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Oral History Transcript — Dr. Jesse Greenstein

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Interview with Dr. Jesse Greenstein
By Dr. Spencer R. Weart
At Caltech, Pasadena, California
April 7, 1977

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Jesse Greenstein; April 7, 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 “Stellar Atmospheres” 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.

Transcript

Session I | Session II | Session III | Session IV

Weart:

I want to start with general questions on how you got into science in the first place. Your family background and so forth that brought you into that. I know you were born in New York City; I don’t know what part of New York City, I don’t know what your parents did.

Greenstein:

All right. You want to start on the youth and background. I was born in Brooklyn, in a then respectable neighborhood called Williamsburg. My grandfather was an immigrant from Russia in 1888 who somehow, by the time I was born, had become quite prosperous. He was in the furniture manufacturing business. He had a large family with about nine children. It was very much a family business; my father later became head of that. My grandfather and father, beginning I guess in about the 1920 period, went into real estate, construction and investment in Manhattan. I moved, I think, when I was three to Manhattan, but my grandfather’s house was still a family center, very much so. He was a remarkable man in many ways. I modeled myself more on him than on my father. Very strong personality. He looked like Teddy Roosevelt. He died quite young. But he had an extremely high regard for knowledge, learning, and especially for being an American, as a result of which he completely cut himself and his family off, as much as possible, from the Jewish background. He had come as a poor immigrant boy. He told me a long story of how he tried to set up in business with penny matches on a tray, and after that experience, he resolved he’d never work for anybody, and he would find the gold on the streets which the legend said New York was paved with.

So, by the time I remember anything, he had a good sized factory. He had a car in which I and multifarious cousins would perch and be driven by the chief teamster of the factory. They were still delivering upholstered furniture with wagons and horses when I first remember this. I remember World War I just vaguely. I, by then, had an interest in science and experiments. The family was a warm close one, with large numbers of people around in Grandfather’s house. He had somehow, though coming with no knowledge but Russian and Yiddish, no knowledge of English, become an omnivorous reader, and he had an incredible library, I think, considering. I really remember how it was. It was a brownstone house, and the ground floor was a library and kitchen. The whole floor was half kitchen, half library. He had books, all kinds of books. And he had books on astronomy. I remember the SPLENDORS OF THE HEAVENS[1], two big volumes, and Isabel N. Lewis, from the U.S. Naval Observatory, something about chasing eclipses around the world. Later — I don’t know how many years later — there were books by Karl Darrow. Darrow I think was a popular writer. Books about the wonders of chemistry, things like that. And my grandfather bought them. I think he read them. And I read them, beginning at the age of six or seven. I remember sitting in the bay window, half a floor down, to get the light, and reading and reading and reading.

Weart:

You used to go over there on the weekends?

Greenstein:

Yeah. It was, as I say, a close family. I was often there. I honestly don’t remember what age we moved, but I do remember still, till age eight or nine, being there quite frequently. My father was also in the same business, involved in it heavily, a successful businessman, and his interests were almost exclusively non—intellectual. But my grandfather, who was an extremely strong kind of person, had both. Obviously somewhere between being a penniless immigrant in 1888, and say 1912 or 1913, my earliest memories, he had managed to move out of the ghetto and completely into a different world. Though Brooklyn doesn’t seem a much different world, it was different then.

Weart:

How old were you, by the way, when your grandfather died?

Greenstein:

Oh, I was about 10—12, somewhere in that age range. He died very young. Let’s see, he was born roughly in 1870, so he couldn’t have been much over 50. The family as a whole was oriented toward both, call it, the trappings of culture, and the making of money. I had 20 odd cousins, and it was always assumed that they would be doing the same thing. So that, unlike most success stories where a poor fellow read his books by the light of fire flies in a cabin in Illinois and makes good I guess I’m one of the first urban drop-outs. I dropped out of that world to become a scientist, rather than into it. And I don’t regret it at all. But is this the kind of thing you want, the minor detail?

Weart:

Yes, this is quite interesting. I wanted to ask, what about your mother? What were her interests?

Greenstein:

My mother read more than my father, books, novels, history. My father loved biography and history, that’s the only thing he liked to read. The whole family had a strong tradition of charity. Since they were prosperous, and since they had changed so rapidly. (My grandmother could barely speak English, incidentally, my father could not speak Yiddish. He knew a dozen words, enough to swear at workmen or something, I guess.)

Weart:

Were you brought up in a religious atmosphere at all?

Greenstein:

No. Anti—religious. On the other hand, there was the at least pro forma for religion, and the respect for “the Book,” I think. It was just a different kind of respect, for knowledge; instead of being the Old World reading of the Talmud or whatever — it was changed. However, the impetus for charity, the absolute need to do something good, was a very clear bit of communication in the world family. I think my youngest aunt worked in what was then called the Henry Street Settlement in the ghetto.

Weart:

These are all in the family on your father’s side?

Greenstein:

Yes. My mother’s family, unfortunately, died very young, with one exception. I barely knew them. I knew my aunts and one uncle on her side, but just barely. So, she got very active in charities and became president of what’s called Hadassah and other things. My father helped found the Yeshiva College, which was then an Orthodox seminary. We have a picture of him with a silver trowel at a cornerstone—laying for Yeshiva University, which was then just a rabbinic school. They did it, I think, out of a sense of duty, not out of any great sense of belief. But they always belonged to things.

Weart:

Did any of this carry over into your own feelings, when you started to think about a scientific career? Did some of that idea carry over?

Greenstein:

Well, I guess the event proves the case. I’ve always had a great conscience, a feeling almost of despair that I don’t do enough for other people, and certainly the respect for learning, which is an hereditary thing for thousands of years, comes from that. I was active for a while in various charitable causes, when I first came to Pasadena.

Weart:

I was wondering, was there any feeling, when you began to think of becoming a scientist, that it was also in some way serving people?

Greenstein:

No. No, alas. I think I’m not — I think that’s just personality. I’ve never had a sense of needing to serve humanity, except in charity, where I can’t do enough for financial reasons. I happen to be interested in art mostly now, and I spend a good deal of money on it, I spend a good deal of money also in gifts to it. I just gave the Huntington Library about 400 items. And if they’re good enough to go to the Huntington, it meant that they were fairly good. I used to collect a lot of things. So, I don’t think I had any sense of dedication. I had a terrific sense of curiosity.

Weart:

At an early age you were reading various things omnivorously. At what point did you begin to think science might be particularly attractive to you?

Greenstein:

Oh, about — certainly between six and eight. When I was eight, my grandfather gave me a small brass mounted telescope.

Weart:

It was specifically astronomy that began to attract you?

Greenstein:

Well, that possibly most, but also radio. I had an early receiver, at the time of crystal detectors, and when I was in summer camp I heard my first voice on the radio, I remember. It was from Pittsburgh to upstate New York. And at camp, that I went to from about eight to ten, I founded the Interesting Topics Club, of which I was president and chief lecturer, with my little telescope as my guide. But I was relatively normal in other pursuits. I just felt that astronomy was fascinating. It was an accident. Chemistry was equally fascinating, in fact, and I set up a lab. Maybe you wouldn’t remember what middle class life was like in New York before you were born. We used to spend summers down at the Jersey seacoast, rent a house, a big house, and I remember — oh, I must have been 13, 14 — setting up a quite powerful rotary spark gap, a motor-driven thing, as a spectroscopic source. Because somehow I’d gotten a small spectroscope with a prism. I think it was Gaertner Scientific Co. or something like that, the kind you’d use, I guess now still, in high school experiments. It had a prism, and you measured minimum angles of deviation. You could see the lines. I tried different sources, by mounting these things on the rotator, and having it spun; and of course it was a terrific radio frequency generator. It was turning at, whatever, 3600 r.p.m., maybe 20 little pieces of metal around the edge: I was out in the kilocycles, you see, which was the radio broadcast band. I had a transmitter at my grandfather’s house, by the time I was 11, I remember. Funny thing, you see — I had the curiosity and I had the money. It’s a very odd thing, you know. Everybody else was self-made — struggles — and I just could buy things. Which is a little unfair, but it also made it a lot more fun.

Weart:

Yes. Your education really took place mostly at home?

Greenstein:

Well, this was in experimental science, you see. I couldn’t do it in my father’s and mother’s house in a New York City apartment. You don’t have a lab in New York City. I had a photo lab and things. I did everything. I graduated, I entered high school at 11.

Weart:

You entered high school at 11?

Greenstein:

I entered high school. It was a common thing to go smashing through. I went through the elementary schools in, what would it be? five years. I could have made it in four. I went to the public schools till then, with no opportunity to learn or do anything about science. But then I went to a private school called Horace Mann School for Boys in Fieldston.

Weart:

This is the same as the well-known Horace Mann that’s still there?

Greenstein:

That’s it. In Fieldston. Horace Mann used to be down —— it was first an experimental school for, I think, Teachers College, then a girls’ school, near Columbia, that’s now vanished. My wife went there, by accident, we never met. They’re separated by ten miles. But the Boy’s school was out in the country, and about half the students were permanently living there. The other half were day students like myself. They had a good chemistry lab, and by then chemistry was fascinating. There were popular books about chemistry. I guess it was also about the time of MICROBE HUNTERS by Paul de Kruif. You know, the famous single books.

Weart:

Yes, I know, I read that one when I was about that age.

Greenstein:

And I’m not sure if it was then or a little later, I never got interested. But chemistry was fascinating, and I made products out of chemistry sets, and I took a very good chemistry course, I remember, at Horace Mann, which is a very rigorous school. A poor physics course. The lab wasn’t as interesting — it certainly was not as interesting as what I was able to do. But I and several other people built a radio transmitter. A high—powered telephone for those days, with gigantic red—hot glowing tubes. And we had a Radio Club, and the older people could get a license. I couldn’t. We talked to Australia, I remember, which is about as far as one could go from New York — by voice. I’d been doing code for some years. Now, of course, this may explain somewhat why I was interested in radio astronomy. But it was just the ability to get a few things done and built, the way you got your hands in a lab situation, which was interesting and not just cut and dried.

Weart:

Were there any teachers that particular impressed you, any courses or books, at Horace Mann?

Greenstein:

That’s a story. If I ever have been in any way influenced by anybody, it was by a Latin teacher. Horace Mann started in the 6th or 7th grade, I entered in high school, the 9th. They required six years of Latin then, so I entered third year Latin with no Latin. The teacher, who was my hero, and I guess I owe him a lot, was what at that time seemed to be a very formidable World War I veteran named Ernest Nagel.

Weart:

The well—known Ernest Nagel?

Greenstein:

No.

Weart:

A different Ernest Nagel.

Greenstein:

Different. I got into the class fresh out of public schools, it was third year Latin, and he asked me a question. I didn’t know anything, so he threw me out of the class. I sat in the hall on a stool for that hour. So it turned out that in about two or three months I had to catch up on two years of Latin. It turned out I liked it. I still remember some Latin. He certainly was a person who impressed me with the necessity for hard work. Because having been relatively bright, and the elementary public school system having been too easy for me, I never had worked at anything regularly, except what I wanted to. And I had to work on Latin. He was extremely good. There was an English teacher, sort of a minor scholar, who got me interested in American literature and poetry. In the class there were two interesting people. One was Eugene O’Neill, Jr. And we had a very good dramatics club. I was stage manager, I didn’t act, I’ve always been a ham, since then. And O’Neill, Sr. came, watched us, preparing some of his one—act plays. I don’t know whether we did them first or not, honestly, but it was very early. Junior became a scholar at Yale, I remember. Then Louis Untermeyer, who’s an anthologist and poet — his son was there, and so again, we had a lot of exposure to contemporary American literature. It was sort of fascinating and untypical.

Weart:

So you were still far from being narrowly specializing at this time.

Greenstein:

Oh yes. I never specialized really.

Weart:

Before we forget, did you have brothers and sisters?

Greenstein:

I have one brother who’s about 11 or 12 years younger than I am. Unfortunately, for that reason, there was almost no contact. When I left New York to go to Harvard, he was three years old.

Weart:

I see.

Greenstein:

But we see each other. That’s the only one, no others.

Weart:

About going up to Harvard, did you expect from an early age to go to college? Was it in the family?

Greenstein:

Oh yes. It was inevitable. It was interesting, it was inevitable, but very few of my aunts or uncles, maybe two of my nine aunts and uncles, went to college. My father never finished high school. Of course, my grandfather had no schooling to speak of. Not in the American sense.

Weart:

When you first went to college, did you have any feeling for what kind of career you expected to have?

Greenstein:

Odd. I would guess that I was inclined toward science, but I had never thought of it as a profession. That’s the oddity, you see, that all of these things I had done were hobbies. I take and still take and drop hobbies rather intensely. And all this lab stuff that I had, there were playtime activities, if you like. I don’t think anybody thought of science as a career in 1925, when I entered college. I was 15 plus, and I guess I thought I would go into business and have science as a hobby, probably astronomy. I’d turned off chemistry by then. In fact, I did in my second year register in astronomy and take courses in astronomy, but I think, given the liberal nature of Harvard education —— it was the height then of non—requirements — I took more courses in English literature specifically than I did in astronomy. I took incredibly few courses in mathematics.

Weart:

Up to the time you graduated or all the way?

Greenstein:

All the way, even including graduate life. I took Osgood’s first calculus. I took one course with a man named E.V. Huntington, who was then lecturing about the early work on the postulational basis for mathematics — what you might call modern mathematics, which was just appearing. Oh, and I did take a course with Graustein, a little more advanced. So maybe I had, after the first year, two and a half courses in mathematics. My advisor was a physics advisor. There wasn’t enough astronomy, really, and –

Weart:

You would have chosen an astronomy advisor if there had been one?

Greenstein:

Yes, but astronomy’s senior person was an eclipse hunter named Harlan Stetson, who was always away up in Sumatra or somewhere after an eclipse. In fact, for two of my four years he was away, and I think the last of that, either my junior or senior year, I gave some of the lectures in the second or third year astronomy course.

Weart:

How did that happen?

Greenstein:

Well, I read books. And he was away. Harvard teaching astronomy then was very differently organized from now. It was isolated in a little building on Jarvis Street, what’s now the Law School campus. It had transits, a small telescope (maybe six inch), and taught practical astronomy, navigation, essentially nothing modern except descriptive astronomy. And toward, I think, my senior year, as a volunteer I gave some of the lectures in whatever course it then was.

Weart:

How did you get picked? Did you arrange it with Stetson?

Greenstein:

Yes; he was the department, in a sense. Except there was certainly by my last year — that’s a different story — a lot more contact between that and the observatory, which was isolated a half mile away, and didn’t have much to do with undergraduates and had few enough graduate students, maybe a half a dozen, if that.

Weart:

So you didn’t have any contact with the people at the observatory?

Greenstein:

No. I really was quite undecided up to my senior year, between literary criticism, which I was most interested in, and science. As I said, I literally did not think one made a profession of science. You know, it’s hard now, because kids decide they’re an astronomy major and that therefore they gotta have a job at a big observatory when they finally finish. I think I was going through, I was there during the birth pangs of American PhD Astronomy education, literally.

Weart:

I’m particularly interested because you were there at Harvard all through the period when they were first starting to build up the department?

Greenstein:

Yes. You see, there’s a big gap between when I left Harvard in 1930, and when I went back for a PhD. I got a Master’s at Harvard. At that time, it was back to the observatory.

Weart:

Yes. Before, you mentioned that in your senior year there was something different.

Greenstein:

By then as I remember it — in fact, I know it’s true, it’s a bit of American astrophysics history — by then, there were some good visitors, theorists — plus of course Donald Menzel who was there already and Cecilia Payne — interested in astrophysics. In my senior year — I’m sure it’s then, not later, it could have been junior, even — Harry Plaskett, who went to Oxford later, was there.

Weart:

As a visitor?

Greenstein:

As a visitor, maybe for a year or a half year. And he was literally the first time I had heard about theoretical astrophysics. It was the time of Milne vs. Eddington on stellar interiors. It was the first time when stellar atmospheres, beyond Henry Norris Russell, were talked about.

Weart:

And you heard about all this in your junior-senior year?

Greenstein:

Yes. I would say it was my senior year when I began going up to the observatory, that it seemed that this was really something exciting and new and very different.

Weart:

Did you find this by lectures or just talking with people?

Greenstein:

No, lectures. I certainly don’t know my academic schedule, but I’m fairly certain that I listened to all the general sort of one-shot lectures, and that I attended a regular course which was given by various individuals on the Harvard staff, which Shapley I think had just invented that year or the year before, where they talked about their specialty. And this if I may remind you was Cecilia Payne, a goddess and wonderful person —

Weart:

Already at that point?

Greenstein:

Oh gosh, she was marvelous. Of course, I don’t remember a great deal, in dates and numbers, but there’s an obvious way I can get the dates within a year.

Weart:

This is fine.

Greenstein:

Bok was there, and had written a thesis on the eta carinae nebulae, which I believe was in Dutch, incidentally. And Menzel was there. Plaskett was there. There was some kind of summer session, and I don’t know which year it was, either ‘28 or ‘29. I believe there was either a summer session or a symposium or a meeting to which I was invited, I think in Michigan, and I met Milne, who was visiting the United States.

Weart:

You went out to Michigan?

Greenstein:

Yes.

Weart:

Was this the University of Michigan Theoretical Summer School? They had summer schools in physics, I thought.

Greenstein:

Well, this either was that, or an AAS meeting or something special. I don’t even know.

Weart:

It’s interesting that already you were committed enough to go to Michigan in order to —

Greenstein:

— by the way, I hate to tell you, I could go because I could afford it.

Weart:

But also because it was attractive enough to you.

Greenstein:

Yes. And the question was: what would I do next year? Graduate year, 1929-30 first year. I’d more or less decided to go, [to graduate school] and I went [to Michigan], and Milne and I talked, I may have somewhere in my papers some scribbles by him, about the essence of his argument with Eddington. He said that stars had tiny little dense cores. I was much more theoretically-minded then, than later. I was fascinated, and he said he could get me dining privileges at University College in Oxford if I would come and work with him next year. I couldn’t get a degree, I couldn’t take courses for credit; American bachelor’s degrees were not recognized. But it would be good, and then possibly I could either stay on or go back. And that actually is what I had planned to do, in ‘29-‘3O. So I met Plaskett and Milne, and I certainly heard Cecilia Payne. We weren’t all that different in age, oddly enough. Then it seemed enormous — ten years. She loved poetry. We would quote T.S. Eliot, I knew even references to T.S. Eliot, I’m a T.S. Eliot buff.

Weart:

Your literary criticism side.

Greenstein:

I was really very torn. Cecilia was very unhappy at Harvard, and here is where I’m not unwilling to see this material open. Harlow Shapley was a great man, but he also was ruthlessly cruel. He used these women, beginning before my time — Henrietta Leavitt, Annie Jump Cannon he didn’t use, but he probably paid her $2000 a year, if that — and there were these three or four adoring, bright people. Adelaide Ames, who did the Shapley—Ames Catalogue. All these women were balanced against each other by Shapley — they were all in love with him, in an asexual way, but they were all dependent on his praise and devotion, and he would give them hell sort of once a month. Cecilia would burst into tears, and she would get hold of me, and we would read T.S. Eliot and talk about things. I really adored her and admired her. She was just great. She loved music, and I loved music. I really must say, hearing her, and hearing about compositions of stars, she — [gets book off shelf]— to get a date –-

Weart:

It’s inscribed to you. Jesse Greenstein, 1927, this is her STELLAR ATMOSPHERES[2].

Greenstein:

You see, that book is a remarkable book, to put it mildly.

Weart:

Yes, it’s a very well known book.

Greenstein:

And if you will think of it in the context of that period, — you see, I think this, and Donald Menzel’s ECLIPSE ANALYSIS, from those old Lick eclipse expedition plates, were the beginning of a Mexican astrophysics. And I had more to do with her than with Donald.

Weart:

I’m interested in the origins of astrophysics here. By the way, I should ask you, did you take many physics courses? Was this expected of people in —?

Greenstein:

I took the routine physics. I didn’t take enough. I took, oh, I guess it would be called advanced math physics, special functions and things. But I have one anecdote which I’ll be perfectly willing to see quoted, because it was typical of Harvard physics then. My physics advisor will have to go nameless. My senior year, some young dry fellow was coming over from MIT, I think twice a week, to lecture on quantum mechanics. J.C. Slater. They couldn’t hire anybody like that at Harvard. J.C. Slater was at MIT, and he’s a pretty good scientist. I saw this announcement, and I asked my advisor, “Don’t you think I ought to take Slater’s course for credit? Or at least go to it regularly?” I’m not sure even that it was given for credit at Harvard. It was its first appearance, that I knew as a student at least, of quantum mechanics. And since this Huntington course had been my first introduction to non-commutative algebra and things, it was sort of interesting — PQ minus QP is not zero. Quite a shock. And my advisor said, “Well, you know, these fads in modern physics, they come and go. I think quantum mechanics will be dead in two or three years.

Why don’t you take a good solid course in an unusual subject in physics, acoustics?” And I took a half year, I couldn’t stand more, on architectural acoustics. They made little sparks, and you could see the wave propagating through models of auditoria. They still can’t build a decent orchestra hall. Well, maybe they can, but it’s by luck. And I — idiot — took this, and I listened to Slater only about half the time. I took some notes. I didn’t take it seriously enough. I never knew any quantum mechanics. I never had any when I was a graduate student. I took what I would say is a routine classical physics thing, and not enough of it. Because at Harvard, you were required to take, say, three courses or something like that, four courses, in your specially to get a degree in a specialty. And I think I took that many in astronomy, certainly, and maybe I took two or two and a half physics courses.

Weart:

I see. So it wasn’t just in astronomy, but even in physics that the most modern things were not so necessary?

Greenstein:

It’s an incredible thing. A year or two later, you know, the world of atomic physics had just been revolutionized, and I missed those two years.

Weart:

You were just a little bit too early.

Greenstein:

It was fascinating, you see, to see the new things. Cecilia’s book on STELLAR ATMOSPHERES. [Looking through the book]. There are things about atomic transition probabilities, and the structure and temperatures of stars, the Saha equation — oh, Saha was visiting Harvard during this period.

Weart:

Oh, I didn’t know that.

Greenstein:

Either then or maybe my first graduate year. And Cecilia measured line intensities. Here’s Fowler and Milne quoted, the MONTHLY NOTICES’ 23—24. She was writing a book published in ‘27, which showed the first applications of anything with a quantum constant, except the black body formula.

Weart:

Were people talking about the idea of bringing in astrophysics?

Greenstein:

I think that must have been going on, but I was only a student.

Weart:

I see, so you weren’t involved in that.

Greenstein:

No. And the main work of the observatory was on photometry and spectroscopy, and that’s what I learned about.

Weart:

Were there any of your fellow students in astronomy that later on became colleagues or went on to anything? Anybody that you particularly worked with when you were a student, studied with or whatever?

Greenstein:

Oh, well, as an undergraduate, one fellow—student has the remarkable distinction that he started Ed Land in the Polariod business by putting up the money. A man named Wheelwright, an old New England family. I forget his first name. But this was later. Well, this may have been how Land and Menzel eventually got together. But in any case, he has distinction. He’s alive, actually, an old man. He lives in Nevada on an enormous ranch now. The other good undergraduates, probably not. It was when I was in graduate school, later, that students became well—known, successful, and dominated astronomy for many years, as you know.

Weart:

Let’s see, now —— you went on and in 1930 took a Master’s at Harvard?

Greenstein:

Yes. Well, I didn’t go to Oxford because I had tonsillitis and had to have my tonsils out, in September or October or something, just before I was supposed to go. So I went back to Harvard, and lived at the Hotel Commander, if you know Cambridge, in an apartment, with a first-year law school roommate. We brought a Rolls-Royce together, an open pre-World War I car, which would be priceless now, and sold it for what we paid for it, even though we were by then in the Depression.

Weart:

Now, by this time you had made your decision?

Greenstein:

Yes. By then, it seemed to me, astronomy was a profession and one I could afford.

Weart:

What kind of career did you imagine you would have, did you see yourself a teacher, or looking through telescopes, or?

Greenstein:

That’s a difficult question. It seemed to me it was fun to be an astronomer I guess a theoretician. It was fun to be a Harvard astronomer. I guess I would have dreamed of becoming a Harvard faculty member, with a house next to the Longfellow House on Brattle St. That was what one wanted to do. It’s not a dream I ever wanted to pursue, later. But I guess it then seemed that there were enough astronomers, there were some of them making a living, and I didn’t have to make a living.

Weart:

What was your family’s attitude towards this career choice?

Greenstein:

At that time, in ‘29, it wasn’t too hard. It was better than my being a poet or a literary critic. During all this time, (I don’t know if it’s of any interest but it just shows how one can stay split) I was very interested in modern literature and art. I brought some. I collected experimental magazines. I had lots from France. I have —— except for some of the stuff I gave the Huntington just now — a complete set of autographed presentation copies of everything by T.S. Eliot, and by lots of modern and much worse writers. At this time a literary magazine called HOUND AND HORN was founded by Lincoln Kirstein, you may remember, a New York City Ballet founder — he’s a very wealthy fellow — and another friend of mine named Bernard Bandler. I was involved in the founding of that and other little magazines, and I collected them. I’ve just given the remnants all away (I sold some of it some years ago). And I knew writers. Certainly my best friends were writers, or people in literature and art, rather than in science.

Weart:

Why did you make the decision the way you did?

Greenstein:

I don’t know. It’s an interesting problem. It could have been either way. Once — I have a nasty story — I wrote what I thought was an absolutely great senior thesis on John Donne. The professor was a man named Mathiesen, and I got it back covered with all kinds of scribbles about “purple prose” and “lurid exaggeration” and “no scholarship here” — He was an orthodox scholar, and I had some romantic idea about the relation between poetry and knowledge, philosophy, and so forth. It was a very weird time. I always regretted that I couldn’t be both. Last might, if you want to know, I read KING LEAR, in a Caltech play reading group which my wife founded in 1951. I’m still a mixed-up kid.

Weart:

You haven’t completely abandoned the humanistic side.

Greenstein:

No, no, I’ve always been very interested in that side of culture. You know, mine is atypical; your other witnesses will be better, because I looked at Harvard so differently. I liked the people in the department, the senior year. It turned out that I wrote a paper about the colors of B stars, my first paper, published in 1930.

Weart:

The first paper in your bibliography is “An Investigation of Systematic Errors in The Tabulated Colors of Stars”.[3]

Greenstein:

You know what that is? I discovered interstellar reddening.

Weart:

I was looking at that paper and wondering —

Greenstein:

That’s what it is. And you know — this is of course hindsight — Harlow Shapley when at Mount Wilson claimed that space in the Milky Way was very transparent, because he had found distant blue stars in the Milky Way plane.

Weart:

Right.

Greenstein:

His photometry was no good. That’s all. Just plain wrong. When he saw my results — it was a small enough place, you know. Somehow I think somebody said, “You know, because there’s astrophysics now, they’ve done a systematic survey of these stars around the sky, Hertzsprung’s color –-“

Weart:

Right.

Greenstein:

And I found a systematic error.

Weart:

Dependent on the latitude?

Greenstein:

Well, if you think of it, it’s right ascension, which, if you observe the middle part of that declination zone of the sky, you’re crossing the Milky Way, right —

Weart:

Right, and then you’ve got galactic latitude —

Greenstein:

That’s right. And if I’d looked at it, it was a really big effect, I would have said, “This is real.” But Shapley, of course, being an authority — and that’s the great lesson of science, as you know, never believe anybody who says, “It is well—known that…— since Shapley had said there were faint blue stars in the Milky Way, this could not be.

Weart:

Was this something that took place directly between you and him?

Greenstein:

Yes. Oh yes. I didn’t say it was interstellar reddening. I said there was certainly something going on in the Milky Way, and he said it couldn’t be, because stars much much more distant, that he’d worked on, were blue, and therefore there must [be something else]. People saw these black clouds in the Milky Way. Of course there’s some local absorption and reddening, but in general, no.

Weart:

What Shapley said, did this affect what you believed, or did it affect just what you published?

Greenstein:

By then I was 18, 19, something like that, and so it affected what I believed and what I published. And being clever, in a kind of morbid way, I dug into the question of whether there could be systematic errors. It turned out that I invented the idea of continental air masses having different extinction, because Carl Rossby, the man who invented the air mass concept, was then at MIT. It was all brand new, and being very much interested and affected by what’s brand new, as we all are, it was obviously an air mass affect.

Weart:

I’m interested in how you came to that problem; in the paper you thank Plaskett and Cecilia Payne?

Greenstein:

Because they were interested in the calibration of the temperature of the B stars. Plaskett’s father had worked on the B and O stars in binaries, they were the most luminous stars. Yet the mystery was that many B stars have the color of the sun, and are rather bright ones. There are stars near the naked eye limit which are redder than the sun. How can that be? Now, their temperatures, from astrophysics of that time, were over 20,000 [degrees K]. Their color temperatures were 6000. That’s why I did it. And then I get turned off by the great man! I believe Cecilia had also thought of interstellar reddening, and been persuaded not to believe it, earlier at Harvard.

Weart:

What kind of relationship did you have with Plaskett?

Greenstein:

Very nice. He was there long enough that he really taught me some astrophysics. The rest I was just reading loosely. And as I said, for some reason, I don’t know the details, I never got into Menzel’s orbit. Partly because of one of Shapley’s great sins, he set Cecilia Payne and Donald Menzel at each other’s throats.

Weart:

How did he do that?

Greenstein:

If you want the dirt, there is dirt — he would tell one that the other had said, say, A is told that B had said that A’s work is sloppy, bad, wrong. Then he would go back to B and say that A had said B’s work was wrong. They found it out rather late in life. But there was long, bitter cleavage. And it’s one of the reasons, in a sense, that Cecilia left astrophysics.

Weart:

What was Shapley’s motive in doing that?

Greenstein:

To be Latin, “divide et impera,” divide and conquer. He kept the place separated and all concentrated on himself. He was a very vain man. I’m a very vain man, but the one thing I do not believe in is internal discord in an institution. He loved it. It gave him a sense of accomplishment. Also, by the way, he had then turned to galaxies already, the Shapley-Ames Catalogue. The Harvard Patrol plates had covered the entire sky. Galaxies were important. Incidentally, when I was still an undergraduate, Shapley was stuck with the idea that galaxies were local. That we didn’t live in a galaxy, but in a lot of little galaxies, together in what was called a super—galaxy, and that Sagittarius was just the center of a cluster of local galaxies. That’s because he didn’t believe in interstellar absorption. The so-called Kapteyn universe, from star counts, or even from Herschel’s star gauges, showed that we lived in a small, highly flattened system, centered on the sun, a few thousand light-years in diameter. Shapley had shown that the globular clusters were a hundred thousand light-years or more away. How could this be? Well, you had a lot of these small galaxies and their collective mass controlled the globular-cluster system.

Weart:

Right. Were you familiar with this?

Greenstein:

Oh yes. That was the Gospel.

Weart:

Well, when people talked about this, you were interested in these problems?

Greenstein:

Yes.

Weart:

Tell me, at this point, as an undergraduate, were you also encountering cosmological problems?

Greenstein:

No. Cosmology had not yet hit. Anyway, it was something that Edwin Hubble was doing.

Weart:

Right.

Greenstein:

That wasn’t Harvard.

Weart:

There was an antagonism, then?

Greenstein:

I think Shapley and Rubble were not the best of friends. I would agree with that statement. Shapley left Mount Wilson to come to Harvard. Rubble did the great work, [at Mount Wilson]. And there was a kind of separation. I heard about the expansion of the universe. It was eight or nine years old, I guess. Now, as to relativity — special relativity I had heard about. Sure. But you see, the physics that went into astrophysics then was pre-nuclear physics, pre—stellar interiors, except in a formal sense; it was stellar atmospheres, and therefore involved quantum theory and Boltzmann, Planck, Saha, and the structure of atoms. I met Russell some time during this period, he was Shapley’s teacher, and I heard about atomic structure, you see. So that much of quantum theory, if you like, was there, but it was the pre-Schrodinger equation type of thing. Four years later, the world had changed.

Weart:

Well, maybe we should press on. But first tell me, from 1930 to 1934 you didn’t do astronomy?

Greenstein:

No. My family went bust. From being a millionaire’s son, I was caught up — since it had been a close family — in family pressures. Since I was apparently one of the brighter and one of the older of the many cousins of the next generation, it was expected I would go into the family business, and not fiddle away my life on poetry or art or astronomy.

Weart:

This was expected even before?

Greenstein:

It was expected, but they were resigned to it; but when there was trouble, they were not any more resigned. It might not even have been practical. They went bust. Lost lots of money, millions. The furniture business was closed down. They owned stores. A lot of the real estate was in trouble. My father was a bank director, and the bank was closed and never re—opened. So there was a great deal of family pressure, and since I was very fond of them, had been very well supported, it seemed to me a good idea at the time, after 1930, to go and set them right. I didn’t know what would happen. I mean, I did not know whether I would go back to science or not. If it succeeded. It took a long time. That’s very personal business. It was hard to decide; I think it was a good idea.

Weart:

To take a few years off?

Greenstein:

To take a few years off. After all, it was 1930, and I was not yet 21 when I got my Master’s. Had I gone on at normal speed, I would have had a PhD by 1933, and I wouldn’t have gotten a job. But it also was good for me, because of my defects that now I understand — I like people with money. I know how to get along with them. I wish I had some. But it doesn’t hurt me to speak to rich people. It’s helped me in money raising. It’s helped me in popular talks, popularization of science, representing my university to the world. Business experience wasn’t a bad thing. But during the time, it was dreadful, because I went through these stages of the Depression, which I guess to me, emotionally, had its most intense moment when the banks were closed, 1932 was it?

Weart:

Yes early ‘32.[4]

Greenstein:

We had an office on the 21st floor of a building, on 41st St. and Broadway. I looked down, there were people all over the streets. Everybody was walking. The business area, the office... [off tape; several minutes lost]

Weart:

I think the significant thing in all that is simply that you had to leave astronomy and you had a hard time of it in the family’s real state business.

Greenstein:

Yes.

Weart:

How did that come to an end?

Greenstein:

Well, there are fascinating things. You know, Roosevelt closed the banks in ‘32 [i.e. 1933]. By ‘33 [i.e. 1934] we were making money.

Weart:

As you say, you went down and up with the Depression.

Greenstein:

Yes. And what happened was that we were mostly in finance, not real estate. We did operate some buildings and manage them, but mostly, if you had a thousand dollars then, you could buy a building worth $100,000.

Weart:

If you had the thousand dollars.

Greenstein:

In cash. And we diddled and dangled around, and I believe — I don’t remember the exact thing — I only worked half time in the real estate business, in ‘33. ‘34, because I worked as a volunteer worker at Columbia.

Weart:

A volunteer?

Greenstein:

Yeah. I didn’t get paid.

Weart:

A volunteer worker in what?

Greenstein:

Astronomy.

Weart:

Oh, in astronomy?

Greenstein:

Well, the story has merit because it involves a great man whom I admire enormously still, and that’s I. I. Rabi. I kept knowing people, I guess, because I had these other interests. I knew a philosopher of science, I forget his name. And at his house one day, I met Rabi. Rabi asked what I was doing. I said I was in the real estate business. He said, “I thought you were a scientist?” I said, “Well, I wanted to be. No money in it,” or “I can’t be.” He said, “Oh, come on. Want to work with me? Want to work in my lab?” I said, “What are you doing?” He said, “Oh, I do things with magnetic fields. I’m able to show that atoms have different momenta,” or whatever it is, with the spin up and down.

Weart:

Right.

Greenstein:

It was the first beam separation business. Like Davison and Germer, but a different experiment. “You want to work with me?” I said, “Well, what will I do?” He said, “You’d wind magnet coils, and you’d take data, and you’d have to work with vacuum systems.” I said, “Hell, I never did any of that. Is there anybody in astronomy up at Columbia?” He said, “Well, there’s this old Dutchman,” (a very conservative and actually non—productive astronomer) “named Jan Schildt.” He said, “He probably has something. I’ll introduce you to him.” Rabi was never a shy person. He never has changed. This was ‘32 or ‘33, I forget. I don’t think he’s changed in 45 years. The next thing, I found myself there, and Schildt had some photographs of historical interest, since they were the first – wet-plate taken with a Columbia University telescope by a man named Rutherfurd. And they needed measurement of something interesting on one of them. I did that. Then he had a big collection of plates on variable stars that Shapley had taken, but had never measured, a globular cluster, and would I like to measure it? So I would go up sort of three or four half days a week, and nights. It was very interesting, because at that time, W.J. Eckert had the first enormous assemblage of mechanical IBM’s.

Weart:

I didn’t realize he had it that early. That would be around ‘33 or ‘34?

Greenstein:

Yeah. In the sort of astronomy department, there was a big lab, and it seems to me, about a dozen of these mechanical things that went “chung chung,” with punched cards. They did things mechanically, adding, multiplying. And he actually ran, I think, as an experiment, the motions of the planets from the year whatever it is to the year 2000 on this.

Weart:

Did you have any contact with or make any use of that facility?

Greenstein:

No, I didn’t, but I got to be pretty good friends with Eckert. What I was doing was not dreadfully amenable to that kind of thing, except that you could store information on the cards. What I would have needed — these were light curves, of rapid variables in globular clusters. Thinking of it later, I asked — I saw him on and off — I said, “Could we have done Fourier analysis of the data in those days?” And he said, “Yes.”

Weart:

But you didn’t ask him at the time?

Greenstein:

No. Because see, he was using all kinds of sines, cosines, of the nth order, and in the various arguments of time to represent planetary motion. And I don’t know about inverting the problem, it’s harder. But he was predicting it.

Weart:

Tell me, I’m interested because it’s part of the history of computers, which is also something that we’re interested in — what was Eckert like at this time? How did he fit in with the astronomers?

Greenstein:

Well, unless I’m mistaken, he started purely as an astronomer interested in planetary motion. You may remember that the greatest figure in straight, orthodox Newtonian mechanics of the solar system was E.W. Brown. Before that, was Hill, a real pioneer. And they developed the theory of the motion of planets, in these enormous series of sines, cosines, etc. of all kinds of things, like the beat periods between two planets. The amplitudes of these terms could be hand computed, and I may be maligning Brown, Brown did it to say 700 terms, and it turned out there was an error in the 40th term or something, and all the others were wrong. That’s libelous, but work like that. It was very hard. And the analytical theory was extremely hard— it was the general problem, N bodies, perturbation theory. Eckert, I think, came to computers because they existed and because he was interested in doing these things, only not in the analytic mode. He still expressed planetary positions in formulae, but now he could really do point—by—point integration. They had to put the effects, the forces from all the planets in. I think that — I remember in fact, this, must have been much later, — IBM set up a lab, just around the corner from Columbia, on the street that goes down to the Hudson River from Broadway, 116th St., and he moved over there. I met him later and said, “What are you doing? Are you going into industry or business?” He said, “Well, it’s a great opportunity, because they’ve got these much more modern computers now, not relays, but elementary electronics, vacuum tubes –-“

Weart:

This is after the war.

Greenstein:

Yes. And so he dropped out, it you wish, of planetary motions, of which he was always fond.

Weart:

He thought it was a great opportunity as a commercial opportunity?

Greenstein:

No, no, a great opportunity to do things. He began it in the Columbia years that I’m speaking of, (and I left in ‘34), he was doing it because IBM was interested in what could be done with arrays of big computers — big — for then and for him, they were a thing to do for applications to all kinds of sciences, including planetary science.

Weart:

And to people like Schildt and so forth this was a very legitimate thing?

Greenstein:

Yes, well, Schildt — I think maybe Eckert was even on the faculty, I’m not sure. But Schildt was interested in it also for another reason. Schildt was interested in stellar motions, and parallaxes and things, and it was a way of reducing lots of data, with more terms in the equations that you could do conveniently on a hand-cranked desk computer. So both of them, I think, saw the computer as a tool of science. I never learned how to use these things, because they were then extraordinarily complex. They had patch boards, in which you plugged from one to the other with telephone cables, like they used to put in old-fashioned switch boards, that kind of thing. So to change anything, you’d have to first lay out the program, such as it was, and then literally change hundreds and hundreds of wires — maybe 50 connecting each one — and they would do a single problem, it meant lots and lots of work. I may have even helped, doing things from an instruction sheet.

Weart:

You had enough contact with it to see that it was quite formidable?

Greenstein:

It was formidable. It was awkward. It was certainly nothing like a little desk computer [pointing to modern desk calculator nearby], where you press a button. But it was very promising, and it was interesting that nobody took it up, in other fields of astronomy, till the war.

Weart:

Did Eckert try to recruit people? Did he try to get people interested in what he was doing?

Greenstein:

Well, I don’t know if he had any assistant. Maybe he had some paid student assistant. I don’t think there was anybody else there who was interested. I don’t know if the physicists even knew about it. That would be interesting to ask — Rabi would know. Rabi said about Schildt, many years later when we got to be personal friends, that Schildt was one of the nicest men he knew, and one of the poorest scientists. Schildt later advised Rabi that there was no point in looking for the hydrogen line at radio frequencies in interstellar space. By then the spin—flip business — which Rabi would be interested in, the change in energy level of hydrogen in its lowest state — had been found. It’s energy was roughly known. And Schildt said there was no point in it.

Weart:

You wouldn’t find it?

Greenstein:

Well, it wouldn’t be much good for astronomy, as he saw it.

Weart:

I see.

Greenstein:

The contrast, if you skip backward — Shapley asked me on my oral exam how I would find hydrogen in interstellar space, except in gaseous nebulae? My thesis was on interstellar dust. And I said, “Well, hell, there might be some low level of ionized hydrogen emission lines in between the dense clouds of gas but if there were neutral hydrogen it would be impossible.

Weart:

Let me ask you one more question about Columbia. Did you have much contact in general with the astronomy department there? Was there a sort of astronomy group, or students?

Greenstein:

That’s all there was. No, all I did, since I was still in business, I’d go up, odd hours, when I could, and measure plates. I forget when I published that paper on the variables in Messier 3.[5]

Weart:

You didn’t feel that you were on the fringes of some active group, or —

Greenstein:

No. I enjoyed Eckert. I don’t know if anybody’s told you about him. He was one of the nicest persons, as a person. He was very human, extraordinarily modest, serious, wry, you know, just a little humor, non-vain. He was just one of the kinds of people scientists ought to be. And he stayed that way as long as I knew him.

Weart:

OK. Well, this takes us up to 1934 then and your return to Harvard.

Greenstein:

Well, in early ‘34 I made a lot of money. My father was out of the doldrums. No, early ‘33. I decided I wanted to get married, which I’ve not regretted, and I decided to leave business, because, one, I was actively interested in astronomy, from the work I was doing at Columbia. Next, I didn’t have to stay in the bloody business any more.

Weart:

Business it was back on its feet.

Greenstein:

It was going. And I wasn’t helping it all that much. My father was a little Napoleon of finance, and it was up to him, sort of. The pressures that had existed, the family kind of guilt or something, vanished. And from then on, in fact, I felt no guilt in living off my father, or from my little accumulated earnings.

Weart:

Your father didn’t put pressure on you?

Greenstein:

No. I told my father-in-law to be that I was going to marry his daughter, which he had sort of expected; that I was going back to astronomy at Harvard; and he said, “From the gutter to the gutter in three generations. “But he –-

Weart:

— was he serious?

Greenstein:

No, that was a humorous remark. He was a prosperous man who had an extraordinarily high regard for knowledge and learning, except that he was religious. He would have preferred it if I had become a rabbi, but if I was going to be an astronomer, it was just as useless, and therefore worthwhile. No, both of them supported us, one way or another, for 10, 12 years.

Weart:

How did your wife feel about it? She knew you were going to go back into —

Greenstein:

Oh, she wanted it. Her family stayed relatively prosperous through the Depression. They lost a good deal of money, but they weren’t hard hit. And she had been at college, Mount Holyoke. We’d met each other eight years earlier, down at one of these beach clubs on the Jersey coast. It was an off again, on again romance. Nobody went steady in those days. It was the Jazz Age. She indicated quite happily that she wouldn’t mind being in a university world, and it seemed to her in fact a great idea. We were married for about half a year while I was still in business. But the decision had been made by then. By the way, I’ve only gotten to 25 years, out of a lifetime — that’s too much. Anyway, we had a complete agreement on that. We were fortunate in that both of our families could support us. When I went back to Harvard in ‘34 to a summer school, I earned $70 in a summer. So it was clear that student support wasn’t going to be a thing that I could live on. As I said, I have an atypical background even the school I’d gone to probably had never produced a science graduate in its history.

Weart:

Which school?

Greenstein:

Horace Mann. It did later.

Weart:

Later on it did.

Greenstein:

Yes. Eric Barnouw, whom you may know, good writer, came from there, and I knew Eric and quite a few others. But the idea of going into science, instead of law or the arts or something, business, was unheard-of. They didn’t oppose it. I think I lived at a break between when science was an amateur’s pursuit, and when it was a profession. Any by ‘30 odd, ‘34, onward, it became a profession for people.

Weart:

You said before that when you went back to Harvard, you found it was quite different.

Greenstein:

Oh yes. Life had changed. First of all, the Menzel school of astrophysics was in full bloom. And the importation of Europeans for the summer was going on. I met Unsold at Harvard. I met Antony Pannekock at Harvard. There were the first refugees, or rather Europeans. The Europeans brought astrophysics to Harvard, and Shapley earned enormous credit for having done that. He brought in Kuiper, whom I first met at Harvard in a later summer school. So almost everybody great appeared. The decisive thing, I guess, in my particular world, was Rupert Wildt who showed up at Harvard summer school and talked about the negative hydrogen ion, which solved all the problems of Russell and Unsold about the composition of the sun — the hydrogen-to-metal ratio changed by 300, overnight.

Weart:

Right, it makes it all hydrogen instead of no hydrogen.

Greenstein:

Right, and you see, Rupert, for example, was just doing Saha equations, but in chemical physics sort of, rather than in atoms and electrons and ions. Menzel had been, or was preparing maybe for that famous Russian eclipse expedition, and the place was full of excitement and life. And there, in I think — well, I know it was the first summer school — ‘34, I left my new wife in New York for three months — I and Leo Goldberg rented Menzel’s cottage, out in the country. He had a nice house by a little lake, there was a tiny little cottage, and I and Leo and one other student who has since disappeared into industry rented the house. Little cottage by the puddle. I think Leo was a brand new student, or maybe he was a year ahead, I forget — he’d come from somewhere else, I don’t know. Jim Baker, and Lawrence Aller were there pretty soon, and the world was — you know, a different world.

Weart:

How did you people interact? Did you meet a lot after hours, or at the observatory and seminars? Where did you exchange ideas with people?

Greenstein:

I guess we’d have to say that the world was so new and so exciting that we talked all the time. There were many good new institutions. Shapley was very sociable and had these parties. That’s one part of it. The other part of it is, he had this facility for being interested in everything, so he instituted, not seminars, but micro-seminars, where people would talk for five minutes or ten minutes once or twice a week during the summer. And there would be all these summer lectures. I went to all of them. I met H.P. Robertson, who became my best friend for many years, at one of these. So all I told you bad about Shapley has to be matched with the fact that in three or four years — well, really, it must have begun by ‘30, when I began to go to the observatory.

Weart:

You were starting to see it then.

Greenstein:

Suddenly, modern astronomy hit Harvard. And Cecilia, however, had started it, almost ten, ten years earlier, and had been squelched.

Weart:

By Shapley?

Greenstein:

By Shapley. The situation also was that there was a great deal of mass production of information in newer areas, like galaxies, and like some high dispersion spectra which had been taken, I think, with one of the Harvard telescopes, with an objective prism. For the first time it wasn’t Annie Jump Cannon’s little spectra, but these were big things, and you could see that there were quantitative things to be done.

Weart:

Now, did you get to your thesis topic? Your thesis was on interstellar absorption. I guess that would be your first —

Greenstein:

Well, you see, what had happened in between, by the way — Trumpler had discovered interstellar absorption and reddening and that turned me on, because I had discovered reddening. This is informal history I really hadn’t.

Weart:

Well, you’d seen it —

Greenstein:

I was a kid, I’d seen it. And other people had seen it. And there was some theoretical work already by Schalen of Sweden, who’d done a lot of computations. Also there had been photoelectric observations. The beginning of photoelectric astronomy was in this period, in Pasadena, mostly, by Whitford and Stebbins, who found, to quote Joel Stebbins, “If you’re looking for a B star in a crowded field, you pick the reddest star.” So it was known that the reddening existed, and there were then questions about ratios of absorption to reddening. And Bok’s interest in star counts, work on dark clouds; he had this stable of not very bright students counting a million stars at a time. He had to do something about interstellar absorption and the structure of the galaxy. It was then to be a tool — reddening, measured accurately, was a tool to get absorption, which was a tool to study galactic structure.

Weart:

So nobody assigned this to you as a topic, you just came upon it?

Greenstein:

The first idea was that I would count stars. But I was not interested in that.

Weart:

For Bok?

Greenstein:

For Bok. Bok was a more attractive person to me, as a person, though Donald Menzel was marvelous. Bok was a lot easier to get along with, and had lots of ideas. I still, I think, hurt a bit from my past, and the idea was that I could do theory, which involved computing, or I could do observation. And my thesis was both, and I think it was the first determinations spectrophotometrically of the ratio of absorption to reddening, for the B stars.[6] I did the theory, and the fascinating thing about the theory in my thesis is that, looking at it now, it was the Schrodinger equation, modified slightly. The same damned functions for the hydrogen atom come in for the dipole and multipole scattering. I was much more theoretically inclined then. I started really with theory, the idea of Milne.

Weart:

I wanted to ask you about that. As I went through your early papers, there’s a tremendous amount of interaction between theory and experiment. Did you first see yourself as a theoretical person?

Greenstein:

Yes.

Weart:

Why was this?

Greenstein:

I think that’s how one started then, because frankly, let me say, the excitement I just mentioned — those who I met in ‘34 to ‘37 in the summer schools, Robertson in relativity, who took me to meet Einstein, Wildt with the fundamental discovery, of the negative hydrogen ion, Unsold, whether Saha then or before, — Oort — and galactic rotation, my gosh! Kuiper, not so much. But these were pretty powerful characters. And theory was really beginning to make a difference, and it seemed logical for me, though I really felt from the beginning my own serious deficiencies in physics and mathematics. And of course, when I said the thing I had to do for my thesis was a lot of computation — it was on a hand-cranked Marchant or Monroe or whatever, and it was a lot of work. But I recognized, and it really is startling to me now, that the expansions that one does for these boundary value problems, on small particles, are exactly the dipole, magnetic dipole, electric quadropole etcetera solutions for atomic and nuclear physics. Just a few terms. I should have put it in quantum numbers. Didn’t need ‘em. So I started work really as a theorist, but the fact is that there were not enough known facts. Take interstellar absorption. There were these two data points, blue-to-visual measures, of the color of stars photoelectrically. A lot later they did six colors. Measuring the spectrum, you get a lot of colors, and what I’m still doing in spectral photometry of stars, with 120 points on them, with modern equipment.

Weart:

So at this point, is this correct — you came to your observations from the theory side? You were interested in the theory, and you had to get observations?

Greenstein:

For example, I was later interested in galactic rotation. And you didn’t know the distances of the B stars, because of reddening. There were just so many obvious gaps, where just a little — it seemed at first — just a little information and observation, and all the problems would be solved. I just felt, well, OK, I’ll spend a certain number of nights outdoors, and you get the facts, and then that will clear up the ratio of absorption to reddening. It’s still worth clearing up. But the method was good, and the answers were good, relatively good. And the computations were not matched till World War II, with the bigger computers. A man oddly enough from Columbia, Victor LaMer, did large particle absorption and scattering, for the theory of smoke screens, of all things. Dispersed or drops.

Weart:

During the war.

Greenstein:

Yes. But by then, the computers were big. The computers work was classified.

Weart:

Right. By the way, during this period, 1937, your paper with Whipple on Jansky.[7] You may have old this story to other people, not sure, but I’m curious how you got into the problem. (off tape)[8]

Greenstein:

The extended atmosphere theory predicts lots of funny things, and one thing it predicts is that the limb darkening, if you could see such an object, would be very peculiar. Say if you looked at the sun, for example, if it were expanded, you’d see a very hot center, and you’d see an infra-red limb; because of the 1/r2 part, the flux isn’t constant. Well, oddly enough, Cecilia — Cecilia Payne — Gaposchkin by then — and Whipple had worked on the theory of supernovae, and I was interested in the radio thing; and I knew stellar atmospheres by then, I could understand this. And it appealed to me because of my interest in interstellar dust. If the center of the galaxy had as many stars — more, as we know it does — but had as much dust, which it doesn’t — then it would be a super super star.

Weart:

Right.

Greenstein:

And that’s what [we thought] Jansky was seeing.

Weart:

Right.

Greenstein:

And so with Fred, [Whipple] who was I think either an assistant professor or instructor, — very accessible guy — I got to this, and we worked it out –-

Weart:

With Fred because he had been working on theory?

Greenstein:

The interesting thing — maybe I ought to emphasize it: Harvard, though it was big, was a very internally communicative place, and everybody knew everything. I was not the best student in the world there. Certainly Leo Goldberg was a better theorist than I, by far. He was working with Menzel. But Fred was independent, and I was interested in dust, and we thought then that interstellar dust and meteors had something to do with each other. So we cooked up this idea. We worked the theory through correctly, and we predicted that what Jansky had observed was in fact the center of the galaxy. And there was such a big to—do about this that they got the public relations office in, and a reporter from the BOSTON EVENING TRANSCRIPT came and talked to Fred and me — “radio static explained by two young Harvard people” — But just before the scientific paper was to appear, and the newspaper announcement, we went — I don’t know why, just cowardice — to see an electrical engineer named George Washington Pierce, and asked him, how do you convert from these units microvolts per meter of Jansky’s? To ergs per square centimeter per second per Hertz? He looked at us as if we were idiots, and he said, “The permittivity of free space, blah blah blah…” It turned out that we had left out I think c/4π We were wrong by 10,000, and that was the truth. Because we’d gotten I think the central dust up to 5 or 800 degrees temperature, squeezing conditions very hard, and the equivalent brightness temperature is really in the hundreds of millions of degrees, the source is non—thermal. Of course, Fred got sick, physically. I got pretty distressed. We stopped the press release. We stopped the technical paper, then rewrote it. And the Boston paper came out with, “Two young Harvard astronomers fail to explain cosmic static.” Let me tell you, that was a trauma. And that has put radio astronomy into my heart forever.

Weart:

In a positive way?

Greenstein:

Yes, I mean, first of all, it was pretty incredible that —— we hadn’t got very far, all a thermal source could reach degrees. If it’s optically thin radiation from interstellar space you could get it to 10,000 degrees, which I helped show after the war, at Yerkes —— you ain’t gonna get hundreds of millions of degrees. You’re not going to get the trillions of degrees of a solar flare.

Weart:

Right.

Greenstein:

You see. And the non-thermal idea was never followed, or thought out.

Weart:

You were still trying a black—body law explaining where it came from.

Greenstein:

Right.

Weart:

I was interested in looking at the paper, you probably haven’t looked back at it —

Greenstein:

No, I have not.

Weart:

The last sentence of it, near the last sentence, says that it’s particularly necessary to investigate more thoroughly the actual dependence of the received intensity on wavelength, “a problem which is now being attacked by one of the authors.” Does that ring a bell? Were you or Fred intending to investigate the dependence?

Greenstein:

What date is that paper?

Weart:

‘37.

Greenstein:

That’s before Harvard radio astronomy operated. I guess we had some fantasy — I don’t know, now. That’s interesting. It certainly was never done. A hope that we would probably work with the radio, electrical engineers, but that year I left Harvard. It was never done.

Weart:

I see. It would have been interesting. OK, let’s see now, have you more to say about Harvard?

Greenstein:

Harvard was a great place, and stayed great, and as you know, the people not only from Menzel’s group, many from Bok’s group, from the later radio astronomy effort, became leaders. Part of it is its sort of vivid communicativeness, which Shapley did give. And so, though I’m extremely against Shapley — and not only for what he did to me, but what he did to Harvard, he destroyed it —

Weart:

— “What he did to you” — in what sense?

Greenstein:

Well, that’s another thing. Let’s leave it out. I have personal reasons to regret my knowledge of him. The other thing he did to Harvard, which is much more serious, is that when he got interested in Left politics — I had been during the Depression, like everybody, interested in Left politics — Shapley became a destructive force for the observatory, as far as money goes.

Weart:

This is already before the war?

Greenstein:

Yes. Before the war. He was so pro—Russian, you see. You know, he got into hot water and was cited by whatever the pre-McCarthy committee was — was it Martin Dies?

Weart:

That was somewhat later.

Greenstein:

Later. That was after the war then. He neglected money raising, of which he had done a modest amount successfully. He neglected his relations with the university, so much so that when I returned as an overseer 30 years later, people asked me what I thought of Shapley, and after a lot of sparring around it turned out that the administration still held a deep resentment and was watching every penny that went into Harvard Observatory and astronomy, because of their long enduring problems based on the Shapley period.

Weart:

Was this primarily because of his left politics?

Greenstein:

Yes. Well, also he neglected the place somewhat, and he stopped raising money. But the thing is, had he left Harvard and done politics, it would have been all right, but he stayed on as the science leader, the director, and let the place go to seed scientifically.

Weart:

I see.

Greenstein:

And it did go to seed, you know. It lived through a low period. I’m fascinated by the sociology of institutions. I’m interested and worried about my own place.

Weart:

This is exactly one of the reasons we’re having these interviews. I’m fascinated with it too.

Greenstein:

I believe that institutions depend not only on the high quality of the people they get and the equipment they can use, if it’s an experimental thing, but on a kind of spirit. And the spirit at Harvard in the late thirties was extraordinarily good. Everybody talked about everything, the latest discovery that came out would be talked of and everybody would hear about it within the week, and so we were just continuously exposed to new ideas and experience. It was just marvelous that way. It made, as I said, some deep impressions on what I did later. I never worked in the Bok area, galactic structure, but I sure admired that openness.

Weart:

Tell me, were there distinctly different groups, people who were interested in different areas or different problems?

Greenstein:

Yes. You see, there was Menzel, the sun and planetary nebulae, gaseous nebulae; and Bok and galactic structure, and no other senior scientists and Shapley and his collaborators cataloguing galaxies. And a few great people like Annie Cannon, who was always there.

Weart:

Where did you belong in this?

Greenstein:

I was a Bok student, but I learned a lot more from Menzel; gradually as time went by and I got more or less accepted in the outside world, Menzel began to talk of me as one of his better students — not his best. Leo [Goldberg] was certain his best. Frankly, I liked both Bok and Menzel as people. Menzel was extremely gregarious.

Weart:

Was there any feeling of different groups being more oriented towards theory or more oriented towards observation?

Greenstein:

Menzel was completely theory and analysis of other people’s observations. The planetary nebulae observations came from Lick, I think, the old ones. And eclipses — he built this great big eclipse equipment for a couple of years while I was a student. The Bok people made do with what instruments they had, which were the photographic telescopes. There was no photo—electric work. It was a little early, but they were also very tardy in taking it up. Then there was an enormous bunch of people doing variable stars, and Cecilia Payne had sort of been pushed out of astrophysics by this internal division, so that she had to do variable stars. She and her husband did them by thousands and thousands, among them the very important Magellanic Clouds Cephaid distribution for example. And the period—frequency characteristics of the variable stars. Cecilia looked at the available better spectra, and it resulted in a later book on the stars of high luminosity, and then she’s written others on other subjects. But generation of high precision data was not a Harvard specialty.

Weart:

At that time.

Greenstein:

At that time. And so, when I went and did the reddening, it was pretty much not a common thing to do, at the telescope. The telescope was mostly for patrols.

Weart:

Was there a feeling that some people were engaged in the exciting new astrophysics, and that there were others who were stuck in old style astronomy? Was there and Old Guard?

Greenstein:

Not really. The Old Guard, if anything, would have been the variable star work, in a sense, because there was no new technique, there was just accumulation of data. But Bok’s students were pretty good. After all, Carl Seyfert, of the Seyfert Galaxies, was a Bok student. Sid McCuskey. Lindsay in Canada, then Ireland. I think there was a rivalry at the higher levels but I don’t think the students felt it terribly. It is true that the students who couldn’t make it with Menzel would go to Bok. But that’s because Menzel’s standards were rather high, on theory, and you could always find a thesis that Bok would dream up for you. I was too independent, and I loved them both really as people. They’re both great, fine people. In fact, a week from now is Menzel’s memorial service at Harvard. I was almost tempted to go. No, they were pretty good people. And having the visitors was a very fine thing.

Weart:

All the people coming through.

Greenstein:

Because that prevented — you didn’t really have to believe that either Menzel or Bok were the greatest men in the world. When Oort came, there was obviously a great man. Chandra [Chandrasekhar] came.

Weart:

That’s right, he was there for about a year.

Greenstein:

And I met Martin Schwarzschild at the railroad station, when he first came to Cambridge as a refugee. He wore a knapsack. Though he had been already in the country for a few weeks with an uncle in New York, who helped get him out of Germany. Shapley helped rescue Schwarzschild. So there are good things about Harlow. But there are such dreadful things about the stress within the observatory that I modeled all my management of places on the opposite — love your colleagues, think you’re all great, you’re all in the best place in the world.

Weart:

This was not just stress between the senior people, but also felt at the graduate student level?

Greenstein:

No, not the graduate. Mostly between the staff, people who worked for the professors. I don’t know, are scandalous stories suitable?

Weart:

Yes, I think they are. Don’t forget, you have the control over the material.

Greenstein:

Menzel did a lot of work during World War II for the military, in certain areas that were at quite a high level of classification. And after the war, when things got bad, with political reaction, it turned out that he had his clearance threatened to be revoked. They told him that they would not renew it. Did you know that?

Weart:

No, I didn’t know that.

Greenstein:

Walt Roberts had the same problem, because he was in the Shapley orbit.

Weart:

I see.

Greenstein:

Now, Menzel was an arrant conservative. But Shapley had got him to be a member of whatever it was — Friends of Soviet Democracy or some other ridiculous organization. I had, by the way, gotten allergic to leftists after my New York period. I had been mildly –-

Weart:

— in the thirties?

Greenstein:

The thirties. I didn’t like it afterwards. Menzel had to go talk to various people; I think “Din” [Edwin] Land advised him, that if he were going to survive as a scientist, to have a clean reputation, and to be any use to science in the country, he would have to fight it through. And at great expense and apparently great personal agony, he eventually won deserved recognition as an honest man, and got his clearance I don’t know whether he did any great amount of government work after that. But this was one of the things. And Walt [Roberts] had the same problem, but I think it was less serious, although I don’t know details.

Weart:

This brings up an interesting question, which is, what sort of things were talked about amongst all of these students, aside from astronomy? For example, was there a lot of political talk going on?

Greenstein:

Sure. That’s the trouble. There was.

Weart:

It was highly politicized? Were these political divisions, left and right?

Greenstein:

Oh, I think the right didn’t talk about it. They were sure they were right. The lefts raised money for good causes. I remember, I believe I’m right, that at Harvard a group got money enough to buy an ambulance for the Finns, pre-World War II, for some occasion or other. And then when the Russians took over a good part of Finland, of course, they had to forget that, and raise money to buy an ambulance — I don’t know if they did that literally — for the Russians, you know. There was a good deal of political do-gooding. I don’t think it was a motive force among most of the eventually successful scientists. But for the older ones who did get involved with government work later, it was trouble. In the 50’s I had to have a very high level clearance, and things came back from the thirties, when I was in New York. It’s amazing.

Weart:

They never, forget.

Greenstein:

They never forget. I was supposed to have been a member of a Communist cell in New York, I was denounced by somebody. They showed me his picture. I may have seen the guy, but it was twenty to thirty years earlier. I didn’t remember him.

Weart:

At least they showed you his picture.

Greenstein:

Yes. Well, anyway, there were good things. There was an active social life. It was very pleasant to be a student there. There was very little money. People had to get along as best they could. The idea that you got fully supported tuition and living as a graduate student was non-existent. My last year, I got the second best fellowship — I think it was $700, and tuition was $400 out of that. I think Leo Goldberg got the best, and that was $900 or something. It’s a very strangely different place from institutions now. Many of the students didn’t go on in science. That’s another thing.

Weart:

You mean the astronomy graduate students.

Greenstein:

Yes.

Weart:

What became of them?

Greenstein:

Oh, they went into industry or other things. They changed careers. It was not accepted that if you got a PhD, you were a professional research astronomer. Perhaps one in three maybe was going to be lucky enough.

Weart:

Why were these students going for a PhD then?

Greenstein:

Well, they would go teach, say, or something like that. They’d teach in liberal arts small colleges, or at even lower levels.

Weart:

What was the feeling? Was there a feeling of competition to see who could wind up as a professional astronomer?

Greenstein:

By then I’m sure there was. I certainly wanted to be. I’d burned a lot of bridges.

Weart:

There must have been some anxiety about whether or not one could get a job.

Greenstein:

I would not want to guess people’s feelings. But I would doubt that more than a third of the PhDs survived in astronomy — research astronomy.

Weart:

Did you have feelings that you might not be one of the ones that survived? Or were you fairly confident?

Greenstein:

No. Since I now wanted to be a professional astronomer, and since I knew what it was paying me at Harvard, I knew I had to rely on my own other resources. Leo Goldberg, on the other hand, just to take a concrete example, was the son of a very poor family. And so he clearly had to make it in science. Jim Baker, who mostly outside astronomy became an optical designer, became I think independently wealthy from that. You did what you could. But the clear thing was that the university did not owe you a living, as a research scientist. Teaching jobs were the relatively easy ones to find. Liberal arts colleges would pay you $2500 or something a year as an instructor, which was great. My anxieties probably existed; I don’t remember them. I was very lucky. I didn’t care, and next I got a fellowship.

Weart:

This is all very interesting, by the way. This is the kind of information that’s really hard to recover, except by asking people who were there.

Greenstein:

Are you going to talk to Leo Goldberg?

Weart:

We hope to talk to Leo Goldberg, yes.

Greenstein:

You will?

Weart:

Yes, he’s on the list.

Greenstein:

I would think it would be very interesting, because he must have had such a different experience. Here I am, a bloody amateur at almost everything. Still am. Interested in everything. Leo’s been a professional, sort of, and a fighter. I think it’d be a fascinating contrast. Also, it would be interesting to know anybody, and maybe Leo would know — anybody who got out of Harvard between ‘3l and ‘37) earlier, who lived through the change, to follow what happened. When I got back in ‘34, the gap was enormous, between my senior year, where I took a course given by staff, and later all the instruction, graduate instruction, had moved up to the observatory — it had probably been an organizational change — there was a head of the department who was now at the observatory. That was one thing. He still was in charge of the teaching. But you now also had the research people to do some of the teaching down at the university. There’d been a bad gap between the teaching and the research, in earlier years. That had been cured.

Weart:

OK, one more question about Harvard. I was looking at your paper on the spectrophotometry of reddened B stars[9], and I noticed that you thanked Shapley for “liberal provision of observational facilities.” You had to go to Shapley to get the use of the telescope, is that it?

Greenstein:

He was director of the observatory. Even now, people visiting here, or visiting Kitt Peak, thank the director. There was a telescope, and I think I and one other graduate student, now dead, were the only users of it, a 24-inch reflector. It was primitive. Shapley was not a great admirer of spending money on instruments.

Weart:

For your own research you didn’t particularly need to go and get money or anything for it?

Greenstein:

Oh, no, there wasn’t any — where? From whom?...From individuals, actually. It would have been possible, and that’s what Shapley used to do, get money from a few friends.

Weart:

You didn’t have to ask Shapley for anything in particular except using the telescope?

Greenstein:

Actually I think the telescope was under Bok’s general supervision, because it was also used for photography. Shapely’s research used the plate collection. And he had this Southern Hemisphere 60-inch which was not very good, later, and used plates taken with a Southern Hemisphere refractor telescope, which I think had been on an expedition I think to Chile, in 1910 to ‘20-odd period, which had taken very good plates of the Southern sky. So that was a galaxy resource. And the Magellanic Cloud plates, of course, had to come from the South. Harvard had observing facilities. They were mediocre. And the difference between that and Yerkes-McDonald, and Mr. Wilson-Palomar in each case, you go up.

Weart:

How did it feel, to go out and use the telescope? This was your first time using a telescope. Did this impress you?

Greenstein:

It was sort of beautiful. I think so. I remember it a very odd arrangement, actually. The telescope was fairly big. It didn’t have a dome. You slid off a small roof, and then there was a kind of walkway, around it. You stood out doors at the top, the Newtonian end of the reflector, the telescope would move by pushing it. You were outdoors. And when it’s clear in Cambridge, it’s cold. (This was out at Oak Ridge.) The only decent clear weather is when you have a storm front in mid—winter, and has gone away, it’s clear, it’s 5, 10, 15 degrees, and the stars are snapping at you. It was very romantic. I guess I really have always — though it’s exhausting — loved the experience of observing at night. I must have had that first feeling there — because you asked me, and I could see myself, in some bundled up clothes, standing outside on the roof and looking into this eyepiece.

Weart:

Well, why don’t we stop right here, because it’s 10 of 12 and we’re near the end of this cassette. We never really know what kind of questions to ask, to get at the sociology. It’s very difficult. I am learning a lot for myself about what it was like — OK, on to Yerkes. How did you get your fellowship?

Greenstein:

I guess by then I was viewed as moderately successful, and there were in the country, instituted originally by Hale, these National Research Council fellowships. I think there were seven, and I was one.

Weart:

In astronomy?

Greenstein:

Altogether, in all sciences.

Weart:

How did you get it?

Greenstein:

I applied, and I got it. I don’t remember — somebody must have written letters of recommendation for me. Maybe being at Harvard was a good thing. I don’t know who else applied that year. Very good astronomers have had it. But of course, there weren’t all that many of them altogether. It was the only fellowship program in the country. You could get a job, if you were lucky, you could get one of these fellowships. You had to be very lucky. I did, and it was very pleasant. Going to the Midwest was a change. I’d never been more than about five or ten miles west of the Hudson River.

Weart:

You’d been to Michigan, you said?

Greenstein:

Oh, that’s right. But I’d never worked there, never lived there. You’re quite right.

Weart:

You’d never lived there. Now, you could have taken this fellowship, anywhere, right?

Greenstein:

That’s right.

Weart:

So why did you choose —?

Greenstein:

Struve was a visitor during one of the summer schools, and Struve, when young, was an extraordinarily vital, active person. And although I’d ne a thesis on another topic, I still was interested in stars and stellar atmospheres, probably largely because of Cecilia, [Payne] and my affection and respect, and reading these books [by her]. So he talked about, I think it was emission-line B stars, most people found boring stuff — and about the stars that were peculiar, active, hot variables, what we now call nova-like or symbiotic stars, the Z Andromeda type. I remember most people hated his lectures, I just found it interesting. As a person he was very reserved, remote, especially for me, then. But I was talking to him, and he said, well, he was also very interested in interstellar matter and reflection nebulae at the time, I had this interest in interstellar dust, and he said, now if I could come to Yerkes, it would be very nice for them and for me. I think, that when you applied for one of these fellowships, you had to list where you might go. I listed that. I had no delusions about going to the Mount Wilson Observatory. I would not have expected to be welcome at that time.

Weart:

Why not?

Greenstein:

There was this rather nasty feud for many years between Shapley and Mount Wilson.

Weart:

You mean, even though you were student of Bok’s?

Greenstein:

No matter — I was a Harvard man. The stories later when I got here! You don’t know what it is to be underprivileged. But anyway, Struve impressed me; he was an observer who thought also about theory, but didn’t do any very esoteric theory. He impressed me very very much, and he was, to my eyes, much closer — since they were generating new observations — to the interaction of theory and fact than Menzel’s group was. I really had a sort of choice to make. I certainly wasn’t going to work on interstellar dust forever. And he was just a strange person and completely different from anybody there. He was just a non—Harvard type.

Weart:

And you were ready to leave Harvard.

Greenstein:

I was ready to leave Harvard, emotionally, yes. After all, I’d lived there altogether seven years. Or eight. Four as an undergraduate, 1930 then 1934-37, — eight years. Good lord. That was enough. I liked Cambridge, but somehow I wanted to go away. And we went. It was an extraordinary experience. Yerkes then had on its permanent staff the sort of great men that you know, and Struve had instituted a system like Shapley had, only now it was a little later and he did it in a different way, of bringing in foreigners. Because he was Russian born and he knew European astronomers. He brought them in more on a permanent basis. So the place was absolutely international, and stayed that way. Next, all kinds of people there were a lot more serious scientists, let’s say, than anybody at Harvard except Menzel (let me put it bluntly).

Weart:

Serious in what sense?

Greenstein:

Well, you know, they were really working on important topics. I was much impressed immediately, although living in a town of 600 people, in the farm country of southern Wisconsin, Williams Bay. That was something of a shock. But the people were fascinating. The institution, however, didn’t have the warmth and social togetherness, but the people were just wonderful scientists… And the other part, I guess, really was that much more than at Harvard, the astronomers at Yerkes (and Struve) stressed the relation with physics, modern physics. I first heard about cosmic rays, you know, in any serious way, when Rossi, I believe it was, came out and gave a lecture in which he said the only thing cosmic about cosmic rays is their place of origin. They’re wonderful tools for high energy physics, already studying odd particles, since atoms, were being split by cosmic rays. I remember that very vividly. Chandrasekhar was as remote and impersonal, if you wish, then as ever. I was more or less frightened of most of the people at first. They knew so much, and I felt in a certain sense that I hadn’t learned too many things and only at a superficial a level.

Weart:

You had somehow a different relationship to them than you had to the people at Harvard?

Greenstein:

Well, one, I was now a junior faculty member, at least. But I mean, they weren’t as close and warm people. This is, you didn’t go and play ping-pong with anybody, the way you did with Menzel. Seeing Menzel and Leo Goldberg play ping-pong is like watching a heavyweight boxing match at the time. Their whole hearts were in it. Well, it wasn’t that way. It was a different life completely. We became, my wife and I, instead a sort of a social center. First, I had brought the gregariousness from Harvard. Next, we had some of our own monies. We gave lively parties, which nobody had ever done except the one official Christmas tea of the year. They weren’t cold, they were just — they were foreign, many of them, and somewhat more remote. But they were much more serious as scientists. So I immediately found myself with some doubts as to whether I was the brightest theorist in the world — which I knew I wasn’t, but in any case, I’m pretty sure the first two years at Yerkes convinced me that I would do theory, but not much.

Weart:

So you became more oriented towards observation?

Greenstein:

Yes, right away. Right away. I had a very high regard for the people there, and really, almost none of them were less than first rate. I learned so much, and now this was more serious stuff.

Weart:

How did you learn? I’m interested in the —

Greenstein:

Well, I went and listened to Chandrasekhar lecture.

Weart:

He was in Chicago?

Greenstein:

No, no everything was at Yerkes. They all lived up there. There was faculty, I think, of eight or nine people, a couple of recent PhD’s, very junior level, myself and Louis Henyey, who was a very remarkable person, much under-rated.

Weart:

Yes, I want to ask you some questions about Henyey…

Greenstein:

He and I immediately got together. That was one good thing. So I had somebody to work with. And then, the division of roles became very easy. Next, Struve, having these foreign visitors who were much more serious astrophysics people — two years, unfortunately, then the war broke out — the last year before, he had Karl Wurm, who was really a first—rate person in what we now call non—LTE[10]. He was interested in comets. He was also interested in the spectrum of shells of stars. He had Albrecht Unsold come for the dedication of McDonald Observatory. And that again is an experience. Albrecht is a frightening man, he’s so bright. And Struve was a frightening person. Of course, he was shy. None of them were arrogant. I would say, insofar as anybody could be immediately friendly, I had become a friend of major scientists, sort of, instead of nice people reporting on what was going on around the world, you see.

Weart:

What was Struve’s style as a leader, a director, administratively?

Greenstein:

Completely autocratic. He would decide what he wanted to do, and tell people what their salaries would be, and tell them what the budget was, and he was going to spend it on what instrument. He in no way conformed to the so-called American ideal. But I think he was a great leader. And as long as he did that, the Yerkes was at its most successful.

Weart:

And did people accept this, in the pre—war years?

Greenstein:

They did. You see, I was first a post—doc, so I didn’t get in on things. They they were very nice to me, and I stayed as an instructor at the same salary. Took me three years to get a 10 percent raise on my salary. Struve kept telling me that I had money and I didn’t need the money, would I mind waiting another year? I got $2800, in my third year as an instructor. That’s not bitterness. But he was autocratic, he knew I didn’t need it, and he had somebody he wanted to do something for, and I was not going to fight with him about money. He bawled us all out for being lazy. But the reason we all took it — I speak for myself, I don’t know whether Chandra was ever quite treated the same way, but everybody else certainly was — is that I couldn’t feel any resentment to somebody who worked twice as hard and twice as many hours as I did, and Struve literally did that. Oddly enough, he had excellent relations with the University of Chicago president, Hutchins, who was anti-science. But astronomy was useless. It was not an engineering thing. It was not in any way a betrayal of the classical Greek ideal of natural philosophers, if you wish. And therefore Hutchins, oddly enough, though he and Struve were quite different people, I think he respected Struve. And he gave him, considering, more money for say new faculty, things like that, than you would have expected.

Weart:

Because it wasn’t a practical thing?

Greenstein:

Yes. Hutchins had a terrible fight with the physicists. The physicists wanted to assassinate Hutchins. He put in these Great Books kinds of things, later, but even from the beginning he thought physics should be taught as it had developed historically, in a deeper human context. They wanted to teach specialties. I had many good friends. Struve brought up (from university campus to Yerkes, which was a summer resort) people, sometimes for weeks, months in the summer. There was always room. The observatory owned a lot of houses. I would say, maybe one week in four, there would be a physics visitor from the campus. They liked it because it was the country.

Weart:

How much did you get down to Chicago?

Greenstein:

Almost never. (Later I did.) But really not. I met these people that way, and I got to like them as people. Later when I went to Chicago we’d see them socially. I became good friends with a few people — Rossi, a bit; Zachariasen, specifically, most. During the war I met others. It was an interesting thing — modern physics sort of suddenly appeared, and astrophysics was getting into what I would call a modern frame already.

Weart:

Was there a feeling at Yerkes again of this transition taking place?

Greenstein:

No, I think — at least when I got there — I don’t know how long Struve had been there. I don’t know how long he was director. Maybe ten, fifteen years by that time. He had established this tradition. The foreigners were there. It wasn’t just that he didn’t like Americans, I think he was getting the best people he could. And getting Chandrasekhar, he had fights with the people at Chicago, because Chandrasekhar was a Hindu, therefore a Negro, therefore not suitable for the University of Chicago physics department. They might even be asked to make him a member of the Quadrangle Club.[11] That had actually been said.

Weart:

They were afraid that they might?

Greenstein:

Yes.

Weart:

I see.

Greenstein:

But Struve was a man of incredible rectitude and moral fiber, and when he decided to do something right, you couldn’t stop him. And they didn’t stop him. If he could get money from Hutchins, he would do what he liked with it. And I think he did very well.

Weart:

Were there any differences in different schools, different groups at Yerkes, people who were more theoretical or more —?

Greenstein:

Oh yes. See, W.W. Morgan, who invented spectral classification in the modern sense, and Keenan who worked with Morgan for many years, then went elsewhere, but still worked with him — Morgan was otherwise completely isolated. He did no theory. Yet he was the first person, in his thesis, Morgan’s thesis, to find these strange element anomalies in the magnetic peculiar A and B stars. Well, he wasn’t the first to note it. One other object had been studied. But he classified lots of them, studied their spectra in reasonable detail. It was the first inkling that stars were not all the same. What they are, we still don’t know.

Weart:

Did this impress you at the time?

Greenstein:

Oh yes.

Weart:

I know it fits in with your interests.

Greenstein:

Well, no, it became so.

Weart:

But did you first encounter this idea direct from Keenan?

Greenstein:

From Morgan. Oh yes. I’d never heard of it. And the idea that I would work on it wasn’t so obvious, except for Struve. You asked, how did Struve run the place? Henyey and I wrote about, I don’t know, ten papers together, and were collaborating on reflection nebulae, and next on H II regions, with Stromgren discovered with something that Henyey and I invented that Struve had suggested. It was very nice that way. The place was fairly lively, and things went fast on instrumentation, if there was money enough. Struve said to me, I think maybe the middle of my second year there, ”Jesse, you want to work on upsilon Sagittarius?” Since I barely had seen the constellation Sagittarius, I didn’t know — I said, “What is it?” He said, “It’s a very interesting star.” I said, “What is it?” He said, “Well, it’s a star that doesn’t seem to have any hydrogen in it.” I had no idea what that meant, at first. And we couldn’t work on it because we didn’t have the McDonald telescope till ‘39.

Weart:

This was before the McDonald telescope.

Greenstein:

Yes, just sort of six months. And I said, “Well, I don’t know, I’ll read up about it.”

Weart:

Struve had already noted that there was —

Greenstein:

Yes. Good astronomers, interested in stars, have an eye — you know, like you smell a Rembrandt behind the dirty wall. Well, it’s like that. He’d noticed that there was something odd. He just said, “Work on it.” I did. Well, you wouldn’t know — I’m not scared of many things, but I was not able, till his very end years, to look at Struve and call him “Otto” without some feeling, is the thunder going to strike? He was in no way harsh or brutal. He was just a great strong person with a moral sense about science. It was our duty to work harder, and if we’d done that, to work still harder. And if we didn’t work 16 hours a day, it was our fault. — [hiatus] —

Weart:

We’re resuming after lunch now, and we’ll go... tell me, what time should we stop today? We ought to se a limit on ourselves?

Greenstein:

Could you stand it till 3?

Weart:

Sure. [Microphone is adjusted.] So, we’re resuming after a break now. Just a little more about the working life at Yerkes. You were saying how hard Struve worked, and I wondered, did everybody there work long hours, say, compared with Harvard? Did you work long hours?

Greenstein:

Well, I was younger. No, I would say, I worked more or less standard hours. Chandra and Struve and Morgan were examples of people who really spent most of their time in their office, working. Struve was an indefatigable observer and measurer, and Chandra had his theory. Chandra dished out his papers as sort of lectures, it seems to me every few months. And I tried to keep up with him.

Weart:

Could you follow what he was doing?

Greenstein:

Up to a certain point, yes. Through about, I would say, nearly half of the stellar atmosphere papers. And it was a pleasure.

Weart:

So you were very much aware of what was going on in stellar evolution and so forth.

Greenstein:

Well, stellar evolution, he was not so active as he had been earlier. He did in fact give very good series of lectures on degenerate stars, starting with the basic physics. One of the things you may not remember was that at one time, there was a terrible argument between Chandra and Eddington.

Weart:

Yes, I know.

Greenstein:

About relativistic corrections to the equation of state of degenerate matter. And there was a colloquium, I think a year or two after I got there, in Paris, on white dwarfs and novae. [The proceedings] for many years was the only book on the subject. Chandra went through that again. So that was fairly familiar, and a couple of the students did stellar interior models, again, on a small desk calculator. These were sort of a year per models, and so there was a good deal of interior work going. The other pioneer efforts that people may not remember — some of the first attempts to do infrared photography and photometry were done there, before and right after the war. Kuiper brought in the lead sulphide photo-conductive cell. The major innovation at Yerkes was the McDonald Observatory setup, which I guess most people have a history of.

Weart:

Yes, at least there exists a standard history. I don’t know whether it’s –-

Greenstein:

I think it’s essentially true. The man who’d been provost at Chicago became ditto at Texas, and they have this unsolicited gift for the biggest telescope that could be built for, I don’t know, a couple of million dollars. So he called up Struve and probably Hutchins and said, “What should we do?” Struve said, “Well, you have the money and we have the talent.” As long as I remember, permanent and visiting Yerkes people used the 82—inch. This started in ‘39. It was only two years after my arrival. I stayed in Texas — in fact, the first month of its operation — and followed up Struve’s edict about upsilon Sagittarae. Though I did observe other things too, that I was interested in.

Weart:

Before we get into that, I wanted to ask you about your collaboration with Henyey the nebular spectrograph?

Greenstein:

Henyey had just got his doctorate maybe a year earlier or later than I...

Weart:

He got his in ‘37.

Greenstein:

OK, same year, then. So when I came, we were both brand new PhD’s. And he was completely mathematical. Struve and C.T. Elvey had worked with photographic photometry or reflection nebulae and emission nebulae, and on what’s called the Hubble relation between the apparent brightness of the illuminating star and the size of the reflection or emission nebulae. And they had also discovered, what’s called diffuse galactic radiation, reflected from the dust by general starlight — not by stars near dust clouds, but just the whole Milky Way light. The theory of dust-cloud illumination was developed in Henyey’s thesis. Henyey was incredibly competent mathematically, and very, very quick in working out ideas and theories. He suffered from a defect of non-publishing. He and I worked out beautifully together, because we were much the same age; he had the mathematical dexterity and I had lots of ideas, and we collaborated very well. The nebular-spectrograph, which is important because it led to the discovery by Stromgren and Struve of the so—called H II regions, the ionized regions in the interstellar gas, grew out of a cloudy night remark by Struve to Henyey and myself, who I think were scheduled on the 40-inch telescope. It was midnight, we were standing in the library, and Struve said — he had on aloof look because one of his eyes was defocused, turned outwards — he looked at one of the two of us, I’m not sure which, and said, “Well. What is the ideal, most efficient spectrograph?” Well, we sat or stood and talked, and in a half hour had the idea — a spectrography with as few components as possible was the fastest and most efficient (which is true). And it was built in the carpenter shop, I think within three or four days, using optics that were going to go eventually to McDonald.

Weart:

The idea just came out from conversation?

Greenstein:

Yes, like that. Struve was like that. He would just ask you either hypothetical or direct questions, which [could turn out to lead somewhere]. (off tape)

Weart:

OK, so you attached it to the 40-inch?

Greenstein:

And the first night was cloudy. It was at least not raining, so we pointed it up at the zenith. By accident, there was an aurora that night, though we didn’t know it, and enough auroral radiation got through the clouds so that when we developed the spectrum, we had a beautiful spectrum of the aurora, probably one of the best till that time.

Weart:

Through the fog.

Greenstein:

Through the clouds. And then we used it at Yerkes, and the more elaborate arrangement was fixed up, on the hillside at McDonald. I used it there, to measure the energy distribution in the Andromeda nebula, and there ran into cosmology for the first time. Stromgren and Struve, mostly Struve doing the observing, found a lot of emission regions, as Henyey and I did, but also found that in the Milky Way, although there was no visible emission region or hot star, on ordinary photographs, there was ionized hydrogen radiation with the nebular spectrograph. That led Stromgren to develop the theory of the Str5mgren Spheres around each hot star. And the interstellar general H II background, which is now a very exciting and complex subject — we don’t know whether the gas is mostly neutral, with a hot phase, or mostly hot with a cool phase — started then, because in the theory that Stromgren developed there were some extremely interesting questions brought up about the ionizing ultraviolet radiation from the stars. Henyey and I observed a comet, I remember, and got the OH and NH radicals for the first time, which were too far in the UV for previous spectrographs. Swings was a regular visitor, and interpreted cometary spectra. This proved quite important. As you know, now, from space the astronauts found OH and hydrogen pouring out of comets. OH was discovered with the nebular spectrograph, and NH could only be observed with it, being at the limit of ultraviolet transmission by our atmosphere.

Weart:

So when you went to do the theory of the colors of reflection nebulae, it was because you had the nebular spectrograph, so you needed the theory.

Greenstein:

No, actually that had started from the Struve-Elvey work, where they’d done it photographically. And Henyey and I did two things. One was the colors of reflection nebulae, which were applications of his thesis work.[12]

Weart:

I see.

Greenstein:

He had used only rudimentary observations. We did more. And then we invented a special gadget that went on the 40—inch, which detected the existence of the diffuse galactic radiation, a continuum which is not H II ionized gas, but it’s the dust reflecting the general starlight. Henyey’s thesis and the work on the reflection nebulae and the diffuse starlight gave a very surprising result, which was that the interstellar grains are extremely highly reflective, brighter than most white paints, brighter than snow, which is rather startling and which is a fact which I think still stands as largely unexplained. If the dusts are silicates, with any impurities, that would not be true. Sand is not as bright as snow. The moon has got a reflectivity of 8 or 9 percent, its albedo. I think you now require around 60 to 80 percent albedo for the interstellar grains, over most of the spectral region, and even in the UV where it’s been detected from space. Well, it was very nice to have a good theorists now that I was doing less theory, though Henyey and I did collaborate. I was able by the way, fortunately, in a paper now in press on an infrared source, to be able to quite Henyey’s thesis and his and my papers from 1938. Which is fun, you know, because normally you never see a quotation more than five years old.

Weart:

Right. So in fact, you came to these problems from two directions. One was sort of a prior interest and the other was when the nebula spectrograph was developed?

Greenstein:

Yes. You often find, as you undoubtedly know, that an instrument creates a problem. Sometimes it’s built to answer a certain theoretical question, and then you get a completely different answer and a completely different theory. Henyey, just to finish this, since not much is recorded about him, had a metabolic disorder of the thyroid which made him either hyper-fat or hyper-thin, alternately. He had to have some surgery, which was not really successful, and he probably died quite young because of that. He also, because he was good at theory and liked to compute was in my opinion the person who later brought modern mathematical methods into big computers for stellar interior evolution. He invented various methods, much later.

Weart:

This was after the war?

Greenstein:

Yes, after the war.

Weart:

At Berkeley.

Greenstein:

At Berkeley, that’s right. He was head of the Computer Center, part time, and he worked a lot at Livermore. He did a lot of stellar evolution, and his students learned the method. He published very little altogether, tragically. When I was with him — I’m impatient — we’d get things out. He was otherwise a perfectionist, and on an important physics problem he was working on at Yerkes, I know that some important things never got finished.

Weart:

Was there in general pressure at Yerkes specifically to publish. Did people say, “Gee, you’ve done this work, now you must publish it?”

Greenstein:

I think in a sense it was in the air. I don’t think anybody had to say it. It was a pretty competitive place, because the senior astronomers there were awfully good, and leaders in their fields, and if you were going to sit around and not get interesting results, you would either not last or not enjoy it. There were other places. But Henyey just was that kind of a person, who took pushing. Some of his students, in fact, in the postwar years, pushed him on publishing his methods of stellar interior evolution computation. He certainly knew more about big computers than any astronomer then. Till recently, I mean, till the last ten years or so.

Weart:

To get back to the nebular spectrograph — Struve and Zebergs, in that book[13] tell a little story about an MS meeting at Ann Arbor in 1938 when Slipher got up and said that the spectrograph was all wrong — it had too much out-of-focus light or whatever, and Struve says, “The Yerkes astronomers listened in stunned silence.” Do you remember that?

Greenstein:

I didn’t remember the quotation. The reason that it was the simplest spectrograph was that in fact the slit was either sharp on the plate, so that you got high resolution, or it was sharp on the sky, in which case you defined the region you were looking at but didn’t get sharp resolution on the line. And we designed it so that the four-inch focal length camera, looked at the slit 60 feet distant — which is not quite infinity, but for a four—inch camera, it’s not bad. But it does in fact blur, if you use it in the proper way with the spectral lines sharp — it blurs the patch of sky you’re looking at. A star would be blurred out over a disk of whatever the defocusing size is. That’s why the later one at McDonald was built, with a 150 feet long total light path. But to do it they needed two more reflections, which lost another 20, 30 percent of the light. But in general, I don’t remember the anecdote, but I was at the meeting. I remember the meeting because there was the most violent lightning and thunder storm I can remember, one night, in Ann Arbor.

Weart:

Were the AAS meetings in general important for you? Or societies and meetings in general?

Greenstein:

In those years, enormously so. Yerkes was isolated, and Harvard had lot of visitors. Yerkes had a few distinguished visitors. So going to meetings was important, and of course had to be arranged. As part of the response, I think, I don’t know who suggested it, either Struve or Struve and Stebbins, from Madison, [Wisconsin] — they again put that on old

Greenstein:

I organized a thing called the Midwest Astronomers Group, which was sort of a rotating meeting for people from Ohio to Wisconsin, which ran for many years — I think it’s still running.

Weart:

Did that start before the war already?

Greenstein:

Oh yes. Going to a national meeting a year, by train, from Yerkes, was about all you could hope to do, and there were no large numbers of symposia. I mean, only the IAU members went to every alternate IAU meeting. It was pretty important to keep in contact. Our closest relations certainly were with Madison, with Whitford there that early. Stebbins was a great personality and very charming. And Ohio State, where eventually Keenan and I think one other Yerkes astronomer went — several, in fact, from Yerkes.

Weart:

You must have kept up correspondence with Harvard people and so forth?

Greenstein:

I? The trouble is one of the great losses I’ve had — I haven’t the vaguest idea where any of my letters are from the Yerkes period. I have none here. They probably stayed at Yerkes, and since there’s almost nobody left at Yerkes, it would be an interesting thing to find out what they’re doing about history.

Weart:

If I hadn’t had pneumonia, I would have been at Yerkes last week, on my way out here, looking into it. I had an appointment with them. The next time I go through, I am going to look and see what they have there.[14]

Greenstein:

By the way, at that time I was not a company man, remember. I was a young, active, pushy scientist, and I was not in any administrative posts at all, except this Midwest Astronomers thing, and going to a meeting was a big deal.

Weart:

Where did you normally hear of new developments? By somebody passing through, or meetings, or periodicals, journals, or letters?

Greenstein:

The ASTROPHYSICAL JOURNAL was edited there. I don’t think Chandra ever leaked anything.[15] I guess we were just plain slow, because when I say there were lot of visitors, there wasn’t the kind of traffic as through Pasadena or Cambridge now, I mean, a visitor was an event. There was less literature to keep up with. I guess things went more slowly.

Weart:

I was going to ask — do you think, if you were behind in hearing of things, did it make any difference? Did you ever have any feeling of being in competition with anyone to get new results?

Greenstein:

[Shakes head, No.] Every place has its own personality. When McDonald came into existence, Yerkes got to be a very active center for observational astronomy; except on galaxies, perhaps the leading one. Mount Wilson was not at its best in those years. And there was no competition. I think the whole pace of things was slower. I published innumerable papers, maybe at the same rate as now, roughly. But I don’t think I ever felt, you know, — out — and I don’t think I cared much. We were sort of building spectroscopy up — quantitative, analytic spectroscopy, where you really studied things in detail. Mount Wilson was doing a lot of stellar spectroscopy at the same time, but never on the same lines as Yerkes, really. The interesting news would be from Mount Wilson, when a paper appeared. It was usually more descriptive than quantitative. There were things like the discovery of these giant eclipsing stars, atmospheric eclipses by very large stars, EpAsilon aurigae, and Beta Lyrae, 32 Cygni are classic problems, some of them still not understood. There were just a couple of places that worked on them. Victoria, Mount Wilson, and McDonald-Yerkes.

Weart:

So you were not in competition with anyone.

Greenstein:

No. See, competition is, I’d almost say, is a post—war phenomena. Its intensity. Astronomy was a hell of a lot smaller. There were people who, it they made an interesting discovery in a line in which you were working, would write you. I would write to the few people who were interested in my area. Unsold, who founded quantitative stellar composition analysis, really, was a very important person, came to Yerkes, — his students analyzed one of the first plates ever taken at McDonald Observatory at high dispersion, a spectrum of a standard B star, Tau Scorpii. I think there must have been at least a half dozen PhD theses on those plates, taken in the first months of McDonald. And then the war came.

Weart:

Let me ask you a bit about your work on this upsilon Sagittarius and so forth. You mentioned how you got into the problem, but there are a few things I wanted to ask you about. For one thing, you 1940 paper[16] — you say that you are indebted to Henry Norris Russell for inspiring discussion of this problem.

Greenstein:

Well, that goes a long way. Russell was a very good physicist, maybe one of the best physicists astronomy has produced, and he did fundamental work in understanding spectra of atoms. He was an encyclopedia. You would mention some atom, and his eyes would roam inward, and he’d talk about the great triad of quintet terms at 1.4 volts — You know, it was incredible. And in a very early paper on the composition of the sun he applied what is really the correspondence principle, that the quantized atom is the equivalent — that all the transitions in it have the equivalent strength of one classical oscillator. And you just took the total intensity of lines of, say, some weak lines in the sun, and called it the integrated transition probabilities, or f-value, 1. That was Russell’s basic paper on the composition of the sun. Then Unsold did it over with modern opacity theory. He got what I think was, on the face of it, even to him an unacceptable answer. Russell sort of side—stepped the issue of the hydrogen— to—metal abundance remarking that it was high. Unsold did it, and did it wrong, because he didn’t know about the negative hydrogen ion. The point is, all these things were then known. Elementary model atmospheres could be computed, or you could use some of Chandrasekhar’s methods to do quantitative analysis, but what you didn’t have was the transition probabilities for the individual transitions. You could guess, or you could talk to Henry Norris Russell, and he would add up mentally all the transitions that he could remember, and he was good. I think in that first paper, I left as an unknown the transition probabilities, f-values, for certain atoms of which nothing was known.

Weart:

He came through?

Greenstein:

Oh — how did I see Russell?

Weart:

Yes. Also, what your impression of him was, he’s such a figure –-

Greenstein:

Well, first of all, my family were in New York. Next, I had a very good friend, H.P. Robertson, a relativity expert, who lived in Princeton, so it was a natural place for me to go after. There was not much activity then in astronomy at Princeton, except Russell and John Q. Stewart, who had helped do that Russell - Dugan - and Stewart book, which is based on an older Princeton astronomy text.[17] (That remained, the best book in astronomy and astrophysics for a generation.) Russell knew about atomic spectra, and Russell also knew all about the theory of atomic spectra, which I had to learn. You see, having no quantum mechanics, I learned the vector model of the atom from a book by Sommerfeld in German, I talked to Russell when I visited, “and he would clarify things; the Russell-Saunders coupling — the L+S to J coupling — multiplet intensities were things that he knew well. The things that one could guess, or do within factors of three or so in accuracy, he could do mentally. There were no wave function computations at this time. There was certainly hydrogen-line strengths but not other atoms. And so, if you didn’t have an answer you could always ask Russell.

He loved to talk. He loved to talk about science. The other thing one must give him credit for is pushing early and late for completion of measurement and analysis of the spectra of various atoms in different stages of ionization, at a time when all the other physicists were finished with atomic spectroscopy — given quantum mechanics the LS coupling or JJ compuling schemes, you could approximate things if an atom’s spectrum was analyzed. He pushed, and it was because of him that Charlotte Moore Sitterley was supported, for I don’t know how many years, at the Bureau of Standards. She deserves of course the credit for the work, but it was Russell’s national status that made it possible for the NBS to support her nearly forever. And even after her retirement, she was still making sure that NBS kept on working on doubly ionized rare earths and things like that. So they’re a remarkable pair, and he was central in just keeping atomic spectroscopy alive. When the Solar Spectrum Atlas came out, I think Russell was getting along in age — you know, the Minnaert Atlas — questions arose of measuring everything in it, to analyze it, again a la Russell. Scientifically that was my main contact with him. His other interests in the visual binaries, masses of the stars, and eclipsing binaries, I knew little about.

Weart:

What was your proposal feeling about him?

Greenstein:

Oh, he was a very admirable person. He looked like what he was, which was I think the son and grandson of a missionary or minister’s family. I would call him aristocratic, and thin, like a Boston Brahmin in many ways. And yet scientifically enthusiastic. I didn’t realize till much later that he was, in fact, very tense, and that keeping things going was not all that easy for him. But he worked intensely. He had an outstanding memory. He had this absolutely adoring wife, who took care of him as if he was a child. He did need that. This is just anecdotal, but it seems to me that for about a year and a half he wore a broken pair of glasses — not scotch taped, but whatever it was then, a piece of tape, tied them together. He certainly could have afforded a new pair. He had a big house in Princeton. But he was just a very old-fashioned kind of person, I guess you’d say, even for then, with a strongly religious background. His wife was deeply religious, and they were both intelligent. He, I would say, was completely unworldly. That’s sort of an impression. I liked him. I was a young squirt and he was a very great man, but he was always polite. He had just incredibly good manners. The usual anecdote, I’m sure you’ve heard, is that he attended every Princeton astronomy colloquium, sat in a large leather chair and fell asleep. And as the applause broke out, he would wake up and applaud, and he would always ask the first question. (I’ve developed the same habits. I sleep, but I don’t necessarily ask the same intelligent questions.) He kept up with science as long as he could, I would say. His health was not good. He was extremely thin. His daughter, Margaret Edmonson, I’m sure knows much more.

Weart:

We’re going to be interviewing her.

Greenstein:

They had a mentally deficient child, who was — or was it his sister? I’m not sure[18] — who lived, it seemed to me, almost forever. They had great troubles because of that. But they were a nice family. You don’t know about Bob Robertson, who’s completely an opposite type, but to go from Robertson, who was a friend of von Neumann, to Russell, was like going back 30 years in time. Russell, I think, did not drink or smoke, and didn’t approve of those things. He certainly would not have approved of immoralities. I have no idea what is behind any facade, but his was to me the proper facade of a great gentleman of the older times.

Weart:

You did sense a certain tension behind it.

Greenstein:

No, I found out later — I didn’t detect it, I didn’t realize — that in fact, maybe like Hale, he kept up this marvelous outside, but at great expense of mental and emotional energy. I don’t know anything about it, except that he was not well — which I didn’t realize. But I admired him. He was a great scientist of the old school, but I think he was ten or twenty years younger than he acted. That was, I think, the oddity: he acted like an older man. But he was an admirable person. And of course, he had enormous influence out here in Pasadena, at Mount Wilson.

Weart:

Oh, I didn’t know that.

Greenstein:

Oh yes.

Weart:

After the war?

Greenstein:

Before and all the time. Well, for one thing, atomic spectroscopy was a big subject here. They made these — A.S. King made — the carbon electric furnace — and it was Russell who kept pushing, so that transition probabilities were measured in the lab in Pasadena. Russell must have pushed that. Russell, when new elements were analyzed, would be in contact with either the elder Babcock or with Merrill, for, a question line “In what star can you find so and so?” He was that kind. By the way, he did ask me things like, that. One of the hot problems right now is, what’s the solar abundance of boron? And I remember going over with him all the possible ways of detecting boron in anything, once I started on odd stars.

Weart:

I see. That’s interesting, because one of the things I was curious about is some of the papers you wrote around 1940, 41. You did Upsi1on Sagittarii, you did Alpha Carinae and some others, and you seemed to concentrate on getting a lot of identifications — identifying a lot of lines.

Greenstein:

I still do.

Weart:

But not so many people were doing this?

Greenstein:

Well, they were doing it here. But the quantitative side, which is in my papers is not in any of the papers from Mount Wilson. They measured and identified the lines, and estimated intensities (off tape) The line lists are great. Morgan did that for the peculiar stars — you know, finding cerium and praseodymium and europium and stuff like that, in the A peculiar stars. But the quantitative side — I don’t think I started it, because people in Europe had tried to do it, but at least I was in a place where we could get good new spectra, with the McDonald high dispersion spectrograph. And if you see a line list, the only other place that could have one a line list like that was Mt. Wilson. And I picked those who stars you mentioned. Dunham, who invited the modern Coude grating — mirror — Schmidt spectrograph with Bowen, did a line list for a giant, Alpha Persei or Gamma—Cyngi with roughly solar temperature, a supergiant. And that was it. There just weren’t any other high—dispersion stellar spectra. Then, in the B stars Unsold did one, very early at McDonald, a Coude plate on Tau Scorpii. And you see, by doing solar type and B type stars, you sort of exhaust the line list of everything except the genuinely crazy stars or the molecular banded stars.

Weart:

The aim of all this is to get into stellar evolution?

Greenstein:

Well, not at that time. In fact, I know when I first thought of it, I had no reasons, at that time, to do it from the point of view of stellar evolution.

Weart:

Then what was your interest in the composition of stars? Simply as problem in itself?

Greenstein:

Yes. Who knew what the stars were made of?

Weart:

Was it also partly because of Russell’s demands, that he was interested in –-

Greenstein:

Russell was quantitative. It was not only identifying the element (and he had these very rigorous rules about when you could say that the thing was identified), but also, how much? And he had done that — I just don’t know how old that first Russell solar composition paper is.

Weart:

When you did Upsilon Sagittarii, and you found that there was very 1ittle hydrogen, did you think of any possible evolutionary significance?

Greenstein:

Oh yes. It was fairly obvious that, — I know it’s true now, I don’t remember when I first said it — there is one other important, strange peculiarity in Upsilon Sagittarii. Which was that nitrogen, whose transition probabilities were completely unknown (and that’s one thing, and neon also, left dangling in my paper) — it was obvious that we had something by then to do with Bethe’s carbon cycle, you see.

Weart:

I see.

Greenstein:

The nitrogen was a symbol to me already, you know. Chandrasekhar was — he’s good at dating things. [Gets book]

Weart:

Yes. You’re looking in the bibliography of Chandrasekhar’s book.[19]

Greenstein:

The [chapter] about stellar energy. The dates.

Weart:

The Bethe was 1939, if you’re looking up the carbon cycle.

Greenstein:

All right. OK. See, you’re better than I am — and Proton capture is considered by Atkinson and Houtermens. (Whom I eventually met.) Bethe and Critchfield — deuteron formation — hydrogen burning — but the carbon burning, you say ‘39?

Weart:

‘39 —

Greenstein:

— here it is, here it is —

Weart:

Early or mid-‘39.

Greenstein:

Yeah. Well, von Weizsacker and also Bethe. Von Weizsacker was a visitor at Yerkes, incidentally.

Weart:

At that time?

Greenstein:

Yes.

Weart:

I see, so you were — as soon as the carbon cycle idea came out, you were immediately —

Greenstein:

— yes. It was not in my field, but the nitrogen excess was very odd. And the helium was obvious. And so, although I didn’t go on dreadfully long on that topic then, it was certain that one had, in this star, evidence for nucleo— synthesis. But the word, I guess, didn’t exist.

Weart:

Did it also seems that these would be highly evolved stars?

Greenstein:

Yes. Well, the evolutionary situation of Upsilon Sagittarii, actually, is almost unparalleled. There are a few stars known which are presumably rather massive in which the core burning products notably helium somehow got to the surface. And these may be precursors of planetary nebular. Because it is almost certain that after this stage, the whole outer envelope goes away, and the very hot core is exposed. The other part of the mystery is the carbon stars, which were known already by this time and which I didn’t work on. Nobody knew how to make excess carbon, at this epoch, and there was even a carbon isotope anomaly known, carbon thirteen. So there was clearly something which showed you what happened inside a star, exposing it at the surface. But one of the troubles is, upsilon Sagittarii is a binary system, and no one knows anything about the other star. It’s left a somewhat bad taste on our understanding of it, unfortunately, because it may be that the secondary is hydrogen-rich. But nevertheless, for those days, without knowing all of this, it was just one startling fact. Alpha Carinae is the second brightest star in the sky, and could be observed from McDonald, though with difficulty, so it was obviously something else to do. It turned out less interesting, but was the first analysis of the composition of a high—luminosity star.

Weart:

You were getting a little interested, perhaps, in what we would now call nucleosynthesis?

Greenstein:

Yes. I sure was.

Weart:

But this was not something you could get to and make a program to do?

Greenstein:

No. One of the things I did, just before the war — and maybe even during it, because I still observed a bit —was, I took a whole series of standard spectral type stars with the McDonald Coude, with that very good spectrograph for those times, with the goal of doing all of the standard stars, to show whether they were all of the same or had different compositions.

Weart:

That came out after the war, didn’t it?

Greenstein:

Yes, that was delayed.

Weart:

Right. That was your first big paper on that subject. I see, but you’d already started —

Greenstein:

Oh, I’d started it long before, because once you saw a peculiar and a normal star, it seemed obvious that the question was whether you could explain all the myriads of lines in all the different types of stars as one composition — or were all stars going to be quite different from each other?

Weart:

Can you tell me, I wonder if you could possibly reproduce what your state of mind was about stellar evolution at that time? Did it seem like a hopeful field, like things were getting sorted out? Or did it seem like a very confusing, hopeless sort of a field?

Greenstein:

Actually, I had just superficial contacts. One, I listened to Chandrasekhar, who was lecturing. Next, we had a few students do theses on individual models, and I was usually on the examining committees at that time. There was an unsolved problem which made stellar evolution look terrible, and that was — in fact, here’s Russell again — which way did stars evolve? The red giant problem. And the red giant problem could not be solved. There was no way, in those years, of building a red giant. In fact, Schwarzschild I think it was postwar, tried a model and was wrong. Opik did it correctly, though nobody ever read his paper. And then Schwarzschild created the correct theory. But for me, I would never have thought of it — one, computing was so tedious and slow. Though I remembered Eckert, no one dreamed that we would be able to push a button and get a stellar model in five or eight seconds or something. I would never have dreamed of doing it myself, and a model really was a person—year. It was in fact a girl-year, because we had two women students.

Weart:

At Yerkes?

Greenstein:

At Yerkes, who did them. An improved solar model was a year. And then, another woman whose name I now forget — Margery Hall, Harris? — did a B star model, a massive star model. Convection was hardly known, and my first hearing about convection and turbulence was when von Wiezsaker visited. He had a little demonstration of an ink drop in a cup of water, and showed the diffusion, and then what happens if you put it in rotation. There’s a differential rotation, and the ink drops get smeared into sheets, Very interesting. It was an idea about spiral nebulae. But there was already this question of convection. I’d heard of it, but it was not for me.

Weart:

What about cosmology? Was it the same kind of things going on?

Greenstein:

At Yerkes, cosmology really hardly existed. The one thing I did with the nebular spectrograph about a galaxy, the energy distribution of the Andromeda Nebula, brought me into direct conflict, like a flea with a tiger, with the great Edwin Rubble. I was very proud of that paper,[20] and it proved that Rubble and Tolman’s analysis of the age of the universe, and the deceleration parameter, and everything, were wrong. We were talking at lunch about evolution. The major correction in faint galaxies is just what you might call the Bolometric correction — that you’re moving the ultraviolet into the visible.

Weart:

Right.

Greenstein:

Nobody had ever measured the energy distribution over a wide range of colors for a galaxy with any accuracy, till I did. And that paper, I was extremely pleased with. I met Rubble and he, shall we say, destroyed me — for the moment.

Weart:

When did you meet him?

Greenstein:

What is the date of the paper?

Weart:

I have your bibliography here. Maybe you can find it quicker than I.

Greenstein:

It may have been after the war, at that. Well, I should have marked it. I marked too many, didn’t I?

Weart:

This was while you were at Yerkes?

Greenstein:

I did it at McDonald. I don’t know when it was published. It was important to me. [Looking at bibliography.] My goodness, it was ‘38. Paper # 20.

Weart:

OK, that’s it — 1938.

Greenstein:

That’s a long time ago. It’s almost the first time, in other words, that the nebular spectrograph at McDonald was used. It just was startling; Andromeda was very faint in the ultraviolet, and if it were redshifted it would be very very dim. According to Rubble’s and Tolman’s analysis, after you put in the various relativistic corrections, you have this bolometric correction, which is to be multiplied by the redshift factor, Z. They used a factor of unity, and I got something like a 3 or 4. If that were true, the density of galaxies would be increasing outward at an unacceptable rate, just like quasars now seem to apparently. And Rubble just wouldn’t believe it.

Weart:

So, you gave a talk at a meeting and he stood up and —

Greenstein:

No, I came out here [to Pasadena], I think, on a trip or something. No, no. I do remember. There was a McDonald Observatory dedication in ‘39, just a few months before the war started in Europe. Unsold and Oort and Rubble were there, and here’s this pipsqueak — by that time, I’d reached the noble age of 30 — but Rubble was a very great man. I asked him if he’d read it, and he said that he had looked at it. I said, “Well, what do you think of the implications?” He said, “At the Mount Wilson Observatory, we know that the redshift correction for galaxies is one or less.”

Weart:

That was that.

Greenstein:

That was that. But that’s just a personal blow. Otherwise, I’ve loved every minute of being in astronomy. It’s all fun.

Weart:

I know. What kinds of relations did the Yerkes people have with Mount Wilson?

Greenstein:

Not very good. They were not close. Mount Wilson was isolated, and I understand that one of the worries they had when they invited me to come here, as head of the department was that I had never used a large telescope.

Weart:

You’d used the McDonald one, but it’s not a “large” one.

Greenstein:

I’d used the McDonald telescope for nine years, and I had not used a large telescope. In their definition, a large telescope was either the 100-inch or the Lick 36-inch. When I got here, I used to sit through committee meetings with my rage bottled up, as they would say, “Well, we’d give observing time on the 100-inch, on the 200-inch, to so and so from Lick, he’s had great experience with large telescopes. But we won’t let Kuiper use it, or we won’t let — “You know, some very good astronomer — because there was a very close Mount Wilson—Lick relation. Yerkes was too theoretical. Merrill proposed at one time to Chandrasekhar that the APJ [Astrophysical Journal] be divided into ordinary APJ and the APJ Supplement, and all theoretical papers be put in the Supplements. He felt no respect for theoretical papers. This is not to say he was not a very good and great astronomer, just that he was not theoretical. And Yerkes was a blend. The same is true of all of Kuiper’s work, Just to skip a little in time, the discovery of interstellar polarization came from Chandrasekhar’s suggestion that some B stars should show polarization, due to electron scattering in their atmospheres. It’s an example of theory interacting with observation, wrong theory.

Weart:

Right.

Greenstein:

And instead, they found the interstellar dust grain polarization. Hiltner was one of the people who went out after that polarization. You know — Chandra says there’s polarization, so look for it. I think it was from that point of view a very successful interaction between people who were so purely observers, and artists like Morgan, semi-quantitative people like I have become, and pure theory.

Weart:

You were never a pure observer, though? You didn’t do much to develop instruments, that kind of thing?

Greenstein:

I never — except, well, that’s not fair, I had at least a half or a third credit on the nebular spectrograph idea. And I did design and build, in 1947 a V—2 rocket solar spectrograph. Which failed. And —

Weart:

And there’s optical design in the war. Well, OK, that’s not quite fair.

Greenstein:

No, I’m not. I’ve been very lucky all my life in having people around who will do my computing for me now, and in any case, do my instrumentation, for themselves, and let me use it. Like Bevoke here, and Jim Gunn. I must say that, I think I’ve never yet seen a person — no, there is one person, that’s Gunn — who’s good in theory, in designing instruments, and in applying instruments to important cosmological problems.

Weart:

It’s very rare. Speaking about cosmology, I wanted to get back to something you mentioned a little earlier, that there was not much cosmology at Yerkes, which is true. Why was that?

Greenstein:

Interesting question. We could have done it at McDonald. We could have gotten spectra of galaxies and could have measured red shifts. I certainly never did, I don’t know of any. Maybe, if you wish to think of it — we did have some interest in stellar evolution. We had interest in interstellar matter, stellar atmospheres, binary stars, eclipsing stars, shells, comets, diffuse emission nebular, double stars — I would say, it’s almost as if we did everything except cosmology. I don’t remember, in fact, when it was that Chandra told me he was leaving atmospheres, interiors and plasmas, and going to do relativity, that he would have to learn it. That’s much later. But I think it’s an interesting observational fact. We didn’t have any good photographic telescope, really, like Mount Wilson did. We didn’t have the mapping type thing, covering the whole sky, that Harvard had gotten from the Southern Hemisphere, and kept getting from the North. I guess the galaxies just were our one major deficiency. Whether Struve discouraged it, whether if a good person wanted to work on galaxies and appeared, he would have gone elsewhere right away — I don’t know.

Weart:

Let me ask you, can you remember either from your Yerkes period or even the Harvard period much discussion of cosmological problems, in the very broadest sense, even philosophical questions of cosmology and so on?

Greenstein:

Certainly, at Harvard, because relativity was a regular feature actually of graduate instruction already. Robertson was the person who got me personally interested during a summer visit, but that was just an accident, Shapley’s interest — must have been a continuing one. But Shapley, you see, and Rubble had absolutely zero contact. There was a good deal of antagonism. And it may be that that had something to do with — Of course, I couldn’t have observed in any way in the galaxy field, except cataloguing.

Weart:

At Harvard?

Greenstein:

At Harvard — whereas at Yerkes and McDonald, we could have. We had a very good fast spectrograph.

Weart:

But there wasn’t this background of interest in relativity and so forth.

Greenstein:

No. Going back to evolution, Shapley photographed a lot of globular clusters. He took them in two colors, and one of my very earliest papers, for which I got material from Shapley and also from Rubble, which was given me at second hand, was one of the first color-magnitude diagrams of a globular cluster. And that leads to stellar evolution. But it didn’t lead me, or anybody there, to observational stellar evolution at that time. One thing, of course — we didn’t know why there were red giants, especially why there were the funny red giants.

Weart:

People just thought that these were different types, different composition perhaps?

Greenstein:

Yes. It was weird. I took some spectra at McDonald of stars in globular clusters. Nancy Roman as a student worked at McDonald and got spectra of the metal-poor main-sequence stars, which had also been found earlier at Mount Wilson by Adams, Joy, etc. They didn’t know what they were, and called them intermediate white dwarfs. But the high velocity stars, and the population type differences, were things one had already noted in Bill Morgan’s work, and certainly in McDonald work at higher scale that I did. But I never analyzed a metal—poor star, till I came here. That’s true.

Weart:

Let me ask a different question, a different subject I notice that around this time, ‘38, ‘39, you first have papers in your bibliography for THE TELESCOPE, POPULAR ASTRONOMY, SKY AND TELESCOPE. Did you begin to become interested in writing for the public, addressing the public?

Greenstein:

I have no idea why I did it.

Weart:

You’ve since become somewhat concerned with the problem of addressing the public.

Greenstein:

You see, Yerkes was so isolated. It’s an interesting question. We had zero public responsibility there or contact. We had very few graduate students, maybe two a year would come — there’d be six or eight students altogether. There were more faculty than students. Courses weren’t given all that often. In other words, I don’t think we had an awful lot — of competitive, public-relations. I wanted somebody to know about me. I remember getting into the newspapers the first time, in ‘48, just as I was leaving, about the analysis of stars, composition — postwar work. And my conclusion was exactly the opposite of the newspaper headline. That I remember. That was when I first learned about the press. But Struve was not public-relations conscious. The whole place really wasn’t. Kuiper made some extraordinary discoveries, and would usually get them in the newspaper. I think there was some feeling that it was slightly low of Kuiper to get in the newspapers.

Weart:

It was really classic ivory tower of astronomers.

Greenstein:

It was.

Weart:

It must have made a great contrast when the war work started. I’m very curious, how it struck you when you switched from doing astronomy to going into designing things for tanks and airplanes and so on. It’s such a totally different type of work. Tell me how you got recruited, how you got into war work?

Greenstein:

Oh, it goes back before the war, Bob Robertson, H.P. Robertson, the relativist, a man I’ve written an obituary for, for the ACADEMY, which is going to be out pretty soon — it took me 15 years, though he’s my best friend, to write it. I couldn’t do it. He got very interested and very worried about war problems, early. He had spent a year or two in Germany, and loved Germans as individuals, but he was conscious of the danger of war, and we talked. And then with the refugee problem, in the late thirties already, everybody was talking about it. And I was asked, well before the war started, to work in two different areas, neither of which I found very attractive. One is now called operations research, and the other was more routine — well, not all that routine — anti—submarine warfare in general.

Weart:

There were people who were interested in operations research before the United States entered the war –-

Greenstein:

Yes. Spitzer, for example, went up and headed a big section, I think, in New York City, of anti-submarine warfare problems. I think, before we were in the war — or at least very soon afterwards. And Phil Morse of MIT wanted me for another thing.

Weart:

Let me switch the tape now.

Greenstein:

One thing about me as a scientist, I wasn’t mathematical, but I think I was a little broader, even then, than most scientists. So, the bigger thinkers wanted me to do various things before the war. I think the particular anti—submarine warfare thing was a random search problem. What is the best way of dropping depth charges, whatever they’re called? The British had been involved in this. Senior American scientists and the British were close for years before the war, when Britain was in and we were not. But I didn’t dreadfully like either of these, and I guess I really didn’t want to leave where I was. And when the war broke out, I was either going to be drafted or do something. I think the person who actually got to me was a person I didn’t know, Theodore Dunham, out here, who started the optics section of the OSRD — NDRC[21]. Maybe because I’d done stellar spectroscopy he thought I would be able to do anything in optics. They were eventually doing cameras and camera shutters, out here, and I think I got a phone call, saying, would I be able to come to Pasadena? I said I would rather do it here at Yerkes. Louis Henyey was really at the center of the work, because Louis was such a good mathematician. We also had for some while Van Biesbroeck, who did his computation on an old-fashioned hand-cranked calculator. So I said, we could probably do it better without moving, and would see which way it went, because there’d only be a few people. What they used our few people for was what I might call “miscellanea”. I never — I did later, but not at this time — did an aerial camera design, but we did everything else that the military or that the civilians advising the military thought they would need.

Weart:

This was at Yerkes?

Greenstein:

At Yerkes. In a very short time, I don’t think it was more than a few weeks after we were asked, got the University of Chicago’s permission to close off some offices and a part of the basement, and we took all the calculators there were and started to answer some simple questions that people asked. It did quite well; the general pattern was that they would call me and say, “We want so and so.” I would say to Henyey, “We need a lens with such and such properties, or a mirror”, and he would go home and come back with 10 sheets of mathematics yielding an optimization, with a certain number of optical elements. And then we’d have to do the detailed design by hand.

Weart:

With the calculating machines.

Greenstein:

The calculating machines. In those days, we had to fight things like priorities — we had a lab, which became quite large.

Weart:

An optics lab?

Greenstein:

An optics lab in the basement. Centered on a man named Fred Pearson who had worked with Michelson grinding the inter-ferometer plates and mirrors for the Michelson velocity-of-light experiment. And somehow or other, he was handy, and –-

Weart:

I gather, incidentally, that around Yerkes you never were in trouble for finding people to do your instruments and so forth. I forgot to ask you that.

Greenstein:

Well, our’s was a tiny effort. The workmen were good. It’s interesting, you’re quite right. We had no electronics, remember. So it was optics. Then after we had the optical shop, postwar, we made quite a few things. The mechanics you know, it’s interesting — were regional. The area around there was settled by people from Scandinavia and Czechoslovakia, Bohemia, and latter were the very good instrumental, machine-tool people. And we had some very good ones. Just a couple, in a tiny old-fashioned mechanical shop. In fact, we had that too. We took that over; the optical shop grew quite large. We had about a half a dozen men, at the largest. It was all non-profit, you know, salaries were paid by the university.

Weart:

— on an OSRD contract —

Greenstein:

Yes. And then the workmen were paid by the OSRD, and it was not negligible. I think, at the largest, there were four scientists, and maybe a couple of machinists and four or five opticians.

Weart:

Tell me, how did it feel to be doing this kind of work? It was a totally different kind of thing.

Greenstein:

Well, for me it was relatively easy. See, here I was back in the Depression again. No, it wasn’t easy. It was terrible. It was very disturbing. But I had to. We obviously had to give up science part-time or three-quarters time, nine-tenths time. I even was asked at one time whether I wanted to work on a super-secret thing which was going on in Chicago, which I didn’t know anything about. And our project was going quite well. It was rather frustrating. Like everything the government told to ten different groups, that they needed something by next week, and we would be saviors of the country if we could only finish it by next week. We sometimes did things in two weeks, to find that there were six other groups who had also done it; then we would find that it was all wasted. The secrecy was such for no good reason, that we never were allowed to talk to the people doing, rival work in the same field. It was a rather odd business. I used to carry things to the military bases, and get them mounted and stuff like that.

Weart:

You did pilot models in your shop and so on.

Greenstein:

Yes. Oh, in some cases, I think we made up to 50 of a kind.

Weart:

I see.

Greenstein:

But for others we’d do maybe half a dozen. Usually they would be tested to destruction.

Weart:

Right. I gather that your feeling was that this was a necessary but unwelcome diversion from astronomy.

Greenstein:

Yes. Of course, it happened to be a war I enormously approved of. It might have been different if the two people who asked me first had not asked me to do purely mathematical topics, which I was getting away from. Optics, though it was numerical, was non-mathematical — I was more practical than others there. It was no hardship for me to talk to a Navy officer and find out what was really his problem. The nicest thing I did, I don’t know how many of them were built, was a camera for taking pictures through submarine periscopes. The worst was a terrible competition to design a telescope for gun pointing on tanks, with rigid space requirements and shock problems. Our design failed the first time, from the point of view of some better one from Eastman Kodak. Then another design we did was optically simpler and cheaper and quicker to make, and they made thousands of them in the last months of the war, which were sold at surplus — telescopes about this long [Holding up hands half a meter apart] and about this big around [a few cm] with a giant eyepiece. Most of the guiding eyepieces in astronomy are either Eastman Kodak or Yerkes designs. Wide—angled eyepieces, thick, nearly solid glass. But of course, part of that was scary. I went to military maneuvers. Never saw people jump out with parachutes, though I went on one of these. Some were connected with what you’d call intelligence-gathering projects, and that involved bad parts of super-secrecy. I found that this got me often into situations where I’d arrive with a thing I’d designed and built at the request of somebody, and give it to them, and then they would exclude me from then on and I never knew what happened. It was wasteful. I was very much in favor of our winning the war; I’d have been dead if we’d lost it, and it was an interesting experience. I gained, at that time, a thing which some of the older scientists have, perhaps a few young ones — a great respect for certain kinds of military officers. They’re extraordinarily good, brave people who, for whatever reason, just really give not only physically their lives, but all their energies, all their life, for something. You know, it’s like science in many ways. The best scientist are like the very best colonels. It was an instructive experience. It scared me. I had nightmares. I didn’t know about the nuclear weapons, but I heard about it. It gave me more nightmares later.

Weart:

At what point did you hear about it?

Greenstein:

My good friend from Chicago, Willie Zachariasen, who analyzed the first crystals of plutonium in existence, at Chicago — called me up one day and said, “There’s a report out it will be in the papers tomorrow, called the Smythe Report — the bomb dropped on Hiroshima was a nuclear fission bomb based on uranium”, etc. etc. It later turned out that Fermi had been milking Chandrasekhar all the time, without Chandra ever being involved in the project, on this. Neutron diffusion is the same as radiation transfer. So Fermi would come, have a weekend with Chandra, and say, “Let’s talk a bit about your work, Chandra –-“ Chandra, I think I heard just five minutes before I did, not from Fermi, but I think also from Zachariasen. But I never had anything to do with that.

Weart:

How did you feel about it when you heard about it, as a scientist?

Greenstein:

Again, you’ve got to understand — I guess it’s hard. I’m afraid I still feel about it that it was the right thing to do.

Weart:

Well, I can understand that.

Greenstein:

You have to have lived through it.

Weart:

No, I don’t have any problem about it. I’ve read the memos and so forth at the Metallurgical Lab, where they’re talking about, “Will the Germans drop a nuclear bomb on Chicago first”? So I can understand very well.

Greenstein:

As a scientific miracle, I was impressed as hell. And the trouble — when he said, “It’s a chain reaction”, I said, “How does it happen”? He says, “you get more than two neutrons per collision”. I said, “Well, then it will go on forever. Will it stop? Will it burn up the atmosphere”? Those were actually the first questions I had about the propriety of nuclear weapons: what would stop it? Well, actually that had been apparently a question at one time.

Weart:

They had thought it out, yes.

Greenstein:

But the fundamental equation of neutron buildup is the same as radiative transfer, and its exact solution which Chandrasekhar had done in his book — was obtained in two places more or less the same time, in Canada and in the United States, in closed form. The formulae I made my stellar-atmosphere students look at, when I started teaching. The formulae each take a blackboard.

Weart:

You said, after the bomb and so forth, you had nightmares about it.

Greenstein:

Well, you know — killing that many people at once. I had been, unfortunately (again, it’s very mixed), I had been very anti—German, but of course the war in Germany was finished. The war in Japan was brought to me by military contacts. I had most to do with the Navy and the Air Force. I quite irrationally just didn’t like the Japs. Fortunately I now admire them enormously. But the people who had fought in the field were really at a loss, afraid. It was almost a moral question with them, the Japs. The Japs didn’t surrender. The Japs didn’t take prisoners. The Japs were non—human. So that I don’t think I worried about that. But I did have nightmares later, because I thought it was pretty obvious that in a short time everyone would have the bomb. I didn’t have any idea how big the project was from friends in Chicago — I didn’t even hear about Los Alamos till afterwards, till that report was out — I had top secret clearance, and I didn’t know anything about the nuclear bomb.

Weart:

Though you were invited to go down there, you could have gong down?

Greenstein:

I could have gone down. They said they had a very secret thing, and I had top secret clearance. It takes a full extra special investigation. But the Yerkes Optical Bureau was sort of fun and I stayed. And we built this all-sky camera.

Weart:

Yes, you and Henyey.

Greenstein:

That’s it.

Weart:

What was that originally for?

Greenstein:

It was a good idea. The training of machine gunners to defend bombers from attack by fighters coming from all possible directions. You remember, they had tail guns and bubbles at the top and at the bottom –-

Weart:

— right, they had to be able to catch things coming in from every direction.

Greenstein:

Well, that was for a training device. There was a center for that somewhere near Washington, one of the naval bases, where a man named Waller had put together seven movie projectors. Then you had seven screens that more or less enveloped you, because you had to have this 180 degree, view. There was a company in Chicago, an advertising company, which took on the film-making jobs Given mathematical computations, you could get a little model plane, on a stand, and take a frame, Then the model would be moved properly, so size, perspective, angles everything had to be changed, and the film repeated.

Weart:

Like animating a film.

Greenstein:

They animated the film completely to show how the plane, coming in on this trajectory, would look. It would transfer from one camera to the other, even. Then, I think the gunner had infra-red or far red that he couldn’t see, attached to a dummy gun, which didn’t shoot bullets, and a blind recording device which would show this success at leading and hitting the thing. One of the things we built say, 50 of was a lead sight, where you’d look into there, and see a set of range circles projected on infinity. So anyway, the wide-angle camera was a good thing. There ought to be more of them. But to do all this animation was really slow and for the birds. And if you could photograph a real plane in a trajectory with an all-sky camera, and project it on a dome, you had exactly the same thing.

Weart:

OK, I get it.

Greenstein:

So there was some genius in Long Island named Captain Conrad — it almost sounds like science fiction — he was my contact. When I say I got to know Navy people, this was a Navy captain. Well, that’s something.

Weart:

It’s 3 o’clock now. Maybe we should come to a halt. I’m hoping we can resume it, maybe next time I come through.

Greenstein:

I think this is extraordinary. Maybe we ought to write a book about me.

Weart:

It’s extremely interesting. We are writing a book. We’re writing your autobiography, sort of.

Greenstein:

All right. You see, I was not at the center of astronomy, if I may remind you modestly. But I lived through it — I’ve had a hell of a good time.

Weart:

— if you weren’t at the center, you certainly visited the center a number of times.

Greenstein:

We’ll stop. But, I met Lyman Spitzer, you see. Re was interested in antisubmarine warfare. The first [AAS][22] meeting after the war, I remember was at Northwestern University, and Lyman and I have been, I think, good friends ever since. A brilliant, charming guy who I think had been a Rhodes Scholar, and then got into the war, and later helped start fusion plasma research. Some of my friends had dreadful results from the war. Thornton Page was a good perspective scientist, also a Rhodes Scholar. Re got into the war two years before it started, eventually became a lieutenant commander in the Navy, and never has did that much science since. The war did a lot of different things, The war, in a certain sense, for me was different than for many, because it had some elements of a return to the Depression in New York.

Weart:

It was like an interruption, a necessary interruption?

Greenstein:

Yes, instructive and humanizing.

[1]Edited by Camille Flammairon (?)

[2]C. Payne, STELLAR ATMOSPHERES. (Cambridge: Harvard Univ. Press, 1925).

[3]Harvard Bull. No. 876 (1930)

[4]Actually early 1933

[5]”The Periods of light-curves of the Variables of Messier 3” Astr. Nachr. 257, p. 301 (1935).

[6]”Studies of Interstellar Absorption,” Harvard Diss. (1937).

[7]”On the Origin of Interstellar Radio Disturbances” Proc. Nat. Acad. Sciences 23, 177 (1937).

[8]Tape recorder lost JG telling about his persistent interest in radio since his youth, stimulated again by seeing AT & T antennas at Holmdela during summers on Jersey shore.

[9]”A Determination of Selective Absorption Based on the Spectrophotometry of Reddened B stars,” APJ. 87, 151 (1938).

[10]LTE: Local Thermodynamic Equilibrium

[11]The Univ. of Chicago Faculty Club

[12]Greenstein and Henyey, “The Theory of the Colors of Reflection Nebulae,” APJ 88, 580 (1938)

[13]Astronomy in the 20th Century, p. 397-98.

[14]Only the Directory files of correspondence have been found.

[15]Struve was editor during this period.

[16]”The Spectrum of Upsilon Sagitarii” APJ 93, 128 (1940).

[17]H. N. Russell, R. S. Dugan and J. Q. Stewart, Astronomy (Boston: Grinn, 1926-1927; 2nd ed. 1938-1945).

[18]His daughter

[19]S. Chandrasekhar, AN INTRODUCTION TO THE STUDY OF STELLAR STRUCTURE. (Univ. of Chicago Press, 1939; NY: Dover, 1957), p. 485.

[20]”The Temperatures of the Extragalactic Nebulae and the Redshift Correction.” APJ. 88, 605 (1938).

[21]Office of Scientific Research and Development, under the National Defense Research Council.

[22]American Astronomical Society.

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