Oral History Transcript — Dr. Halton Arp
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Halton Arp; July 29, 1975
ABSTRACT: Childhood and unconventional early education; Harvard University: impressions of courses and social climate; Caltech, Mt. Wilson, comments on Walter Baade and background of Baadeís theory; differences between astronomy and astrophysics; early professional career work on Magellanic clouds; interest in peculiar galaxies, Viktor A. Ambartsumian at the 1957 Solvay Conference; Fritz Zwicky; Atlas of Peculiar Galaxies; comments on published papers: Distribution of Quasars compared to Maarten Schmidtís work with similar title; Edoard Stephanís quintet; work on discrepant red shift with respect to the Friedman universe; future research interest, non-professional interests. Also prominently mentioned are: Basch, Bart Jan Bok, Subrahmanyan Chandrasekhar, William Alfred Fowler, Jesse Leonard Greenstein, Edwin Powell Hubble, Milton Lasell Humason, Bernard Lovell, Rudolph Leo Bernhard Minkowski, Jan Hendrik Oort, Edison Petit, Robert Richardson, Allan Sandage, Maarten Schmidt, Harlow Shapley, Dick Stoy, Vanderlaan, Gerard Henri de Vaucouleurs; Atlas of Peculiar Galaxies, Institut de Physique at Solvay, and United States Navy.
Wright:This is an interview with Dr. Halton C. Arp at the Offices of the Hale Observatories, 813 Santa Barbara Street, Pasadena, California, on July 29, 1975 by Paul Wright on behalf of the Oral History Program at California State University at Fullerton. Well, Dr. Arp, will you tell us at length about your childhood and your earliest interests in astronomy?
My childhood? Well, I was born in New York City in Manhattan and my father was an artist and he lived in Greenwich Village and we moved around a lot when I was a child. We were in various art colonies and so forth. I had a very peripatetic youth living in a different place every year or so and connected with creative people, artists and people like that. I think that it was such a volatile, emotional atmosphere so that as a young child I turned to reading and literary things and eventually science as sort of a counter balance along this wild creativity and so forth. I never went to school until I was quite old, the fifth grade, and then I skipped into the 7th grade, so I only had one year of schooling up until the 7th grade. So that enabled me to do a lot of reading, developing interests on my own.
I look back on that as quite an advantage, in one sense, it was obviously a disadvantage in the sense that I had not developed my socialization skills. When I did go to school, you know, getting along with other people, that was extraordinarily difficult. But on the other hand it allowed me to develop my own interests in depth. I guess it meant that I didnít learn so much in a sense of a rote way of putting it back, but that I got so that I could figure things out. Of course the reason I had to go into the 5th grade, when I started, was because I didnít know my multiplication tables although Iíd been reading Freud and various things such as Bertrand Russell, very high level things, and I didnít even know the multiplication tables. So I got kind of a jumbled kind of mixed up youth, pre-school life. Then I went to a public high school for a couple of years. I was a non resident and so that meant that I was excluded from all athletic activities, drama clubs and so forth, things like that. So then the last two years in high school I got a scholarship to a prep school in the East, Tabor Academy. So I left home essentially at the age of 16 and I went to live at the prep school for the last two years. That was absolutely marvelous, I flowered there. I lived right on the school, I could take part in all the athletic activities and all the club activities and that was really great. It was a very important thing.
Wright:Where is Tabor?
It is in Marion, Massachusetts. When I was there it was an Honor Naval school, we had a young headmaster directing the faculty at the time. It was a very friendly place, a good place. They were building up, he was an ex-headmaster from Deerfield, and they were building prep school relationships with Harvard. So when I went to Tabor I had the idea that I was going to the U.S. Naval Academy because already at the time I had the notion of the thing I was going to do the most was to study astronomy, to learn astronomy, to be an astronomer. I figured from the economic uncertainty in my childhood that the only way to do that was to get into the Navy, where they paid you, and you could get in the U.S. Naval Observatory. It was a great shock to me when the headmaster came towards the end of my time, he said, ďWell, why donít you go to Harvard.Ē I thought that all that would be fine, but where do you get the money and so forth. Well, actually he arranged it, because I was on a scholarship, and I was a top student at the prep school. It was the only reason I got a scholarship to Harvard.
That was a new vista that suddenly opened up in front of me. But then I went into the Navy for a year, a little more than a year, just at the end of the second World War, and when I came back out of the Navy, I had the GI Bill, and so that took me through three years of Harvard. I accelerated then and went through in three instead of four years and the GI Bill just carried through that time. So it worked out financially just great. And of course when I got into Harvard as a freshman Id read all the Harvard astronomy series and I lived in the Hayden Planetarium when I was in New York and things like that. So when I went as a freshman in Harvard and they asked me who I wanted for a freshman advisor I picked the name Bart Bok, and I was astonished when they said that I could have Bok as an advisor. He was enormously influential in my early career at Harvard. He sat me down at the beginning and said, ďwell, you know if you want a gentlemanís C out of this college you can get it, you donít have to work very hard, on the other hand if you really want a first class education all the facilities are here and itís up to you, you can get them.Ē So I scurried around for three years and had a marvelous time.
When I got out of Harvard Iíd had all my astronomy courses, graduate courses which was a fortunate thing because when I came here to Cal. Tech. the department was just starting out and it was almost all physics and no astronomy. Bok was very instrumental in my coming to Cal. Tech. too, because Harvard was going through a convulsion at the time, in the sense that Shapley was just retiring as Director, Conant was president, the Board of Trustees always had a very sort of hate relationship with Shapley because he was politically liberal. Then when Shapley retired they saw the chance to not put Bok in as Director, as everyone expected, but to shift the Directorship around. They got rid of the Harvard Southern Station, at any rate the whole effect with Harvard astronomy crashed for the next decades. Bok was smart enough to see that and coming as a graduating student he told me Iíd better go to Cal. Tech. That was another new idea for me, I thought if I was good enough I could stay at Harvard and he said well, he tried to get me to come to Cal. Tech. He said itís a very high academic standard there and maybe you wouldnít be able to make it. Of course that was the thing that tipped me, so I mean I had to come to ask for Cal. Tech. and got my Ph.D. in 1953.
Then I went to South Africa for two years and did research on the Magellanic Clouds. So by that time I seemed to go off on my own, they, here, didnít want me to do that, they wanted me to do some rather safer things, pedestrian things like globular clusters and so forth. They sort of had a post picked out for me nearby, near enough to be on tap but far enough away to be out of trouble. I think already they sensed at that time that I was a little bit of trouble and that I wasnít really stable enough. Even though, I graduated in 1953, and Hubble and Baade, one of the few things they agreed on, they wanted a nova search done, particularly Hubble, in M31. That meant going up on Mt. Wilson to live for two years and observe almost every night, just picking up novae, I think I discovered thirty in two years or something like that. I wasnít terribly excited about it. I didnít think it was that important a project and, in fact, it turned out to be a fundamental project, but not that important. My judgment, I think, was correct on that. On the other hand, it was clear to me that if I was going to demonstrate stability and reliability, the kind of thing that they wanted, you know, in order to insure my getting access to some telescopes for research, I was going to have to do something like that, so I did it. But even after that they were not quite satisfied that I was stable enough for the hallowed halls and so then they wanted to farm me out to a local college and I didnít want to do that, I wanted to do research. So I got a NSF grant to go to South Africa for two years and I was prepared to go down with family and two children for seven hundred pounds a year. [laugh]
Wright:So was this connected with Indiana University?
Arp:Yeah, you see what happened, I got the NSF grant or I wanted to apply for the NSF grant but this place here had a policy of not accepting any Federal money and that may have been partly an excuse. So anyway, I had to scout around for someone to support me, an institution that would support that proposal and Frank Edmondson at the Indiana University at the last minute said he would be glad to support it. So they did and when they did so, essentially I was a Research Associate at Indiana University for two years down there. I was down there, there werenít many astronomers in those days, there were very few and I published a lot and I was well known. Lick Observatory made an offer to me to come but then I was nearing my end in South Africa, and then Mt. Wilson and Palomar Observatories knew here that it was now or never if they were going to offer me a job and they did and I accepted it. There were other aspects of that too and probably I shouldnít go into them on tape.
Wright:Maybe we could get back to that later.
Wright:What was your familyís reaction to your interest in astronomy?
Arp:My mother and father?
Arp:They approved of it. They generally approved of intellectual activities, that is, my father who was an artist, sometimes, well, was depreciatory of things academic, intellectual endeavor as such. I mean he had mixed feelings, he had ambivalent feelings about it. He was sort of a self taught philosopher but made fun of proper academics. My mother had more respect for academic procedures but I donít think they understood in detail really what it was to be a scientist or astronomer. I did generate a lot of interest in cosmology and astronomy in early childhood talks with my father about what was the nature of the Universe, how far was it out and did it ever come to an end and questions like that.
Wright:You mentioned that you spent some time in the U.S. Navy. What type of work did you do there?
Arp:That was in the electronics technician program, that was the Captain Eddy program. What the Navy did towards the end of the War, they decided that this had become an electronic war and they needed electronic experts badly, desperately, and then they decided that they just didnít have them and they didnít exist, so they had to train them themselves. So what they did, they had a systems electronics aptitude test, the Eddy Test, and high school people, engineers, people of all walks of life and ages took this exam. It was really an aptitude test on mathematical capabilities and if they passed then they were admitted into this special program. The Navy endeavored in a yearís intensive training to turn out top flight electronic technicians who could tear down and build and repair radar, sonar, any kind of electronic systems and I found myself in pre-radio with guys with Ph.D.ís in mathematics and physics and guys who hadnít graduated from high school yet. We were all thrown together and given a cram course and every week we had a test and they cut a certain percentage off the bottom every week for 52 weeks, and we kept rolling like that!
Wright:I think they still use that same technique. I didnít go through that particular program myself, but I was trained as an electronics technician in the Naval Reserves here in Pasadena, but I think the regular Navy up at Treasure Island, San Francisco, still does something like that where they cut off the bottom portion of the class.
Arp:That is where I wound up, Treasure Island. I finally just completed the course when I was discharged. I was stationed at Treasure Island on shore patrol duty in San Francisco and I was too young to buy a drink in a bar. We used to operate out of a Chinatown Station, in San Francisco, a rough neighborhood.
Wright:During your high school and undergraduate work at Harvard, what impressions did you have of your courses there?
Arp:The courses at Harvard were divided into two: one was the Humanities, the English, literature and so forth. They tended to be quite challenging and quite stimulating because there were quite a few good people. There was an ambience of intellectual creativity so the science courses were good too, but they were much more cut and dried. You had to bring your own stimulation to those courses. Again, in prep school, high school, no I guess prep school, again the literary ends were quite stimulating and the science courses began around a routine, you know, solid stuff, learning intrinsically, they did not have the same intellectual adventure as the Humanities courses.
Wright:You took your bachelorís degree at Harvard in astronomy, is that right?
Arp:Yes, that year we had a choice of bachelor of science or bachelor of art. So I took bachelor of arts.
Wright:Iíve discussed with Jesse Greenstein both the social and political climate at Harvard during the late 1920s and early l930s. I wonder if you could characterize the climate after World War II?
Arp:Yeah. I came in that first wave of post-war veterans and those veterans were the best class Harvard ever had. They were serious, buckled down, did hard work, got good grades, and so forth. There was a political climate as well. Most of the students were making up for lost time and getting good jobs, but the political interest, what there was I remember, centered around the American Veterans Committee. The organization was made up of, I would say, liberal people who had idealistic notions for the society. One of the things they wanted was to form a counter organization to the Veterans of Foreign Wars and the American Legion. They considered these groups self serving, right wing, conservative, without imagination or scope. So the American Veterans Committee campaigned for such things as no special rights for veterans, not clamoring for all those bonuses and setting forward the motions for social change and social reform. The group was active on campus at that time, but then, just at that time, just as I was graduating, the anti-Communist McCarthy era came up and the AVC was smeared by that as many organizations were at that time. Everybody got caught in that, it was very sad.
Wright:In the astronomy courses, I assume you did some lab work, is that true?
Wright:What equipment did you use at Harvard?
Arp:We used small telescopes around the Harvard Yard up near the Observatory, transit circles and so forth to do basic astronomy. The major observational experiences out at Oak Ridge Station which was up in the country. They had an eight inch refractor and a sixteen inch refractor, patrol cameras, and a Schmidt that Bok helped put up. So the students would go out and observe there and there was a sixty inch reflector, which was a pretty big reflector. The weather was terrible so you could not do serious research, but it was a good training ground. Some people did research.
Wright:Do you have any anecdotes about your lab work there?
Arp:One of the things I remember vividly was Art Hoag, who is now Assistant Director at the Kitt Peak National Observatory. He was my section man, Instructor from the Astronomy I group. He took us out to teach us how to do transit work, to tell the time to a fraction of a second by the transiting of stars. We spent almost an hour trying to locate a star. We finally discovered we were off by an hour because of Daylight Savings Time. [laugh] That was a vivid memory. They used to have Open Night at Harvard, too. They had a fifteen inch reflector and they had the public come up. It was usually trained on a planet or something like that. One night a little old lady came up. The eye piece was down near knee level, she said, ďlook, that is not a convenient place for me.Ē [laugh] She wrenched it up so she could see it better.
Wright:What impressions do you have of your electives at Harvard?
Arp:I remember taking the Philosophy of Science under Phillip Frank, big course! We listened to lectures and wrote papers and so forth. I donít remember how it all came about, but we all got the same idea about the same time; maybe life was going to reverse the Second Law of Thermodynamics. I remember writing a term paper on that. A little while later, Frank started talking about it in class. The idea just seemed to come up. Those electives were fun. Other classes, not really electives, like German, that was not very fun, I didnít enjoy that too much.
Wright:Are there any professors that you recall that impressed you? You already mentioned Bok. Did you work at all with Shapley?
Arp:I met Shapley, I knew him a little bit. I was an undergraduate and he was the Director. He was friendly, it was a good contact, I responded to him as a contact. I remember my English courses were interesting at Harvard. I had for the first year of English, the first half of the year, one section man who was just dreadful, I couldnít do anything right. He criticized everything I wrote and he said I was disorganized and a poor writer, it was a constant battle. I was trying to say I should try to express my individuality. Then the second half of the year I had an English Section man who was just the opposite. We studied Moby Dick and Brothers Karamazov and things like that. He emphasized so much the objectives for creative thought and analytical thought. That was a very exciting course. Somehow something went ďclickĒ there and that was important. He was enthusiastic and sharp, always trying to analyze and see the meaning. The writing just flowed easily for me, it was interesting for me.
Wright:You mentioned that Bok was instrumental in you being selected or decided to go to do your graduate work at Cal. Tech. Do you have anything more you would like to comment about that?
Arp:No, except that Bok was always very wise about those things. Bok inspired a whole generation of astronomers and astronomy students. He had an enormous talent for inspiring students, working with them. He treated them as if they were important and they responded.
Wright:Do you have any anecdotes you might care to share about Bok?
Arp:Gee, no nothing specific. There are many, but I have nothing else to say.
Wright:As a graduate student, here at Cal. Tech., who were professors who impressed you particularly?
Arp:Well, Jesse Greenstein had to impress me since I had to take Stellar Atmospheres from him. [laugh] It was a very difficult book and we had to slog through it somehow. Professors at Cal. Tech. were very difficult. There was a tremendous emphasis on being knowledgeable and being right, and so forth. The strong emphasis was on knowing a lot and on the physics. The physics was not really my main interest. My main interest was really in astronomy and discovery in a sense. Looking back, I donít think there was anyone who was inspirational at Cal. Tech. They represented people who were responsible for presenting the course material, they had considerable ability themselves, but as for actually communicating that, I felt you essentially had to do it on your own. They really couldnít communicate.
Wright:While you were a graduate student, I believe about this time, Baade conceived of his Population I and II stars. How did you perceive the importance of this work to astronomy in general and astrophysics in particular, at that time?
Arp:Oh, at that time it seemed very important, it was a simple, bold stroke. I was enough aware of astronomy to know, to sense and feel, it was a very important step to break up the age differential between the stars and the galaxies that contain so many bright, blue, young stars, gas and dust and on the other hand this other group natural separation contained the old stars. I thought it was as fundamental distinction and, as a matter of fact, it was discussed in the Hoyle Symposium program a few weeks ago in Venice. After Baade annunciated the Population I and II and the thing had been around for maybe five or ten years, I forget exactly how long, they held a symposium at the Vatican. They called all the top people together, and they were going to make some progress or some pronouncement or something like that. They decided, and I think that this is the way things get messed up. I guess they decided that they were really going to improve things by making instead of two populations, now they said six or seven populations, it was really crazy. The top people in the field were there, Oort, Morgan, Baade, and all these people. Baade resisted for a long time and they finally wore him down and he came back to Cal. Tech. here and started telling us about the seven populations that they constructed. I was wild, even as a young scientist at the time, I stood up and I said, no, I thought it was absolutely crazy and it is wrong and it just muddled up the field and it was a step backwards. I was for berating Baade in whose mind, you know, I was the only student that Baade ever had, he was my Ph.D. advisor. I was really sort of reading Baade out for giving in to this. And in fact it has turned out to be bad. The populations disappeared. Mercifully. It was just a glaring example of how the top people in the field can get together and make absolute ďmushĒ out of things. [laugh]
Wright:Do you have any anecdotes you might care to relate about Baade?
Arp:The anecdotes about Baade are legion.
Wright:Maybe some that might stand out in your mind.
Arp:I donít know, you see the word anecdote is a little misleading. I think, like amusing stories or something that happened. But Baade was a continuing personality, forceful and vivid personality and he had amusing ways of doing things.
Wright:I think that might give some insight and could be of interest.
Arp:He was just a pure, straight photographer in a sense. He never did spectroscopy. He made fun of people who did spectra.
Wright:He rarely published, I believe.
Arp:Thatís right. As a matter of fact, he insisted on having separate dark rooms in the telescopes. One for the people who could direct photography like himself and the other for what he called the pigs, the spectroscopist who slopped the dark room up and made messes and shouldnít be allowed in a top flight dark room. [laugh] What did you say before that?
Wright:He rarely published.
Arp:Oh yes, that was the other thing. He did take very carefully guided photographs, and the best photographs that anyone took at that time. So whenever he was in conference or whenever anybody was discussing what a certain situation, whether in astronomy or any controversy, arose, he would always settle it by saying, well, I have these photographs in my desk drawer that show such and such, and then, of course, everyone would shut-up because they couldnít say anything more. [laugh] He had tremendous enthusiasm for astronomy.
Wright:I understand he observed in shirt and tie?
Arp:Yes, I think most of the people did in those days, you know. Astronomy in those days was quite formal. For instance, Hubble would sit down in a very formal position at the head of the table, and the napkins would be laid out just right. They would have a shirt and tie and so forth. They would eat leisurely, and it would get dark, and they would continue to eat leisurely until the dinner was done, and then they would go leisurely and start leisurely observing. Well, not like now, long before it gets dark you bolt your food and run off to the telescope to be sure you are just absolutely ready to go the minute it gets dark. Hubble was a very formal person and there was some rivalry between Baade and Hubble, too. Baade felt Hubbleís reputation was a bit overblown and of course Hubble did not take good plates. This was a matter of scorn on Baadeís part.
Wright:Do you have any insights into Hubble? Did you know him at all?
Arp:Yes, I knew him and he was the one that wrote the recommendation that I do the novae research on Wilson. He did everything in the grand manner. He could not write an inter-office memo without it sounding like the Preamble to the Constitution. I mean it was just grand eloquence, but very nice, no problem there.
Wright:How did you perceive the field of astrophysics prior to your decision to concentrate your efforts in this field?
Arp:I never thought of myself as an astrophysicist. As a matter of fact, thatís an anecdote I can tell. When I arrived from Harvard I was convinced I was an astronomer. There was never anything else in my mind. And when I went into nuclear physics course with Willie Fowler, who was teaching at the time, we all handed in our blue slips in the beginning. When he went through the blue slips and he announced proudly to this group, he said, oh, we have an astrophysicist in the class and I started looking around to see an astrophysicist, pretty interesting. I tried to find this astrophysicist, but finally Willie pointed to me and said, ďyou!Ē And I said, ďIím not an astrophysicist, Iím an astronomer.Ē I never accepted that term about astrophysicist. I think, that one of the underlying currents right now in astronomy today is a deep seated struggle between the physicist, to be blunt about it, and the astronomer. Physicists believe that the universe is just another example of laboratory physics, just another arena for their laws to work in. And I think a few true astronomers, at least I believe, that there is in astronomy most important fundamental new processes which have yet to be discovered which are transcendent to physics in a sense. I donít know if itís going to be right, weíll have to see. But a lot of physicists are shifting in to astronomy so I mean, I think, for other reasons, I think they sense it. But they bring different skills and different approaches to the astronomy. They approach it as a deductive exercise, as if they were trying to prove again and again the things they learn in the laboratory and learn in their courses and I think the reason that they are going to fail is that they donít look on astronomy as an arena for discovering new things. They look at it as an arena for proving old things. Thatís a fighting statement.
Wright:So youíve touched on this briefly, but perhaps you can elaborate a little bit more on it. After receiving your Ph.D. you became a Carnegie fellow at Mt. Wilson and Palomar Observatories. Did you work at Mt. Wilson or Palomar or both places?
Arp:No. Just at Mt. Wilson.
Wright:So you used the 100 inch?
Arp:The sixty and one hundred inch. But essentially just the 60 inch for two years on that Nova search, night after night, a tremendous grind. I did a little research, a little variable stars and globular clusters and so forth in between the novae. So essentially it was just a huge project on stellar novae.
Wright:Who were the members of the staff at the time?
Arp:Edison Petit, Seth Nicholson, Paul Merrill, Baade, and Hubble, of course, Ira Bowen, Rudolph Minkowski, and Milt Humason.
Wright:Do you have any insight you want to share about some of those people?
Arp:Yeah. Well, they all were so different. Petit was quite a joker, a very quiet guy, he was old when I knew him. But still very much a practical joker. Sly, sense of humor and quite a good instrument man. Humason, of course, was a very wise guy, he had come up from a mule skinner to be Hubbleís assistant, and a very good astronomer in his own right. And of course Zwicky. I know Zwicky pretty well.
Wright:How about Robert Richardson?
Arp:Yeah, I knew Bob Richardson, too. He was a great character.
Wright:I talked to him.
Wright:He is quite an interesting person.
Arp:Yeah. He caused a lot of consternation around here when he was here. He told the Board of Trustees they should pay more and that was considered unthinkable. They told him to go someplace else. Then he wrote science fiction stories in which the characters were barely concealed members of the staff. Minkowski was an awfully disorganized and sloppy guy. I remember his desk was absolutely piled high to the sky, so full that whenever I took a plate in to show him to see this object or that object, I watched him very carefully. The minute he put the plate down it would start to slide off the desk and Iíd have to catch it. [laugh] I wanted to do a thesis on galaxies, all about ultraviolet nuclei and stuff like this which was long before quasars were discovered, compact galaxies and things like that. I was burning to do the thesis. Minkowski said it was the worst thesis he ever heard of and Baade agreed. They were quite close and then he said, no, absolutely impossible and he put me on another thesis instead. Well, in fact, I think that the thesis would have probably been an excellent thesis, the really stand out thesis as things developed.
Wright:I think you have already mentioned you worked on the novae and novae search study. Now for 1955 to 1957, you were a research associate at Indiana University down in South Africa and that was exclusively on the Small Magellanic Clouds. Is that right?
Arp:Yes. A little bit on the Large Magellanic Clouds but mostly just essentially on the Small Cloud. And I set up those sequences, the Cepheids and the color-magnitude diagrams, and so forth. That was a great moment for me actually when I went to South Africa. Because for the first time I was treated down there as an independent and important astronomer and not as a student up here, and that sort of allowed me to grow in a professional sense. I remember Dick Stoy, who was Her Majestyís astronomer on the Cape, treated me very nicely. Treated me royally. He was a very warm person, in spite of him being English and colonial in a sense. A very real and warm person. He asked my advice about things, we had good talks, just that relationship helped me to mature. Then I worked at the Radcliff Observatory with Thackeray, who was the director. He also was a nice person in that respect.
Wright:You did your observing at Radcliff?
Arp:Radcliff and the Cape. I went between the two.
Wright:What kind of equipment did they have?
Arp:Well, Radcliff had a seventy-four inch reflector which was a silvered mirror at the time, that was a big instrument. And then at the Cape they had a eighteen/twenty four inch refractor which I used to calibrate the stars, the bright Cepheids and then the faint work was done with the reflector.
Wright:Now I guess in 1957 you returned to Mt. Wilson and Palomar Observatories as an Assistant Astronomer. At that time what was your research interest?
Arp:At that time it was almost totally globular clusters and novae and Cepheid variable stars and galaxy populations, stellar populations, stellar evolution. But Iíd always wanted right from the beginning to get into galaxy research. I just really, in a way, bided my time to get into concrete research.
Wright:So one of your earliest papers was on the reduction of photoelectric observations by electronic computer. Would you care to provide your perceptions of the importance of this work, at the time, to astronomy in general and in astrophysics in particular?
Arp:Well, at the beginning of the computer revolution, I came back from South Africa with a lot of photoelectric observations and up until then we all reduced them by hand by just computing out extinction and making transformations and so forth, graphically. And Cal. Tech had a Datatron at the bottom of Throop, which was in the Administrative Building which was just a little room. And they had a computer machine there and I got the advanced idea wouldnít it be fun to just have a program and it would do this all automatically. So I went down and spent, I forget the manís name now, he is now with JPL doing a lot of computer things like that. But I was not in charge down there and I walked in and said Iíd like to have these programmed and he laughed, he had his feet up on the desk. He laughed and he pulled open his desk drawer and pulled out this great big manual and said, here, read that and go program yourself. I did. After I went back we worked with cardboard punch tape at the time and if the computer didnít work, we kicked it and things like that. And I got the program going and reduced it. But since then things have escalated to the point that you canít get near the computer. I donít know programming now. I wouldnít attempt to program.
Wright:But that actually was something of a pioneering effort, would you say?
Arp:I suppose, yeah. It, I think, was the first computer reduction of photoelectric stuff. Thatís right, and then the coefficients that I worked out. As we got more data we improved the coefficients a little bit and then eventually I went out of the photometric business and went on to other things, and I really havenít paid much attention, but other people developed fancier programs. But essentially, basically, I guess the same things.
Wright:One of your sustaining interests has been in the Magellanic Clouds. You mentioned how you came about observing the Clouds. I would like to know more about why you originally became interested in the Clouds as a subject.
Arp:Well, that was a straight forward program when I was in Graduate school and Sandage and I were very close friends. It was very clear that the Hubble program was going to be carried out by step by step calibrations of the distance scales, first photometric distances within our galaxy, clusters of stars, clusters of globular, galactic clusters and then out to the Cepheids and then the nearby galaxies and then further galaxies and so forth, and then you get the distance scale versus the red shift way out to the edge of the universe. We were going to find out how the curve curved over and how much mass there was in the universe, and how old the universe was. That was the program. And so I had been working on the determination and calibration of globular clusters, Lyra Cepheids and so forth and the obvious next step was to go to the Magellanic Clouds, calibrate Cepheids and calibrate the nearest galaxies to us. That was the general program in those days, it was a step by step thing.
Wright:Well then your comparison of the Cepheids, with periods of less than ten days in the Small Magellanic Cloud and in the region of the Sun, you concluded that the Small Magellanic Cloud Cepheids had greater amplitudes. Would you comment on your perception of the importance of this work at that time and the present day theory of stellar evolution?
Arp:Well, at that time that was just one of a number of observational indications that said to me that the chemical composition of the stars in Magellanic Clouds was different from the chemical composition of the stars found in our own Galaxy, and, in fact, the metals were poorer than in the Clouds. Well two things happened. First, I arrived at that conclusion, I concluded from that rather conservative, orthodox theory that fitted in with orthodox theory of galaxy formation. Secondly, that result was immediately challenged by some of my colleagues who said that wasnít so. So there was a big controversy and debate. That was the first controversy I got into. Now subsequently, as it turned out, in fact I was dead right on that and that Small Magellanic Clouds do have lower metal composition and as a matter of fact the Small Magellanic Cloud do have the least metal and the Large Cloud has the next most and our own Galaxy has more. So I was quite correct in that and I feel pleased at that, although by now, now that the controversy has been settled, no one pays any attention. No one says isnít it great that you were right. But there is an irony involved in the sense that the orthodox theory that I thought that supported so well, the theory that galaxy formation, star formation as a function of density and then clouds representing low density formation, star formation which gave the low metals, that all fit together so nicely that I felt pleased with, I feel now as if the conventional orthodox theory of star formations are highly suspect, to me. So I am not at all pleased with the idea that that was such a great synthesis that I performed. I think the main fact falls in the end, into the trap of misinformation and misassumptions. In other words, if it turned out that star formation is much different from what I think it may well be, then the upshot about the theory will not be very important, even though I was right in a technical sense.
Wright:About this time you did some color index calibration for stars through black body radiation. If this could be considered a shift in your research interest, why did you move in this direction?
Arp:Oh, I did that initially because I wanted to calibrate the super nova. The super nova came up in NGC7331 in a lot of observations made which I coordinated and wrote a paper on. And in order to calibrate, in order to figure out what the observation meant for super novae, I had to figure out what the color characteristics would be for a black body, certain temperatures. So it was an interesting problem. I went into that to look into some of the theory and the great approximation and so forth. Then it was subsequently done, almost immediately afterwards, by Sandage, who came essentially with the same answer but who changed things a little bit and that was the beginning of a time which he felt he had to do everything again, and better or something.
Wright:As an observational astronomer the importance of the response of light to various photographic plates systems cannot be over emphasized. How did you come to write your paper on the transformation of photographic magnitudes about 1961?
Arp:Yeah, well that was also on the super novae and what people were doing with their observing with all the different sorts of photographic systems, the different filters, and in order to make, in order to get the observations all together on the same graph, we had to transform to one common system and so I wrote that paper for this purpose.
Wright:It was kind of an ad hoc type of thing.
Arp:Yeah, it was an empirical way of getting various peopleís observations on the same system. We were trying to standardize our system. I tried to emphasize we should all use UV system. For a while I got Zwicky to use 6T13 filter photographic plates. [laugh]
Wright:In a paper on the polarization of a filament which connects two galaxies, you indicated that the outer zone was a strong emitter of synchrotron radiation. Youíve since written a number of papers on the interaction of galaxies and peculiar galaxies. If this was the first paper in this area of interest, why did you become interested in this area at that time?
Well, I began to get interested in those interacting galaxies because I felt that that was the only place where we had laboratory experiments on galaxies. An experiment being performed on the galaxy would tell us what the galaxy was, and what was going on. And that early paper you mentioned, the polarized filament, I was doing polarization surveys at the time on the idea that magnetic fields were important in galaxies and that the polarization of these magnetic fields was polarization, but, in fact, I found out that I didnít find any polarization. This is one of the only facts I found, one of the two facts I found on polarization. The other was galactic nebula NGC 1999. But this was the only galaxy that showed much polarization and still today that observation is still quite controversial and I was trying to repeat it just last year, of course with new photoelectric devices. Because it goes against what you would expect.
Synchrotron emission coming from a filament that you would expect to find, maybe scattering polarization, thatís what I expected. But in any case I later came to the conclusion that magnetic fields are not so important and began to gradually realize the importance of explosive and ejecta, ejection phenomena in the galaxies and gradually led into the present, my consuming interest. Which is what goes on in the nuclei of the galaxies and the ideas that I had about galaxies, being ejected, protogalaxies, quasars being ejected to form galaxies and whole deep developmental, the cosmogony of where galaxies come from. And just at about that time I got the scent of the suspicion that the orthodox, conventional viewpoint of the galaxy formation was not correct. That seemed so big and so interesting that I followed it ever since. I started studying these peculiar interacting galaxies. I came independently to the conclusion that Ambartsumian came to in 1957, I came to, I donít know, 1965 somewhere in there, 1964-1965, just by studying the galaxies the photography Ambartsumian had done, beginning to get into the classification of looking up and trying to figure out. I came to the conclusion in fact that we were erupting and throwing out material and stuff like that. And then when I read the Solvay Conference in 1957 in which Ambartsumian spoke, then it was just an enormous revelation that Ambartsumian had seen the same thing prior, independently. Do you know the story of the Solvay Conference?
Wright:No, I donít. I think that would be interesting to relate.
Yeah, I was just in Jodrell Bank giving a talk there and Sir Bernard Lovell was there. He was at that Solvay Conference 1957, he reminded me of that situation which I already knew. The situation again, the Solvay Conference is a very top level conference, where in the past they have had Einstein, Planck, Bohr and all these people down through the years. So theyíd run it in astronomy down through the years also. Theyíd invited the top people at the Solvay Conference, also there were Oort, and Lovell and Hoyle, all the top astronomers. And they decided for some reason that they had to get a representative from the Soviet Union and they figured well, they heard about this Ambartsumian. They invited him from the Soviet Union and he came, nobody knew him. He came and gave this paper which nobody understood. What they thought was complete trash and they thought it was so crazy. Bernard Lovell was telling me that they were embarrassed because it was so bad. They didnít want to be rude to this representative of the Soviet Union, so they didnít say much but they were really embarrassed by the paper.
But then they went on about the important business and this paper was published in the proceedings. That was in 1957. Well, about eight, nine, ten years later it began to appear that the things Ambartsumian had said in his paper, that far from being crazy, were, in fact, quite true and as time goes on his paper got more and more prophetic, more and more far reaching and insightful. When I was with him at the Brighton IAU, the IAU before Australia, six years ago, and I was sitting next to Oort, and Oort said to me, ďit turned out that Ambartsumian was right.Ē And so it was generally concluded, I still donít think they realized how right he was. I mean, I still, Iím sure, my opinion, contemporary astronomers really have not grasped the extent to which he is right.
Wright:What was the essence of this paper?
Arp:Well, he just looked at galaxies on the Palomar Sky Survey. He said, well, galaxies eject other galaxies, free galactic material and they form other galaxies. And you see that the implication of that was to rock the whole foundation of our ideas of where galaxies come from. The whole idea is just the Big Bang, diffuse medium, galaxies condensed, clouds form, thatís how galaxies are formed. Ambartsumian was saying something completely different. He was saying that the material comes from inside of galaxies, goes out and forms other galaxies. And if you carry forward the implications, if you believe that, then you begin asking yourself questions like, was the Big Bang really like this generally assumed or maybe started out with one body which had successive fragmentation, or maybe the universe is turning itself inside out from inside. You see this way raises really unsettling questions which contemporary astronomers are not prepared or willing to face at all, despite what I think is the beginning of an enormous amount of evidence piling up in this direction. Thatís where it is nowadays.
Wright:In your paper on a very small condensed galaxy, you concluded that other galaxies of this type could exist, that had not been photographed. Would you care to comment on the significance of this discovery to astronomy?
[laugh] The significance is practically nil because of the following situation. [laugh] Now Iím really going to let it all hang out. At that time quasars had just been discovered. They were radio sources that looked like stars but have very high red shifts. Now there were three of us working down at Palomar at that time who understood very well the implications of this, Zwicky, myself and Sandage. I mean we all realized that there were radio stars that look like this at high red shift, there was probably a good chance that there were stars that were non-radio objects, i.e. very condensed galaxies with high red shifts and this was a big discovery which we sensed was true and we were all going after it, observationally. We were trying to get some observational evidence to publish a paper on it. Well Zwicky was looking at compact galaxies with the Schmidt telescope and I discounted that effort as not being a very serious threat because I thought on a small scale the Schmidt is not going to be able to see that compact galaxy and if we take with a big reflector and then they would look very uncompact, un-quasar-like.
On the other hand, I was doing the Atlas of Peculiar Galaxies, I was getting a lot of 200 inch photographs. I was looking very closely at things that looked almost stellar, and I figured that if I found something that looked almost stellar on a good thing on a 200Ē plate and damn compact galaxy pretty close to a quasar. Sandage also had, I mean I presumed, had thoughts along this line. So Zwicky was publishing his papers on compact galaxies. I found these objects which I felt were very significant and sent in a note to the Astrophysical Journal Letters and a letter to the Astrophysical Journal. At the same time, Sandage was taking some spectra from compact radio quite objects that he found, and he wrote this big paper which he called ďa major new constituent in the universe,Ē in which he claimed these non radio galaxies new constituents of the universe. I sent my paper in on compact galaxies or whatever before him, he sent his after mine. Mine was sent to the Letters which should have appeared before the main paper. His was sent to the main journal which should have appeared after mine. But, in fact, the editor of the Astrophysical Journal, Chandrasekhar, who was a friend of Sandage at the time, decided that this, Sandageís paper, was so spectacular it should go into the main journal.
So actually, even though it was submitted after mine, it came out ahead of mine and the whole attention was concentrated on that paper and my paper was absolutely ignored. In subsequent years people have gone back and have said that mine was a very good paper and mentioned it, but essentially the whole focus of attention, publicity, was on Sandageís paper. But then, of course, the irony was that he had overestimated the number he got, so the paper was attacked viciously. Lynes and Kinman and some of the other people attacked it viciously and there was a great crisis where he, I forget, offered to resign or something, and it was just a great crisis over that of which I was sitting on the sidelines at that point. Now Zwicky comes into the picture. Because Zwicky was fuming mad because his work on the compacts was ignored at that same time and for the same reason, you see. So Zwicky wrote these hot notes to the Astrophysical Letters saying I published this before Sandage, he didnít reference this, and that the discovery was really mine. What was valuable in the discovery was really not Sandageís at all. Oh, there was a fearful mess. I mean, things are still tender on this point and if you read Zwickyís little red book which you should, you know this book on Compact Galaxies and Post Eruptive Galaxies.
Wright:No, I donít.
Arp:Read the introduction of that book. Itís really extraordinary. When that book came out, and came down into the Library, [laugh] it was recommended that it be excluded from the Library, and the librarian refused. [laugh]
Wright:While weíre on the subject of Zwicky, would you care to relate any insights into his character?
Arp:Yeah, Zwicky was a very, well in my opinion, a very bright and, I can hold forth on Zwicky for a long time. He was born and raised and educated with that great generation of European physicists, Sommerfeld was his teacher contemporary, Pauli was a contemporary, I guess. And he came over here as a crystallographer and then he switched over to astronomy and I think he felt he could just do all astronomy single-handedly and he appeared to have a tremendous ego, which grated everybody the wrong way. But he was very capable, I mean, he did a lot of excellent things. In fact, there was something in back of that ego. You know, I mean, he produced massively. But of course he ran into terrible opposition here with Baade and Hubble and all the people later down at Cal. Tech. and stuff like this. Constantly he was very loud, outspoken, bombastic. A kind of person who was constantly talking about himself and it was very hard to appreciate the finer side of Zwicky. [laugh] But there was a finer side and I liked him. He was a nice person to talk to. It was a shame he had the kind of personality that was difficult to understand.
Arp:Yes, it was counterproductive.
Wright:In your important paper on that peculiar galaxies and radio sources in 1967, you concluded most of these quasar red shift and a component of the radio galaxy red shifts are due to a cause other than velocity transformation of the galaxy. Now was this the genesis of your ideas on discrepant red shifts of quasars?
Yes, that was the key. When I saw what I finally concluded to be an association between these high red shift quasars in the local nearby galaxies, that was the key that locked everything in. There was a funny thing how that came about too, as a matter of fact. Because you know, when the quasars were discovered and the radio positions came out, those radio positions were very secret and only certain optical astronomers got to make these startling discoveries and it was easy for an optical astronomer to go to a telescope and put them in a position and take the spectrum. And theyíd write a sensational paper. I wasnít one of those astronomers who got those secret positions, [laugh] so I was sort of elbowed out of the quasar field.
So I felt like everybody else did, that there were objects out on the edge of the universe and they were going to solve all these cosmological problems, radius of the curvature of the universe and so forth. But since obviously I was excluded from that research, I figured well, Iíd do the next best thing, which was to find out how galaxies formed and then I set about just doing that with peculiar galaxies and I felt that I was completely out of the quasar program. I was just doing cosmogony of galaxy formation. Then one of the great twists of irony was that when I got through with the Atlas of Peculiar Galaxies, I went back to look to see which of these galaxies were radio sources and I found that surprisingly not many of them were radio sources because a lot of them were torn up and there were ruptures and everything and I expected them to be radio sources. As a matter of fact, I found out that many of them were and I was very surprised at this, and a friend of mine in Argentina had just at that moment sent me a picture of a peculiar galaxy rupture, a ruptured galaxy and so forth, with some radio sources quite nearby.
I had some cloudy weather down in Palomar, it was raining so I figured well, Iíll go look around my peculiar galaxies to see whether perhaps there were radio sources in the general vicinity and all of a sudden I saw these radio sources tend to pair, be associated with the galaxies. All of a sudden I realized, concluded that what was happening with these galaxies were rupturing and sending these radio sources out and then when I saw that some of these radio sources turned out to be quasars I realized that the red shift had to be intrinsic and it couldnít be velocity red shifts and that was just the genesis of the whole thing. But the irony was that when I was right back into the quasar business which I thought I was completely out of. [laugh] And I think if I had access to the positions like everybody else, that I probably would have gone along with the conventional theory of cosmological distance and so forth and not be forced to take this other look.