[Bok, 1972]
Bok, 1972 (Photo courtesy of NRAO/AUI/NSF)



NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with Bart J. Bok
At The University of Washington
December 5, 1978 and December 7, 1978
Interview time: 1 hour
Transcribed for Sullivan by Pamela M. Jernegan

Note: The interview listed below was either transcribed as part of Sullivan's research for his book, Cosmic Noise: A History oF Early Radio Astronomy (Cambridge University Press, 2009) or was transcribed in the NRAO Archives by Sierra Smith in 2012-2013. The transcription may have been read and edited for clarity by Sullivan, and may have also been read and edited by the interviewee. Any notes added in the reading/editing process by Sullivan, the interviewee, or others who read the transcript have been included in brackets. If the interview was transcribed for Sullivan, the original typescript of the interview is available in the NRAO Archives. Sullivan's notes about each interview are available on the individual interviewee's Web page. During processing, full names of institutions and people were added in brackets and if especially long the interview was split into parts reflecting the sides of the original audio cassette tapes. We are grateful for the 2011 Herbert C. Pollock Award from Dudley Observatory which funded digitization of the original cassette tapes, and for a 2012 grant from American Institute of Physics, Center for the History of Physics, which funded the work of posting these interviews to the Web.

Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event.

Sullivan

Ok, this is continuing with Bart Bok on 7 December 1978 with a bit more of the interview that was started on 5 December 1978 and actually another part of the interview was back in 1971. Now you were saying that the main function that you saw of the observatory at that time...

Bok

Was basically this: to explore several different aspects of 21 cm research, rather than to plan a long range major program like the Dutch in spiral structure or so. We were also aware of the fact that, say in Sydney, Joe [Joseph L.] Pawsey and [E. G.] Taffy Bowen and John Bolton had first of all people who were very much better trained in background of the field than we could have, but I felt very strongly that there was a need to have astronomically trained and astronomy-appreciating young people come out and help as staff members in the radio astronomy, because the radio astronomy that there was at that time in the United States, John Kraus, for example, and others, was all oriented away from astronomy and more toward electronics. And I think we succeeded in that, in that we got people like, well, Dave [David S.] Heeschen, Frank Drake, [T.] Kochu Menon, Campbell Wade, Ed [A. Edward] Lilley, Nan [Nannielou H.] Dieter--there were about twelve of them altogether that worked in there. And for example, you can now see it in Campbell Wade. Campbell Wade still thinks on fundamental positions. The reason why he's so effective in that is that he knows damned well how to handle precession, galactic rotation, and all the fundamental things of astronomy.

Sullivan

Right.

Bok

So I think we succeeded in that way. The other thing is, if you ask where were the contributions made, I think first of all the fact that the Gouldís belt came out in atomic hydrogen, the second thing is that we showed- Bob Lawrence helped out with that and Kochu too with me- we showed that the darker spots had no excess concentrations of atomic hydrogen and then, as we said already at the Paris Symposium, Tom [Thomas] Gold and I were the ones who argued that that must mean there's a lot of molecular hydrogen- itís just too cool to keep the atomic going. Then there was Kochuís thing on the Orion Nebula which I always felt was in some ways one of our biggest contributions, and Dave Heeschenís first indication that the curves near the galactic center had dips in them and self-absorption.

Sullivan

Self-absorbing, right.

Bok

So there were quite a few things that came out of it, but I would always claim that the biggest thing was that we were a training ground for people who had contact with us. I must admit to one sin, that we believed in purchasing black boxes. And the purchasing of black boxes is not the ultimate solution. But that we felt that we had to get quickly into the business and with [Harold Irving] Doc Ewen appreciating the astronomy and being quite competent in the black box business, we went in with him and it was sort of a little bit of a flyby-night affair. But we did get the good people out and they got very, very prominent in the setting up of Green Bank and that was going on at the same time.

Sullivan

Right. And of course you didn't have the funds to set up a whole receiver laboratory.

Bok

No, no, my God. If I'd done that, the whole thing would have gone to pieces and we would never have gotten off the ground. We were lucky enough that we could get $200,000 for the 60 footer after Mrs. Agassiz gave us the $25,000 for the 25 foot.

Sullivan

Well, along that same line, you obviously felt that the U.S. had a need for these sort of...

Bok

I had a very strong feeling that the future of Milky Way astronomy was going to be half radio and half optical. None of my colleagues agreed with that. They all said, well, - I told you the [Gerard] Kuiper story-flash in the pan sort of thing. And I felt very strongly that from now on we had to play the piano at all ends.

Sullivan

Right.

Bok

And therefore, we had to begin to train astronomers who would be able to move back and forth even though they were not properly electronically trained from one part to another.

Sullivan

Right. I'd like to pursue, though, in the U.S. versus other countries. What do you see as the basic reason why the U.S. lagged behind in the development of radio astronomy?

Bok

Nobody took an interest in it. Very few people...

Sullivan

Then why did they not, I mean?

Bok

Because they hadn't looked closely enough at the potential. Jesse Greenstein in a way, he was early in the game, one of the very best ones but for the rest in the Ď30s, early Ď40s, and even after the war, everybody was busy with other things.

Sullivan

Do you think it might be that they had a couple large optical telescopes whereas other countries didn't?

Bok

Yes, thatís right.

Sullivan

And they had more to keep them busy?

Bok

They had lots to keep them busy and they all felt, I felt until I got into it, that the things I was going optically were basic, and the rest was side issues. But then when I came back from South Africa in í51, Ď52, talked with [Edward] Purcell and Ewen especially, then suddenly the whole thing began to blossom up. Another person who had a lot of effect on me was John Hagen. John Hagen lots of people didn't like him but he was a very good friend of mine and he was a great help in seeing the direction that things would go. More so than for example John Kraus. John Kraus was a competent electronic engineer who didn't mind setting up big projects and ran them well, but- [Arthur] Covington was basically a solar radio physicist who did his things on the sun and there wasn't much vision elsewhere. The, of course, the other thing that came in was that [Jan Hendrik] Oort and [Hendrik C.] van de Hulst and I had long been close friends, and that made it very easy for me to hear from the other side, and then I was very fortunate that Joe Pawsey came to Harvard early in Ď52-Ď53, and he and I became very close friends. Out of these things it was natural that I was one of the few who saw to it that I got to know the radio astronomers. We went, mostly at our own expense, to the Jodrell Bank Symposium on Radio Astronomy. It was one of the early ones, where [Rudolph] Minkowski was practically the only other astronomer who was there.

Sullivan

Are you talking about the 1953 or the 1955 one?

Bok

The 1953, the early one. Or 1952.

Sullivan

1953 it was.

Bok

Then 1953. Not the 1955--by that time things had become already respectable.

Sullivan

Well, just from the two group photos, you can see the difference in the number of people that attended.

Bok

Oh, yes, the whole thing, í55...

Sullivan

Yes. That photo is in two spilt into two. Itís about twice as many people. I realize it's difficult to disentangle your own character, but what was it that allowed you to see that this field was going places? What was it about the way you looked at it that was different from your colleagues?

Bok

Well, I had the vision. I was very impressed with the Dutch early spiral pictures, that suddenly we were getting through the muck in the Milky Way that I hadn't been able to get through, but had been pushing and pushing for. And here suddenly was a God-given opportunity to get through it, and we had a man who could build the black boxes at a price, right in our backyard! And therefore it was silly not to become involved in it.

Sullivan

Were there many other optical astronomers worrying about spiral structure in the early Ď50s?

Bok

Yes, yes. There was...

Sullivan

[William Wilson] Morgan?

Bok

Morgan. But Morgan never looked at radio astronomy at all, and Bill Morgan never looked at the southern hemisphere either. Even now the Carina feature hardly figures in Morgan's thinking. But he did, of course, the basic breakthrough with his precision classification of spectral types of luminosity and got the first real spiral arms drawn.

Sullivan

Okay. Along that same line is it simply a coincidence that it was the same year, 1951, in which the hydrogen line was discovered and the first optical tracing of spiral structure also came out. Is that just a coincidence?

Bok

I think it was a coincidence. Because in a way the optical tracing of spiral structure started with Walter Baadeís survey of the Andromeda galaxy, and Walter said to Bill Morgan, "Bill, if you want to find out about spiral structure in our Galaxy, you ought to learn to classify B stars properly, get their distance, find where they are, and you have the spiral feature." In the meantime, the Dutch had their 21 cm thing, but that ran entirely separate from each other.

Sullivan

Right. Okay, along this same line...

Bok

It ran independently with one exception. Oort was, of course, at the height of his power and the height of his glory and Oort was the one who knew about both these things and was deeply involved in both of them.

Sullivan

And in trying to...

Bok

In tying them all together in a unified affair. But the Dutch radio astronomers were not as perceptive as Oort.

Sullivan

Right. About the actual spiral structure that was being found, the Dutch, of course, produced these maps with all these filaments and arms and so forth. What was your attitude at that time towards these maps? Did this seem like this was definitely the way the gas was?

Bok

Yes. Near circular, slight tilt and near circular spiral arms

Sullivan

So there was not much questioning about the validity of the whole kinematic picture and so forth?

Bok

No, but by that time, we had no [W.] Butler Burton around to tell us that there were velocity produced fields that could do it just as well, and little disturbances and edges. So in a way, we were very unsophisticated about it, and took the Dutch results, where there is a peak, you pass through the spiral arm. And now if we had had Butler around in those days, it would have been very bad. I donít think we would have looked at it as much.

Sullivan

But now as to the actual matter of how you connect up the spiral features, now there were some arguments. And I have a little paper you wrote in Observatory in 1959.

Bok

Yes, I thought that Cygnus and Carina arms were both together.

Sullivan

Right, and you argued with the establishment view, meaning [Frank J.] Kerr and [Gart] Westerhout and Oort about the Carina-Cygnus feature, and also about the Orion spur and they called it an arm.

Bok

Yes, and some of these things are still going on. Orion is really much more of a spur. Looking at it, the principal thing where I think I made my contribution was by convincing everybody that the Carina arm was the major feature and much bigger and more bountiful than the Orion spur, which was sort of a connecting link.

Sullivan

Right.

Bok

And that we had basically, the Perseus feature, the Carina feature, and the inner-Sagittarius feature. And whether the Carina and Sagittarius were tied up, I was against this because there are gaps, very big gaps in between, and the gap between the Carina and Sagittarius feature is almost as big as the gap between Cygnus and Carina feature.

Sullivan

Yes, yes.

Bok

And that's why I drew this little diagram and said maybe the two of them got together the other way and that was a good thing to make it clear that one couldn't know how all this went.

Sullivan

Yes. What do you think, if you look at all of the work that was done on galactic structure until 1960 or 1962 or so, what were the important things that gave us a new insight into the nature of the Milky Way that we hadn't had before? I mean, we knew it was a spiral before.

Bok

No we didn't.

Sullivan

We didn't?

Bok

I used to say in the 1930s at my public lectures, "In 300 years from now if I come back and am permitted to ask one question, the question will be 'Does the Milky Way have spiral structure? Yes or No?'"

Sullivan

I see.

Bok

No, no. We thought it would have it, but there was no proof for it whatsoever, but I did one thing back already in the Ď30s? Starting in 1932, I used to argue that Carina the feature was the most prominent spiral arm that there was anyway. But no astronomers of note knew the word Carina or had any idea what it meant. And for that reason, this never flew off the ground and nobody listened to me.

Sullivan

Okay, so we knew it was a disk but we didn't know if it had spiral structure.

Bok

We weren't sure. It seemed most likely there would be.

Sullivan

Right. And of course the radio observations showed that there was an awful lot of gas, which was of interest.

Bok

Yes, that's when the radio came in, and that that gas had peaks in the 21 cm profile, and in the early days we all accepted that a peak meant you were crossing the spiral arm in that direction.

Sullivan

Did the observations change oneís ideas of the interstellar medium greatly?

Bok

Not especially, I don't think that affected it much, because I don't think my ideas about the interstellar medium changed much after the 1930s. We certainly needed the interstellar absorption and there [Robert J.] Trumpler came in. But we had the interstellar absorption lines and they did what they ought to do. We had the nebula and so on, so I don't think there was a very basic change except that the atomic hydrogen came in strong with the 21 cm line.

Sullivan

Right, but the parameters of the interstellar medium didn't change that much for what one expected?

Bok

No. We had arguments whether they were in clouds or uniformly distributed, and these arguments we can still have.

Sullivan

It's still going on, you're right. So really the revolution in the interstellar medium--I think there has been one-but that's been more the last ten years than in the Ď50s?

Bok

Yes, yes, yes. Particularly in the recognition now, of course- that's why I've gone back to star formation.

Sullivan

Which wasn't being worried about much at all in the Ď50s, was it?

Bok

No, no.

Sullivan

Maarten Schmidt, of course, wrote his little paper, but there wasn't much concern about that. Okay. In your book with Priscilla [Fairfield Bok, his wife], in the 1957 edition, you have a chapter on radio astronomy, but I was very interested that there was no mention in that chapter of synchrotron radiation.

Bok

That was all still too early. And I must say I was much more impressed personally with the 21 cm stuff; I felt very strongly that that ought to come out. The synchrotron was difficult to do, Bernie [Bernard Y.] Mills was getting the first synchrotron edges, but they were difficult...

Sullivan

In terms of spiral structure. But of course we had radio sources, we had the galactic background.

Bok

Oh, yes.

Sullivan

And it was a problem to understand what was the source of the emission- it couldn't be too hot a gas, I mean that seemed unreasonable.

Bok

I just did not know quite what to do about it. Neither did Priscilla. But we did this- we brought the things in- our book is, after all, not one on radio astronomy, it was a book on the Milky Way.

Sullivan

Right.

Bok

But of course radio astronomyís contributions came mostly from the 21 cm results in those days. And the radio sources, of course, there were two types--there were the HII region sources- and I thought we mentioned those.

Sullivan

Oh, you did. And the supernova remnants.

Bok

Yes, we did those. The rest of them were colliding galaxies, you know, like the Cygnus source and all these interpretations.

Sullivan

And you did mention the general galactic background. But there was no mention of what it might be caused by.

Bok

No, no. In principle became I think because I didn't know and neither did Priscilla.

Sullivan

Although I gather from, if you were going to these radio astronomy meetings in 1953 and 1955 at Jodrell and the 1958 Paris Symposium, you certainly heard about the ideas of synchrotron emission.

Bok

Oh, yes. That's right.

Sullivan

But you were not accepting them as...

Bok

Well, not really basically yet interested, seeing no direct application to our own galaxy- that's what it came down to.

Sullivan

Well, the only thing I have left is if you can remember any impressions of these meetings, anecdotes or papers.

Bok

Well, the first meeting I remember, the one at they had at Jodrell Bank.

Sullivan

In 1953.

Bok

In 1953, right. I was scared stiff. I said, "I don't know any of these people. I know Minkowski but for the rest I don't know anybody." And we sat, Priscilla and I during the whole meeting, sat two rows from the back- I remember we didn't have the nerve to get up forward and we got to know, among others, Leonard Huxley, who sat beside us and was also quiet.

Sullivan

He was sitting in the back, too?

Bok

In the back, so we got acquainted with the future vice chancellor of our University. But Len Huxley and the Boks became close friends, but sitting sort of scared in the back. And we gave a few brief papers on the beginnings of our radio plans at Agassiz Station. But I came to that one, principally, to find out what the heck was going on.

Sullivan

That why it would be valuable for me to hear, if you can try to remember, what was your impression- I mean who struck you as the dominant figures, or what as the important problems?

Bok

Well in those days, of course that's when I got to know Bernie Mills, Martin Ryle - we saw quite a bit of Ryle, and Ryle showed us his first array that he had at Cambridge, and, that was a great moment. You suddenly had the feeling that you were in the presence of wholly new things. Bernard Lovell, I was exceedingly impressed with. Just the people who were there were an impressive group. Christiansen was there. Joe Pawsey was not at that meeting, I don't know why not but he was not there. And then there were people like [Ludwig H. C.] Biermann whom we had known, and Henk van de Hulst, and Oort, and so, with whom we naturally communicated rather easily. The Paris one, when I went there I began to feel like an accepted big shot, and I just marched in and sat on the second row and had a fine time. And Ed Lilley and Dave Heeschen were there and the whole gang- and by that time we felt it was an established thing and we were going places, and going places as fast as we could. And then in connection with the Paris Symposium, after that, the IAU Meeting came up about the same time...

Sullivan

Well, there was one connected with the Dublin meeting in 1955.

Bok

That's right. And the Dublin meeting is where I heard I had been nominated by Joe Pawsey for the directorship of [Mount] Stromlo [Observatory], and by that time I began to feel like a reasonable big shot, and knew what was going on, and knew all the people in the field and things were easier. But the first meeting was a scary affair.

Sullivan

At the Paris Symposium, there was a lot of dissention over radio source counts and so forth.

Bok

Yes, yes.

Sullivan

Which you probably remember. But in the 21 cm field, I get the idea that there was not a great amount of dissention; in fact everyone was cooperating very much.

Bok

Everything was coming together. Butler Burton hadn't been born yet, so none of us really had an idea that the radio thing might blow up in our faces fairly soon afterwards.

Sullivan

But why do you think that these fields developed differently? Was it just a matter of the personalities in the fields?

Bok

Yes, yes. In 21 cm, of course, there was one dominating and domineering person, Jan Oort- donít forget that- and Jan Oort ran the whole business like a typical Jan Oort affair; whereas in radio astronomy there were from the beginning, three sort of separate big things sticking out in the synchrotron radiation, galaxy counts... there was Joe Pawsey with Bernie Mills, as his big chieftain in the whole thing, there was Martin Ryle on the other side, and then there was Bernard Lovell.

Sullivan

Right.

Bok

As the third one, so there were three strongly competing, disagreeing groups that all worked together.

Sullivan

Or did not work together.

Bok

Worked in the same area not "worked together."

Sullivan

Okay. Well, that's about it, unless you feel there are any other areas of pre-1960 radio astronomy that...

Bok

No. The only thing is that one has to be very careful of the tendency for radio and optical not to cooperate; it seems to be there all the time, on both sides.

Sullivan

Even today?

Bok

Even today. And that goes on and on, it went on later on, for example, at Stromlo, where my successor was Olin Eggen, who said immediately, "No more contact with these silly poops at Radiophysics."

Sullivan

That was in 1966?

Bok

1966-67. "No more contact; we have important astronomy to do." And then, of course, in some ways, people like Bernie Mills can on the other side be just as firm in saying the only thing that you need is- astronomy is just a field where you apply your advanced electronics, but it doesn't take any knowledge of astronomy- itís a simple, stupid field. So it comes from both sides and it was I think very nice that Joe Pawsey and I worked together, who had this dedicated view that it wasn't that way. In Holland, Oort and Van de Hulst had helped to hold the thing together. In Britain there was a long time when for example the Astronomer Royal wouldn't have much to do with radio astronomy.

Sullivan

Right. And now we have [Francis] Graham Smith as the head of R.G.O. [Royal Greenwich Observatory].

Bok

Yes, yes. And we have Martin Ryle as the Astronomer Royal.

Sullivan

Right. But do you think there ever was an era, and if so can you name the date, when radio astronomy became accepted as part of astronomy--or has it always been distinct?

Bok

No, no, no, no. I think there are two things--radio astronomy got accepted by astronomy I would say around 1956-57, and astronomy got accepted by radio astronomy about the same time. It's a mutual affair, that when I first came in I felt I was looked upon with considerable suspicion, not by the physicists, like Ed Purcell or Norman Ramsey- that was fine- or even by the Doc Ewen. But the other ones were suspicious. But Joe Pawsey never had this, and Joe was a very great unifying force.

Sullivan

But you're saying after three or four years you felt this had gone...

Bok

But when I arrived in Stromlo I felt there was no problem at all of having close collaboration with the radio astronomers. And they used to come to us, and we'd go to them.

Sullivan

Right. What do you think were the key aspects that allowed this transition to take place? Was it simply that the radio astronomers?

Bok

We got better acquainted with each other, getting acquainted with each other. And attending each other's symposia and having International Astronomical Union Symposia- both optical and radio, and then in the forming of Commission 40, which of course was a very important part of the whole thing.

Sullivan

Okay, well, thank you very much.

Bok

Okay. That ends the interview with Bart Bok on 7 December 1978 at the University of Washington.


Modified on Tuesday, 16-Dec-2014 15:52:54 EST by Ellen Bouton, Archivist (Questions or feedback)