Oral History Transcript — Dr. Martin Schwarzschild
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Martin Schwarzschild; July 30, 1975
ABSTRACT: A preliminary interview with Martin Schwarzschild prior to the Sources for the History of Modern Astrophysics Project. They discuss developments in astrophysics and astronomy and possible people to interview for the project and why.
Weart:Itís understood that this is for the use of the project, and that nobody will make any further use of it without asking your permission. Nobody will quote from any tape we make.
Schwarzschild:No, and particularly since we are now going to discuss names. Isnít that right? I have to rely on your discretion.
Weart:Right. What I would like is for you to tell me what you think have been some of the most important developments in the field, letís say since the time that you first became aware of what was happening in the field, and what names you would associate with these developments.
Schwarzschild:All right. May I, right away, say, there is the solar system, with lots of development in celestial mechanics, and in the physics of the solar system, and lots of theoretical effort regarding the origin of the solar system. That is a field I know nothing about. But a possible good source of advice, sort of as a senior man, just retired, is FRED WHIPPLE, the former director of Smithsonian Astrophysical Observatory. I think heís certainly a person that comes to mind.
Schwarzschild:Right. But I mean, that is a field, both on the celestial mechanics side, and on the physical side, Iím terribly ill acquainted with.
Weart:Thatís fine, because so am I, and one canít study everything, and frankly Iíve decided that in this study, we wonít cover too much of the solar system except for internal constitution of the sun and so forth, which relates very closely to more general astrophysics.
Schwarzschild:Now, if we think in terms of objects of study rather than techniques, which may not be the most useful, then in a very rough way, we cover a large part of modern astrophysics if we think in terms of stars, individual stars, stellar systems — our galaxy but also other galaxies, individuals — and then the assembly of galaxies, essentially cosmology. So maybe we should go through these three fields, to which contributions in all the modern fields of techniques, really, are full. I mean, you could also divide it by optical astronomy, space astronomy, radio astronomy and to some degree one should not quite forget that one wants to be sure that there is also a distribution by techniques.
Weart:Right. We can talk about that a little later, perhaps. Iím sure there are some men whose names are more associated with techniques than with the particular objects, shall we say. I think thatís fine. Why donít you start with the objects, letís say, with the stars. And the period weíre covering, I guess, would be back to about the time you were a graduate student.
Schwarzschild:All right. Iím speaking without having thought about it before — one of the first big steps in roughly the time period you mention was the determination of the chemical composition of the surface of the sun, by [Henry Norris] RUSSELL, who is not alive. And ever since, a phenomenal development of spectroscopy of stellar atmosphere has occurred. And again thinking in terms of roughly my age group or even a little older, so that they remember — JESSE GREENSTEIN at Cal Tech certainly has experienced in his own lifetime very strongly this development, and has played a magnificent role himself.
Weart:Heíd be a good person to interview, too, wouldnít he?
Schwarzschild:Yes. Very lively, and an extremely nice person. Occasionally he has strong opinions. Thatís up to you historians, to try to put into the right light. (Laughter) I mean, one big very important name during that development — and indeed for the whole also, organizationally, for astronomy in this country — is STRUVE. JESSE GREENSTEIN would be a very good source. Connected, but largely driven by different group, is the field into which my own work falls, the stellar interior, which has an observational side, largely through the photometric work of clusters of stars. There, the person who has played, to my mind, the key role is ALAN SANDAGE. Heís not of Cal Tech but of the Hale Observatories. Heís in Pasadena, the Santa Barbara [street] address. But there are many, many more people. SANDAGE is a somewhat more complicated person, but I think a person that has played, historically, a terribly important role. Not only in this field, but also in the cosmological field, which has interactions, so itís very natural that he has been active in both fields. And therefore when we come to the cosmological field, I think it will be very difficult to avoid. I mean it would be terribly natural to consider him on the list. The stellar interior, particularly stellar evolution, has a very large portion purely on the theoretical side. There, in the earliest part, of that period you mentioned, CHANDRASEKHAR would be a person with a very strong historical sense, very much in the English tradition, you know, — an active historical sense.
Weart:You know, his papers have already been deposited, at University of Chicago.
Schwarzschild:I mean, he is of a stature that is of an extraordinary kind.
Weart:It also shows his great historical sense, too, that he should already have made the arrangements and put them there.
Schwarzschild:I see. He has a much greater sense of science history than the majority.
Weart:Did you see he had an article recently in BULLETIN OF THE ATOMIC SCIENTISTS, just the last month or so — quite interesting Ė- I think around May or June.
Schwarzschild:Which one? On which topic?
Weart:What was it on? Well —
Schwarzschild:Wasnít there a lecture he gave, an honorary lecture, on patterns of creativity? Shakespeare, Beethoven and Newton?
Weart:No. Iíve forgotten whether it was about Eddington or about Einstein, I think about Einstein. And cosmology. But Iíve forgotten —
Schwarzschild:I see. He has worked in very concise periods — drop a topic, start a new one — normally writing a book at the end of every period.
Weart:I see, just like an Englishman, as you say.
Schwarzschild:I see. I donít really know the patterns.
Weart:I think the classical people did do that.
Schwarzschild:And that sounds, when I mention his name now, very much like his first period, his first book. But I mean, heís a few years older than myself, and in scientific accomplishment far my superior, so as far as he has been active, which was — he sort of switched out of that field somewhere around 1945 or something like that.
Weart:What other names would you associate with the early, letís say the pre-war work on internal constitution of the stars?
Schwarzschild:Well, the introduction of nuclear physics into the theory of stellar interior was a fantastic step, and there, the key step was done by BETHE and VON WEIZSACKER, both of whom are alive, BETHE in this country, I think, to get a feeling altogether, not just in that field, but over a much wider field in astronomy, of the growth of interest of physicists in — doing active research in astrophysics — in their formal capacity as physicists, I think BETHE might just be the right man to describe — A former student of him. ED SALPETER, a t the same place — substantially younger than myself, entirely brilliant, and also, I mean, grown up as an official physicist, has become a very major contributor in the field of stellar interiors — one of the main ones.
Weart:You mean even currently? What period are you talking about?
Schwarzschild:No, even currently he is very active — but itís not his only field. Personally BETHE entered astrophysics only for a very short spell of essential work. Thereís that one famous paper, that gave the source of the energy for the bulk of the stars. Independent and essentially simultaneously with VON WEIZSACKER, BETHE gave some things more than VON WEIZSACKER. Theyíre always both quoted. And of course that was in 1938, which really was a banner year from that point of view.
Weart:Because of that?
Schwarzschild:Because of that. Now, in the early phases, very early phases, I mean, of course, there are the famous names like EDDINGTON and MILNE. I donít know that thatís really — thatís the first call to Ė- thatís a little before the time you want to cover —
Weart:Yes. Theyíre of interest too, of course.
Schwarzschild:I mean, you are thinking in terms of international astronomy?
Schwarzschild:I think BIERMANN in Germany, Munich — He played quite a role — yes? (interruption)
Weart:I see we have a whole file drawer labeled ďstellar interiorsĒ here.
Schwarzschild:My life is so largely in that field.
Weart:All right, BIERMANN, who else? Perhaps one shouldnít say, who else, but what other major developments and people you associate.
Schwarzschild:If I may be so forward — may I consider myself as a possible source of description of —?
Schwarzschild:— particularly the exciting early phases. The roles that, for example, OPIK, an Estonian, played in astronomy — his role and HOYLEís role. And indeed, the question of interviewing HOYLE is — well, his interest in stellar interior, I donít know how large it still looms, but heís obviously one of the —
Weart:Heís obviously on the list.
Schwarzschild:An enormously imaginative figure. Whether his own evaluations, I mean, who contributed what, will stand the test of historic study, is quite different. But his influence, if not directly, by way of him being right, but indirectly, by him stirring everybodyís both ambitions and imagination, has been enormous. As an objective source of evaluation, I personally would not put him so high. But as an important factor in driving astrophysics forward, — very tops. On the theoretic side, I was talking about, you know, the interrelation of OPIK, of HOYLE, and of GAMOW and of CHANDRASEKHAR. This whole very exciting period around the time when nuclear physics gave the break, which was I think an unusually interesting period, unusually interesting from the point of view of the interrelation of a relatively small number of people — pretty well those I already mentioned. BENGT STROMGREN, the Dane, and myself, and then a whole slew of the younger generation. Now, I do not know how far in fields like that you want to go.
Weart:Iím curious, do you feel that the developments letís say since the war have been as important as the developments before the war?
Schwarzschild:Well, actually, you see, this Ď38 was just about the point where most everybody stopped doing astronomy. So the effects of the Ď38 development really were absorbed into solid research only after an interval. The period to in any case, Ď55, was the first decade, Ď45 to Ď55, to really get nuclear physics into the theory of stellar evolution. And since then, more and more stellar evolution has become a contributor to cosmology, and therefore the work of the younger people since then has taken different turns. Particularly it is starting now to go into the final phases of stellar evolution, where people like ARNETT and others come in, who really is a nuclear physicist, but sort of second generation. He played a very big role. Now, one person whose evenness of judgment and importance of contribution I think probably should be considered is WILLIE FOWLER, also at Cal Tech. Heís a straight nuclear physicist who very early decided to essentially put his life into doing that nuclear physics that astronomers needed. Therefore, his participation was entirely on that part of astrophysics. But also, I mean, the collaboration with the atmospheric people, like JESSE GREENSTEIN has been enormously high, and I think heís terribly balanced in his views.
Weart:You could give me some other names. Iím very interested in the postwar period. 1955 is 20 years ago now.
Weart:And even 1965 is not that recent.
Schwarzschild:Of the young people in this country, ICKO IBEN in Urbana, and PIERRE DEMARQUE at Yale, I would consider sort of, you know, solid centers. And they have still younger people around them, like PIERRE DEMARQUE has LARSON, and actually ARNETT is with ICKO IBEN. In fact, I think for the field of the stellar interior, that might be enough names. I mean, they themselves —
Weart:— they will generate more. Schwarzschild — have other feelings. One person that perhaps one should consider in a much wider frame, is CECILIA PAYNE-GAPOSCHKIN, whose most famous work really preceded RUSSELLís in the same field which I mentioned, but who I think has maintained a width of view and a general interest that is not reflected in her own work.
Schwarzschild:Also I think, although there she might be quite emotionally involved, the whole development of Harvard under SHAPLEY, and then after SHAPLEY under MENZEL and LEO GOLDBERG — I mean, Harvard is an important center.
Weart:So now weíre to the galaxy, or clusters and the galaxy.
Schwarzschild:The galaxy. Right. There, the looming figure is JAN OORT in Holland, officially retired, but magnificently active.
Weart:I see, so he would be a good person to interview.
Schwarzschild:Oh yes indeed, it would be a shame if you missed him.
Weart:I must say, his Ė- OORT has been very prominent on everybodyís list so far.
Schwarzschild:Right at the moment, among living astronomers, few would not likely consider him the record(?) astronomer. His influence has been entirely fantastic, beside his own work. He was here in the spring for two weeks.
Weart:You know, one thing I must do, when this project has started, I must find out when these people are coming near the New York area, so I donít have to go to Holland or whatever, in order to be able to interview them. Schwar1zschild: One of OORTís sons lives here in Princeton. He is with the Geophysical Fluid Dynamics Laboratory. BRAM OORT. It may be more proper to write to JAN OORT and find out when he makes his next visit.
Weart:Right, Well, his son — fortunately all this is still some months in the future, so —
Schwarzschild:But he has been coming here.
Weart:I see, so he comes fairly frequently.
Schwarzschild:Once a year or so. If his health keeps well. I mean, heís not that young. But he has been very well, up to now. Now, I preceding him and simultaneous with him, LINDBLAD in Sweden played a big role. He is not alive. His son is now the director of the Stockholm Observatory, PIER LINDBLAD, I think thatís right. Iím not that sure of the first name. Now, going on, in galaxies, there is one field that obviously I am very aware of, even though I have never worked in it, and that is interstellar matter, gases in galaxies, and there I think few would disagree that my own boss, LYMAN SPITZER, has been practically throughout the time, a leader. But one of his students, GEORGE FIELD, who is now the director of Harvard and the Smithsonian [Observatories], you know they are now combined in the directorship, is certainly one of the substantially younger — SPITZER and I are about the same age, and GEORGE FIELD is one of the —
Weart:— next generation?
Schwarzschild:Right. And I think would generally be considered as one of the keener, in that field. Now, BART BOK, who just retired, in Tucson, has played an important role in the research on galactic structure. Though possibly not as strong, as a scientist, rather than through his unbounding enthusiasm that he has imparted, and good advice and steering of younger people, has really set quite a record. He was for a while, for ten years, I think, out of the country, after a very big fight in Harvard, a consequence of the succession of SHAPLEY, and was the director of Mount Stromlo Observatory in Australia. But he did come back, and certainly can — well, he must be just a little younger than OORT, and also got his PHD in — I think so — in any case, most of his education in Holland. Now, quite a bit of both stellar research, when it comes to neutron stars, pulsars and also galactic research is in the X-ray region. And there, one of the original pioneers, leading up to these particular, most exciting topics that have come out of it, is HERB FRIEDMAN, but that is again a representative in my age group. He is head of the Naval Research Laboratory, and has played major roles in the space program. He was one of the three or so original pioneers who visited to put their livesí energy, into rocket work as early as Ė what were these German rockets —
Schwarzschild:V-2ís, right. He really — I mean, if you want the beginning of the history of off-the-ground, space astronomy, HERB FRIEDMAN is one of the outstanding, very early pioneers. I think one of the names that one should also very seriously consider from a variety of points of view is LEO GOLDBERG, who is the director of Kitt Peak National Observatory, and who has contributed both to questions of stellar atmospheres, enormously — he would be, I would consider, by far the best source on the growth of national observatories, the phenomenon of national observatories, which is certainly, as an organizational phenomenon, terribly important.
Weart:Yes, one of the things I wanted to ask you about was in fact exactly that.
Schwarzschild:So, you see, he was in Michigan under — not under MCMATH, actually LEO was the director of the university observatory, and MCMATH had his private solar observatory. But MCMATH was a driver towards the national observatory, and Leo therefore was involved. MCMATH was in some sense very unrealistic. He knew his way around Washington magnificently, but he didnít know his way around the scientists all that well, and therefore LEO played, from the very very beginning, in the first year, sort of a behind the scenes very important role.
Weart:In the scientific community?
Schwarzschild:Well, and as an advisor to MCMATH in his various, — he could tell much more. And I think he will not blow his own horn improperly I think one can tape LEO GOLDBERG, on that score, very importantly — By the way, I did not mention solar astrophysics, which normally is segregated from the stars, because on the sun, you can study not just the surface or the interior, but you can also see the hazy outer part.
Weart:Donít tell me, you know, I spent three years doing that.
Schwarzschild:Iím embarrassed, I should have remembered. In that field, well, you can pick your own candidates, but you can agree that LEO GOLDBERG Is —
Weart:— yes —
Schwarzschild:— is one of the key men. On the instrumental side, though again in the older group, is JACK EVANS, the just retired head of Sac Peak [Sacramento Peak Observatory]Ö
Weart:— when did he retire?
Schwarzschild:He retired. His age just came. The best younger man now at Sac Peak, and I think he is now the director, in fact he certainly is, is DICK DUNN. Now, he was —
Weart:— a great instrumental man.
Schwarzschild:A very great instrumental man, and I am not clear what sense of historic proportions he has, but as a figure he is —
Weart:Itís hard for me to evaluate — again, you know, Iím not old enough to have much of a sense of where the people that I know get placed — Iím trying to stay away a bit from solar physics especially because Iím too close to it. Other people can concern themselves with thatÖ but, back to galaxies now, galaxies and beyond, weíve not quite finished with that.
Schwarzschild:Right. The study of the galaxies, of course — HUBBLE has played an enormous role. Heís not alive.
Weart:How do I spell it?
Weart:Oh, HUBBLE, right.
Schwarzschild:Sorry, itís my pronunciation probably, and your spelling.
Weart:I keep thinking of HERBIG, I donít know why. HUBBLE.
Schwarzschild:HERBIG, by the way, would be a fascinating man, when it comes to interstellar matter, on the observational side. How even and broadminded is another question, but as a person, very very marvelous.
Weart:HUBBLE clearly. Actually HUBBLE is one of the very few people that thereís been some historical work done on already. Heís far enough back, and people have started to do it.
Schwarzschild:If you want my personal opinion, I think that his fame has been built up without any rera1%.relation to his actual contribution. I think he sort of fell into place, as —
Weart:He found a constant — where his name, that sort of thing —
Schwarzschild:Yes. I donít mind that that constant was named after him, but I mean, that doesnít, thatís no measure —
— for the contribution. I think that HUBBLE is one of the, to my mind, I suspect, one of the cases where the circumstances have made him a scientific hero. And, if I may be brutal enough to your profession, to say that I think it will not be corrected, that it has gone too far. I believe that basically the suspicion, but one could really check that, obviously, of an expanding universe existed before him. After all, SLIPHER had found the preponderance of the red shifts, isnít that right, before HUBBLE. I would not be one bit surprised if HALE had not clearly in his mind, for the 100 inch, that this problem should be there, and that HUBBLE as a youngster, energetic, strong — he was really an athlete, is that not right, fell into it. The spectroscopic observations, the radial velocity measurements, to the best of my understanding, but I may be very prejudiced on that point, would never have happened with any reliability if it hadnít been for HUMASON. Who started astronomy as a mule driver, when he was a boy of 14 or something like that, driving up the parts of the 100 inch, up to the mountain, and slowly got himself persuaded to be accepted, first as a janitor, then as a night assistant, and so on, and then deputy director.
He had never an education. And in that sense he never was an astronomer, but he was a magnificent instrument user, of course not an instrument designer, and essentially the observational material, at least the spectroscopic observational material that made the red shift curve, was based on HUMASON. HUBBLEíS plates, I mean plates that HUBBLE took himself and developed himself, were as scratched and dirty as they came — I remember discussions with the photographer of the observatory. He said whenever he had to prepare a plate of HUBBLEís for publication, he had to practically repaint it. Thatís a little excessive — And the star counts of HUBBLEís were ferociously poor, and HUBBLE had absolutely no concept how wrong they were — even though he could have estimated it. Indeed, I remember my teacher in Gottingen, HECHMANN in the field, telling me how completely unwarranted HUBBLEís deductions were on the basis of the possible accuracy that HUBBLE could achieve at that time, and did achieve. Now we know theyíre completely wrong. And essentially, after the famous papers — I think they were in 1935 and Ď36 — one, HUBBLE alone, if I remember right, and one HUBBLE and TOLMAN — HUBBLE essentially stopped doing science and waited for the 200 inch. This is my version of HUBBLE. The famous hero that I believe is an historic hero, not a real hero.