparsecs across, the mean density of that should be the same as in another [equal and] disjoint volume.
I can see that you have your fingers crossed.
Yes. Because it’s at the limit of the data. I would like to see uniform radio surveys of faint sources [across] the whole sky, so we can be sure that there are no big gradients across the sky.
Do you remember when you first heard about the horizon problem?
I don’t remember. Perhaps in the late 1960’s.
Do you remember how you regarded the horizon problem? Did you regard it as a serious problem for the big bang model?
No. This did not interest me. I’m an observer of galaxies. My own interest in cosmology has been the concept of heterogeneity — the hierarchical structure of the universe — and, of course, the work on the Hubble constant, in the past fourteen years now.
Did your view of the horizon problem change at all after the inflationary universe model came out?
You are making me talk about a subject I don’t know. My reaction is this: The big bang model is the dogma. It’s got to fit and be saved at all costs. And you will notice that cosmological models always have more free parameters than facts. When something doesn’t fit in the standard model, like the homogeneity of the three degree background radiation [the cosmic microwave background radiation], someone comes up with a bright idea to save the standard model. And this makes some people, like [H.] Alfven, very mad. Basically, I think that the big bang model has been so imbedded now in our thinking; it has [become] the ultimate truth. And, it’s funny, because I knew Georges Lemaitre in the late 1940s. In 1948 we had in Paris a ‘Semaine de Synthèse’ organized by an association that each year brings together the specialists in one field of science and tries to see what the situation is in that field. In 1948, we had one of these study weeks on “The Universe at the Birth of the Earth”. There were only two astronomers on the team of speakers, [Evry] Schatzman and I. But Georges Lemaitre had come to Paris and was present. He visited my lab and spoke very kindly. Because I was the only extragalactic astronomer in France he was interested in what I was doing. I remember vividly that he complained — he was very sad about it — that he thought he had produced a very nice, cosmological model, the primeval atom. And his impression was that nobody wanted to pay any attention to what he was doing. To which I replied that he should take it easy, take the long view and wait a little longer, because — I was speaking from France in 1948, remember — obviously the ‘party line’ was that there cannot be any creation. Essentially it was not popular for a Catholic priest to come up with a cosmology that’s opposed to Marxist theology. But things have changed. In fact, in 1977, when my wife and I were visiting in Armenia, and had dinner at Byurakan Observatory, I said, “look, now that we are between old friends, I’m surprised that the Soviet Union, which was to produce a new kind of man, free of all the prejudices of the old society, has not come forward with something brand new [in cosmology]. You are all followers of two Roman Catholic priests. Yes, you are all followers of Copernicus and Georges Lemaitre.” And we laughed. That’s something that has puzzled me. Nothing drastically different has come from the Soviet Union. You might say that’s just proof of the unity of science, and different societies just cannot come up with something new. I must say that this is not quite fair to Ambartsumian, who did propose explosions of galactic nuclei for reasons unknown, and spoke of the new physics of nuclear matter [in the nuclei of galaxies that is].
May I ask you a question about the inflationary universe model, even though you said that it’s not your interest?
Yes. Inflation was invented in order to fix a very serious defect of the standard model. If you are allowed one or two more assumptions each time there is one difficulty, where is the check in the theory? That’s what worries me. There is no check.
Well, [the inflationary universe model] does predict that omega is equal it one. It does have a prediction.
You could regard that as a check.
If we can show that omega is equal to one.
Or if we can show that it is not equal to one.
Yes. But that’s beyond our power. We are still arguing about the dark matter. I know it’s the fashion today. There is dark matter everywhere, but time and again people say that in this or that particular system they don’t see any dark matter. I’m wide open to new evidence here. I will accept anything that’s based on observation that can be repeated and checked.
Do you think that the inflationary universe model is speculative in this sense?
I am tempted to believe that the concentration of efforts in making the big bang fit no matter what is ... Maybe it’s the right direction if we know that we have hit the truth. But if we have hit the truth now, [if] we can calculate the universe back to the Planck time, what will the cosmologists do in the 21st century? Is it plausible that we have all the answers now? I keep asking that question.
Yes, you asked a version of that [question] in your Science article of 1970.
Yes, that’s right. I think it is very dangerous when we don’t want to consider other possibilities. As I mentioned to you before we started recording, I am upset that the establishment will not spend the time necessary to show where the nonorthodox cosmologies go wrong. There have been some discussions, but many [of the nonorthodox cosmologies] are just ignored.
I have just a few more questions to ask you. Do you remember when you first heard about the so-called flatness problem?
I’m not sure I understand what your question is.
This is another one of these problems with the big bang model. Some physicists feel that it is unlikely that omega would be so close to one 1060 Planck times after the beginning of the universe, that [such a result] seems to require a very fine balance. Do you put any stock in this problem?
No. I believe this is not the type of topic I am interested in because I don’t know what it means. I don’t know how a whole universe can be created out of nothing. When we were in Rome in 1979 for a cosmological meeting, we lecturers had a private audience with the Pope. He gave us a fine speech in Italian, about astronomy and space and about the big bang. He made it very clear that he was all for the big bang, because, essentially “We told you so.” Here, I am just a layman, but I cannot really believe all the intricate physics that is being done on scales that are far beyond anything we are dealing with [on earth]. What the standard model, or the modified big bang, claims is that an enormous mass of matter and energy occurred out of nothing at the beginning of the universe. I have a question that I ask my students to illustrate my position here. “What was God doing during the time before?” I know what the answer of physicists is: “This is not a question you should ask because this is a mystery. There was no time and there was no space.” The theologians used to make it even simpler. “You should not ask those questions, brother, because otherwise the Inquisition will start being interested in you.” So, I really believe it is premature to deal with such large, enormous extrapolations. I’m not saying I favor some other cosmology. I say I don’t know.
Do you think that in the last ten years theoretical cosmology has gotten too far away from the observations?
I think so. The observations are struggling to reach a z [redshift] of 4. There was a paper some years ago at the American Astronomical Society meeting that was entitled “z = 5 or Bust.” The author was looking for large redshifts, you see.
Maarten Schmidt told me in the interview I did with him that when he was a young astronomer his goal was to measure the highest z that he could measure.
Yes. That’s a good ambition. Of course, that was very much the hope of [Milton] Humason and [Edwin] Hubble for many years. In fact, this quest for the next biggest z has been a very good tool to sell large telescopes to governments. “If only you give us a little more money, we’ll build a bigger telescope, and by golly we’ll see that relation [between distance and redshift] curve, and we’ll get q0.
But you would probably say that’s very far from talking about the first microsecond after the big bang?
Look, I’m totally ignorant of detailed nuclear physics. People will say, “This is out of his depth.” But I think the nuclear physicists don’t realize we just haven’t got enough data. Even with nearby galaxies, we keep discovering new properties, new things. I have spent my life trying to study the nearby galaxies, where you have some resolution, where you can get spectra. You know this excess of blue galaxies in distant clusters, and these galaxies at large distant that doesn’t quite fit this and that? How do we know that the universe is chemically homogeneous on very large scales? How do we know that the types of stars in distance galaxies are the same that we find in our galaxy and in nearby galaxies? To what scale in the universe must we [go] to reach chemical homogeneity, considering that we now have overwhelming evidence that we see extraordinary things in the distribution? Also, how do we know that the frequency distribution of types of galaxies that we observe nearby is the same out there [at much larger distances]? Even if we assume that G [Newton’s gravitational constant] is constant, nuclear reaction rates are constant, and everything is easy, the types of stars we see in very distant galaxies may be significantly different from [the types] in nearby systems.
What you are saying reminds me so much of the letter that [Wilhelm] de Sitter wrote to Einstein in 1917 about Einstein’s static model. De Sitter came out with his cosmological model [shortly afterwards]. De Sitter knew a lot more astronomy than Einstein, and he wrote to Einstein: “How can you be sure that the universe is homogeneous and static? What we see is only a nearby snapshot.”
Of course. In de Sitter’s time, the existence of external galaxies was just beginning to be established, by first [K.] Lundmark, then by E. Opik, then Hubble, in the early 1920s. The concept had been around for a long time, but the proof came after 1918. It’s true. Repeatedly, we have looked at our neighborhood and made extrapolations that can be false. When we measure distances — you have not asked me any questions about H0 perhaps you ought to avoid it — we assume that the fellows beyond the river are the same size as us. We measure their apparent diameter [and from this infer their distance]. But, if they are very distant, we just see these creatures moving on two legs. Suppose they are penguins? We misidentify. So there are all sorts of problems that come up when you extrapolate to very large distances. One point I wanted to make about the ad hoc modifications of theories to force fit the standard big bang is the question of the space density of quasars and evolution of quasars. We find in the standard model more and more quasars per unit volume as we go to larger z. This is fixed by postulating a time evolution of quasars. But as Souriau and his students have pointed out, if you had a cosmology with nonzero lambda [the cosmological constant], you could have a uniform density of quasars. And, of course, [you can also have this result] in nonorthodox cosmologies, like Segal’s. Souriau has pointed out that even in the standard big bang model, if you accept lambda as a free parameter, then you find that the value of lambda that assures constant density of quasars at all distances is the same value that he finds from the strange gap in their space distribution. I don’t know if you are familiar with the work that Souriau has done in the past 10 years. It is well worth investigating. [He is] yet another nonorthodox theoretical physicist who has looked at [cosmology].
May I ask you two more questions in the last few minutes?
They are more speculative than the ones that I have asked you. You’ll have to put aside some of your natural scientific caution. If you could design the universe any way that you wanted to, how would you do it?
That’s a question that never crossed my mind. There is only one universe. It’s here and we’d better accommodate our thinking to it.
O.K. Let me ask you one final question. There’s a place in Steven Weinberg’s book The First Three Minutes where he says that the more the universe seems comprehensible, the more it also seems pointless. Have you ever thought about this question of whether the universe has a point?
Oh you mean finality? The question of final causes?
However you would interpret the statement. Weinberg doesn’t elaborate. You can interpret it as finality if you wish.
I tend to agree with Weinberg’s opinion, but I fail to see why the Universe should have any purpose (understandable by us). The remark sounds almost nostalgic. The concept that the Universe should have a goal strikes me as a remnant of anthropocentric thinking (cf. the recent emergence of the so-called “anthropic principle”). Surely we do not believe, four centuries after Copernicus, that we are the center and wonder of the world and, a century after Darwin, that we were created in his own image by am anthropomorphic God (how insolent to the Deity!). From what we know of the incredibly small mean density of matter in the Universe, of the frequency of solar type stars, of the fiercely hostile environment of most of the Universe, of the improbability of producing self-propagating forms of life spontaneously by cosmic processes, and of primitive biota evolving to rational intelligence capable of creating science and religion and philosophy, I wouldn’t be surprised at all if it turned out that we were the only ones in the Universe to be worrying about its origin, meaning and purpose (if any). A sheer accident. Now, I know all the arguments in favor of the plurality of inhabited worlds. This has been very popular with people through the ages because that’s what they want to believe — that ‘We are not alone’. Why do you think we still have astrology and religion and superstition, permeating practically all mankind? That’s what people want. They want the world to be concerned with their well-being, their future. Scientists may even wish it ‘made sense’ in some way. But as I point out to my students sometimes, if the Universe was created to produce mankind — and especially rational man and his modern civilization and everything that man has developed in the past ten thousand years (a split second on the time scale of the Cosmos) — it’s an incredibly inefficient mechanism. The idea that there is a ‘purpose’ to the Universe (usually implying some specially significant role for mankind, since who else is there to decide on ‘purpose’ except us?) just doesn’t make sense to me. I remember the title of a book which impressed me as a student: ‘The Impassible Universe’, whose author I can’t remember now, but it made the same point. So, while I personally would concur with Weinberg’s view, but don’t lament the apparent lack of point to the existence — or of goal or purpose to the operation — of the Universe, we must also at all times recognize the limits of our knowledge and keep open minds. We don’t know what new facts and concepts will emerge in the future. Let me finish with two quotations. One is a witty remark by the great French catholic thinker and scientist Teillard de Chardin who once wrote that he was always amazed that there are people “whose goal in life is to prove that life has no goal." The other from Shakespeare, who has Hamlet admonishing his philosopher friend: “There are more things in Heavens and Earth, Horatio, than are dreamt of in your Philosophy” (Hamlet, Act 1, Scene 5). This neatly sums up what has been the guiding principle of my life as an astronomer.
 Couderc, L’Architecture de l’Univers (Paris: Gauthier Villars, 1930)
 P. Berget, Le Ciel (Paris: Larousse, 1925)
 Eléments Théoriques et Pratiques de Photographie Scientifique (Revue d’Optique: Paris, 1946); La Science de la Photographie (Elzevir: Paris, 1947); L’Astrophotographie d’Amateur (with J. Texereau) (Revue d’Optique: Paris, 1954), Manuel de Photographie Scientifique (with J. Dragesco, P. Selme, H. Faraggi, and H. Tellez-Plasencia) (Revue d’Optique: Paris, 1956), La Photographie Astronomique du Daguerreotype au Telescope Electronique (Albin Michel: Paris, 1958) several of which were later translated into English, German and Russian.
 E. Hubble, “A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae,” Proceedings of the National Academy of Science, vol.15, p. 168 (1929)
 G. Lemaitre, Nature, May 9, 1931 and October 24, 1931; also The Primeval Atom (D. Van Nostrand, 1950)
 H. Shapley. “Galaxies,’ (Philadelphia: Blakiston Co., (1943)
 E. Hubble, The Realm of the Nebulae, (Oxford U. Press, 1935)
 G. de Vaucouleurs, “Sur la Loi de Distribution de la Luminosite dans les Nebuleuses Elliptiques et leur Structure,” Comptes-Rendus de l’Academic des Sciences, Paris, vol 227, pg. 586 (1948); “Recherches sur les nébuleuses extragalactiques", Annales d'Astrophysique, vol. 11, pp. 247-287 (1948)
 G. de Vaucoleurs, The Observatory, vol. 69, p. 150 (1949)
 G. de Vaucouleurs, “Sur la Contribution des Nébuleuses Extragalactiques à la Lumière du Ciel Nocturne,” Annales d’Astrophysique, vol. 12, pg. 162 (1949)
 E. Hubble, “The direction of rotation in spiral nebulae,” The Astrophysical Journal, vol. 97, p. 112 (1943)
 G. de Vaucouleurs, “Orientation Spatiale et Sens de Rotation de la Nébuleuse Spirale NGC 2146,” Comptes-Rendus de l’ Académie des Sciences, Paris, vol. 231, p. 32 (1950)
 G. de Vaucouleurs, “On the Distribution of Mass and Luminosity in Elliptical Galaxies,” Monthly Notices of the Royal Astronomical Society, vol. 113, p. 134 (1953)
 G. de Vaucouleurs, “Extragalactic Students in the Southern Hemisphere,” Occasional Notes of the Royal Astronomical Society, no.18, vol. 3, p. 118, “A Survey of bright galaxies south of -35° declination with the 30-inch Reynolds reflector,” Memoirs of the Commonwealth Observatory, No 13 (1956)
 G. de Vaucouleurs, “A Revision of the Harvard Survey of Bright Galaxies,” Australian National University Mimeogram, Canberra (1953)
 H. Shapley, Harvard Bulletin, No 890, p.1 (1933)
 F. Zwicky, Publications of the Astronomical Society of the Pacific, vol. 50, p. 218 (1938)
 G. de Vaucouleurs, Astronomical Journal, vol. 58, p. 31 (1953)
 V. Rubin, “Evidence for a Rotating Universe as Determined from an Analysis of Radial Velocities of External Galaxies,” Astronomical Journal vol. 56, p.46 (1951)
 G. de Vaucouleurs, “Further Evidence for a Local Super-Cluster of Galaxies: Rotation and Expansion, Astronomical Journal, vol. 63, p. 253 (1958)
 G. de Vaucouleurs, “The Distribution of Bright Galaxies and the Local Supergalaxy,” in Vistas in Astronomy (Pergamon Press: London, 1956), vol. 2, p. 1584
 Editor’s Note: In addition to the quotes from Walter Baade and Fritz Zwicky denying the reality of large-scale inhomogeneities, there are also quotes on de Vaucouleurs’ blackboard on the Hubble constant and one from the French physicist Augustin Fresnel: “Nature does not care for our analytical difficulties.” (1826)
 G. de Vaucouleurs, “The Case for a Hierarchical Cosmology,” Science, vol. 167, p. 1203 (1970)
 G. de Vaucouleurs, “Recent Studies of Clusters and Supercluster,” Astronomical Journal, vol. 66, p. 629 (1961)
 H.P. Haynes and R. Giovelli, “A 21st Centimeter Survey of the Perseus-Pisces Supercluster. I. The Declination Zone +27.5 to 33.5 degrees,” Astronomical Journal, vol. 90, p. 2445 (1985)
 V. de Lapparent, M.J. Geller, and J.P. Huchra, “A Slice of the Universe,” Astrophysical Journal Letters, vol. 302,p. L1 (1986)
 G. de Vaucouleurs, The Astrophysical Journal, vol. 131, p. 585 (1960)
 E. F. Carpenter, Publications of the Astronomical Society of the Physical Society of the Pacific, vol. 43, p. 247 (1931); The Astrophysical Journal, vol. 88, p. 344 (1938)
 C.V.L. Charlier, Ark. Mathematics, Astronomy, and Physics, vol. 4, no. 24 (1908)
 P.J.E. Peebles, The Astrophysical Journal, vol. 189, p. L51 (1974); Astronomy and Astrophysics, vol. 32, p. 197 (1974)
 T. Kiang, Monthly Notices of the Royal Astronomical Society, vol. 135, p. 1 (1967)
 T. Kiang and W.C. Saslaw, Monthly Notices of the Royal Astronomical Society, vol. 143, p. 129
 Kalinkov et. al, “Super clustering of Galaxies,” IAU Symposium No 79, p. 276 (Reidel: Dordrecht, 1978) and references therein
 N.A. Bahcall and W.S. Burgett, “Are Supercluster Correlated on a Very Large Scale?" The Astrophysical Journal Letters, vol. 300, p. L35 (1986)
 I.D. Karachentsev, Communications from the Byurakan Observatory, 39, p. 95 (1967)
 L. Ozernoy, “Traces of Photo Eddies,” JETP Letters, vol. 10, p. 251 (1969); Dynamical Parameters of Galaxy Clusters as a Consequence of Cosmological Turbulence,” Soviet Astronomy, vol. 15, p. 923 (1972); “Regularities in Systems of Galaxies and the Relation to the Problem of Hidden Mass,” Soviet Physics Uspekhi, vol. 18, p. 260 (1975)
 See Ref. 5.
 See Ref. 23.
 unpublished letter, dated April 1, 1917 in the Collected Papers of Albert Einstein document 20-551
 W. de Sitter “On Einstein’s Theory of Gravitation and its Astronomical Consequences,” Monthly Notices of the Royal Astronomical Society, vol. 78, p. 3 (1917)
 H. H. Fliche and J. M. Souriau, “Quasars and Cosmology,” Astronomy and Astrophysics, vol. 78, p. 87 (1979)
 I. E. Segal, Astronomy and Astrophysics, vol. 18, p. 143 (1972); and “Mathematical Cosmology and Extragalactic Astronomy,” (Academic Press: New York, 1976)
 S. Weinberg, The First Three Minutes (Basic Books: New York, 1977), p. 154