Oral History Transcript — Dr. Nicholas Mayall
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Nicholas Mayall; February 13, 1977
ABSTRACT: This focused interview treats the social and scientific relationships among Mayall, Hubble and Humason. Topics include Mayall's early work on redshifts, the preservation of his papers, thoughts on theories of the universe, ground and space based astronomy, his work at Mt. Hamilton, his move to Kitt Peak, and public relations of astronomy.
Shapiro:Would you give me your name please. So we'll have it on the tape.
Mayall:My name is Nicholas U. Mayall.
Shapiro:Now, first to correct that notion (discovery of red shift).
Yes. Many persons refer to Hubble's original work as the discovery of the red shift; this is not really true because the red shift phenomenon was first uncovered by V. M. Slipher's extending his spectrographic observations of galaxies beyond the brightest ones like M31 (Andromeda Nebula) and other Messier spirals. He was the first astronomer to find the much larger red shifts — way beyond previous such knowledge for nebulae. At that time, about 1914 to 1924, it was not established which objects were inside or outside our own Galaxy. Hubble's great contribution was to establish an extragalactic scale of distances, and to relate the red shifts with that distance scale. And, during the years of early formulation of that relationship, his principal contribution was to determine distances of increasingly fainter galaxies, particularly of those in clusters, while his colleague Milton Humason began to take up where Slipher left off, by measuring increasingly larger — much, much larger — red shifts, by a factor of more than 20.
Shapiro:Hubble never did make any red shift measurements himself at all, is that right?
Mayall:Yes, he did very little spectroscopy, but occasionally he would spell Humason. He knew how, but his main effort was on the distance scale and characteristics of galaxies.
Shapiro:When did you first meet Hubble?
Mayall:I think I first met him when I went to the Mt. Wilson Observatory as a computing assistant during my second graduate year, in the summer of 1929. I came down from the University of California at Berkeley, after my first graduate year, because I wanted to gain experience in observatory work before I returned to do my doctoral thesis. I stayed and worked at the Mt. Wilson Observatory, Pasadena, for the two years 1929 to 1931. During that time I not only became acquainted with Hubble, but I also ended up working very closely with him and Humason. As a result, with their suggestions and influence, I selected the topic for my doctoral dissertation, which involved counts of nebulae on plates taken at the Lick Observatory with the Crossley reflector.
Shapiro:Sky survey plates?
Mayall:They were not a sky survey. They were plates that had been taken by previous astronomers, principally H. D. Curtis, and some by me to fill in the gaps in their distribution. Hubble was interested to get another point, from independent sources, for his relationship of numbers of nebulae with limiting magnitude to which they were counted. He wanted to see where the point would fall among those from the 10-inch Cooke camera, and the 60-inch and 100-inch reflectors. The Crossley 36-inch reflector plates seemed likely to give a point at the lower end of the relationship that Hubble was working on. I did the additional observing and analysis and published the results in a Lick Observatory Bulletin (No. 458).
Shapiro:What year was that it was published in?
Mayall:I got my degree in June 1934, and I think the paper appeared late in 1934 or early in 1935.
Shapiro:But you just worked with Hubble in ‘29 and ‘30 and then...
Mayall:I was down there working generally around the Mt. Wilson Observatory, not just for him. I worked in the spectroscopic group, and with a half a dozen or more different astronomers. But my interests for research became crystallized in the field of extragalactic research through my association with Humason and Hubble at that time. From then on I worked with them as a junior colleague at Lick Observatory, while they, of course, worked at Mt. Wilson and Palomar.
Shapiro:So you were at Lick then between 1930 and...
Mayall:No, after I left Mt. Wilson in 1931 — not Palomar because it was not yet built — I had one more year of courses at Berkeley in 1931 to 1932. I went up Mt. Hamilton in the summer of 1932 to do my thesis at Lick, and I stayed on there for 28 years.
Shapiro:Were you a resident at Lick — on Mt. Hamilton — did you stay on for 28 years?
Mayall:Yes, except for the war, June 1942 to October 1, 1945.
Shapiro:Yes, and did you keep up contact with Hubble?
Mayall:Oh, yes, especially after the war.
Shapiro:How did you arrange contact? Did you go to Mt. Wilson; did he come up to see you?
That is right; both ways. And he arranged from time to time meetings in Pasadena of what he called "kindred spirits" in his field, and he always was kind enough to invite me down, and we reciprocated on Mt. Hamilton. The director at that time in 1945 was Dr. C. D. Shane, and he supported these group meetings. He, too, became interested in counting galaxies. So he invited Hubble and Humason on several occasions to meet with us at Lick. And this went on for — Oh, maybe once a year, for quite a number of years. It gradually expanded to include other fields than just extragalactic research, and by the time that I left in 1960, and Dr. Shane retired from the directorship in 1958, the meetings had almost become too large to manage; I don't know whether they were continued after I left.
Shapiro:What did they call those meetings? Did they...
Mayall:They were very informal — just staff...
Shapiro:Did Hubble use that term "kindred spirit" with any frequency or... was it just you...
Mayall:No, not only me, but also those who were interested in the type of research that he was doing.
Shapiro:Were there any surprising or anomalous results from galaxy counting or any distributions that were unusual, like clustering or super clustering — there's been some talk about clustering and super clustering?
Mayall:Super clustering at that time was not a very lively subject because the counts of galaxies had not yet reached a comprehensiveness that they did later on, especially with the Shane and Wirtanan counts. These were made on a different basis, which was a survey to a certain magnitude limit over the whole sky area observable from Lick. Hubble was interested particularly in the distribution in depth — with distance — rather than over the sky, although, of course, he was interested in that also. Area wise, Hubble's counts clearly displayed, in detail for the first time, how the obscuration along the plane of the Galaxy could be outlined — very accurately indeed.
Shapiro:He had no picture of the Milky Way galaxy, then...
Mayall:Well, he had plates spotted all over the northern sky at regular intervals, and as the Galaxy's plane was approached, fewer and fewer galaxies were recorded on the plates. Within a degree or two of the plane, there are hardly any galaxies found. So he was able from the surface distribution throughout the Galaxy to locate what became known as Hubble's "zone of avoidance." This ran along the galactic plane, and his counts defined the obscuration much more precisely than had ever been done before.
Shapiro:Did you consider that you were a friend of Hubble's as well as a colleague?
Mayall:Yes, and it was one of the most exciting and stimulating associations that I had during my career.
Shapiro:Could you describe it a little bit?
Mayall:Well, he was interested first that I was interested in working in the field. Also, he was always very helpful and very stimulating to me. We wrote each other often, and you may have seen some of the correspondence between us, on file in the Huntington Library. That may give you some idea of what our relationship was, which was in the nature of a senior to a junior colleague. But he never treated me at all in a condescending manner, always as a colleague in the same field. And he was very friendly to me in many ways. In some of the meetings that were held in Pasadena, he would invite me out to his house for breakfast, which he himself prepared, so I got very well acquainted not only with him but with Mrs. Hubble and some of his friends and colleagues from Cal Tech, whom he invited down there in San Marino. He was a close friend and colleague of Richard Tolman, a physicist at Cal Tech, and that's how I became acquainted with him. So I would say that our relationship was much more than just a colleague in the field at another place — we had a very close friendship besides.
Shapiro:What was his main excitement as far as he conveyed it to you?
Mayall:I think it’s how he — I don't know if this term is original with him or not — but he used to refer to his main interest as the ''cosmological problem By this he meant the best model that would fit the universe as a whole, whether it was open or closed, more or less in accordance with the possibilities suggested by relativity. Since he was not a relativistic theorist, I think he relied very much on counsel and discussion with Richard Tolman, who was a very competent man in that field. For Hubble, I think, the central problem eventually for him became the question of how do you establish what model of the universe is the right one, and what do we need to do — observationally — to discriminate between the different types of models from the relativity theory predictions. He was chiefly concerned with the detailing of these observational discriminants among the different models of the universe, and what would be required in the way of resources to make the discrimination. I have a definite impression that this concept and his research program had a lot to do with getting the 200-inch for Palomar. In those days, his work was really the liveliest — well, I'm prejudiced — productive, and exciting fields of current research. He was finding out, really for the first time, how big the universe is and what's in it. And he was — as I like to say — bringing the universe down to earth and out of the realm of metaphysics to which cosmology had previously been limited.
Shapiro:Did he have any prejudices about the kind of model he hoped to find?
Mayall:No, I don't think so. He had quite an open mind on those models.
Shapiro:Was it conditioned by any religious views or...
Mayall:No, not at all. I never heard him voice his views on religion.
Shapiro:No. Would he have liked, for example, to have found a Big Bang model…
Shapiro:— or a closed model or a...
Mayall:No, he didn’t have a “closed” mind on any of those possibilities. He was extremely cautious and very reserved in his conclusions from his own work. For example, he never used the term “velocity” because in those days people hadn’t come to accept it — there wasn’t yet enough evidence to say that these red shifts represented velocity. So he adopted, and used to the end of his life, the non-committal term “red shift”, which is what is measured on the spectrograms of galaxies. Since those days there has been increasing evidence that there’s no other explanation that has much chance of competing with an interpretation as a velocity phenomenon. I think he was, in some respects — and this is purely hindsight – overly optimistic that if the 200-inch were used to its limits, it would discriminate among the various models of the universe suggested by relativity. I really think he believed that it was possible to make this discrimination with the 200-inch, and it may very recently have been made, still very near the threshold, particularly by the work of Alan Sandage. He has pushed it very much farther than Hubble left it, but it’s still pretty near the margin of error.
Shapiro:How would you describe that? As the final curve in the velocity distance relationship? The final change in that linearity?
Mayall:Well, not only that, but a more accurate definition of the Hubble expansion parameter, which is the rate of increase of distance with the red shift, and on that Sandage has done a much better job. I mean, he has contributed a whole lot more observation to establishing the scale to greater distances based on some of the same criteria that Hubble used, and on other newer ones. Sandage has extended the distance scale with a higher precision to a greater distance. But the distance scale used to extend to the very limits of the universe is still mainly based on the red shift, not on many other parameters. At the present time, Sandage has calibrated the relation out to probably some of the nearer groups of galaxies, which are a little more distant than the VIRGO cluster. So in that sense, I would say that he has narrowed the possibilities, but there is still a lot of room for discussion.
Shapiro:Didn’t Hubble privately, aside from his official statement, aside from his scientific caution, sometimes in private conversations talk about his feelings about the universe and his concept of it privately...?
Mayall:Not to me.
Shapiro:Or his feelings about or what he expected to find. He didn’t ever confide or...?
Mayall:He never went out on a limb as far as...
Mayall:Even privately. Not with me he didn’t. No, he was inclined to stick very close to the facts as he knew them. But he was always looking ahead as to what he would like to do, or what he thought might be done to help narrow the choices. But he never told me that he had his mind made up.
Shapiro:His problems. Did he have problems with things like going right, or what did he express as some of the major obstacles in his way?
Mayall:Well, he was a very reserved man when it came to his own thoughts and his own life. He was very reserved with almost everybody. I never observed that he sort of “let his hair down” at any time. Not to me, anyway. Of course, I was very much a junior colleague, I was many years...
Shapiro:How much younger were you than him at that time? You were...
Mayall:Let's see — he died in 1953 and he was born in 1889, wasn't he?
So that's 11 and 53 or 64. So he was 64 in 1953 and in 1953 I was 47.
Shapiro:So you were some 16 years his junior.
Mayall:Yes, and that...
Shapiro:As far as his work was concerned, what did he feel were the problems — other than the private problems, but as far as the work was concerned, what were the challenges and the problems? Obstacles?
Mayall:Well, I think it involved primarily instrumental development — a means of getting observations of fainter galaxies faster and with higher accuracy, including red shifts. You see, Hubble was primarily involved in the observation of magnitudes and colors of the galaxies and, for brighter ones, their internal motions. But it was his colleague Humason, and also later Minkowski, when he came on the scene who pretty much carried on the spectroscopic side of that work. Hubble was always trying to get a more precisely defined scale of apparent magnitudes to fainter and fainter limits, along with colors, which are not just measurements of brightness in one pass-band, but in several pass-bands. This extension became possible when the photoelectric cell was developed for faint sources, because it greatly increased not only the accuracy of the photometric observations, but also the linearity of the scale to the faintest magnitudes.
Shapiro:When did that start to influence his measurements?
Mayall:Well, he did not involve himself very much in the use of photoelectric photometry, but he encouraged his colleagues, Joel Stebbins and Albert Whitford from Wisconsin, to work on Mt. Wilson. They exploited that technology as far as they could with their resources. It was somewhat extended later by William Baum to fainter objects, but now, of course, astronomers can go much fainter with electronic image devices.
Shapiro:Yes. Incidentally, where is Baum now? Is he at Flagstaff?
Mayall:Yes, he's at Flagstaff.
Shapiro:Is he retiring?
Mayall:No. Well, I don't know, but I doubt it.
Shapiro:But as far as you know he's at Flagstaff.
Mayall:Yes. The last time I talked to him was up at Flagstaff.
Shapiro:How long ago was that?
Mayall:Oh, within the last year or two.
Shapiro:OK. I'll have to call him. Do you know of any tapes that exist of Hubble? When he died in '53, tape recording was just coming into use and there were wire recordings earlier, and disk recordings even earlier. Do you know of any tapes that might...?
Mayall:I don't, but I don't think I'm the one to be asked that question. I think Mrs. Hubble would know.
Shapiro:Yeah, well, we asked her and she didn't...
Mayall:She didn't know?
Shapiro:How about photographs? Do you have any photographs of yourself and Hubble?
Mayall:I have a photograph of him on my desk down at the AURA headquarters.
But that's about all I have.
Mayall:Of Hubble; he's standing next to the 48-inch Schmidt on Palomar.
Shapiro:Do you know of any outstanding photographs or movies of him that we could obtain?
Mayall:No, I don't. Mrs. Hubble may — you see, I wrote his biographical memoir for the National Academy of Sciences, and — about the photographs — she had some and selected the one that she liked the best, and so of course I included it in that memoir. But the one I like the best is the one she gave me of him standing beside the 48-inch — it's so typical of him, and that's the only one I have of him.
Shapiro:Well, whom should I go to for photographs? I've been to Mrs. Hubble or her collection at the Huntington, to the Mt. Wilson and Palomar collection; I've been to the Cal Tech collection. Can you think of any resource that I may have overlooked?
Mayall:Does Huntington have any?
Shapiro:Yeah, we have quite a few there.
Mayall:I don't know of any others than that. Unless by any chance he — he was an Anglophile, he admired the English, their way of life and their conservative and understated type of expression — he admired that — he was a real Anglophile. And it’s possible that — he lectured over there a number of times — that the Royal Society would have some photographs of him.
Shapiro:Or recordings, hopefully.
Mayall:I don’t know.
Shapiro:Yeah, I might check that.
Mayall:You might check with the Royal Society.
Shapiro:I’m checking with the BBC.
Mayall:That was much later, I think. I don’t know that he ever appeared on a radio program. At least I never...
Shapiro:I think he did for the BBC.
Mayall:Well, that maybe a happy hunting ground I don’t know about.
Shapiro:I’m going to explore that.
Mayall:Well, the fellow that I would ask over there is Prof. William H. McCrea, of the University of Sussex. He’s a Professor of astronomy, possibly on the point of retirement, I think.
Shapiro:All right. I’ll just drop him a line. I wrote to Phil Daley, incidentally, and I wrote to the BBC Radio Department and the BBC Archives.
Mayall:Well, I also think you ought to contact somebody in the Royal Society.
Shapiro:He’s a member of the — what is it called officially?
Mayall:The Royal Society of London.
Shapiro:And that’s an Astronomical Society?
Mayall:No, it is a society for all of science. There is in addition the British Astronomical Association.
Shapiro:Yeah, but you think it’s the Royal Society.
Mayall:The Royal Society is the one I would suggest you contact first.
Shapiro:And do you think it would be an imposition if I wrote to McCrea and asked him...
Mayall:Oh, no, because he's been very interested and active in the field of Cosmology.
Another fellow, with whom I've pretty much lost contact in the last few years, is J. G. Whitrow. He has written papers, and I think even a book, on Cosmology.
Shapiro:Where is he at?
Mayall:I think he's at London University, but I'm not sure. He might have moved. I haven't seen him in recent years. But I know he's very active in the field and he was a young man just coming into the field about the time that Hubble died. I first met him in 1955 as a young, very brilliant fellow.
Shapiro:You've had some experience with public communication through your own efforts, the efforts of your staff, at the observatory. What would you tell a general audience about Hubble and his work? Just a little about Hubble himself, about his work and the importance and significance of it. What do you think would be useful for a lay audience and what would be interesting. I’m asking you to write our script for us...
Mayall:Well, I like to think — although some of my colleagues would not go so far — I like to think that Hubble did for the Universe what Shapley did for the Galaxy, and what Galileo did for the solar system. Each one of those individuals opened up a greater volume of space — really opened it up for research, with enormous impact on Man's view of his place in Nature. Galileo did it with his first optical observations and, of course, the Herschels were very active in Milky Way star counts and nebulae cataloguing… The one who really showed where our solar system is in the Galaxy, and what its size is, was Harlow Shapley. He did for the Galaxy what I think Galileo did for the solar system. The next step beyond that was to show how our Galaxy was situated in the Universe, and Hubble did that. That's what I would tell the public, to begin with.
Shapiro:Yeah, that's OK. And do you think that's more important than red shift or...?
Mayall:Well, that's part of it.
...in establishing the scale of the universe Hubble, of course, used the red shift — his Law of Red Shifts, or the increase of red shift with distance. It was on the basis of that law that he demonstrated the vast scale of the Universe, and the generally uniform distribution of galaxies within it. I think he stands alone in this achievement.
Shapiro:Did — you didn't do your thesis under Hubble?
Mayall:More or less — yes, I did.
Shapiro:Would you consider that he...?
Mayall:He suggested that I look at the Crossley plates, take new ones and count all the galaxies on them. Then analyze the counts to find one more point on the curve relating the number of galaxies per square degree to limiting magnitude. He suggested it, I carried it out independently.
Shapiro:But was he officially in charge?
Shapiro:Who was officially in charge?
Mayall:Oh, there was a small committee at the University of California at Berkeley, and it had on it one thesis advisor to me, but he took very little part. My defacto advisor was Hubble, and the committee just went along with him.
Shapiro:Your defacto — your unofficial you mean...?
My unofficial one, yes. For each PhD candidate the University set up a small committee, and one person was designated as an advisor to the candidate. He saw to it that the dates were met; the thesis prepared and filed — all that sort of thing. I can't remember much about that committee because I didn't have much to do with it. I think that Dr. W. H. Wright, the director of Lick Observatory, was on it at that time, but I really don’t remember. I would have to look up the program of my fina1 examination — it's on that.
Shapiro:But we couldn't say that you were his graduate student?
Mayall:No, no sir, not Hubble.
Shapiro:Sandage was really his only graduate student. But he inspired your thesis and guided you, but officially...
Mayall:Hubble was the one who stimulated my interest in the field, and then we collaborated informally in many ways subsequently. But during the formal curriculum — meeting PhD standards — that was done at Berkeley and at Lick Observatory, and Hubble didn't take any part in that.
Shapiro:Are you getting sunburn on the back of your head? Are you sure you’re OK?
Mayall:No, no, I'm OK.
Shapiro:How are your plans for the preservation of your papers or — the AIP wanted to know? First, how are they organized, what is their extent?
Shapiro:You haven't begun that...
Mayall:No. I have a letter from the librarian of the American Philosophical Society, a Mr. W. J. Bell, Jr., with whom Spencer Weart communicated and to whom I described the situation in detail in several letters. So, if you want to find out what it is, ask him about it.
Shapiro:Oh, OK, he [Bell] has all the information?
Mayall:Ask him — I put it in a letter to him, after he (Dr. Weart) wrote to the librarian at the American Philosophical Society. I just got a letter from Bell, before I heard from you, the day before yesterday and he is very anxious that their library get some of my materials.
Shapiro:Is Dr. Hetherington still discussing the Mayall-Hubble correspondence project?
Mayall:Well, he's in Iran and I haven't seen him since he was through here and made that interview last May. I had one letter from him when he was about to leave.
Shapiro:OK. There are a couple of questions that David DeVorkin who's working with — have you met David DeVorkin?
Shapiro:Well, he's working with Spencer Weart. And he wanted to know what your mother's educational background was.
Mayall:Primary and secondary schooling. She was not a university woman; a high school education.
Shapiro:A high school education. Why did your father move from Illinois to California?
Mayall:He was a mechanical engineer in Illinois, and he was working for the John Deere Plow Company. He wanted to move west to work with the Holt Caterpillar Tractor Company in Stockton, California, because he thought it promised a better future for a mechanical engineer.
Shapiro:Why did ASP give their library to Berkeley? Do you know?
They simply had no proper place to put it at that time in San Francisco. They did not have a regular office, and they wanted to see more use be made of it. This meant having it properly stored so it could be consulted. Prof. A. O. Leuschner, head of astronomy at Berkeley, agreed to take it, and he asked me to organize it. I had previously worked two years in the Main Library.
Shapiro:And did you ever meet Curtis at Lick Observatory and if so, what was your impression of him as a person and as a scientist?
Mayall:I never met Curtis at Lick Observatory. He had left there many years before I got there. But I did meet him on one occasion in the East. And now I can't recall where it was — it might have been in Washington — it might have been in New York. And I only got an impression— it was really only a brief meeting — and I didn't have any significant discussion with him.
Shapiro:What were your impressions of Russell at Mt. Wilson?
Mayall:Oh, my, he was a tremendously stimulating man, but not particularly in the field in which I was interested, extra-galactic research. At the time he was there as a Research Associate of the Carnegie Institution of Washington. He was working to put on a firm quantitative basis the abundances of elements in the sun and in the stars. On the basis of quantum theory, which was just then being developed, he was among the first to attack these problems. And while he was there he gave some very interesting lectures in that field, but they were then unrelated to extragalactic research.
Shapiro:So he had nothing to do with Hubble, then?
Mayall:Well, Hubble may have been interested in his work, and vice versa, because both fields were tremendously active, just developing. And I became much better acquainted with Henry Norris Russell later on, when he came as a Morrison Research Associate to Lick Observatory, where he spent some time. However, this was much later, when he was approaching retirement from Princeton, but I got very well acquainted with him then. His interests were primarily in stellar atmospheres and the elements and properties of them — especially abundances of elements.
Shapiro:Did you know of any discussions between Russell and Hubble?
I don't know of any...
Shapiro:Any exchange of interest or that they stimulated...
No. I’m sure they got together, because they had seminars almost weekly down there, in the library of the Mt. Wilson Observatory, and they were such outstanding men. I’m sure they got together and influenced each other.
Shapiro:I want to ask you about Humason, if I could? Did he understand the import of his work with Hubble? I’m familiar with Humason’s background and...
Shapiro:... I just wanted to ask you of what Humason thought and felt about Hubble’s work, and about its significance...
Mayall:Oh, he had a very high regard for Hubble. I wouldn't say he idolized him, but it was one of intense admiration for his work. And he himself — Milt Humason, was such a modest man, because of his minimum educational background that he was inclined to lean over backwards rather than to give opinions on what his work might mean. His main concern was that, whatever he put out, it be reliable. Also to get spectroscopically as far out as he could, with as many red shifts as he could in fainter clusters of galaxies by using and developing new instrumentation.
Shapiro:You had long conversations with Humason?
Mayall:Oh, my yes.
Shapiro:What did you talk about? What was the main thrust of your conversation?
Mayall:Oh, we were very close friends, and we would talk about everything under the sun.
Shapiro:Mainly, chiefly. Can you think of any chief threads or currents of conversation?
Mayall:He was a pretty shrewd man in evaluating character, particularly of visiting scientists of whom there were many, coming and going all the time. He had an uncanny knack of locating who were the pseudo-types, the elite-types that looked down on others that were on the support staff around there. And he unerringly — it didn't take him long — found that some big-name men had feet of clay; that sort of thing.
Shapiro:So he talked about personalities...
Mayall:Oh yes, he was very much interested in personalities.
Shapiro:And what did he say about Hubble to you, for example?
Mayall:Oh, he looked up to him as his highest standard of behavior and character.
Shapiro:How was Humason himself treated by Hubble and by others?
Mayall:Hubble treated him magnificently. I never observed him to say,
"Do this or do that.” It was always, "What do you think of doing" this, or, "Do you think you could observe" this — usually work on increasingly fainter nebulae.
Shapiro:How did he put it?
Mayall:He would talk to Humason in a way that would encourage Humason's immediate interest and desire to go out and do something. I have cited this before, but I don't recall if I mentioned it to Hetherington or not. Here is an example: I was up on Mt. Wilson with him, I think during 1930 or early 1931, when Humason was observing one of the faintest galaxies he had ever observed. He had exposed a whole week on this one, and he told me he was going to take the plate out and develop it. I was up there working with the 60-inch telescope, and he invited me to come over when he took the plate out and developed it. So I was in the dark room when he developed the plate, and as soon as it had hypoed clear enough, he held it up there in front of a light box, and looked at it and said, “My God, Nick, this is a big shift!” Then he handed it to me — it was a very small piece of glass — and I saw the calcium H and K lines, which we knew like our right hand. They were shifted way over to hell-and-gone from where they should have been. This proved to be a red shift of 20,000 km/sec, and it was probably more than twice the biggest one he had ever obtained before. He was simply jubilant. I looked at it and said, “Well, if you have any doubting Thomases who think what you have been measuring was in only your mind, why, you won't have any after they see this.” Even some of his colleagues didn't believe that he was properly identifying the lines, to get such large red shifts. And the farther he went, the more skeptical some of them were — even a man like Shapley was skeptical of what he was doing. Anyway, that's sort of beside the point...
Shapiro:No, it isn't...
Mayall:... but then, after he had put the plate to wash, he said, “Nick, we got to celebrate this” He said, “This is the biggest thing I've ever gotten” So we went down to his room, he opened a closet and took out what he called “Panther [juice].” (He actually used a four letter word in the brackets.) I don't know what it was — some kind of booze. I wasn't knowledgeable enough then to know what it was. But he said, “We got to have a drink to celebrate this.” So I had one, it was too strong for me to have more than one, but he had several while we celebrated that big red shift. He went to bed and I'm sure he slept soundly. But I went to bed, wondering well, now, what is the reaction going to be for Hubble. The next day we got up a little before noon and went down to breakfast at the Monastery, where he said, “I want you to be with me because I’m going to call up Hubb1e and tell him what we have” He got Hubble on the phone and told him he had this fine plate showing H and K shifted way over here to hell-and-gone. I had my ear right close to him to hear what Hubble said, and what Hubble said I’ll never forget. He said, “Milt, you are now using the 100-inch telescope the way it should be used” (laughter) And I was there and heard him say it.
Shapiro:What was the object; incidentally, do you remember that?
Mayall:Well, the object didn't have any name, but it was one of the brighter nebulae among a number of fainter ones that formed a very faint cluster that Hubble or somebody else had found. Hubble had told Milt before he went up there, “Milt, I think this cluster will have objects showing red shifts in the range of 20,000 km/sec”, and he hit it right on the nose. It came out 19,700 km/sec when it was measured. It seems that every time Hubble predicted a red shift for a cluster that he had worked on, he hit it right on the nose. Humason took him literally, saying to me, "If Hubble tells me this cluster's going to have a red shift around 10,000 or 20,000 or 30,000, I believe it because he's never made a mistake yet.”
Shapiro:Did they ever work together on the same night; I mean one using one telescope and the other using another telescope?
Mayall:Very rarely, during the two years I worked with them.
Shapiro:The principal instrument was first the 60-inch then the 100-inch then the 200-inch. Was that correct?
Mayall:That's correct, yes.
Shapiro:With them alternating. One of them making observations one night, the other the other night, or how did it go?
Mayall:Well, of course, they couldn't both use the same large telescope at the same time, so they weren't working together — they overlapped a little bit, but not very much. And also they never got all the time they wanted on those big telescopes; they had to share it with other members of the staff.
Shapiro:So Humason would go up for 4 nights and then Hubble would have it for 4 nights or how did it work — generally, this is very general?
Mayall:Well, as time went on Humason's exposures got longer and longer, so he was given runs of, oh, 7 to 10 nights. In those early days, because...
Shapiro:That was Humason?
Mayall:That was Humason, because a single spectrographic exposure could run a whole week, which was not at all uncommon.
Shapiro:But Hubble didn't need...
Mayall:Hubble, of course, didn't need such long exposures for direct photography. His longest ones normally were just a few hours. And most of the time they were less than that, just an hour or so. Occasionally he would take 3-hour exposures, and some 15- to 20-minute ones.
Shapiro:So he would have three or four day runs?
Mayall:Well, usually more than that because he would work at one telescope and then go over to another one; in fact, he used all the telescopes on Mt. Wilson pretty much interchangeably for a while.
Shapiro:The 100-inch and...
Mayall:The 60-inch, and the 10-inch Cooke camera.
Shapiro:He would use the 100-inch sometimes, and the 60-inch others.
Shapiro:For all direct pictures?
Mayall:Well, he had things he could do with the 60-inch that did not require the 100-inch. Thus when he was working on the faintest nebulae, he would use the 100-inch, and on the brighter ones he would use the 60-inch. And, of course, sometimes even though he had the 100-inch, the seeing would be so bad that it was unusable. Also he could have superb seeing with the 60-inch, which would be better than the 100-inch under bad conditions. Therefore, he had bad-seeing and good-seeing programs for both telescopes.
Shapiro:What was Hubble's real forte ... what were his strengths? As an observer, as an acute observer, as a man who knew what to do and when to do it, as a designer of programs, you know, how would you describe his real strengths? What did he have that other astronomers didn't have?
Mayall:I thought, and still think, he had a broad gauge vision. Some astronomers don't have this. Of course, the field itself is very wide — the Universe is about the biggest thing you can think of — but I would say he had a vision that was very comprehensive, including almost any aspect of individual galaxies, and of millions of them in relationship to the bigger frame of the Universe. He had that broad gauge interest of how things fitted together.
Shapiro:How was he as an observer, he wasn't as good as some, for example, or how...?
Mayall:He was adequate, he was conscientious, but I would not say meticulous. He was somewhat slipshod in the darkroom — not careless — but he was so anxious to see what he had that he would cut corners, such as not always using fresh developer or hypo, or cutting the time for fixing and washing.
Shapiro:Kind of like an artist...?
Mayall:Yes, he wanted to find out fast what he had, and he was not too concerned with getting the last drop out of the plate by special technology, and so on. He used the conventional apparatus there.
Shapiro:Did you ever work with him on the mountain?
Shapiro:You worked together on making observations? How did you work together?
Mayall:Well, we never worked at the same telescope together, but very often — when I was a student there — I was there working on his programs and Humason's, not on red shifts but in other respects. I took many of the plates with the 60-inch Hubble used in his galaxy counts — hundreds of those.
Shapiro:How was he working the whole night through? That was pretty rigorous. Did he enjoy that?
Mayall:Yes, he did.
Shapiro:He enjoyed that whole... You would describe him also as an outdoor man?
Mayall:Yes, he was very much an outdoor man, and during his vacations he would go fishing; he was a very enthusiastic dry-fly fisherman, of trout.
Shapiro:What were his main interests? His work and astronomy...?
Mayall:Certainly his main interest was astronomy. He was very interested in the history of science, particularly in the range overlapping where incunabula was fading, just preceding and following the invention of the printing press. He was very interested in a man called Nicholas of Cusa, who lived in the 15th century, I think. Hubble had a very fine collection of rare books, and I had the impression he was very well informed of their contents, authors and historical significance.
Shapiro:What was the main thrust of Cusa’s views, do you remember?
Mayall:Not very much — only that he had a view of the Universe that Hubble thought was ahead of his time. It was sort of metaphysical, but Hubble admired him because he felt he had a vision of things — a philosophical attitude — that appealed to him.
Shapiro:What did you think of this fellow?
Mayall:I never became well enough informed to know him as a cosmologist.
Shapiro:But Hubble was enamored of him... Did he ever quote him or say what he thought?
Mayall:Not to me, he didn't. No, I found this out pretty much from Mrs. Hubble when I was down there going over a lot of material for the NAS Biographical Memoir. I found out more about Hubble then than I ever had before. I really found out what kind of fellow he was — although I suspected what he was like — from her journals. Have you read those journals, her personal journals?
Shapiro:It’s hard — they're rather difficult to read and because they're hand written. I didn't have that much time to go through them, so I kind of thumbed through them. But what do you think they summarize?
Mayall:Oh, I think they give a pretty good picture of his character. I think that she is inclined to put him on a pedestal and, the longer time goes on the higher the pedestal gets. She is, I think, a little over enthusiastic in that respect. But those journals gave to me the first inkling of what kind of personality he was behind his reserved facade.
Shapiro:Could you describe him?
Mayall:Well, I would say that they confirmed my opinion that he was a very noble character. He had very high standards of personal behavior.
Shapiro:Could you describe those standards, for example?
Mayall:Well, he was very modest; he didn't like any kind of boastfulness. And when he dealt with others he used very much understatement, like the British do when they ta1k. He had a very dry humor, it never got robust or guffawing, or anything like that; it was more the English, a very dry type of humor. He was also very careful about not giving offense to the people around him; he was always very considerate of others, particularly those on the scientific support staff.
Shapiro:Was Mrs. Hubble interested in his vision?
Shapiro:How did she describe this vision?
Mayall:Well, she didn't have any scientific background, but she simply idolized the man. She recognized that he was a great man in his field and practically worshipped him.
Shapiro:I'm just trying to characterize this vision as a... Did it... Was it about science and science's ability to come to grips with the real world, or was it about some feeling about the Universe of galaxies itself, were there religious overtones associated with it, or...?
Mayall:My impression is he was like I am. I consider myself to be a non-religious person, and I never heard him get wound-up on anything religious whatever. I think that was one thing that attracted me to him, because he was not a zealous missionary, a crusading type — anything but that. But he did have broad interests apart from his science. He made himself available for many other activities at Cal Tech, and he participated effectively and conscientiously. He served for many years as a, I think — I don't know what you call it — a director or trustee of the Huntington Library. And he served the administration in many ways at Cal Tech. He was a very good friend of Millikan, and possibly an advisor.
Although he did not avoid any particular community activity, he kept a very 1ow profi1e. He would work behind the scenes, because he abhorred publicity. In particular, he did not like to be interviewed by reporters — he would do his best to avoid them if he could.
Shapiro:He had some problems with Harlow Shapley, Shapley later said some unkind things about him and I don't know if you've read Shapley's books?
Mayall:I read some of them, yes.
Shapiro:Some of them, yes. Did Hubble ever express himself to you about Shapley?
Mayall:Not personally. The nearest he came to that was when some publication would come out from Harvard, not necessarily with Shapley's name on it, although Shapley was the moving spirit in their programs of extragalactic research. Every now and then he would be reading something from Harvard, and I might have come in his office for some reason. He would look up from reading the paper, would slap it down, or point to it, and say, "I don't like slap dash research." That's about as far as he would go. (Laughter)
Now another matter in which I observed his restraint in dealing with others was the following. This other situation refers to the controversy he had in regard to VanMaanen's measurement of rotation of galaxies. I was pretty much a middle man between them, particularly in my second year down there, because I was asked to make out the observing programs for the 100-inch and the 60-inch telescopes. And those men were not speaking to each other that is, Hubble and VanMaanen. They would pass each other in the hall, and completely ignore one another. So I'd have to shuttle between them to find out what nights they wanted, how many they wanted, and I'd have to resolve the problem, usually with help from Humason. Humason had become tired of this situation and had asked me to be the in-between man. Well, I knew there was considerable tension there, and that much of it at that stage was actually in a process of “distillation,” which finally led to two very short papers that came out as Mt. Wilson Contributions. But neither one of them really tried to convert me to one side or the other; in fact, they very rarely spoke of this problem to me. The only time I can recall I heard Hubble speak of it was when much longer papers had been prepared. These had been given to Dr. F. H. Sears, who was the editor of Mt. Wilson publications at that time. Finally Sears and the director, Dr. Walter S. Adams made the decision that the two sides should be presented in extremely brief papers. And it was about this time that Hubble got word from Sears and Adams, and he was mulling over the decision, when I happened to come in. I saw what the paper was and asked him how he felt about it, because I hadn't heard him say very much. I knew what was going on from other members of the staff who had talked to me about the matter. So I said, “Well, Mr. Hubble” I always called him Mr. Hubble — he liked Mr. and didn't like Dr. — while most of the support staff called him "Major”, because of his World War I command assignment.
Shapiro:Did you ever call Hubble Edwin or...
Mayall:Oh, no, heavens no!
Shapiro:Even though you were friends? Even at home?
Mayall:Even at home — always Mr. Hubble.
Shapiro:Because of that age difference between you?
Mayall:Well, I felt I wanted to pay him that much respect and that he would rebuff any familiarity from anybody. Even Humason didn't call him Edwin. The only persons I knew who called him Edwin were his wife, and maybe a few of his colleagues of similar seniority at Cal Tech.
Shapiro:Who, for example?
Mayall:I think Tolman was one who called him...
Mayall:Yes. Nobody called him Ed; he would never have allowed that.
Another interesting thing: he dropped his middle initial early in his career.
Shapiro:Why is that? What is the thing about the middle initial?
Mayall:I never found out. I asked Mrs. Hubble one time, “Why did Mr.
Hubble drop his middle initial?” And she said, “Well, that's something
I don't wish to speak about."
Shapiro:Was it a first name or a last name that the, what is the...
Mayall:Well, the name that initial stands for is “Powell.” Now I don't know...
Shapiro:Is that the root...?
Mayall:That I don't know — I don't know what the background is for that name. Anyway, he dropped it, and after I found Mrs. Hubble was unwilling to tell me, I of course didn't press the point.
To return to the first time I heard Hubble say anything about this controversy with VanMaanen, I asked him, “Well, how do you feel about this abridgement of all this work, with the publication of only two, short, separate papers?” He reflected for a little while, maybe 30 seconds or so, and finally said, “My attitude is 'no compromise'... And, of course, he meant no scientific compromise, no watering down of his views toward the evidence and similarly for his opinion of VanMaanen. He didn't mention VanMaanen by name, but he repeated, “My view is 'no compromise'." And that's all he ever said to me about that controversy with VanMaanen — he never spoke of it again.
Shapiro:What was your view of VanMaanen?
Mayall:I felt, without being actually involved in the measurement of the plates that VanMaanen had been taken in by systematic errors possibly resulting from emulsion distortions or asymmetric images on the plates.
Shapiro:Was it due to carelessness on VanMaanen's part?
Mayall:No. I think it was due more to a certain amount of ego that he felt he could measure those plates more accurately than anybody else, which wasn't the point. Even if he did measure them most accurately, those measurements still probably had basic systematic errors. I suspect the interna1 measurement error was sma1ler than the 1atter, but so far as I know he made no evaluation of the probably larger external systematic errors. Unfortunately, he regarded criticisms of his results as criticisms of his competence in measurement. That I wouldn't question — I think he was an excellent, careful measurer. But that was irrelevant. The point was that what he was measuring had inherent systematic errors that had to be evaluated, and his mistake was not to evaluate them. That's my chief reaction to the controversy.
Shapiro:Did Hubble have any view of the Eastern establishment? Did he ever express anything on that?
Mayall:Well, I think I summed up his view of some of the Harvard results. I don't think he felt that way about some other places in the East. But I don't know now who else back there, other than Shapley, was very much involved in extra-galactic research. At that time there weren't too many others working in that field, especially near the threshold, because they simply didn't have the equipment and resources to do it? They had to work with what they could get as visitors to the
Western observatories, or work up material that had already been published by the Mt. Wilson and Palomar Observatories.
Shapiro:Did Hubble ever talk about Einstein as a person and as helping to shape some of Einstein's ideas...?
Mayall:Not to me, but I'm sure he must have with others down there. You see, when I was there — I was actually there when Einstein came for a visit — he was given an office right across the hall from Hubble.
Mayall:At the Observatory offices on 813 Santa Barbara Street.
Shapiro:Oh, I didn't know that.
Mayall:Einstein was there before he then went to Princeton and...
Shapiro:How long was he at that office opposite Hubble?
Mayall:I don't remember. He was there the year that I left, in 1931. How much longer he stayed I don't know, but I think he was still there when I left in June. That was an interesting situation, because the great man — well, you could walk down the hall and just look at him sitting at his desk. There also was a woman in the room, sculpturing a bust of him. Reporters were trying so often to get in that the Observatory finally put locks on the door, so they couldn't just wander in. Then they had to go through the main office and get permission. Otherwise the great man was found to be pestered. His wife was trying to protect him from all sorts of cranks. I never spoke to him, but he attended meetings and seminars that I did, and occasionally I sat pretty close to him. Sometimes he'd get up and ask questions and make remarks, but he was treated just like anybody else on the staff. He was no great man to them, at least socially. Once I came down to see Hubble, and Einstein was in Hubble's office talking — so I do know they talked — but...
Shapiro:You don't know the nature of the conversation?
Mayall:No, I don't know...
Shapiro:Did Hubble ever say anything to you...?
Mayall:No — no.
Shapiro:And what was your view of how Hubble helped to shape Einstein's theories? Did you have any kind of inkling or feeling...?
Mayall:No, I had no experience...
Shapiro:Did Einstein visit Hubble at his home?
Mayall:I don't know about that either. He was not there at any time I was, that's all I can say. At that time I was only a graduate student and I was taking these two years off to get some practical observatory experience, so I was way down on the totem pole, just a computer assistant there. But I regard those two years as the most influential ones in my whole career. I learned so many new things and met so many fine men; it really opened my eyes to what was going on in astronomy.
Shapiro:Did you feel that Hubble was a scientific conservative? Did you think of him as being conservative?
Mayall:I think of him as a conservative in the manner in which he reported his work. I think he was conservative in putting it on the record. I don't think he was conservative in his concept of the universe. I think he had a very open mind on what might be going on, and he was always thinking of ways to probe a little farther, to get a little more accuracy in the distance scale, to get more information about internal motions in galaxies, and more about the globular star cluster systems that appear around some of the brighter galaxies — things like that. I felt that he had a lot of good foresight and certainly a broad vision, but when it came to writing up the results of his own work, there he was, I would say, restrained and conservative. I admired him for it, and tried to do likewise with my publications.
Shapiro:Hubble wasn’t himself, personally flamboyant or flashy, as one might say?
Mayall:No, no, he abhorred that.
Shapiro:He abhorred that. But yet he liked some of the people in Hollywood, some of the Hollywood people. Now how does that — was that at a later time in his life, or how?
Mayall:That must have happened later, because I was not around at any time when I might have known about that.
Shapiro:For example, he went to Disney studios and he knew some actors and actresses as well as people like Stravinsky, who was in a different category — those are distinct groups — on the one there's Stravinsky and the Hollywood — did you know anything about that...?
Mayall:I did not have any special knowledge of those activities.
Shapiro:When you knew him and when you were around him, he did not know any of those people?
Mayall:Well, I don't think so. I don't recall any references to them or being told about them.
Shapiro:Because there seems to be a change in his life, that later on he did seem more interested in publicity, more interested in being a part of the Hollywood — not to a great degree, I'm talking about a rather subtle thing — so one suspects that there might have been a change in his life and...
Mayall:I don't think I could speak on that. The last time I saw him he was still very reticent and shy of publicity, as far as I know. He didn't like to be lionized, and he appreciated, when he would come, say, to Lick that we didn't arrange any press conferences, or anything like that. He didn't like that sort of attention.
Shapiro:I want to just ask a question about yourself. Mt. Wilson and Palomar was the place where galactic research was going on primarily, is that right? And yet your career took you to Lick Observatory. Did you want to be at Mt. Wilson, or did circumstances just prevent it or what... Here you were in one place quite distant from Hubble and his work...
Mayall:When I left Mt. Wilson, I wanted nothing more than to go to Berkeley and to Lick to get my degree, and to go back and join the staff at Mt. Wilson — Palomar was not yet in operation. Well, it didn't work out that way. There was a little thing called the Depression that came along. When I left Pasadena, both Hubble and Humason said that they hoped I would be able to return. But neither of them could make a commitment because they didn't know how long it was going to take me to get my degree and neither one of them was the director down there. But they said that they hoped I could join the staff. However, Hubble told me that he thought that he had a commitment for funds to take the 60-inch telescope to the Southern Hemisphere to do some extra-galactic work down there and he said if that came to pass he’d like me to go down there to work on that program. And I said nothing would please me more, the Southern Hemisphere opportunities greatly attract me, and I would like nothing better than to get there and to cultivate what was then a virgin field, and still is in many respects. So when I left in 1931, I had these hopes. Well, I didn’t finish up, really, until the summer of 1934. By that time, much of the money that was likely to come to Cal Tech and Mt. Wilson just vanished. The stock market wiped out many of the Cal Tech Associates who were contributing funds, and had hoped to continue contributing to their programs. One of these was this Southern Hemisphere venture, and the funds for that just vanished overnight. So there I was with my new degree, and no place to go. At Lick, at the end of my fellowship there, which was in 1934, I came within a week of having to leave Lick to go down and try to earn my living in any way I could think of. However, just about when I had to pack my bags and clear out my room, I went to speak to the director, to whom I said, “Do you have any kind of a job here that I could have, which would let me stay on here? The director then was Dr. Aitken, a very nice, kindly old man, who didn’t know much of what was going on in extra-galactic research. He said, “Do you really want to stay on?” and I said, “Yes.” He said, “Well, I can’t offer you a staff position, because we don’t have any money for another position... After a pause, he said, “But I do have some very small funds left over from the assistant janitor — it can’t be very much... And I don’t remember the exact amount, but it was in the range of $1200 or $1500 per year. Then I said, “I’ll take anything, what do I have to do to earn it?” He replied, “You will have to do routine chores like looking after all the clocks and chronometers, the seismograph records, and help the other astronomers on the staff.” He added, “If you have any time left over, you may use that for research”. So I said, “0k, I’ll take it”. Well, that job lasted me through one year, and then about that time, Dr. Trumpler on the staff went to Berkeley. His position as a full-fledged astronomer made available to the Director an astronomer’s salary. There was also another young PhD there, A. B. Wyse, a very good friend of mine, who was subsequently killed in the war. Trumpler’s salary was divided and given to him and me, but each share wasn’t sufficient to get us on the lowest rung of the academic ladder. It was still a few years before I finally got on the Lick scientific staff officially. I was appointed to the staff in 1935 or ‘36, I think, as an assistant astronomer.
Shapiro:What was the significance of the galaxy counting, as far as contributing to the picture of — what Hubble called the cosmological problem.
Mayall:Well, the surface distribution of galaxies outlined accurately for the first time what the pattern of obscuration was along the Milky Way plane, because we’re looking, as you know, in that direction, through it. And I think galaxy counts have done the best delineation of where the holes are, where the opaqueness is, and what the thickness of the obscuring layer is in magnitude. Secondly, the galaxy counts gave the first quantitative evidence of the distribution of matter and its density in the Universe; these data came mainly from galaxy counts, and from the masses of galaxies that were determined in various ways. The counts also gave a determination of the distribution of the galaxies in space, which on a larger scale is more or less uniform. There are certain clumpings — clusters — but on a grand view they average out, as far as we can find and count them. From the mass determinations of individual galaxies we are able to get an estimate of the average density of the Universe, which is of great value in relativity theories of the universe — the average density is a key parameter. Does that do it?
Shapiro:Yeah, that’s fine, that’s good. Was there anything you found — we’ve discussed this before, but this is just a different way of posing it — perhaps you’d have an idea — would Hubble have particularly liked any kind of universe, or not liked any other kind?
Mayall:I think he maintained until the end of his life a very open mind on that question. He did not embrace any particular theory, so far as I know.
Shapiro:Did he ever talk about big bang, did he ever use that term?
Mayall:No, not very much...
Shapiro:Or Friedman’s model, what did he call the singularity, Friedman’s singularity, did he ever refer to that?
Mayall:I never discussed it with him. In fact, in all his conversations, at least with me, he never used the term “radial velocity” for the larger red shifts; of course, for the smallest red shifts, the radial velocity of proper motion of the galaxies dominates, for internal motions of a galaxy, he would use the word “rotational velocity” and for motions of galaxies in clusters, which were of a different, lower order from their red shifts, “Velocity dispersion.” So he did use “Velocity” for those cases where there was very good reason to believe that it was a motion, that that part of the red shifts were velocity shifts. But much farther afield, for more and more distant galaxies he would not use the word “Velocity”…
Shapiro:He would use it as far as motions of stars, would he not?
Shapiro:He would use red shift velocity?
Mayall:Well, the term red shift really was coined principally when they became so big that they didn’t correspond to any velocities that we really knew of.
Shapiro:I see. So you wouldn’t use red shift in terms of stars in the Milky Way, or nearby stars...
Mayall:No, because they could have red shifts and violet shifts, plus and minus.
Shapiro:Yeah, but I mean, you wouldn't even use the term red and violet shift, you'd just talk about radial velocity...?
Mayall:That's right, and that could be plus or minus.
Shapiro:Who invented the term red shift? Or when was it first used, as far as you know? Slipher, or...?
Mayall:No, he used radial velocity. That's an interesting question, and I've never taken the trouble to try to track it down. I cannot be sure that Hubble coined it; if he didn't, he really used it. I think it is possible that the term first appeared in the early relativistic theories of the properties of the Universe, especially those by
de Sitter and Lemaitre.
Shapiro:He gave it notoriety and...?
Shapiro:He gave it publication...?
Mayall:He gave it identification.
Shapiro:Identification. And you don't remember if Slipher used the term red shift...?
Mayall:I can't recall it. In his first papers, giving results of spectrographic measurements for the Andromeda nebula, and for some of the bigger and brighter nebulae, he referred to them as radial velocity in his papers, but I cannot pinpoint his use of the term red shift. Some of his papers were published near the end of his activity in that field. They overlapped a little with Humason, and Humason was definitely using the term red shift when I came down there in 1929. Although I didn't have much to do with him in 1929, in 1930 he was using the term red shift, and so was Hubble.
Shapiro:Well, we can certainly trace that in the literature...
Mayall:It would be interesting to track that down.
Shapiro:Yes... Do you have any cosmological preferences?
Mayall:No... I don't know enough about the theory to judge properly.
Shapiro:Well, you hear about the big bang theory and theories of beginnings and... Do you have any preferences...?
Mayall:Well, I'm more persuaded about the big bang theory for this reason: that within the past decade or decade and a half, physicists discovered this low temperature (4°K) microwave radiation, which appears more isotropic, the more it is extensively measured. It's really there, as a residual kind of a noise level in those microwave frequencies, and it's been explained as a remnant gas from the expansion of the big bang — it's just about what it should be in temperature and distribution, on the basis of the big bang theory. Now, whether there are alternative explanations of the phenomenon, I don't know, I'm not qualified. I'm not competent in that field.
Shapiro:How about in the departures in red shift linearity with distance have you heard about any, or...?
Mayall:Well, I've read the latest papers by Sandage, and I still think that the margin of error is uncomfortably large for the result he gets. I think he'd be the first to say so. Even the Hubble parameter, the factor that relates distance to velocity — he's got it down to 55 kilometers per second per million parsecs — I think he would concede that it's uncertain by 50%. Some others might say it’s more uncertain, perhaps by a factor of 2. But there you join a school of thought.
Shapiro:Who’s Sandage's principal opponent in the field of Cosmology, or who would tend to differ with him the most — if we were going to present two people, one Sandage with his views, what other person stands in your mind as holding contrary views?
Mayall:Well, you've probably heard of “Chip” Arp, haven't you?
Mayall:Well, Arp has some red shifts for a few objects in small groups or clusters, and they seem to stick out like sore thumbs — they either have too small a velocity or too big a velocity for the group. He has found and evaluated what he thinks is adequate evidence that these are real departures from the general law of red shifts — that there are departures of thousands of kilometers from the mean curve. One could say that he is one of the principal workers in the field who does not accept the closeness of the linearity that Sandage has found.
Shapiro:What was your opinion of the controversy between Abell and de Vaucouleurs?
Mayall:Gerard de Vaucouleurs?
Mayall:You mean George Abell and de Vaucouleurs?
Shapiro:Yes, on the reality of super clustering?
Mayall:I confess I have not read those papers. But I do know from my work with Jerry Neyman and Elizabeth Scott, who used the Shane-Wirtanen counts, they tend not to rule it out as an alternative interpretation of some of the statistical properties of the galaxy counts by Shane and Wirtanen. I think they have provided a much more comprehensive observational basis for statistical analysis — especially for Neyman, who is a marvelous mathematical statistician and probably has few peers in the world. Also, I believe what he says in the end — more so than I would these other fellows whose knowledge of statistics are minimal compared to his.
Shapiro:How do you feel about the isolation of the life at Lick Observatory — you were there for such a long time — whether it was good for astronomy or bad for astronomy and whether it’s getting better now that the resident observatory no longer exists?
Mayall:Well, I think for these days, and probably even for those days, isolation was a bad thing. It was much more difficult to get up and down in the earlier days, of course, so the staff was almost required to live up there. At the present time, it's not so hard to get around, and so there's not that reason to live up there. But another factor enters, and that is it's much more costly for a funding agency to maintain a full staff residence and support population on the top of a mountain. It is very expensive, and probably for that reason alone they should not live there unless they really have to. Another thing, if the director lives up there also, he has to be a city manager and adjudicate all sorts of squabbles in the households. It takes a lot of his time, as I know from living there. Also, the schooling becomes a real problem for the children of the staff, and, I too, ran into that. Thus my conclusion after experiences at both places, Mt. Hamilton and Tucson, is that I don't think a major observatory should have all facilities on the top of a mountain. I think that concept is obsolete.
Shapiro:How about the benefits of it, of having instruments there and the men working with their instruments...?
Mayall:That is true, it was very useful, and I could get from my house to the Crossley telescope in 5 minutes. From the time I'd decide I'd go up and observe, I could be at work in 15 minutes.
Shapiro:Weather changed... or?
Mayall:Yes, if weather changed, or somebody gave up a program, or some unpredictable situation. From that point of view it was nice for an astronomer, it was not so happy for the family. Mt. Hamilton had only an elementary school, through the 8th grade. At that point the kids either stopped their education, or had to go down and go to public schools or private school. And this wreaks a hardship on families.
Shapiro:Who supported the 120-inch project, and who was opposed to it?
Mayall:I would say most of the Lick staff supported it; in fact, I can think of only one man who was not in favor of it and that was Dr. W. H. Wright — he was the director when I returned in 1945 from Pasadena after the war. He felt it was not right to use so much public funds for such a large telescope and he was against it mainly on that principle.
Shapiro:It was only because of the funding that he was opposed to it?
Shapiro:He wasn't opposed to the idea of a 120-inch...?
Mayall:Well, he wasn't opposed to large telescopes as such, but he thought it was too much public money to put into that sort of thing. Fortunately, the President of the University of California didn't feel that way about it.
Shapiro:And then public money was spent...astronomy became publicly funded much more...
Mayall:Much more than it did at that...
Shapiro:As a matter of fact, public funding is so far exceeding...
Mayall:I heard — his is the only opposition I ever heard that...
Shapiro:That's not on the basis of the merits of the telescope...?
Mayall:No, no, it was his view about the proper use of public funds especially from the state.
Shapiro:Do you think the 200-inch telescope — how about the building of the 200-inch? Where was the opposition and where were the proponents?
Mayall:Well, there were some doubting Thomases mainly because they thought it could not be done. They thought it impossible to make such a large mirror of adequate accuracy of optical surface, and that it could not point with sufficient precision mechanically to take advantage of the highest optical quality. And there were times during testing when it looked like it might not work, because of troubles with the mirror support system. Fortunately for the project, the right man came along at the right time, and he was Dr. I. S. Bowen, professor of physics at Cal Tech, when he was named director in 1945 of the Mt. Wilson-Palomar Observatories. It was also the time when merging of the staffs of Mt. Wilson and Ca1 Tech astronomy staffs, with a single director for both installations, was agreed upon. “Ike” Bowen was one of the most remarkable men I've ever had anything to do with, and he was just the right man for the job, although I think Hubble would have liked it. Bowen had a superb knowledge of optics, an excellent knowledge of mechanics, and a distinguished career in physics that led him into astrophysics. He boned up on astronomy, probably knew more astronomy than some of the astronomers down there, and had a very broad mind when it came to science. Under his direction and personal involvement the 200-inch project was realized and brought into operation by Ira Bowen within 3 years; — it began operation in 1948.
Shapiro:But who were the people who opposed it, and on what grounds you say on the grounds that it wouldn't work — but how about on scientific grounds that there was no need for a 200-inch telescope?
Mayall:I never heard any opposition on the basis that it was not needed scientifically. My contacts with doubters included those who felt that the technology — the state-of-the-art of mechanics and optics — were not up to it.
Shapiro:Who were those people, who opposed it, didn't think that?
Mayall:Mostly astronomers who didn't know much about the project or the subject. They were old timers who were not astrophysicists, and who had not had any experience with large telescopes, or they had had some bitter experiences trying to work with large telescopes, because they didn't know how to use them.
Shapiro:Like which telescopes?
Well, I saw men come to Mt. Wilson and try to use those big telescopes, and they flopped because they didn't have the skill, and they were too old to learn. Astronomers like them thought that bit telescopes couldn't be operated properly if they couldn't operate them, so they would oppose anything bigger. But they were definitely of the older, I would say classical type of astronomers, not the young men — they were entirely different but there was a stratum of older, so-called classical, astronomers that hadn't yet made the acquaintance of 20th century astrophysics. They didn't really feel the need for a larger telescope for what they were doing. Some even thought it was a boondoggle...
Shapiro:Hubble was a strong advocate, wasn't he...?
Shapiro:What did he say, did he say anything to you about the need for it and were you on any committees with him, or...?
Mayall:I served on no committees with him, no.
Shapiro:For the building of the 200-inch telescope?
Mayall:No, I wasn't involved in that.
Shapiro:You didn't — Hubble was very heavily involved?
Mayall:He was on what was called the “program committee.” His responsibility was to outline a research program for the telescope, but the man who was the executive officer who really guided the design and construction, was Dr. John A. Anderson, a physicist at the Mt. Wilson Observatory.
Shapiro:There was a problem of flexure-free support...?
Mayall:Yes, that was one of the major problems, to design, construct and test a mirror support system for that big mirror. They actually built almost 3 complete systems before they wound up with one that was adequate. The first one that they had did not work very well at all, so they rebuilt that almost completely as a second one, but it still had difficulties. But they were able to modify that one further after tests, to the final one, which performed adequately. They had a lot of problems with the mechanical lever system that never made the press. Their experience and ours at Lick with the 120-inch, when we got going many years later, convinced us that with new developments, we did not want to use that system for the 4 meter telescopes for Kitt Peak and Cerro Tololo. Instead we went to the pneumatic air-bag system.
Shapiro:Which is highly successful — did that solve the problem?
Mayall:Oh, that completely solved the problem, much more simply.
Shapiro:There’s no more problem?
Mayall:As far as flexure-free mirror supports, we licked that problem...
Shapiro:All telescopes now have that problem licked, do you feel?
Mayall:Most that have been built, especially the bigger ones that came after the Kitt Peak and Cerro Tololo ones, all use the same system.
Shapiro:And who was the one who proposed that mirror support?
Mayall:We did not originate the idea, but at Kitt Peak we went out on a limb to apply it to much larger mirrors. The first one that was really used, and was of any size, was the astrometric 60-inch at Flagstaff, at the U.S. Naval Observatory station there. They demonstrated how successfully it could be done, that principle was sound.
Shapiro:Would you just, in a very brief way, describe that principle, just very simply?
Mayall:Well, the nearest thing I can compare it to is a water bed incidentally, we have one in our house here — and although these pneumatic support systems are not filled with water for the telescope mirrors, they work well with air. They serve the same function, so the blank just really floats on an air bag. This system does not have isolated points of support like those in mechanical systems. The mirror is supported uniformly over its entire surface, with several concentric bags, and there isn’t a point on it that gets more or less than the required compensating force.
Shapiro:So this has been very successful with the 120 — have you had any problems with it, with the 120-inch?
Mayall:No, because the 120-inch doesn’t have it.
Shapiro:Oh, I thought...
Mayall:No, we have a mechanical lever system for that telescope because we designed its support system based on the experience at Palomar. That worked fine, except it was very difficult to get properly adjusted initially, and keep it in adjustment. My experience there convinced me that, when I came down here to Kitt Peak, although a decision had been made for the 84-inch telescope to have a lever, a mechanical system, I decided when the big telescopes came along we’re going to try to find an alternative solution. The alternative solution adopted turned out to be this air bag support.
Shapiro:Ok, I’m sorry, that’s for the 150-inch that you...?
Mayall:That’s for both 150-inch telescopes.
Shapiro:But the 120 at Lick still has...
Mayall:That has a mechanical system, a lever system.
Shapiro:And are they still having troubles with it?
Mayall:No, because for one thing it’s not as big a telescope as the one on Palomar, the 200-inch, or the Kitt Peak 150-inches. The smaller the telescope, the easier it is to make the necessary tests and adjustments mechanically. If you had a 50-inch, well, there’d be no question at all. But when you get to these big ones you run, the mechanical problems become almost insurmountable.
Shapiro:And the 200-inch still has mechanical problems...?
Mayall:Yes, but they’ve learned how to live with it — Ike Bowen showed them how.
Shapiro:They learned how to live with it.
Mayall:Yes, they learned, because it would be enormously costly to replace it.
Shapiro:The pneumatic system would be...?
Mayall:Well, it’s partially hydraulic, in the sense that there are some tubes, around the edge of the mirror, that have mercury in them instead of air, because they have to have a restoring force in a very small space, because between the edge of the mirror and the telescope structure there’s not much room.
Shapiro:But that system was not available to you when you built the 120-inch?
Mayall:It was not yet tried — it was available, but we did not realize how good it was until it was demonstrated later at Flagstaff with the 60-inch astrometric telescope.
Shapiro:But you just tried to profit as much as possible from the experience with the 200 inch?
Mayall:Yes. We had some very good help from them — excellent advice, particularly from Ike Bowen, who was then director and was the one who made that mechanical support system work. He was the one who knew how to adjust it, and he was almost the only man down there who could. At Palomar when the star images went bad, he’d go up there and make the readjustments to shape them up. He was fantastically good with all optical design, adjustment and testing.
Shapiro:I worked with him on a number of occasions and always enjoyed it...
Mayall:Oh, I’m glad you knew him.
Shapiro:Oh, yes, quite well, and we put him in our film, you know, “The
Universe from Palomar,” we had him in the film and I was responsible for that and 1 spent quite a lot of time with him — he was very helpful to us on about three projects...
Mayall:He was a marvelous man. I got to know him very well because we worked together during the war on rocketry, and finally on the A-bomb in the Mohave Desert.
Shapiro:How did your family feel about leaving Kitt Peak and coming to Tucson?
Mayall: You mean — not Kitt Peak, Mt. Hamilton.
Shapiro:Mt. Hamilton, yeah, excuse me.
Mayall:Well, my children were pretty much away from home by then; it was 1960 when we left there, and they weren’t there at that time because they were still going to college at University of California, Berkeley. So my daughter was not 1iving there, and neither was my son, so there was no problem in their leaving Lick, they had already left. We had decided, my wife and I, that we’d just about had it after 26 years on the mountain. Also I was beginning to feel the strain of observing on my health, and I figured I'd been in one place long enough. Thus I opted for a changed life, and really got it down here in Tucson.
Shapiro:In looking back over the period of your working life and thinking about the problems of cosmology, what do you think was done that was right and what was done that was wrong? If you had it to do over again, what would you do differently: as far as instruments and programs?
Mayall:I don't think the programs would have been much different and the best thing I can say is, I wish we had gotten the big telescope sooner.
Shapiro:Like, which one, the...?
Mayall:The 120-inch. At Lick the largest one I could use was a 36-inch. But I knew what could be done with the bigger ones down south, at Palomar and Mt. Wilson, and my ambition, as long as I was at Lick, was to try to get a larger telescope, so I could work more effectively in the field with Humason and Hubble. Well, I'd just about realized that ambition and was ready for the pay-off, when I left.
Shapiro:Yeah, it seems that there were 2 conflicting feelings — one, you had this new instrument there to use and the other, you were tired of the mountain, is that...?
Mayall:That was partly it, although, I would say, a very heavy factor was what I thought was going to be the challenge down here. I had been associated with the group that selected Kitt Peak and organized the AURA Corporation to build and operate it, about 2 or 3 years before I came down here. I had seen what potential the place would have, and I also felt that my contribution to American astronomy might be made better here than by staying at Lick.
Shapiro:Yes, how did you envision that contribution… how did you think...?
Mayall:By bringing into being these new, large modern resources on Kitt Peak, and possibly in the Southern Hemisphere on Cerro Tololo. I had much more to do with the initiative at Cerro Tololo in Chile than I had on Kitt Peak in Arizona. For it the master plan was already in being, the construction was under way, and my first job was, of course, to carry through on that plan, which we did in about 3 or 4 years. But I was “in” on the Southern Hemisphere project from the very beginning of the Corporation's involvement in it. And I was the one who was around when we unexpectedly got the money for the big telescope, the 150-inch.
So I feel that I had more to do with starting Cerro Tololo than I did with Kitt Peak. That is to say, I felt more rewarded, more satisfaction there, because I started literally from the ground up, before it had even been selected. I helped to look for the sites on mule back, hiking and by plane and helicopter, all of which I didn't do for Kitt Peak.
Shapiro:How about the genesis of the Humason, Mayall, Sandage paper, that was just one, next to last...?
Mayall:Oh, yes. There was a lot of correspondence on that, and it's pretty well spelled out there. Also, we reached a sort of common consensus towards it by just informal discussion. We felt the material would be more useful if it were all in one place, than separately. In the first place, I had to get the Lick director to agree to that, because so much of my work was done at Lick. That was Dr. Shane, who is a very enlightened man in many ways. He thought it did great credit to Lick if I was involved in a joint paper, so he said do it by all means, and we'll have a reprint probably as a Lick publication. He thought it was great that I, Humason, and Sandage would want to cooperate on this paper.
Shapiro:And what were the separate roles of the three people?
Mayall:Humason wrote his part, I wrote mine, and Sandage wrote his.
Shapiro:And then how did you get them together?
Mayall:We exchanged papers, data and ideas, and various colleagues made suggestions. Between us there was no pressure applied to change. Milton
Humason found some; errors by me, I found some errors by him, and both of us found things we didn't like in Sandy's paper. He was generally cooperative, but he stood his ground on some theoretical things, as he should, because that was his strength. We never said, "You've got to do this, or I won't have my name on it." We never reached that stage.
Shapiro:How about the future of ground-based astronomy?
Mayall:I think it's great. I don't look for it becoming obsolete because of developments for space astronomy. There's a great amount of basic material in ground-based observations that is needed to interpret the new results. I see a close complementarity between ground-based and space astronomy that is absolutely required — one can't really get ahead without the other, especially in these new fields like x-ray astronomy and infrared astronomy. I think the problems of modern astrophysics don't pay any attention in what part of the electromagnetic spectrum they occur. However, ground-based observatories, in my opinion, are not going to be able to measure up to their potential if they don't cooperate actively, jointly, and fully with scientists who are working in space astronomy.
Mayall:And radio, of course. I think it was unfortunate the way radio astronomy developed, without serious, closely-related, facilities and staffs with optical astronomy.
Shapiro:How about the direction of the instruments, is the direction in the way of making them fully electronic or what do you think the relationship would be between — well, first I have to ask you about the future of the instruments, you know, the use of them, with electronic devices, is that the future?
Mayall:Oh, it's not only the future, it's here right now. There's so much electronics involved now that optical observations as I knew them are almost obsolete.
Shapiro:What is the big advance-photon...?
Mayall:The big advantage is the much higher quantum efficiency of the photoelectric process in which they deal with the emission of quanta from photosensitive surfaces that are far more efficient than, for example, the photographic emulsion. The second thing is the use of this digital technology, where they chop up the signal, the energy signal, so they can process it in a way that does not introduce non-linearity or distortions in the data, which is one of the big problems for precise work with photographic emulsions. The third thing is that such techniques are very adaptable to computers. You can process the data fabulously fast, not only fast, but enormously larger amounts of data. You can process tens of thousands of observations with these new techniques, sometimes so much as to be swamped. Computer science is just revolutionizing data acquisition and analysis in astronomy, and in other sciences.
Shapiro:Would you say that the days of the direct plate are limited?
Mayall:They are limited, but far from obsolete. As soon as they develop a 2-dimensional image tube — not just 1-dimension ones they use for spectra with a sizable area and very fine grain, that is, very small sensitive detectors that approach the resolution of the photographic plate, or better, then photography will...
Shapiro:How long do you think that will be...?
Mayall:It's on the verge now — it just depends on how much money they can put in it. The technology is there.
Shapiro:As far as red shift measurements, you wouldn't ever do red shift measurements any more by direct photography.
Mayall:Oh, no, well, they can do it, but...
Shapiro:It wouldn't be very meaningful. Almost all red shifts...?
Mayall:Most faint spectroscopy is done by electronic imagery — electronic emission with a variety of detectors — in the infrared, for example. So I think this is a good way to go. They routinely work on sources with stellar magnitudes now down around 21 to 22 with the 84-inch telescope, which is utterly fantastic compared to what we could do only a few years ago.
Shapiro:You're talking about spectroscopic?
Mayall:Direct photography too, but for a very small area. They don't have large area detectors as yet, so they have to squeeze the image down optically to use the very small area of an electron image tube.
Shapiro:You're talking about electronically generated images?
Mayall:Yes, and stationary electron images, too, without raster scanning.
Shapiro:Because in the end of our film, we want to point to the directions that astronomy is headed toward, particularly in respect to cosmology and to research in this area, and so we want to talk about the big instruments being adapted to electronic imagery and also to the radio telescopes the VLA that will be completed in a few years and to the space telescope — as the directions. So that’s why I wanted your view about...
Mayall:Well, this technology involving electronic detectors and imagery and digital analysis with computers is just revolutionizing all sciences, and especially astronomy. That is the really big thing, it’s very active now, and the only thing that limits it is more money. I think that probably they could use 5 times as much and get there much faster.
Shapiro:Is the science — the science for doing this is available and the technology is available, too, probably, it’s only a question of hardware, is that...?
Mayall:Well, they have to continue to do the basic research in this field. I think they have the competence to extend the present threshold and the technology to develop these thresholds. Some of it is pretty much still in the experimental laboratory stage, and has to be adapted to actual usage routinely at the telescope. That’s where the bottleneck is now.
Shapiro:If we were to say that the measurements that Hubble and Humason made, aside from his pictures of galaxies with help in galaxy classification, but if we talk about his measurements, photometric, spectroscopic, that those measurements... Now the question is, aside from the direct plates showing galaxy classification and types — spiral, etc. — would you say that Hubble and Humason’s measurements could now be done electronically...?
Shapiro:And done much more efficiently...?
Mayall:Oh yes — it’s being done...
Shapiro:Would you just describe that?
Well, present technology would very readily produce the information — the observations obtained by Hubble and Humason — faster...
Shapiro:Like photometrically and spectroscopically — say how would they be done today?
Mayall:Photometric measurements can now be carried to a much fainter limiting magnitude, and far more accurately with present electronic techniques. And the same thing can be said for spectroscopy of faint galaxies for measurement of red shifts, and internal motions in galaxies. Where they are not yet quite up to speed is in covering a large field, say, that would match a good photograph — an equivalent of a photograph — over a large field to cover, for example, a large spiral galaxy. They cannot do that yet — but they’re on the way.
Shapiro:But as far as plotting the Hubble constant and...?
Mayall:As far as obtaining the basic observational data, like the measurement of faint magnitudes with precision to very faint limits — they can do that very much better now. And the same thing holds for spectra — they can get them much faster — in a matter of a few minutes in some cases, and certainly not more than an hour or so - at a far fainter limit; in other words, fainter galaxies with bigger red shifts.
Shapiro:And the Hubble constant, as far as these measurements go, is there still linearity, is it still... or has there been any curve in these new measurements?
Mayall:I would say, if curvature is there, it is very close to the margin of error. But it may be within 50% if you’re an optimist — or only within a factor of 2 if you’re a pessimist.
Shapiro:OK. Is there anything else you can tell us that you think ought to be in our film — do you have any instructions for us or guidance or...? Thinking about the public and what the public thinks about astronomy and what might be useful in the way of public communication?
Well, I think when it comes to informing the public, their attention span is not too long, so I think something of the order of 2 or 2 1/2 hours is far too long. Another thing I think about it is you should get as graphic and pithy as possible. I think astronomers, some astronomers, and I may be among them, like to go on and on, and I think this is where good science writers can come in. They can keep things concise, and yet have them accurate scientifically. And I think the more graphic you can make a difficult situation — most people don’t know what the significance is of a black and white line diagram. I don’t mean graphic in that sense, but a visual impression of what the relationships are that you’re trying to show. I think one of the best things that have ever come out — the observational basis for the velocity-distance relationship — is to show a sequence of direct photographs of galaxies, first the large ones and then those of smaller and smaller size, with alongside them the corresponding spectra with an arrow showing red shifts of the H and K lines. That is a basic type of information, which in my experience has shown that more souls have gotten the message, than by any other means I can think of, as far as the law of red shifts goes. In that display you have what the phenomenon really looks like; actual galaxies and their red shifts, and those two go together to give the formal velocity-distance relationship. But it is very difficult to go all-out with such mélanges, for example, to show departures from linearity, velocity dispersion in clusters, rotation of galaxies, etc.