My Graduate Study in Astronomy after the War
I returned to the U.S. in time for Christmas, 1945; then, with Dr. Storer's blessing, entered the Graduate School program in Astronomy for the spring semester. The university was filled to overflowing with returning veterans making use of the "G.I.Bill." The Mathematics Department was especially in dire need of instructors, and I was pressed into part-time teaching of algebra and trigonometry. Dr.H.B.Smith was the chairman of the department, and some of the students told me that the "H.B." stood for "hard boiled." Admittedly he would accept no nonsense or dishonesty from students (in this latter connection Dr.Brewster, the chairman of the Chemistry Department, and neighbor of the Storers, declared to me that "Some of the students are so crooked they have to screw their shoes on every morning!"), however, in working for Dr.Smith I found out that he had the best interests of the students at heart.
Dr.Max Dresden was a new member of the Physics Department in 1946, and taught a number of courses on theoretical physics; while I was writing this, the notice of his death on October 29,1997 appeared in Physics Today, June 1998, p. 90, where it is stated that he had been the thesis adviser to more than sixty Ph.D. students (this is truly a remarkable accomplishment). Without doubt he gave the best lectures in physics that I was ever privileged to attend, and I took quite a few of his courses the next two years. I had hoped to take relativity, but it wasn't offered in those years, so instead enrolled in differential geometry and tensor analysis from Dr.P.O.Bell of the Mathematics Department. Also, I took orbit computation (of an asteroid or comet) from Dr. Storer, and started to compute my first orbit. We used a textbook by Dr.R.T.Crawford that was saturated with trigonometric transformations, and of course we performed the calculations using logarithms. I was able to follow the formulas, but had difficulty with the logic behind them. During the summer I did some sober thinking, and decided to apply vector analysis. Things started making sense, and fairly soon I acquired an active rather than a passive understanding of the basic concepts. This, in turn, led to my M.A. thesis on Vector Methods Applied to the Theory of Orbits, which I completed the following school year. It also became possible for me to calculate an orbit in about six to eight hours (this was speedy for those days), and I calculated three orbits as examples to be included in the thesis. While I admit that some of this speed could be attributed to my new understanding of the subject, yet most was caused by my being able to use the new Monroe mechanical calculator that Dr. Storer had acquired via the Physics Department (it cost $1500; quite expensive for those days). I cheerfully abandoned logarithms as my main calculation tool.
I passed my final oral exam in August of 1947, and then applied for entrance to the graduate school of the University of Chicago, Department of Astronomy. Dr.Gerard P.Kuiper, associate director of the Yerkes Observatory, Williams Bay, Wisconsin, responded with an optimistic reply to my application, and I was enrolled for the fall quarter. The entire staff of the observatory, including faculty and students, resided in Williams Bay, and it was rarely necessary to visit the university campus in Chicago.
The astronomy faculty consisted of Otto Struve (Director of the Yerkes and McDonald Observatories), G. P. Kuiper, S. Chandrasekhar (in charge of students), G. Münch, A. B. Meinel, W. W. Morgan, W. A. Hiltner, T. L. Page, J. L. Greenstein, W. P. Bidelman, Kaj Strand, G. Herzberg, Van Biesbroeck (Prof. Emeritus); also, Jan Oort, Van de Hulst, and A.Blaauw were visiting professors from the Netherlands, and B.Strömgren (Director of the Copenhagen Observatory) from Denmark. This was a high-powered faculty indeed! Later in 1971 Herzberg would win the Nobel prize in chemistry, while in 1983 Chandrasekhar would share the Nobel prize in physics with W.Fowler. In addition there were a number of high caliber visitors from time to time, and it must not be forgotten that there were three post-docs, Glenn Hall, Marjorie Harrison and John Phillips. Finally, there were fourteen graduate students enrolled for that quarter: Henry Chun, Art Code, Douglas Duke, Frank Edmonds, Robert Hardie, Dan Harris, Henry Horak, Su Shu Huang, Narahari Rao, Nancy Roman, Arne Slettebak, Ann Underhill, Marvin White, Marshall Wrubel. There were also many support personnel, for such things as maintenance, secretarial, optical and mechanical construction, etc. For more information a history of the Yerkes Observatory from 1892 until 1950 was published in 1997, the year of its centennial (Yerkes Observatory, 1892-1950, Donald E.Osterbrock, University of Chicago Press / Chicago and London; Dr.Osterbrock became a student at Yerkes the same year that I was taking my finals there).
It is my opinion that Dr.Struve was the best director that Yerkes Observatory ever had. He not only possessed a strong character that enabled him to be a capable administrator, but also he carried out extensive research himself; in his lifetime he published close to a thousand papers. On top of all this he edited the Astrophysical Journal(commonly referred to as the Ap.J.).
The astronomy graduate curriculum consisted of a two year cycle of courses plus another year devoted to the thesis. Chandrasekhar (called Chandra by his friends) taught one course each quarter, and his lectures were very well thought out and presented. I never saw anyone who could write so fast on the blackboard, and it was difficult to keep up with him; needless to say we didn't have audio recorders or video-cameras. The other faculty members taught courses perhaps once a year or two. Kuiper also gave well organized lectures, as did Struve, but Struve covered a voluminous amount of material very rapidly. Fortunately we had access to a very good technical library in the observatory where we could study many of the original articles and references, but much time could be spent in such pursuits, since there were no copying machines in those days. We took two or three courses each quarter, depending on what subjects were offered, and tried to do a little research on the side. Colloquia were given every Monday afternoon, and kept everyone alert to the most recent investigations.
Chandra was the first theoretician to be hired anywhere in the U.S. as an observatory staff member; the original thought to do this came from Struve, and he was able to obtain the necessary backing from Chancellor R.M.Hutchins. Struve explained to me that the Ap.J. had lost considerable prestige when it had turned down the publication of Saha's important theoretical papers on ionization and excitation (this was prior to Struve being the editor). I would guess that Struve, realizing that the content of astrophysics was changing rapidly, felt the need, particularly as editor, to get advice from time to time from a capable theoretician. Later in 1952 Chandra himself became editor of theAp.J.
I had first become acquainted with the name Chandrasekhar (`one who holds up the moon') when I was a meteorology cadet during the war, and portions of his book on stellar structure were required reading. Chandra turned out to be a very stern taskmaster, and didn't want to be bothered with anything trivial. I remember that he interviewed me carefully when I first arrived at Yerkes and even read my M.A. thesis which I left with him. Later he asked me why I had not published it, and thought I should do so; however I never seemed able to find the time.
Chandra's research in the late 1940's concerned the diffuse scattering and transmission of light, and he was writing paper XXII on this subject for publication in the Ap.J. Since I wanted to do a theoretical thesis, it was quite natural for me to get involved in the same subject. He suggested that I work on a radiative transfer problem that involved applying a procedure due to the mathematician Erdelyi for inverting the Laplace transform, but it turned out that the method required too many significant figures to be practical. One advantage of having Chandra as one's thesis adviser was that he never lacked problems of the appropriate order of difficulty for graduate students; so he next suggested that I apply his theoretical results to the available data for planetary reflection, including the polarization. This was not so easy, for a number of reasons that I'll not go into here, and much calculating was required (I used a Marchant mechanical calculator). In broad outline I was following a paper of Gerasimovic, who had been one of Struve's professors many years previously in Russia.
I stayed out of Chandra's way, and worked by myself. I spent much time comparing my results with those given by Gerasimovic for similar scattering laws; there was poor agreement, and I worried a lot about this, although I didn't have confidence in the Russian's use of Eddington-factors for scattering problems (the Eddington-factor scheme was not a genuine approximation method, because it lacked a convergence mechanism). Also, I had completed some comparisons of Venus photometric data with calculations using some of Chandra's more precise formulas. Eventually Chandra wondered what had happened to me, and called me into his office. I showed him my many comparisons, but I didn't really know what to expect. He looked over the graphs and numbers, asking various questions. Then to my relief he expressed satisfaction, saying that my disagreement with Gerasimovic's results was to be expected. Of course it was realized that I still had much work to do in comparing theory with observations, and he wanted me to continue. After this, his attitude towards me became much more friendly and positive, and I in turn learned to appreciate him better. Eventually, after about a year's work, I completed my thesis (Diffuse Reflection by Planetary Atmospheres, Ap.J. 112, 445, 1950).
It was then necessary to pass two oral examinations. The comprehensive exam was quite stressful, since it wasn't exactly a pleasant experience to stand in front of seven or eight of the best professors on the planet who can question you about anything in the universe! By comparison the thesis oral was a pleasant walk in the park! I received the Ph.D. in astronomy and astrophysics at the end of the summer quarter, 1950.
During my last year of graduate study I was fortunate to be Struve's graduate assistant, which was an education to me in itself. I primarily assisted him by measuring spectroscopic plates of binaries, calculating orbital elements, etc. Also, he was working on his book Stellar Evolution, and I prepared some things for that. Previously, in 1948, I had married one of Struve's assistants, Gertrude Peterson, who along with Alice Johnson and Margaret Phillips (Struve's secretary) helped Struve prepare papers for publication. Gertrude and I have been married fifty years as of 1998, and have three children: Henry Louis (49), Karl Emanuel (45) and Paul David (42).