Oral History Transcript — Dr. Jesse Greenstein
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Jesse Greenstein; July 26, 1977
ABSTRACT: Childhood in New York City; studying astronomy and literature at Harvard (1925-1929, M.A. 1930); work during the Depression in real estate and at Columbia; graduate-education in the new astrophysics at Harvard (1934-1937), contacts with H. Shapley, C. Payne, H.N. Russell; work at Yerkes from 1937: nebula spectroscopy, stellar composition, stellar atmospheres; contacts with 0. Struve, S. Chandrasekhar, B. Stromgren; optical design work during World War II. Move to Cal Tech, 1947, contacts with W. Baade, I. Bowen, F. Zwicky, N. Schmidt, L. Dubridge, etc.; organization, administration, research conditions, and allocation of observing time at Mt. Wilson and Palomar Observatories; work in building up astronomy department at Cal Tech, character of staff relations, and fund-raising. Postwar work oil, abundances of elements, white dwarf stars, high-dispersion spectroscopy, radio astronomy, and quasars; ideas about cosmology and other topics. Involvement with military advising at Cal Tech from 1950, satellite reconnaissance, and industrial advising; early work on rocket astronomy and as senior adviser to NASA (ca. 1957-1977). Editor of ďStellar AtmospheresĒ series; work with National Academy of Sciences and author of its 1972 astronomy survey; efforts to popularize astronomy. Ideas about large space -- and ground-based telescopes. Particular attention is given to the organizational strengths and weaknesses of important astronomy organizations.
Weart:I had a couple of general questions that occurred to me. One was, have you ever had any interest in science fiction?
Greenstein:I have a strong antagonism to it. I find it boring-especially the more fantasy. It irritates me as very bad sentimental literature. I canít stand Ray Bradbury. He makes me ill, physically, to listen to. I think the universe is too beautiful to be trusted to third-rate writers. Sorry.
Weart:Thatís fine. I suspected it the other day when you said you liked bug-eyed stars but not bug-eyed monsters. Another question, going back over your whole career-has your professional life ever been affected by anti-Semitism?
Greenstein:Thatís a reasonably good question. I donít think so. Itís impossible, of course, to say; when youíre successful, you get adopted anywhere. I think itís rather remarkable how little the effect was. Iíve been conscious of the existence of anti-Semitism. I find it in some of the wealthy people with whom I deal, as an unconscious thing which they are anxious to kill off in themselves. I really admired some of the ways people who, by social background and position are likely to have been anti-Semitic, do their best not to be. I would guess that in the early days at Chicago, there was more trouble from the older university members than one would expect for the enterprise of bringing theoretical astrophysics from all over the world, and probably some anti-Semitism, among people who died off in the forties. But thatís been my only knowledge of it.
Weart:At Harvard you werenít particularly aware, even though they were doing the same thing?
Greenstein:—undoubtedly, but on the other hand, I never felt it, or at least I resolutely hid any acknowledgement that I noticed it. It takes an effort of will to be insensitive. On the other hand, itís such an easy thing to be oversensitive. I donít think itís an operative problem, now, in science. At one time I made a mental count of Cal division heads, and there were only two non-Jews as division heads.
Weart:Maybe in an earlier epoch you wouldnít have found any Jews.
Greenstein:Thatís possible. Well, I donít know, Millikan, for example, was I think a genuinely religious man, and whether he had any prejudice is hard to say because he was so positive of the virtues of high-flung Protestantism. But the people he brought in, that is by the time I reached here the people who were already here, showed that this hadnít really worked. One of the most distinguished (Jewish) physicists, Paul Epstein, had been here since he was a very young man. Iím trying to remember — there were a few more.
Weart:It really was a question I should have asked you when we were covering the early part of your career.
Greenstein:Iíve never felt it, I know it exists.
Weart:It was more a pre-war phenomenon, I think. Well, to get back nearer to the present, I wanted to start off by asking about some of the classified work. Not, of course, to discuss classified subjects, but Iím very interested in the sociological side of it. I suppose it would have started during the big Korean War scare, the Defense Department got into a lot of things. Thereís two aspects one is Samos, Pied Piper, ďBig BrotherĒ or whatever youíd call it the other is the project here at Cal Tech. Which one did you have contact with first, the project?
Greenstein:The first. That graduated me to the other.
Weart:Why donít we talk about Vista a little bit. How did you get introduced to it? You hadnít been doing military work for about five years or something, I suppose?
Greenstein:Well, it was a very high level request, to Cal Tech and Dubridge, and he put the resources of Cal Tech whole-heartedly into it. Fowler was operating head. Dubridge was head. Lauritsen was very active. It brought in many people from outside, from all over the country. Specifically it also brought in J. Robert Oppenheimer and Edward Teller, and sowed some seeds for Tellerís later attacks on Oppenheimer. However, the general pattern was that people gave up their scientific work. Many of them gave up their teaching; not all, It was a cross-disciplinary effort. It moved away from Cal Tech into an Army-owned enclave in Pasadena called the Vista del Arroyo Hotel, which I think was an abandoned government-owned base. But it did entail hard work, and an awful lot of traveling. And enormous broadening of horizons, in a certain sense, of interests beyond technical questions — questions of the interplay of technology and military operations were very central. So it was an education, and I met some interesting people in the process. I think itís not classified to say that it was a study of the use of tactical nuclear weapons. This was not exactly a popular idea with the Strategic Air Command, and wasnít dreadfully popular with the military at first. Yet itís something thatís gradually been adopted for the defense of Europe, for example. I was head of a group which specialized in information-gathering technology, insofar as it affected military operations, air, sea and land. And out of it came various sub-projects which continued. I donít think we were all that original in many of these areas. But it was a high enough level of operation that the military did in fact listen. They had to listen, and they did listen.
Weart:Was it primarily physicists, physicists and astronomers, physicists, astronomers and chemists?
Greenstein:Oh no, there was everything — sociologists, biologists, historians. For example, Korea taught us a great deal (which we have unfortunately not used) about small-unit warfare. What happens to a dozen young American boys from New York City when theyíre left in a jungle with people whom they donít quite view as human, and who have no technology, but who fight. Itís a very distressing area.
Weart:I remember reading some of S.L.A. Marshallís things on that.
Greenstein:Yes. He was in Vista, actually, as a consultant. We had, in fact, quite a few Operations Research Teams that went out to Korea. Senior members of the group went to Korea to see things in operation.
Weart:Did astronomers have different roles from physicists?
Greenstein:There werenít all that many astronomers involved, actually. It was mostly physicists, Iíd say. Chemists were heavily in it, I would think the astronomy group really was rather small, Iím trying to remember. I know at least one who worked directly with me, that I stole from Carnegie. But it was a physicistsí project with a secondary emphasis on the social sciences. But since war is also chemical, with normal explosives, and other kinds of warfare involve chemistry and biology, they were there too. I think itís the broadest thing Iíve ever been exposed to, in its interests.
Weart:It wasnít compartmentalized, then? You were aware of everything that was going on?
Greenstein:No. There were certain areas so highly classified that ďtop secretĒ wouldnít get you near the building. So I was not aware of most of what proved to be, in later history, the drastic effects of the struggle between the tactical weapon and the very large strategic weapon, which surfaced soon after. That was being fought out among some of the big shots in the group and their outside advisors.
Weart:Were you mainly concerned with the Army or the Air Force?
Greenstein:The whole — this was a three-service thing (perhaps least with the Marines, now that I think of it). A lot with the Air Force, a lot with the Navy, for my own work, and the product, that is information gathering, was also for the Army, I went to maneuvers, saw parachute jumpers, visited field headquarters in these mock wars, where you could see intelligence being received and not being used. In fact, I donít know if you know the Navy word, Combat Information Center, CIC the usual transliteration is ďChrist, Iím ConfusedĒ. Too much information, before the big computers, was just not usable in the field. I was interested in reconnaissance. It was in fact true that so much information arrived that was digested long afterwards, when it was no longer valid information, that one of our big pushes was to make information use faster, It was interesting very much, Iíd guess, like a large corporate business. How do you know where you are, what yore doing, how much money youíve lost?
Weart:An accounting problem there.
Greenstein:Yes. And thereís no time to wait. You have to act.
Weart:None of this used your specific astronomical knowledge.
Greenstein:Well, the part I did which was connected with reconnaissance, though it was a more general thing than photographic reconnaissance was somewhat related. And there were various attempts, exactly in that area, to see how to use established astronomical discovery techniques, for example to see how things changed.
Weart:I see, you do have a similar problem with digesting a tremendous mass of data.
Greenstein:Well, you donít now, with the computer anything that moves on Mars would have been noticed. It probably would have rung an alarm bell in the Viking headquarters, I think, we know now, where information is enormous and the usefulness of it immediate, you have to mechanize it. I learned about the importance of high technology, and this 25 years before it hit astronomy. It really worked the other way. Out of the interest in seeing at night, for example, came the image-intensifier project — not here, at Chicago I think, and thatís had an enormous effect on astronomy. It went the other way. Weíre borrowers. We donít create an awful lot of technological information in some of these fields.
Weart:Yes, I know in areas like infrared the military applications have certainly come first.
Weart:Again, the sociology of it Iím curious, because it certainly is quite unprecedented, itís surely one of the first big interactions between the military and a university in peacetime, and all the more complicated because all three branches were involved, should think it would just be a sort of a confused mess, a lot of frictions — difficulties between the civilians and the military people —
Greenstein:Sure. Sure, but again, it wasnít quite peacetime. The cold war was pretty hot. I think most people were acting as if it was a war, or as if there was an enormous war just a few years away. The miracle of our time may be in that area that we survived, through this quasi-peace. I think the pressures on people were like those of a war. Nobody was bombing Pasadena. On the other hand, the existence of nuclear weapons made everybody pretty sure that Armageddon was just around the corner. I think thatís the mood which made cooperation possible. There certainly were differences of opinion. We were at cross-purposes with a major United States strategy. We were asked to discuss, and did discuss, tactical warfare; and most of our dollars had gone into the big bomber and the nuclear weapons for strategic warfare. So naturally we got into a terrible conflict, which has never been resolved. Thereís just a balance, peaceful balance of a kind, between different ambitions among the military planners.
Weart:Well, is there anything else we should say about that before we go on to Samos?
Greenstein:No, I would rather not go into details of which of these things I continued afterwards. Probably some of them are sensitive still.
Greenstein:I got into the general area of being an advisor, in a wide variety of technology-related reconnaissance, information gathering techniques, I found it interesting. And Iíve been convinced really, by what little I found out about real war, from — I was interested in the fact that one shoots an enormous amount of steel into the landscape without knowing where any target is. The Vietnam experience showed that modern technology at first did very little good. To quote a very witty friend of mine who came back from Vietnam when we were just barely engaged in it, ďWell, you know, Jesse those sonsóofóbitches donít stand around waiting to have their picture takenĒ. And this is unfortunately a very true observation. Thereís no real technology valid in a swamp, unless you blow up the whole swamp and everything around it. So this did and still does present a challenge. It did involve ultimately enormous expansions. I was in all of the technological sides, optical, infraóred, radar, electronics, etc. Information-gathering and ó using techniques. It was the early day of the general use of the computer.
Weart:How much of this has been translated over into your astronomical work?
Greenstein:I just learned an enormous amount about how engineers and large corporations with research labs are good in building a gadget to do anything, The main problem was to find how to fit the gadget into an enormous working system. Maybe thatís like astronomy. I think what I learned is a general philosophy of respect for technology, and a worry about how technology can be made usable by any idiot astronomer, maybe I realized what a system is. Because, when it comes to the big computers at the telescope, or the big programs operating on telescopic data in real time, itís a systems problem. And that isnít all that different from the military operations I learned about. They were way ahead of the applications in peaceful scientific technology.
Weart:You feel pretty free now about using a computer?
Greenstein:I do, until it stops. Iím not one of these people who can sit down and type out various things and get it started, and reload it. I can push a button to re-start it, but not if I have to find out whatís sick. But most of the younger scientists either have built these things, or designed their own programs, or have worked enough with them so that they can do night-time trouble-shooting.
Weart:Do you do some programming and so forth?
Greenstein:No, Iíve never programmed. But I can use anybodyís program, sort of, until it gets too complicated and itís late at night.
Weart:So youíll do the control cards or whatever and make a run, I see.
Greenstein:Funny, most of it now is conversation with the computer.
Greenstein:And itís this interactive business, which is useful, I guess you could say the systems approach has gotten into science. The interactive picture processing (I think they call it) at Kitt Peak specifically, but less fancy, the image restoration lab at Jet Propulsion Lab, working on originally very poor pictures, would be examples of interacting with masses of data.
Weart:Do you feel that, aside from yourself, many astronomers have taken over some of these things that perhaps they first learned in military studies — taken over attitudes or knowledge to astronomy?
Greenstein:I think maybe not so many astronomers. Certainly some. But much more, the people who work for us. People who started, letís say, in infra-red heat-seeking missile techniques, or even in television, night vision devices, and gradually dropped out of the aerospace industry and found a niche in the academic world. We owe them an enormous amount. The development of the most commonly used area detector, the silicon intensifier vidicon, goes back to Jim Westphal, who learned his electronics in the oil exploration business where again, itís a matter of money, to do the thing right and do it reliably under field conditions. I think you canít exaggerate the importance of this interaction of the most advanced technology with astronomy. And our pressure on advanced technology to build something a little bit better and a little more reliable. I think this has been a real boon. Itís brought astronomy into the middle of the 20th century. When I first came, the most we had was a photoelectric cell and galvanometer, not too many amplifiers. Then amplifiers, then pulse-counting amplifiers, then recording on tape, punched cards — we were very slow. And when I say we, I mean the whole community of astronomers was terribly slow.
Weart:I have a feeling, Iíd like to ask you whether you think itís correct, that of all these military things, it was the reconnaissance satellites that were probably the most important for astronomy. If we view astronomy in the larger sense as including the planetary shots and the space telescope to come and so forth. Would that be a fair statement, that reconnaissance satellites were particularly important?
Greenstein:I think yes. A lot of the technology for reconnaissance is just going over into the space telescope, and the space telescope really asks more. In fact, in the very early days, people would say, ďWell, Jesse, donít you think it would be nice if we turned one of these things upside down and got you a picture of ďThe skyĒ? Iíd say, ďWell, why donít youĒ? But I never got one. At least, they never gave me one. But it was interesting. You see, Iím certainly in no way a leader in this; Jim Baker designed a camera about which, (I guess) Khrushchev said, ďThis is a very good camera.Ē When it was downed with the Uó2. No, a lot of people had contact with technology, and some went fullótime into it, I certainly didnít.
Weart:I am curious to get a few things about your involvement. There were various things that got started — the Air Force Development Planning Board, the Beacon Hill Study — were you on the Air Force Scientific Advisory Board?
Weart:Were you on the panel for physical sciences or the intelligence reconnaissance panel or whatever it was called?
Greenstein:I donít remember. If thatís what it says — I donít remember, no, I was on that for some years.
Weart:The subpanel, the first chairman was Kistiakowsky, and then it was Baker, and then Carl Overhage.
Greenstein:Oh, youíre quite right. I worked with him for years. Quite.
Weart:OK. I guess the question I have here, again, a sociological question; did any differences of view develop particularly between people who came from industry and people who came from the academic world and people who came from the military? Were there differences of viewpoints?
Sure. Why not? Thatís what life is. One, everybody wanted fundamental new ideas. And if new ideas had to be generated, I would guess they would come either from basic research scientists who do brainstorming about some difficult problem, or theyíll come from people in the military or industry who are working on specialties and define something which they may not necessarily know how to build, but which they see the need of; theyíre close enough to operations to see that if it existed, it might get used. The real differences, I think, were in the process of suggestion and frustration, usually — you know, nine out of ten very good suggestions, you donít get listened to, and the one that gets listened to may get built and may not ever get used. So the actual amount of damage or good anybodyís idea ever does is small. What you have to get used to and I guess thatís really a sociological thing is that a scientist, when he has a problem, is used to carrying it through all himself, or with a team which heís supervising or cooperating with. And in all the interactions with industry and the military, you are perhaps an idea person; you work out a difficult problem and get a scientific answer, which they need, and then you lose contact with implementation. Yet if in the real working research and development game, as in an industrial research lab, you go the other way. You have a solution, but it may not be the one for the right problem.
Or itís an expensive way of supporting second-rate engineers. Yet there, in industry, theyíre much more likely to get things used. One, theyíre more practical, so when the thing comes out as a breadboard, research-type thing, it can immediately be understood and evaluated by potential users. But the astronomer comes up with a set of equations. A lot of the work, in which I was particularly involved for a short time, involved questions, say, of the earthís ionosphere and effects of various things on the ionosphere. A lot involves communication via the ionosphere or beyond. In these things a scientist could say, ďOh well, you can work at such and such frequencies, or you can develop very high altitude scatter from meteor trails — itís a sporadic but almost omnipresent scatterer —ď But then whoís going to carry that thing into a communications system? Itís certainly not the scientist. So thereís a real permanent builtóin frustration quotient in it — Most scientific advisors, I think, lived in a state of ulcerative rage and frustration. Yet they knew there was no way to change it, because they couldnít go into the arena and spend full time. Itís foolish for an advisory committee to spend two days a month on a very important project and think that anybody will listen to them, because the other 20-odd days the responsible people are working, and theyíll go off on their own direction. I donít think thereís a cure. Itís the difference between idealism and realism, between philosophers and kings.
Weart:So the role was more to provide new ideas, perhaps, or to shoot down some bad ideas, that kind of thing?
Greenstein:Yes. Shooting down bad ideas is certainly the most constructive. It saves money. Everybody can do a back-of-the-envelope calculation to prove that something might work, or that something else just canít work. Thatís a very important role for the scientist. On the other hand, most scientists are pretty ambitious and pretty protective of their own ideas, and want their ideas to be used.
Weart:Could you identify any of the decisions that you took, or that one of these reconnaissance panels took, as being a decision that eventually got implemented, as being sort of your decision, or was it too complex?
Greenstein:Well, things I worked with others on certainly did get implemented, yes. But wouldnít claim anything for myself, as an individual. That would be Ė
Weart:— no, but that the panel that you were on was the panel that was responsible for deciding between particular systems, for example?
Greenstein:Yes. I even know a nice example, which is in fact the U-2. Much has been written about that. The planning and recommendations for the reconnaissance satellite were shot down regularly (at a higher level) then any of our advisory panel on reconnaissance satellites had access to. It was shot down because some people — and I know in fact who were involved — knew about the U-2. But many of the military officers whom we were working with, didnít know about the U-2.
Greenstein:So they were enthusiasts, and we would make a recommendation and say, ďThe time is drawing near, get on with it, boys.Ē Then suddenly, they got on with it; there were no more U-2 flights. It was not quite that simple, but it was held back by a couple of very distinguished scientists whom I liked and respected, who knew what was going on.
Weart:But they didnít tell you why it was being held back?
Weart:I see what you mean about the frustrations.
Greenstein:By the way, weíre not talking about me or crazy guys, weíre talking about a group, half of whom were really right in this business. Building cameras, building side-looking radar. Two companies I know of were started, big ones, as a result of this study groupís activities. And carried on the job very well.
Weart:One of the questions I wanted to ask was, I noticed that you were on the scientific advisory boards of Hycon and Itek. Did Itek come from Richard Leghorn?
Greenstein:He was one of the founders. Itek was one of the companies I mentioned that was started. In fact, when they invited me Iíd almost forgotten all this background. I was not involved with their classified work, when on that Board.
Weart:What did you do as scientific advisor?
Greenstein:Help them lose money. Thatís not trivial. They had a section involved in highly classified work, where I never even walked. But their technology was related to space probes, cameras that orbited the moon, cameras that orbited Mars. I think they built the Mars landing camera, in fact. Perkin-Elmer was another company, with which I was never directly connected, in the same business. They were interested in the space telescope. Later I found that people at Perkin-Elmer were old friends from the past.
Weart:I see. But these original connections didnít have to do with your getting involved with either Itek or Perkin-Elmer?
Greenstein:No. They did get me involved with Hycon, which built tactical operations cameras. And thatís a local company which was bought by McDonnellóDouglas. By the way, most of these companies were looking also for things outside military business to do. Because having the military as the only source of business is very bad as far as making money, growing, or being stable to survive peace. About Hycon, friends on the Scientific Advisory Board got me involved with them, I happened to be, for many years a personal friend of two of their successive presidents. All these companies, however, lost money because of my advice. Because as you know, most aerospace companies donít make very much out of these high-technology, one-of-a-kind or few-of-a-kind devices. Research in the better aerospace companies is like an overhead charged against their profit-making activities. Only in very big companies is there enough research to do anything really productive of, say, civilian business. Both of those companies, by the way, were later involved with energy research early — solar energy, specifically.
Weart:What, did they see the handwriting on the wall?
Greenstein:Oh yes, they sure did. Iíve seen the handwriting on the wall, on energy — I think itís 16 years ago, I wrote a fairly good bit (I thought) on solar energy. Especially on the idea of regional development, since I lived in the Southwest, where solar energy is obviously something you can have.
Weart:What other contacts have you had with industry?
Greenstein:Very few. Iíve not ever been a consultant. I donít like to work for pay for people, except in this advisory capacity. Iíve never done weekly consulting. I worked with RAND, which is not really industry, on a more permanent basis.
Weart:Thatís part of the military business.
Greenstein:Some of it was. Oddly enough, at that time whatís his name, Kellogg wrote the first good report on the science of satellites, using established modest-sized available missiles to launch things. That was way pre-Sputnik. And RAND also was interested.
Weart:He talked about that with you?
Greenstein:Yes, he was a real pioneer in this. Iím trying to remember the other. You asked about the sociology of scientific projects — one of the interesting things, to me, was the importance of history and social science, to give a decent perspective on technology applied to anything. A place like RAND was full of historians. They were trying maybe to predict future wars from past, but they were also interesting about the past. I think the broadening base is the social implication of technology (letís put it that way, without being Marxist and saying ďscience and societyĒ) — Itís true that 15 to 20 years ago people were already worrying about whether the American people would accept nuclear power, because of its scary nature.
Weart:Theyíre still worrying about it.
Greenstein:Yes, thatís our trouble. I wasnít involved, but the first major National Academy of Science discussion of this pointed out the very probable resistance of the people to sitting power plants near them. Just as long as itís somewhere else, itís OK. They recommended that the AEC spend ten times as much as it was then doing, I think, on study of things like nuclear waste disposal — another current issue. And nobody listened, and the AEC vanished into ERDA and still they were way behind on a goal that was studied 10 or 15 years earlier. They were warned about careful planning of nuclear waste disposal. So I must say that if any important issue on science and technology comes up now, I worry first about, how will the ordinary person accept the new technology? Rather than, is the new technology possible? I donít know what the environmentalists would say if we would manage to be able to build an enormous energy solar power farm out in the Mojave Desert which has a population of a few people per square mile; thereís no better place in the world for it except for the lack of water — Iíll bet you there would be a terrific environmental fuss. And you have to be able to predict these things before you commit yourself to even make the studies and learn how to build the gadgets.
Weart:OK, I had some more questions about your scientific work, but first, anything else about the ďmilitary-industrial-academic complexĒ?
Greenstein:I think in brief resume, I would defend its operation against the criticism from the Left that scientists should not be involved without having control. I would say that, although it was largely frustration, it had to be done and it has now to be done. I think the type of interaction that existed, where basic research scientists had to cope with real problems, is good for both sides. Itís educational. Itís democratizing. And I would recommend it for young people. But on the other hand, during the period of Left academic leanings, it was certainly unpopular. Itís getting a little bit more accepted again now. I would think that itís a dangerous thing, you see, to leave the military and the industrialists all together by themselves. Itís much better to have this outside, broad base of scientific involvement.
Weart:Did you feel at the time when you were involved in these things that this was one of the points of your being in that? Or were you more concerned simply with getting a job done? And did you have discussions about these things at the time?
Greenstein:Yes. We thought about it. I think that the civilian control of the military does involve the responsibility on the part of the educated civilian in this case, the scientist and engineer, the academic world — to deal with the military. If you donít youíre going to lose control. I think a lot of people did it also for a general philosophical, patriotic type reasons.
Weart:Did you ever exchange any words at all with any of the Russian astronomers who were doing the same things over there? Did you ever get any feeling from them, as to their feelings about all this?
Greenstein:I would rather not discuss my opinions of the Russian scientists. No, theyíve all been terribly hypocritical: they claim that none of them were involved in any military project. Oh, maybe you know this story — when Severny had a 100-inch telescope built on the Crimean Observatory grounds, he visited us several times. He said he didnít know how good the telescope was, he hadnít seen any pictures with it, he doesnít know what theyíre doing; it was after all mostly connected with satellites and space work. He wasnít interested. Now, that was clearly untrue, because he was a good loyal party member and director of a big observatory. He knew. I donít really feel I have gained anything by personal exchange with Russian scientists.
Weart:OK, now to get back to this abundance study that you began, or really got geared up to, in 1956. You indicated the other day that this was sort of designed to make use of spectra that you had already accumulated, is that right?
Greenstein:Well, both to use what I had, and to use what I could get. Or was getting. Since even in those days (itís worse now) there were too few users of the bright-of-the-moon time, it was a subject where post-doctoral fellows and older visiting research associates and senior scientists could get access directly to telescopes as well as to my plates. I think it worked out pretty well. The graduates of the project are still doing spectroscopy, in Japan, in Europe, for example. Spectroscopy sort of died in the United States, or nearly died, in the sense of highóresolution stellar spectroscopy. But Europe is doing it, and doing it pretty much along the old conventional lines. The theoretical emphasis, which was largely European, led to a whole new independent development of model atmosphere programs (in Germany, specifically) which has been extremely good, and the astronomers are quite interested still in atomic and quantum physics. I must say that Europe and Japan are doing more spectroscopy than the United States.
Weart:Would you say that the Hale Observatories, and other observatories in the United States, when they have a choice between different instruments, will pick one that is more useful for extragalactic work?
Greenstein:Yes. Itís almost a feeling of persecution on my part. Weíre trying to up-date, and have in fact updated the big Coude spectrographs, leaving us only 10 to 20 years behind times. In the field of faint object spectroscopy weíre at the ďstate-of-the-art.Ē Weíre unhappy about the performance of the 200-inch Coude and are trying to rectify that. But right now, we have image tubes at every focus, near infra-red image tubes at two foci, red to blue image tubes at four foci in the spectrograph. And then the linear diode arrays are now in, and weíre frequently using the image photon-counting system of Boksenberg, from University College London, who comes here with it. I think heís done seven round trips with it. The AngloóAustralian telescope now has a permanent system like that, and he may leave his prototype, which is what weíve been using, with us in the future.
Weart:When you say youíre 10 or 20 years behind the times, you mean, not only behind the state-of-the-art but behind what people may be doing in Europe?
Greenstein:Right, or especially at Kitt Peak and McDonald. Except for the new linear diode array, which will be supplemented with whatís called a CCD (charge-coupled diode) array fairly soon, weíve been using image tubes or photography. Or interferometry, which is modern, if you wish. We have Pierre original interferometer permanently at Palomar. On the 100-inch, theyíve built high-resolution scanners to look at the chromospheres of stars, and that is perhaps the only really modern gadget there. Every now and then one of the SIT (silicon intensified) vidicons is put in, but itís a makeshift device. Now, I think for a very modest sum we could upgrade the Palomar device with these area detectors, like Boksenbergís which is a television device, or the SIT, and have a near state-of-the-art. But weíre still using some things which have been in use on faint objects for eight years.
Weart:At what point would you say — I know that when you came here in the 1940ís, I wouldnít say there was any imbalance. At what point did the nebular stuff begin to run ahead?
Greenstein:Well, I think perhaps eight years ago, that would be a fair statement. Thatís about right. Optically, with photographic plates, the was as modern as the nebular spectrograph. It was the change to image tubes. This was done in the Cassegrain focus at the 200-inch, went through several generations of image tubes; I put an image tube in — from this Air Force contract so thatís 1970. Thatís when we got the first image tube into the Coude. Then later, Hal Zirin put in this near infra-red S-1 and studied stars for the 10830 helium line. But thatís about all, till just the last year or so, when at least our own gadgets, used in the Cassegrain spectrograph, can now be used in the Coude. And look at our reliance on the Boksenberg device, half a dozen years old, with a much better one built for the Anglo-Australian telescope — when I say state-of-the-art, I think in the faint object spectrograph weíre better than anybody else; in the weíre coasting behind on othersí shirt tails.
Weart:Now, is this because there just arenít as many people around that are interested in high-resolution spectrography? Or is it because of policy decisions that are being made?
Greenstein:Itís both. For example, my own lack of interest in highóresolution spectrography came because it was so easy to make fascinating new discoveries of an almost descriptive kind on faint objects. Even photographically. I just felt I was able to do these new things, and apply what I knew, but in an almost trivially simple way. It was much easier on faint objects because — I guess itís a general statement that if anything is interesting, itís a faint object. Itís not just perverse. Itís just that a faint object is often far away, and if you look to larger distances have a number of ordinary objects, but eventually the first peculiar rare object will be found, Studying around the edges of the HertzsprungóRussell diagram has been my hobby for the last 15 years almost.
Weart:Thatís one of the things I wanted to ask. It would be quite impossible for me to discuss all the different things youíve worked on, because youíve written many papers on a lot of subjects — peculiar stars, as you say, going around the Hertzsprung-Russell Diagram, comments on various kinds of nebulae — I wonder if thereís any sort of general working pattern here? How do you choose a particular problem? Some are not in your main lines of work.
Greenstein:Iíve always felt that I donít have the staying power to stay with a field a long time. I get bored. And next, I am willing to learn enough about a new topic, quickly, and I like to. The abundance project came out of interest in nuclear energy generation, and the resulting changes of composition — that is, it had a direct physical base. These other things have a base in the fact that there are unexpected physical phenomena, quite coarse and obvious ones when you look at them, which can be studied, where a new first step can be made. I did in fact take the first high-resolution spectra of comets. It came out of the fact that when (I was) at Yerkes, people were working on comets and Swings had developed the theory of the excitation of molecular emission bands by resonance fluorescence, that was understood. But when a bright comet came along, here I was with what was then the best spectrograph in the world. Thereís no reason not to see what the comet spectrum is like on a much bigger scale, just to satisfy curiosity.
Weart:You had a night, so you turned it on.
Greenstein:Well, actually it was a little more than that. When a bright comet came, I would beg and borrow pieces of nights. Comets are usually observed at sunset or before dawn, and so I did a lot of observing. I could never myself have analyzed those spectra, because any one is half a yearís work — there are literally a thousand lines, at the resolution we can get, in a good cometary spectrum. The new physical phenomena that came out were explored mainly by people from the abundance project. In, fact my plates, some of them, have even been to Poland (where one or two of them got broken, but they came back in pieces and have been used again) and in Belgium — which is a nice bit of international relations. I have, in other words, old associates. I think I wanted to see what we could do that was different; whether anything new could come up. And new things did come up. I found first, with the low resolution nebular spectrograph, the forbidden oxygen (live) in comets, and Swings and I wrote a paper on that. Itís important for the theory of charge transfer from the solar wind to the molecular gases in comets.
Weart:I have to flip this now. The impression I get, in a way, is that one reason youíve studied so many different things is that you had a very good instrument at hand.
Greenstein:Sure. The other is my own personal preference, I am in no way an important scientist. In no one area — except white dwarfs possibly — am I a leader. And it comes because I really get bored, I could have stayed with any one of these topics and made a respectable contribution, but Iíve tended to change subjects. I like change for itself, and I certainly like, most of all, to study a new area, to see it first and where I get the pioneering ideas. And then I leave the subject. Letís stay with comets for a minute, because itís a beautiful example. We had a better instrument than anybody else. I knew a little bit about the subject. I donít like molecules — I donít mind diatomic but I hate complicated molecules. Theyíre hard to understand, and you really have to devote a lifetime to get an intuitive feeling about the spectra and structure of complex molecules. There are several things that happened. With the higher resolution, I found that the resonance fluorescence explanation of Swings had a second-order effect, which people kindly named after me. If you look at the coma, say, a few ten thousand kilometers of the central part of the comet, certain lines within a molecular band are stronger on one side of the comet than (they are) on the other, and that seems implausible. I invented the idea that the comet had internal motions or rotation, and so the doppler shift permitted certain lines to be excited, by coming out of synchronism, sort of, with the solar spectrum, which had the same lines. To have a Greenstein effect, which is the second-order Swings effect, is not dreadfully exciting, but it was still the kind of discovery I like to make.
Greenstein:It was fun, and Iíd always treated the first discovery in any area as fun. It takes a little working out, and then I tended to drop it. But I want to be a pioneer in almost anything. Of course, there are more serious aspects to what you can do if you have the best equipment, and that is, you can do what no one else can do, and what it is therefore your duty to do. Itís your duty to work on the faintest possible objects.
Weart:Because of your being here?
Greenstein:Yes. Nobody else could do it. I think I take that part of the use of a large instrument seriously.
Weart:And by faintest possible object, youíre including nearby stars, very faint dwarfs, that kind of thing?
Greenstein:Yes. I worked on the red giants in globular clusters, and Iím sure Iím the first there. I got the best spectra at high resolution, and been analyzed three or four times by myself and colleagues, and then by former colleagues. There are a few stars near us in our galaxy which are like the stars in globular clusters, really only few. One of these has been done by maybe ten other people — one of these field stars, which is like a globular cluster giant. In moderately good conditions, getting the spectrum of one of these photographically is a whole night with the 200-inch. In poor conditions, Iíd have one spectrum that was taken over parts of three nights and only moderately well exposed. Well, thatís hard work. And you either feel that you canít do it if you have small equipment, you canít — or that itís very hard and you should do it. But then, is it my duty to stay with it? I guess my psychology is such that, having done it and provided the first look, and having worked on a few of the papers, Iím finished. We found the forbidden oxygen line in absorption in some red giants. Thatís rather interesting. A very high dispersion problem.
Weart:Is this connected with the fact youíve done quite a lot of papers in collaboration?
Greenstein:Yes. In this area, high-dispersion spectroscopy, quite seriously, one star is roughly two or three months of analysis — it goes back to my Yerkes days. If you have a model atmosphere program you can do the theoretical predictions rather quickly. But even then, identifying the right lines, unblended lines, and finding their atomic properties is a very time-consuming thing, and only a scientist can do it. Thatís why itís been neglected till recently. There havenít been enough good scientists who look for the new problems. Weíre also, by the way, limited in wavelength coverage, so that you couldnít just ask a question like, ďWhat is the carbon-to-nitrogen-to-oxygen ratio in oldest possible stars?Ē The straight forward attack just doesnít work, in the blue and visual region of the spectrum. It works, it happens, in the infra-red. The big programs to do the high-excitation lines of those elements in neutral atoms —
Weart:Is there any typical way that you would work with a collaborator? Would you typically do the observing and measuring, and someone else do the interpreting, or something like that?
Greenstein:Not really. In the cases where I had material, where I had done the observing, I would do more as the research developed. Otherwise, collaborators who were here would work with our telescopes. The 100-inch was used enormously by this abundance group. I often could work out the first, rough answers. I tend to write the papers also for groups, because I like to synthesize. I would guess I left measurement and computer analysis, if that was needed, or model atmospheres, to others, and then would be involved in the final interpretation a great deal. It isnít that I donít like to think. Itís just that I donít like to stay with a subject forever, I like to get and expose, try out, new ideas, new leads.
Weart:I understand. After a certain point, it gets kind of dull.
Greenstein:Yes. I tend to have a boredom factor in my scientific work.
Weart:Thatís probably one reason why you have studied so many interesting things.
Greenstein:Thatís true, and thatís why Iím not a great expert. For example, interstellar polarization on which I —
Weart:— you did quite a lot, yes —
Greenstein:— a lot — I never did any observations, and I havenít even stayed current with the current theory.
Weart:You went in, and interpreted it, and got out.
Greenstein:Yes. And that may be a good thing. Maybe not. Itís the way Iíve done it. And I think itís also the way that a very big telescope demands that you live.
Weart:Iíve heard other people say similar things about working here.
Greenstein:Yes, the pressure is great. The recent rapid development of the ability to work on fainter and fainter things just pushes you. Thereís a dynamic.
Weart:More pressure than there used to be?
Greenstein:No, no. Thereís real competition now, thatís pressure. But Iím just saying that, since we can work on such faint things and so quickly, since I can get a spectrum of a 20th magnitude M dwarf with the Cassegrain SIT with enough detail to make it worth studying, in around, I would say, in 15 minutes —
Greenstein:Nobodyís ever worked on 20th magnitude M dwarfs. Iím working on them. Now, Iím looking for the faintest stars on the main sequence.
Weart:You have looked for those before, but now youíre really looking for them.
Greenstein:Yes. Now the apparent magnitude limit is down by a factor of 40 in visual light, and by working in the red, if I wanted to — we havenít yet started that — we probably could work on any star known, to the 23rd magnitude. Thatís an M dwarf (pointing to a spectrum). I donít know what weíd find in the infraóred because nobodyís looked.
Weart:I see. The sky at Palomar is around 22nd magnitude, per square arcsecond isnít it?
Greenstein:Yes. But you can work well below the sky.
Weart:OK. Now, a question about a somewhat different subject. It turns out (as you may know if you looked at The Science Citation Index) the thing youíve worked on which is the most cited is that book you edited on stellar atmospheres.
Weart:Yes. You get an average of I guess 30 citations a year, to J. Greenstein, ed., STELLAR ATMOSPHERES, and whatís particular interesting about that is, probably nine-tenths of the people who use it donít ever cite it.
Greenstein:Are you kidding? Iíve never seen the citation index.
Weart:Well, thatís great. But it turns out it is your most cited thing. Itís funny, I looked this up for Chandrasekhar, and it turns out his most cited thing is a REVIEWS OF MODERN PHYSICS article he wrote in 1942 on stochastic processes, that all the physicists use. Anyway, even if we didnít have the citation studies, weíd know very well that this is a very widely used book, so I think I ought to ask you how you came about to edit it? And what principles you followed in editing it?
Greenstein:(Taking book from shelf, looking in it) 1960. Well, I guess strongly interested in the field, and working in it.
Weart:How did you get picked to edit this thing?
Greenstein:Kuiper was the editor-in-chief of the series. I had known him a long time. I guess he thought of me, thought I would be willing to do the work. I donít remember. I chose the authors, that I do remember. I had a strong insular choice, now that I look at it.
Weart:Youíre looking through the table of contents here.
Greenstein:Essentially, only (counts)Ö five of the 19 articles are by others, strangers, the rest were intimate friends, acquaintances, colleagues etc.
Weart:Does this possibly say something about the fact that you know well the other people who are doing stellar atmospheres?
Greenstein:Yes. And also, a good number of them were from the tradition that I had come from, if you wish — that is, of looking at different kinds of stars, trying to explain them quantitatively — and therefore they were friends or associates. I think itís a fair statement that Iíve written a paper with all but, I think, three of the 20-odd authors that are in here. Several of them were my students. A lot of them were here. A lot of them were from the Yerkes group. Itís an insular book. On the other hand, the good theorists, basic theory of line formation, non-thermal phenomena in stellar atmospheres, were not insular — In fact, Lawrence Allerís articles, I remember, I asked him to write in a certain format; they are essentially manuals of how to analyze a star. And (they) give a very brief overview, essentially, of the interpretation of the Henry Draper classification of stellar spectra as a temperature and luminosity sequence.
Weart:You saw this, in fact, as being in part a manual for —
Greenstein:— oh yes. Some of them are not manuals. Others are. And I think it was sort of thought that these would be supertexts or collaborative monographs. Most of the Kuiper books are better organized than the usual monograph with a dozen authors who came together for a scientific meeting and then somebody puts together a book out of it. This was a very much better planned book. THE BASIC ASTRONOMICAL DATA book (Vol. 3, 1963), which was edited by (K. Aa.) Strand, was consciously planned. The large telescope book (TELESCOPES, Vol. 1) was so planned. I think almost all of them were very conscious attempts to cover a field.
Weart:Did you do a lot of editing on it, in order to fit it all together?
Greenstein:Yes. And I must say my wife did even more.
Weart:Is that so?
Greenstein:She did it to get them into English, and to get them organized. In fact, my wife and children did the index. We had our rather large house covered with index cards. The general feeling I have about the Kuiper volumes is that theyíre really quite good, and only the one on extragalactic astronomy, which has been over-delayed, is really maybe just too late. Kuiperís idea was good. At first it seemed nonsense. A lot of people were critical; I was critical. I had some differences of opinion with him. He wanted to be co-editor, since this was partly supported by the government, there was discussion of Kuiperís role in things. Most of the volumes eventually came out individually edited. After he dreamed of the series, got the money to get it started and the University of Chicago Press to print it, he had lost interest in the areas covered by these books. I still refer to my volume. I think itís still good Iím glad that other people do.
Weart:Itís still being referenced. It certainly is. Does your wife, by the way, help you on other things?
Greenstein:Oh yes. My wife was an English major; she went to Mount Holyoke. She was very conscious of style, form, elegance. During the abundance project she rewrote almost everybodyís papers. The writers had to realize that science is not produced or communicated by mumbles. And she had quite a problem.
Weart:She must have had some understanding of the content, then.
Greenstein:Only minor, enough. She is non-scientific, but she understands what people are trying to say, and points out that they havenít said it. Itís a long business, been extraordinarily useful in these things.
Weart:Tell me, how do you think the fact that you are an astronomer has affected your marriage?
Greenstein:Good God. Well, she certainly had to be used to being alone a lot. She has many outside interests. She was most interested in the theater. When we were in Williams Bay (Wisconsin) she ran a community theater for seven years. Sheís acted, persuaded me I should read — I canít act. She does things outside with people. She started a play reading group at Cal Tech which celebrated its 25th anniversary last year. So had to keep up her own side of things, her own interests. Sheís been forced to be hostess to some terrible bores, and also to some of the nicest people in the world. Sheís quite good with people, so sheís learned how to bring out the best in scientists. She finds out more about, say, a visiting scientist, than I find out. She tells me what my problems are going to be, for example.
Weart:Sounds like my wife.
Greenstein:Well, itís been a most enormous asset, a happy one.
Weart:OK. Let me shift ground once again. Weíre in the fifties, sixties, now. Velikovsky. What did you know of, what was your attitude toward, the Velikovsky affair?
Greenstein:I knew very little. I got involved when the first apparent suppression of his work by people from Harvard happened, with Macmillan Publishers, I think it was — I may be wrong, which publisher it was. I donít really remember details, but I think I got invited to a meeting at the publishing house on a discussion of academic freedom, freedom of expression and repression of controversy. I think Cecilia Payne-Gaposchkin, and maybe it was Shapley still, and maybe Donald Menzel, had put some pressures on the publishers and then felt a little worried. I just vaguely remember being called in with other people to one meeting. Iíve had nothing to do with it since. Iíll sign anything attacking him on general principles. I have much tolerance for what you might call off-beat science. I donít mean scientific discoveries like radio astronomy —
Weart:— no, I know what you mean Ė-
Greenstein:— but just deliberately perverse, sort of personalized science.
Weart:How did you feel at that time? Can you recall how you felt about the idea of somehow influencing the publisher?
Greenstein:I thought it was all right. If the publisher is going to claim to be a publisher of scientific books, and puts out on his book list and heavily advertises a crank effort. I must say I donít feel terrible guilt about having held the hand of whoever initiated the repression. I wasnít terribly involved. Iím against astrology. Iíve appeared on a TV program attacking astrology.
Weart:Organized by Bart Bok?
Greenstein:No, one out here. It was completely local thing. Armin Deutsch got interested in the scientific disproofs of astrology, and I think thatís how it came about. We got on a show with a dreadful man who writes books, where we were supposed to look like pedantic idiots, but I thought we came off pretty well.
Weart:You mean the typical TV thing where they have to show both sides.
Greenstein:Thatís right. Cleveland Amory, thatís it — a simpering New York socialite. I think we gave him what for. I deplore the irrationality movement, and I think it should be attacked. I have no hesitation about not knowing the details, in fact, but I recognize irrationality. I donít like young people getting into religious sects. I have no objection to very mystic religions, I think they have great content. But I donít think young people should get into them as drop outs from the drug culture. So I do my best, but itís not my particular forte. Iíve been on a lot of TV.
Weart:Yes, I wanted to ask you about that.
Greenstein:Oh, on the positive side.
Weart:Yes. Youíve been involved in public education, public information ďBirth and Death of a StarĒ, thatís the one I know of thatís probably been shown the most youíve been in other things. Have you ever had much feedback from your appearances on TV? Have your colleagues or friends or people called you up about it afterwards?
Greenstein:The trouble is that the scientific community, which sees these things, knows all of it, and mostly finds it boring. Theyíre usually polite. I donít think it does you any good as a scientist to be involved. Very rarely does it get a commendation, saying, ďThat was a good jobĒ or ďit carried the message of scienceĒ.
Weart:Do they ever criticize you for using your time on these things?
Greenstein:Not here, I wouldnít be surprised if half of my best friends think itís idiotic, but they donít say that. The ones I like most — not ďThe Birth and Death of a StarĒ — thereís one thing called, I think, ďWhy Man CreatesĒ, which was done by a man named Saul Bass —
Weart:— yeah, right —
Greenstein:Won an Academy Award.
Weart:That wasnít the animated one, was it?
Greenstein:Partly, but it had live actors and actually a dancer. The image was of someone trying to build a wall, a construct which wouldnít work, followed by a group of short interviews with scientists. That thing won an Academy Award. The interesting thing is that it is still being shown in the school system out here, at different levels. Itís also shown in Washington, D.C., I know, because I ran into it not long ago. And the children of scientists — or the public will say, ďWell, gee, my son saw you or my girl saw you in that, just wonderfulĒ, That is worth doing, clearly. It was well done, and I think was a success. I was in an NBC special 90-minute program in 1960-something with Sandage and Hoyle and Fowler, which cost many hundreds of thousands of dollars ;and was nationally shown, and which has been buried. I think itís because itís so long that it couldnít be repeated on commercial (TV). It was done by NBC and not by the non-profit groups, so it isnít in the public broadcasting arena. But Iíve enjoyed it. Oh, Iíve given, what was it, I think 12 lectures for school teachers in high school and community college things, on the radio.
Weart:What kind of feedback do you get from non-scientists on all this? Did you ever get much response from the public, when youíve talked on the radio or been on TV?
Greenstein:What little you get, in letters at least, is from cranks. They say, ďIím glad you said so and so, it proves my theoryĒ.
Weart:Youíd probably hear from cranks anyway, without appearing on —
Greenstein:— right. Then the other part of it is the general public. You asked me whether this helped raise money. As I said, I donít think it helps raise money. It certainly does get some feedback from people you meet who happen to have seen things. And generally, thatís been a positive reaction, the only positive evidence I have that public relations is good for science. That is, a lot of people whom I just meet by accident will suddenly go back into their memory and say, ďI saw you on so and soĒ.
Weart:So they do recall.
Greenstein:They do recall. Nobody, out of this, has come up and given us money, unfortunately. But I have a feeling that people who donít like it, donít talk to you about it, and people who do, do remember it; generally itís been a good thing for science. I donít do as much of it as I used to. The best thing I did was a set of radio interviews with a man named Gerald Leach which was a three-part BBC series. That, oddly enough, though it was radio and a long time ago — since I think it was also broadcast later and rebroadcast many times in the United States thatís had the most comments, except ďWhy Man CreatesĒ. That was at the time of the argument about Steady-State and the Big Bang and the origin of chemical elements, a sort of philosophical contribution about the kind of science I was doing. Whoever he was, I think heís now one of the heads of BBC he did it very well, and he did bring out the sort of (question) what is the significance of science? and the popular philosophy about The Universe and God.
Weart:Well, now comes the quasar story. Actually, even before it really became quasars, you had some interest in peculiar galaxies as radio sources. According to one of the papers you wrote, Bolton had suggested to you that 3C 442 was a double galaxy. T.R. Matthews, a radio astronomer here, suggested that you look at Hercules A, and you found a rather large red shift. So this raises questions about how you got started in this kind of business, your relations with the radio groupÖ?
Greenstein:Formerly, I was a member of the Owens Valley Radio Observatory staff, and was on their steering committee until last year, I think.
Weart:Why was that?
Greenstein:Well, because Iíd gotten it started and chosen the first people — not alone, but Iíd been responsible for getting the thing going. And Bolton was a non-astronomer. He established good relations with the Santa Barbara St. people and with people at Cal Tech. But the knowledge of optical astronomy in the radio observatory was not great, and they were mostly providing better and better positions, which was important — so it required a user group of optical astronomers. This group consisted of Baade, Minkowski, Sandage, myself, and Maarten Schmidt, who, though heíd been here before, when he came back was now strongly interested in radio astronomy, and began to do radio galaxies also. I think I was just one of many. But since I was here first, I was one of the early ones. Tom Matthews is an interesting person in this history, because for some reason heís never done much science by himself, but he did much of the interpretation of the properties of radio galaxies when the optical astronomers had measured their brightness, red shift, color, etc. Also he was interested in their angular diameters, and therefore linear diameters when you had a red shift. I think the particular things that you mentioned that I did were connected with objects of large linear size. And that was my sort of special interest: where was the high-energy radiation coming from, way out beyond the optical image of a galaxy? Whereas Baade and Minkowski had been specially interested in the apparent collisions that seemed to be occurring between doubles in radio galaxies, I was interested in what happened when that had happened — this explosion of the magnetized plasma.
Weart:So you had the assumption that the galaxies had collided, and that something was going on?
Greenstein:Yes. We grew up on that. It was wrong, largely, unfortunately. It was just before the Shklovskii theory of synchrotron radiation.
Weart:I see, so you were also interested in this problem of where the radiation —
Greenstein:— yes, in —
Weart:— you been interested much earlier in that too —
Greenstein:— yes; in Ď55, thereís been enough radio galaxies discovered and studied that I wrote a paper attempting to interpret their energy output in terms of collisional energy in a Manchester IAU symposium in 1955. Bolton and I went to that. It was the last gasp of theory based on thermal processes in radio astronomy, because I still used free-free radiation theory and kinetic energy from collisions. There was little concern yet about the magnetic energy, and especially the high-energy particle energy, though those concerns were already apparent. That was a very short-lived interest, and especially with Maarten Schmidt here there was no point in continuing, since that was what he was going to do for quite a few years. We do have a sociology, a pattern within the observatory which says, if a person has an established problem on which been working a long time, itís probably better not to work in that area, because youíll only get little odds and ends and youíll likely irritate a colleague.
Weart:Though sometimes it does happen.
Greenstein:It does. It does happen, and there was a great deal of rivalry when it came to the radio stars, straight competition. Weíre not above a good internal competition, but in general I think itís kind of an understood thing that if a person is spending most of his observing time for several years on a project, unless you think heís an idiot and that you could do it infinitely better, itís probably not a good idea to spend any time on it.
Weart:It will be hard for you to get ahead of him, in any case.
Greenstein:Yes. And then, questions of collaboration. At those times, and I think still now, this is still somewhat more an individualist than a team effort place. In any case, my interest did not last all that long nor did I do that much about it. But I did get involved with Tom Matthews, who is not unrecognized but just hadnít done very much by himself. Tom also got involved with Alan Sandage on the point sources of radio emission, quite early — pre-quasar red shift. There were quite a few individual papers on blue stellar objects, some of them emitting radio waves, others radio quiet, by Sandage specifically, and Sandage and Matthews. They had already done a good deal on the radio stars before the red shifts had been measured. They were interpreting them as stars. So was I. I wrote a theoretical paper, presented at a NASA symposium in New York; but fortunately, just a few months later, the discovery of the red shift occurred, so my silliness never got into print.
Weart:Well, in the Mt. Wilson-Palomar Observatory REPORTS (l960-61, p. 80) it said that you were talking about 3C 48, it appears to be a 16th magnitude star, Greenstein believes that the star is the remnant of a very old supernova.
Greenstein:Thatís right. Thatís it.
Weart:It got into print.
Greenstein:Well, thank God that was a short report. As youíve probably gathered, a lot of great scientific discoveries appear only in the Directorís report —
Greenstein:— and are never followed up.
Weart:Thatís right. You were trying to identify them as perhaps rare elements —
Greenstein:— Yes, the whole theory was based on the idea that the radio stars were supernova remnants. From the accounts of supernovae and their frequency in space I could figure out the distance to the nearest supernova remnant of a given age, and compute the decay of its radioactive elements. In fact a pretty good piece of low-energy nuclear physics was involved. I invented what was called a light-element S addition process. The S process is usually to make heavy elements from iron but there is a cycle among the light elements, which I think ends at unstable sulfur and decays back to a lighter element, which could produce a whole bunch of abundance anomalies in carbon, nitrogen, oxygen.
Weart:All this was built up around these —
Weart:These radio stars. Now, Iím curious, thereís a shift here. At one point youíre doing radio galaxies, and at the next point youíre doing radio stars. Did you see any connection between these?
Greenstein:Oh well, yes, the point was, here were — the excitement was that here were apparently stellar objects, therefore stars in our galaxy, which were detected by radio waves. And they were not M dwarfs, which could have been expected, because of super flares, to emit radio waves; they were blue objects. So it required a quite extraordinary model to understand them.
Weart:So was the idea that, whichever kind of radio object it was there was something very powerful and unusual going on?
Greenstein:Well, almost certainly that the same peculiarities of a big radio galaxy which one way or another involves expansion of plasma at, say, between a tenth and a half the speed of light, in ordinary radio galaxies this same, call it ďfairly highóenergyĒ phenomenon must be happening when we saw these little starlets. We thought that these were happening on a very small scale. But direct input of high-energy particles, from radioactive decay, was the model.
Weart:I see. I had a question, by the way. Sciama in his book on modern cosmology suggests that when Minkowski identified Cygnus A as being very distant, he says, ďThis unfortunately helped to convince people that most of the others would be fainter and so would even be out of reach of the 200-inch.Ē Does this seem to make sense?
Yes. Except that eventually it didnít convince. That statement seemed true, i.e., if you have a certain amount of radio power emitted from a very strong radio source, you would guess that this is either typical, or perhaps the upper limit to the power; and in that case, as you go to very large distances, the optical source would fade into invisibility. And in fact, the faintest and largest red shift galaxy that Minkowski ever measured, 3C 295, a very high-luminosity galaxy, was at the absolute limit of technology then, of photography and spectroscopy, and it was a pretty bright radio source. Therefore the fainter ones might not ever be photographed. In fact, the radio astronomers got irritated at the optical astronomers. They said, ďWhy donít you take spectra of (what were called) empty fields?Ē If there is an object within to exaggerate, because itís never that good — one arc second of such and such a place, and no optical object could be photographed, take the spectrum anyway. Maybe all the power would be in one emission line or two emission lines. I donít know that anybody ever did the experiment, but I remember arguments about our conservatism. Because thereís no reason to expect that objects donít exist beyond the normal limit of any given telescope.
It was a very confused period. A more light-hearted anecdote, which maybe youíve heard, is a bet I had with Minkowski. You see, these discoveries on the radio stars were coming in more or less one or two a month — new stellar objects detected by radio, identified optically, spectra obtained. And every one had a different red shift, we now know. Naturally. To the eye which thinks that each one is a star in our galaxy, they all have different lines. So somebody would come in after measuring some plates on his last run and tell Rudolph (Minkowski) and me, ďI got 3C so and so,Ē and Iíd say, ďAny lines you can identify?Ē ďNo, theyíre all different.Ē And thereíd be this silence, I remember a crack which is psychologically curious. I said, ďWell, all of them are orthogonal sets, in which all cross products — I mean, one set or other — are zeroes, No common propertyĒ. It really is an amazing business that out of that no one would deduce — and I said it often enough, that they were at the wrong place in each one. And thatís why they were all different. And thatís the truth.
Weart:But you didnít associate that with red shift?
Greenstein:Thatís the incredible thing. We sat there for three years, making silly cracks like that. And Iím guilty.
Weart:You imagined a linear displacement, instead of a stretching, or whatever?
Greenstein:Even a stretching wouldnít have been so serious, though quite right. It was just that, for some reason, the fact that they were star-like on radio frequencies and star-like when studied optically Ė-
Weart:— so you just hung up on looking for the particular lines that matched.
Greenstein:This is the stupidity and resistance to change of even good scientists. I hate to think what it means about our lack of knowledge in other areas, sometimes.
Weart:Of course, thereís also the problem that thereís 100,000 spectral lines, and you donít have any idea what the state of ionization is in these objects or what their elements are, so you can always find a spectral line —
Greenstein:— thatís right. Thatíll go back to the quasar story in a moment. Let me just say, we had two bets — one, I bet Rudolph that we would never find an ordinary star by radio means. And then I generalized the bet, and offered a prize of a case of wine or whiskey to anybody — I had a lot of wine that would do — anybody who identified a real star. The other bet, when the quasars were found, was that I would give another Greenstein Award to the first person with a red shift of more than 100 percent. And Schmidt got, not a redshift more than 100 percent, but instead a redshift more than 200 percent. So they skipped the 100 percent and got into the 200. Then I paid off at 350 percent to Peter Strittmater, and now the Award stands at 450 percent, unclaimed. But we were so ignorant of what was going on that (although these two bets were separated by a few years) the bets represent the fact that it was a matter of sporting competition, it wasnít science. We just know what was happening. No, it was very logical to go from the big radio galaxies to the tiny objects. Had we thought of it, you know, we could have said, ďWell, Hercules A is many minutes of arc across, and this is less than a second of arc, therefore itís that ratio, 100 times furtherĒ. But that wouldnít have worked. The distance would have been bigger than the universe, really at the edge. At linear extrapolation, anyway, it would have been ruined. It was a very peculiar period, where very good scientists were just all held up by a mental block. The most extraordinary little bit of personal history is that, as far as I can find out, I took the first spectrum of any quasar ever taken. Itís called Tonantqintla 202, and I took it because it was a faint blue star near the north galactic pole, found by the Mexican astronomers to be very blue. On the plate envelope, when I took it, I wrote, ďPossibly old nova, weak emission linesĒ? Or ďDCĒ which means ďdegenerate star, continuous spectrumĒ. Itís in a 1965 paper by Eggen and myself as a white dwarf.
Greenstein:Yes. The paper was written in Ď64. And although the quasars had been found, it still leaked into that paper Ė-
Weart:— Oh, I see —
Greenstein:— and I think itís the largest numerical error in the history of astronomy. Because as a white dwarf, itís 20 parsecs or 30 parsecs, and as a quasar it has in fact a red shift of 0.37, which fortunately later Oke and I found out. It was going, in other words, from about three billion parsecs to, call it, 30 parsecs. Itís only wrong by a hundred million. Itís a worse error than Ptolemy or anybody, any Greek, on the size of the earth or the distance to the sun. By 100 million times, we are wrong! So it was very confusing, if you look back; we were confused then. We knew it was exciting. And as far as Iím concerned, the solution, which is the canonical one, is that you get your mental blocks released by seeing either something so obvious that it strikes you on the head, or having somebody tell you something which releases, again, your mental inhibition. I mentioned that Iím very interested in how people make scientific discoveries, and how you can bet on people who will make them. This is how one builds a good group of scientists, by having this feeling as to whoís likely to be creative or not, And in this case, the whole group proved itself a hollow fraud, if you wish, being good and very bright and having the best technology for the time, and yet not seeing something. Then when Schmidt — well, you know the story, I wonít repeat that. That depended on very good radio measures of position, identification of a bright object with a small red shift, so that the lines were clearly recognizable.
Weart:Recognizable as falling in a spectra series.
Weart:So then he found 3C 273.
Weart:He found that red shift. So how did you hear about that, and what did you do?
Greenstein:Well, Maarten is a clever and a sound person, and he took more and more plates, first. And he kept it quiet till he was certain. This anecdote is printed too many times, but itís true. He said he had something interesting to show me, and I went to his office, down at the end of the hall. He said, ďJesse, what do you think of this?Ē I looked at it, and it was the hydrogen series, only in the wrong place, and a couple of other lines. I looked at it again. He said, ďWell, what do you thinkĒ? I said, ďGee, itís marvelousĒ. He said, ď16 percentĒ. Now, this is the thing about mental processes that I think is unbelievable. I said, ďNo, 37 percentĒ. He said, ďNo, itís 16 percent red shift, hydrogenĒ. I said, ďNo, no; 3C 48 had 37 percent red shiftĒ. It took me the time to look, to realize it was red shifted, and to remember that I had figured that the lines of 3C 48 could be identified if they were in the wrong place by 37 percent. I figured it out mentally, because thereís not a scrap of paper in existence. Iíd measured half a dozen lines. You think of the obvious things, and you find, gee, theyíre all wrong by looks like, no, 30, 40 percent — I just never took it seriously. Well, Maarten had taken it seriously, but he asked me, as a spectroscopist, and we spent the rest of that day, going over and over the Rydberg formula to see if the lines could arise from a heavy element, which had a different nuclear charge, and which would have a series in the wrong place — a hydrogenic series but at the wrong wavelength.
Weart:Yes, that would have been my first guess, actually.
Greenstein:I think boron would have done it, or something ridiculous like that.
Weart:But then you said the hell with it, itís hydrogen.
Greenstein:If itís gotta be boron, thatís the end! Exactly. I think that was it. You just had to insert you know, an N and N prime and Z in the Rydberg formula that would give you some line at this place, and it just wasnít going to work. Anyway, his other important contribution was that his plate showed, at the very end, the ionized magnesium line, which I had seen in a solar spectrum taken from rockets years earlier. So he identified that as ionized magnesium, and I said, ďWhere are the forbidden linesĒ? Theyíre not there. I said, ďWell, thatís pretty obvious. Thatís possibleĒ. And there he was. Immediately I went to Tom Matthews and I said, ďWhat about this 37 percent in 3C48Ē? We had apparently discussed this, but just —
Weart:You had mentioned it to him?
Greenstein:Or he had mentioned it, or Bolton, Bolton says he had mentioned it to Tom or me. In any case, nobody has any evidence written down on paper, 37 percent. But I recognized it immediately when I saw it was a red shift.
Weart:Another question. In a SCIENTIFIC AMERICAN article in 1963, you say that the fact that Schmidt saw the oxygen II line at 2800 —
Weart:Oh, I see. It says oxygen II here. Was it magnesium II?
Weart:OK. At any rate, that that was really a key. Was that how you got the 37 percent?
Greenstein:Well, in fact, in 3C 48 the strongest line is magnesium II; let me just see, itís — (punches quick calculation on desk calculator) — yeah. I had identified it as oxygen VI. The error of wavelength is 1 angstrom, and itís a line 100 angstroms broad. So, the very strong oxygen VI — the only strong transition in the optical region, although there are a lot in the ultraviolet, say in the Skylab solar spectra — sits right at the wavelength of the redóshifted magnesium II. Now, in the object Schmidt had — the forbidden lines if present are very weak, so it was unlike a nebular spectrum. And the hydrogen might have been some other hydrogenic series. It turned out, it really couldnít be, it wasnít too good. But the clincher was that he had identified this new line right at the end of the spectrum, just beyond any comparison line I think, even.
Weart:He probably had not thought of the magnesium II line at all.
Greenstein:No, he had. He had.
Weart:— but you knew that in 3C 48 —
Greenstein:— oh no, I never did, except in this unknown, speculative, unconscious period, you see, which none of us can reconstruct.
Weart:Yes, why should you come up with magnesium? Because one part of the problem is if youíre thinking of oxygen VI, youíre not thinking of magnesium II.
Greenstein:No, but you see, other things were involved in 3C 48. It happens that, I think itís forbidden neon V, is in the good region, and ....(uses desk calculator) yes, it just moved on top of He II, 4686, thatís it.
Greenstein:Itís just an unbelievable set of coincidences, you see. I was doing perfectly valid spectroscopy which was wrong.
Weart:These lines are very wide, as you say.
Greenstein:Yes. And also, it happens that all the lines used were the strongest lines. The funny thing is that too much knowledge of spectroscopy prevented people from doing the obvious thing. Because Minkowski had no trouble in using lines at red shifts up to 40 percent.
Weart:Yes, for his galaxies.
Greenstein:For galaxies, because in galaxies you knew there was emitting gas, especially in disturbed galaxies. I believe another seminal little piece of information we all had was that Ike Bowen had gone through tables of energy levels and predicted the far-ultraviolet spectra of planetary nebulae, a private job he never published, and which everybody here had seen. When the lines were identified, then the question, why werenít they the lines one normally sees — i.e. with very strong forbidden lines in 3C 273 — brought me into the thing from the astrophysical point of view. And thatís how Schmidt and I later worked together, trying to get a model.
Weart:Right, weíll get back to that.
Greenstein:OK. But as to the discovery moment, by him, he could tell you best. I think it was just straight patient, careful exclusion of every other possibility. It was the object. It had a crazy spectrum. The identification was based on a perfect position, due to lunar occulations observed in Australia. They leaked up here and were sent either to Bolton or to Schmidt or both, by the observers in Australia. Of course, the Australians were very sensitive, because they had made the thing possible.
Weart:I wanted to ask, when you and Schmidt knew about it, at what point did you tell other people?
Greenstein:Well, then I got Tom (Matthews) because Tom had been involved in telling me about 3C 48. (And possibly in the speculation that the lines were in the wrong place, which neither of us took seriously or we would have published it; because you donít even have to identify them, once you say theyíre in the wrong place, youíve identified everything). And I said, ďMaartenís going to publish in NATURE, how about us getting the information together on 3C 48Ē Which is clearly red-shifted and is bigger, and very high luminosity, and has a more normal spectrum. You see, 3C 273 is in fact somewhat a freak. Itís got a small red shift, itís bright apparently. I think itís the brightest quasar still, in apparent magnitude. And it has an extremely unusual spectrum. If all of them had been like that, by the way, we wouldnít have identified anything, because if you suppress the forbidden lines, and if the Balmer hydrogen lines shift out of the normal spectral region, youíve got to go to red shifts of 300 percent to get the Lyman lines into the photographic region again. So itís a very fortunate circumstance on 273.
Weart:Sometimes people feel that they want to hold back from discussing their work, either fm publishing it while they work it up more, or perhaps they wonít discuss with certain other groups, especially at some early stages of the research. Have you had experiences like this? Was it stronger during the quasar days or at other times?
Well, from there on things got a little sticky. The reason actually I went to Tom Matthews almost first was that he and Sandage had a paper in press on the radio stars, in which a full interpretation of their continuum colors was based on the idea that they were stars, of a very strange color. That paper was not changed, except that an addendum or footnote, I forget which, was put in, which said that since the discovery of the red shift, these objects are clearly very small galaxies at large distances, and all the luminosities have to be multiplied by such and such a number and interpreted as small or tiny galaxies. They werenít sure. Nobody was sure — whether galaxies or clouds of gas in galaxies. Everything else still stood in their paper, except they were not stars and were 1010 times more luminous. Or more. So that was a thing where we had internal cooperation. For example, Sandage had given me all his plates of 3C 48, because he had been taking these blue radio stars. I had only this one, which I had good spectra of; he just get any further and so heíd given them to me. And I had measured them and exhaustively studied them. It was much later that we got a little bit into difficulties, because in a certain sense we were stepping into the cosmological problem with a vengeance. Within I donít know how many months, red shifts of over 200 percent had been found by Schmidt, who took spectra of some very faint blue stellar objects with radio emission and identified the lines, based largely on Bowenís list.
Now, he and Bowen got along fine. But here we were, he specifically, apparently in conflict with people working on the long-established problem of large red shifts in cosmology. Well, not in conflict, but stepping in. And next of all, it destroyed the beauty of what had been found, and still is true, the use of galaxies as standard candles. Because the next thing was that the quasar red shift — apparent brightness diagram is, or was, mostly a scatter diagram with almost no apparent correlation. There are some bright quasars with large shifts, and there are some faint ones with small. Thatís not true in typical galaxies, only in dwarfs and things. So there was some tense feeling. In particular, I think, Alan Sandage resented my incursion into his field, since he had been my student — rather a Papa-hurting-Sonny syndrome — and I donít blame him. Actually, itís for that reason that I left the field.
Weart:I was going to ask you why.
Greenstein:I just did not want to participate in a thing which fundamentally was divisive. Iím perfectly willing to do astrophysics, if I could, about quasars. And I did later, on the multiple absorption line things, because I had the best photographic spectra of quasars. Higher resolution than Maarten used, and I had spent more time on one or two objects. But I did not want to go into cosmology, and I didnít want to be running a race with people whom I greatly admired and who devoted all their time to it.
Weart:OK. Before I forget, you wanted me to ask you about where you think creativity comes from. Where do your ideas come from?
Greenstein:If I did anything, it was bring together some good people. I made minor mistakes. I think in fact theyíre pretty minor. And to me the question was, how could you guess the long-term ability of a person as he gets a little older, to continue to understand novelty, to be open to it? And if you wish, the quasar discovery was a kick in the pants against any complacency that one had about people, in an ordinary scientific way, seeing what they are being told by nature. That is, we are acting without imagination or without sufficient imagination. When you have a puzzle for several years, and have all this evidence, someone should have done it, right out of just plain good common sense or scientific imagination. I guess I use this as an example of what I would now look for, if I were looking for new people. Itís a Zen Buddhist ability to look at things with an empty eye. That is, without prejudice. This was the biggest mass self-hypnosis into a prejudiced state that I ever —
Weart:— you feel it is almost a mystical process? You say, Zen Buddhist.
Greenstein:I use the word because itís a procedure which I guess you can call vulgarly brain-storming, free thinking, or psychologically, keeping a contact with your subconscious or the stuff between consciousness and the subconscious mind. I donít know whether I really did that division in my head or did it on paper, but I canít find any paper. Itís rather interesting. You go on, worrying about what it is that prevents you from being trapped by your own knowledge. And thatís why I mentioned the Zen Buddhist business, not that I believe in Buddha or Zen, but that the process of freeing the mind is the essential feature. You have to, of course, know science too. (But) there are loads of people who know an enormous amount and never do anything. There are with the opposite defect, who publish incredible papers with absolutely no scientific content. The guy has done an enormous exercise, thereís no result, really.
Weart:You mentioned (off tape) that some people use new technology.
Greenstein:Well, nowadays youíve got to; if youíre going to get a new fact to challenge your imagination, youíve got to be willing to change. There are people, not only in our own staff but everywhere who picked a problem 20 or more years ago and are still working on it. Itís dull, and the paper when it will eventually appear will have plots or something as a function of time. Letís say itís a long-period variable, well, there are a thousand longóperiod variables. I just donít think thatís going to lead to any novelty. And yet when Baade looked at the properties of long-period variables as a function of their space motion, he immediately noted that the short period long-period variables, those of less than 100-day period, have very high space velocities. It was one of the keys of his population type synthesis.
Weart:So sometimes it comes out.
Greenstein:Well, itís somebody else, not the person who did the light curves, or who tabulated them, or made statistics. Baade noticed this, and he noticed this about the cluster-type RR Lyrae variables — that there they were, and they had high motion, and those with highest motion had the weakest lines.
Weart:OK. To get back to quasars, then almost the next thing was Greenstein and Matthews, then you had Schmidt; rejecting a gravitational origin for the red shift by spectroscopic arguments.
Greenstein:Well, Iíd say that was almost the most constructive thing we did.
Weart:Iím curious about that.
Greenstein:Well, thereís no question that if you have an unexplained kind of object, the proper thing to do is to have all plausible if fantastic theories. And the most interesting physical phenomenon to give you pseudo velocities, give you real red shifts, is gravitation. White dwarfs, of course, had known, but small, gravitational red shifts. The question was, was there any way you could make a big one? It turned out later, from really basic theory — and I wish I remember who showed this first, whether it was Tommie Gold or Dennis Sciama, I think it was Sciama who did it — that no star could be supported by internal pressure with a gravitational red shift exceeding 37 percent. Then the model builders here, and that was Fowler and Hoyle, really tried harder, and came up with the idea that you had a massive cluster. And since [in] a cluster with that much gravitational potential, itís crowded; it turns out that the stars would hit each other all the time. So Fowler and Hoyle made them neutron stars. Or maybe it was first white dwarfs and then neutron stars. Tiny things.
Weart:In your 1963 SCIENTIFIC AMERICAN article, as a concrete model you imagine an excited cloud of gas, diameter of about 600 light years, mass of 109 sums. You say, ďIt is uncertain whether or not it contains any stars.Ē Is this responding to that super-massive object model?
Greenstein:No, I think itís actually still before that model in time. But I donít know the date of that Fowler and Hoyle paper.
Weart:It was about that same time.
Greenstein:OK, well, then we had heard about it, and I was in a sense responding. There was no evidence, you see, for any stars in the quasars. And in any case, by then the non-thermal continuum had been explained by Shklovskii, and the Crab Nebula had been explained as non-thermal relativistic electron continuum.
Weart:Right. Then the next year after that, 1964, there was your paper with Schmidt on the quasi-stellar radio sources 3C 48 and 3C 273, and aside from the book, this is your most cited paper.
Greenstein:The things I really liked donít get mentioned. By the way, how does the citation index work if you have a collaboration? Is it the first authorís name or?
Weart:Let me think. Theyíll do it under both authors, only up to a certain point. If there are 19 authors, I donít think they do it under each one. I forget exactly how it works.
Greenstein:Well, that was a good paper, if I may say so. It turned out that Maarten was getting more data, and we thought more about it, and we talked a lot, and I was able to do a little more of the astrophysical theory.
Weart:Did you sort of both work on these spectroscopic ideas?
Greenstein:Oh yes. That was a genuine collaboration. He was providing the facts; he had been observing other objects in that interval with bigger red shifts. We then knew that the existence of forbidden lines in 3C 48, but only weak ones in 3C 273, meant a density change — thatís an established technique in planetary nebular theory. We came to really crazy discussions, which turned out possibly to have been relevant, though theyíre barely mentioned. What we really tried, I think, was to think of all parts of physics that might affect these objects. Take gravitational red shifts as an example. We could exclude it, because of the perturbation — if it were nearby and if it were so and so distance, it would perturb the motions of stars in our own galaxy. Things like that. Then we thought of electron scattering, which got in only as a footnote, because it was a last-minute idea. We thought of everything that could happen. And we exploited the effect of density on the occurrence of forbidden lines to get a maximum density.
Weart:In the model you finally came out with, you ruled out gravitational red shift, and you said it would be a small mass, maybe 10 solar masses, surrounded by shells. You imagined a series of shells, in which the various spectra originated, the radio I think coming from the farthest-out shell. And then you say, if their age exceeds a thousand years, continued input of energy is required from some not directly observable source — which a couple of years later, I guess in the YEARBOOK,you called ďobject X.Ē You said it could be, for example, matter and antimatter, or the collapse of a supermassive object, and so on, Iím curious how this picture has evolved, where it came from, and what your thinking has been since, what you think now.
I think actually we were led by observational fact and intensive interpretation to the model, that there wasnít much in the way of an alternative. For example, at the electron densities that suppress forbidden lines, as in 3C 273, essentially no lowófrequency radiation could get out, even if the thing were, you know, a few centimeters thick, because of internal reflection from that high an ionospheric density. I think that those were good days, in that the amount we knew about the quasars was not beyond coping with. The multiple absorption lines, which have been found since, are I think beyond our present understanding. We had, of course, also, the thing you mentioned, the analogy with the radio galaxies — we were not sure whether these things were in galaxies, or whether they were isolated. The rapidity of speculation by theorists of course kept giving stimulus. I think, about that time, the idea of, call it retarded black holes left over from the creation, from the Big Bang, was advanced by several people. But certainly for me, it was by Yuíval Neíeman from Israel, who was visiting Murray GellóMann, I think, at the time. He said, ďWhy should it have all expanded at onceĒ? If you just have a high enough density fluctuation — So I think I left open at all times the idea it was brand new matter.
Then Edward Teller, whom I knew moderately well, kept bugging us about anti-matter. From a physics point of view, he would love it to be anti-matter annihilating ordinary matter. And next, it would make sense of the energetics, because then you get 100 percent conversion of mass into energy; with a black hole you get only a few percent, now, into radiated energy, Teller was really a fascinating nuisance. I was in the hospital in early Ď65, for a long siege. I was sick for a long, long time. And the first human being that Iíd seen except my nurse and my wife when I was home, was Teller, who insisted on seeing me with new business. He marched up and down and popped his great eyebrows, and it was wonderful, because I came back to life trying to fight Edward Teller. Because I just couldnít believe in his anti-matter bit. So we were very much aware, essentially, of all speculation. But the facts, or the pseudo-facts, limited us. Now, if the red shifts are not cosmological, of course, we were as crazy as we could be.
Weart:There you havenít changed your opinion.
Greenstein:I have not changed. Here I am, being just as conservative as 12 years ago.
Weart:Thatís all right. I donít hold that against you. What is your view on quasars now? Would you still describe it in terms of an object X?
Greenstein:Yes. Well, I think we now know so much that the quasars arenít all that weird. Letís say that I have a particular fondness for a rational scenario. Therefore, I think I would accept the idea of fairly massive black holes, near the center of galaxies. Or even isolated black holes in intergalactic space, which would be like the retarded expansion — in the latter case, they would be in contact with intergalactic gas, which is of very low density and therefore is a lot harder (to get enough energy from). If you put a supermassive black hole in the center of a galaxy, or even in the wings, you get some agreement with the observation that the outer fringes of some quasars are clearly stellar, and have the same red shift.
Weart:You feel that this is a fairly likely explanation, it will turn out?
Greenstein:I think so. There are nice big speculative ideas applicable. One which traces back through a long time is Phil Morrisonís (I guess) idea that organized rotation is a very important phenomenon. Itís quite different from thermal motions in a gas. Heís put what he calls spinors in the center of galaxies. He did that years ago when there was very little known. I donít think itís unreasonable. If you take (the fact) that stars are dying, and that gas, because of angular momentum considerations, falls to the center and builds a not very massive black hole, then you produce ordinary radio galaxies; and if you go further, you can have the quasars.
Weart:Do you think thereís likely to be a black hole in all galaxies, our galaxy, normal galaxies?
Greenstein:In ours? Sure. Why not? Thereís something funny at the center, thereís a real singularity. The space density at the center, I think, is deduced to be 100,000 times higher than the average. From direct observations of this galactic center, source of infra-red and radio molecules and everything. So, it may not be all that exotic. It seems to me an attractive idea.
Weart:Black holes sound exotic enough to me. But weíre used to them now.
Greenstein:Then you see, by the way, thereís a thing called the BL Lac (BL Lacertae) objects — which are essentially very violently variable stellar objects, which seem to have galactic fringes and modest red shifts, and most with no emission lines.
Weart:Right, and Seyfert galaxies.
Greenstein:And Seyfert galaxies. In fact, by the way, assuming red shifts, to be cosmological there are many Seyfert galaxies which are brighter than a large fraction of the known quasars.
Weart:Right. In this, was there any particular point at which you began to think more of black holes and less of other things, as being the likely explanation? And also, of black holes in galaxies? Or did this sort of creep up?
Greenstein:Gee, I really donít remember. I would have said it crept up. I would think, by the way, that my present feeling that itís got to be explicable that way, even if I donít know the details, comes from the Xóray observation of things as simple as Xóray binaries with black holes.
Weart:Which youíre now interested in. Let me flip this. I notice youíve mentioned a lot about your relationships with physicists, at this point. I wondered particularly, how much you met with the physicists in discussions of quasars and these things? There was this SINS seminar.
Greenstein:Yes, that came out of the older nucleosynthesis work, and kept going in this area, later to gravitational astrophysics, relativistic astrophysics.
Weart:Is that still going?
Weart:How did that start?
Greenstein:Well, the Stellar Interior Nucleosynthesis Seminars (SINS) started when we were in really close cooperation with the Kellog low-energy physics group, who were doing nuclear reactions and abundance work. The seminars changed topics when highóenergy astrophysics, radio astronomy phenomena, relativistic electrons came in. The subjects were still close to astronomical observations. Fred Hoyle, who had originally been directly connected with astronomy, became connected with Fowlerís laboratory. I guess he has stayed close to Fowler and comes (to Cal Tech) more than once a year. It was a very stimulating place to try out new ideas.
Weart:Would people take turns giving little talks?
Greenstein:They would talk about their own work, usually unpublished, or review other papers.
Weart:How many astronomers went to that?
Greenstein:At first, quite a lot. I would say itís dropped off, I havenít gone in recent years, because, one, I changed fields again, done some stellar evolution work, and those I go to; I spoke there last year. When the X-ray binaries came along there was again a rebirth, because the question was, were they merely neutron stars or did you have to have a black hole? We had then a big group already under Kip Thorneís contract in relativistic astrophysics.
Weart:Did people from Santa Barbara St. come down for that also?
Greenstein:Sometimes. The relation has been getting thinner, steadily. The young people, when they join the staff will come. The older are too busy, or something. Iím too busy. And I canít keep up with everything.
Weart:Youíre not doing that kind of thing right now.
Greenstein:I should. But on the other hand, they had a very bright student working over there (I wish heíd worked for me), and his thesis was on horizontal branch star evolution, from the point of view of whatís called semi-convection, very abstruse; there was quite a flurry there. When the magnetic stars —
Weart:Did they discuss all these things?
Greenstein:Yes. Anything that might involve higher than ordinary thermal energies. Now it happens thereís a big growth in cosmic ray physics there, and observations from space, and experimenter on the Vela (satellite).
Weart:I guess these space observations keep the thing going.
Greenstein:Yes. Well, just last year or about a year and a half, when they found from the Apollo-Soyuz flight two very hot white dwarfs, there was a new rebirth of collaboration between astronomers and physicists. And then it dies. Itís a very good seminar. Willy (Fowler) is keeping it going, even though heís away a lot. I think itís his existence that keeps it going.
Weart:I see, OK. One last question about quasars. You already told me why you stopped working on them, which is a question I had, but I am also curious: you stopped around 1966, and also at this time you wrote your SCIENCE YEARBOOK article, where you closed with a little poem. I have the whole thing here —
Greenstein:— oh yes —
Weart:ďHorrid quasar, my heart for you is full of hate...of Einsteinís world youíve made a mess —Ē Did that kind of feeling also have something to do with your stopping work on quasars?
Greenstein:Well, there was a period when quasars got into an obnoxious state. I guess that was more or less that for me. I think weíre back in that state, not only with question of the non-cosmological red shift, but in the multiple absorption lines.
Weart:Those were two things that were both appearing around then.
Greenstein:They were, Bahcall, Sargent and I wrote a paper, with Bahcall doing developing a computing machine search technique for red shifts. That was an extremely abrasive experience, and after that I thought, itís not my subject.
Weart:It was abrasive because you were showing that there wasnít any particular regularity in the absorption lines?
Greenstein:Oh, itís such a mess. And itís only gotten worse. No, there are almost certainly objects which have a few systems of absorption lines, formed in an expelled shell.
Weart:Oh, that business.
Greenstein:But there are some in which there are so many lines that the usual interpretation is that theyíre all Lyman-alpha at individual discrete red shifts. Now, when I said that Maarten Schmidt and I had come to a ridiculous quasar model — we tried to figure out the possible density fluctuation in the gas, in a quasar, that would produce the kinds of spectra the relative intensities that were being observed. Not really just the two we wrote about, but we knew some of the general problem. We came up with a model in which there were about 10 filaments of gas, of which you see only a few at any one time, projected on the bright disk of the non-thermal Object X, This is a possibility. Itís like solar prominences gone mad. Maybe thatís what it looks like, myriads of intertwined filaments with magnetic fields and so forth. Some of this could explain the multiple absorption line problem. I think we really tried to think of most of the physical phenomena. We did stick rigorously, through that Ď66 article, to the idea that there were no such things as non-cosmological red shifts, the only explanation of which seemed changes in the natural constants. I mean, thatís not the only thing that could be going on, but is a sort of reasonable idea. Thatís been really still kept alive — that the quasars are brand new matter where the electron has a different mass, running into problems with fundamental particle theory.
Weart:Youíve mentioned that you have a preference for non-exotic —
Greenstein:— Well, life is exotic enough without that one. It happens that I had done, and kept doing, the following which derived years ago from Humasonís work. Humason had gotten galaxy spectra out to reasonable red shifts, 20-odd percent, where he got enough absorption and emission lines to make a useful measurement and he had noted that the (calcium) H and K lines kept the same separation, scaled by the red shift. Now, what that means is that the ratio of the fineóstructure constant, to the Rydberg, is staying constant. Dick Feynman looked at it. I talked to Feynman. He followed it up and made plots; Humason provided the data. And really, to red shifts of 20 percent, the ratio of the constants was constant. Now, unfortunately, for further such tests in almost anybodyís theory of changes of natural constants, youíve got to go to red shifts like 100 percent — to get any conclusions, and then youíre in the region of the quasars. But itís still true that there are doublets visible, especially in the absorption lines, and their splitting is the same fraction as the change in the scale of the atomic spectrum. I think it leaves just one possible pattern of change of the constants, and itís not a terribly attractive one. Recently people have made experiments on ďtired lightĒ. So I have a feeling that itís going to take a deep revolution in physics, to accept changes in the natural constants.
Weart:OK. To get back to 1966, you had these very complex systems of red shifts. You had the peculiar galaxies, and the possible non-cosmological explanations and the thing you mentioned earlier, that they just didnít fit into a red shift-magnitude diagrams. All these things just began to seem too messy?
Greenstein:Well, it certainly was and is messy, and gotten very much better. Really it hasnít. The quasars are obviously intrinsically wildly different from each other, and even change wildly in time. I forget what the maximum is now, but on the order of a week, a change in the factor of ten.
Weart:This is something that you simply have to attribute to Object X?
Greenstein:Yes. Or to more than one Object X. You look at the apparent rapid — superliminal, they now call them greater than the velocity of light — expansions (observed by) radio frequencies, one explanation is the so-called Christmas tree, where little lights go on in difference places. Itís a thing which I guess weíll ultimately understand. But by then, Iíd gotten sort of revolted, and wanted out of it.
Weart:Is it by the scientific feeling, or from social things that were going on?
Greenstein:Well, some scientific dislike. A thing so beautiful as this — this great discovery gets mired down in a myriad of details. And the details are obsessive. If you canít explain anything, you know, if really found something that was against the accepted laws of nature, from a quasar, and really believed it, you would really be in trouble! So you canít just disregard all the details. There is no obvious breakdown of the laws of physics. But every now and then you would feel, it seemed to me, assaulted by this terrible dread that — my God, itís really going to fall down this time! It was a great period, and I shouldnít say I disliked it. By the way, thereís a whole set of quasi-poetry.
Greenstein:Itís called quasi-poetry. In that volume, in the first Texas Symposium — (gets book from shelf)
Weart:Oh, thatís something I have to look at. I havenít gotten around to it. OK, Iíll look it up.
Greenstein:Yes. Quasi-poetry, itís called. Thereís half a dozen. This has nice introduction, on the history. Youíve seen that?
Weart:Let me see.
Greenstein:It has reprints of all the pioneering articles. The introduction, on history, is not bad. Itís wrong, but itís not bad.
Weart:OK. Iíll definitely look that up.
Greenstein:Yeah, here is some of the history.
Weart:I see. OK, well, I think this is enough for today, itís 2:30. How do you feel?
OK, weíll call it quits.
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