Interview with Bernard F. Burke, 22 September 1981
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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.
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Transcribed by Sierra Smith
Sullivan
This is doing a follow up interview with Bernie Burke at NASA Ames on 22 September 1981. Well last time we discussed the actual discovery of Jupiter in which you established that even then it had a steep spectrum because you knew it was much stronger at one frequency than another and it was burst like and so forth. And then you did quite a bit of follow up about a year after that [Talking over one another] with an interferometer that you built for that purpose. What was the main thrust of that, what was the approach to trying to figure out what was going on?
Burke
Well, we tried to do two things. One was of course to pin down the synoptic behavior. The other, we deliberately built the array with cross dipoles so we could see the circular polarization.
Sullivan
Was that an analogy with the solar burst that you thought it might be circularly polarized?
Burke
Yeah, but knowing the solar bursts were circularly polarized, it was obvious that we wanted to check on the same possibility with Jupiter, of course it did turn out strongly circularly polarized.
Sullivan
And what about the system period? [Alex] Shane’s paper came out at a very early stage showing a rotation period.
Burke
Yeah but Shane’s paper showed a rotation period that was clearly tied too closely to system 2 and that was presented to the scientific public at the same meeting that our results were presented because we had sent a letter to him saying that we had found it and that he may well have Jupiter noise in his records.
Sullivan
Now which meeting is this? The Manchester?
Burke
This was the Manchester meeting in 1955.
Sullivan
I see, and did you go to that personally?
Burke
Yeah, I was there. Our data had been distributed ahead of time but I remember that I think it was [David W.] Dewhirst that gave a comment that our data showed that it fitted system 1. We didn’t think you could do anything that good and not try to do any statistics. Of course the Australian data showed clearly that it was close to system 2 and when the colloquium volume came out Dewhirst had expunged his remarks on system 1.
Sullivan
I was just reviewing that this morning and indeed, it says, "Dewhirst, ‘I can find no periodicity."
Burke
Right. That’s not what he said at the meeting.
Sullivan
Was it just a matter of time base that enabled...
Burke
Yeah, that is we had single point measurements through the Mills Cross whereas if you have an interferometer that follows it for an hour or two a day you get a much better sample and that’s why we built an interferometer that was deliberately designed with dipoles north-south, cross dipoles: one North-South and the other East-West. But the array running North-South so that the array had a broad pattern East-West so we could get a good record of the synoptic behavior and actually I think that three of us all came to the realization that system 3 was...
Sullivan
As it came to be known.
Burke
As it came to be known. We did not call it system 3; all we did was point out that another rotation period other than the system 2 period fitted our data much better and of course at the same time Roger [Galey?] and the Florida group had come to the same conclusion.
Sullivan
Was that some puzzlement or were you willing to accept another one if you had two already, two systems already?
Burke
Oh yeah, that is it was clear that there was already an atmospheric component in the rotation. The general feeling that all of us had was the system 3 was more likely to be tied to planet itself.
Sullivan
Oh I see, it was somehow more firmly rooted to...?
Burke
Well we could see that there was strong circular polarization which meant that there was a the magnetic field and the magnetic field was certainly more a measure of the solid body, solidly not quite the right word, but the entity that we call Jupiter, there is a magnetic field there. There may be shearing motions inside Jupiter itself but they were much longer time periods than the things that you see in the cloud nebula.
Sullivan
I guess that’s right. This evidence really is the first of a magnetic field on Jupiter or one would have suspected it would. There was no spectroscopic evidence?
Burke
No, I think that we probably did have the first evidence far the magnetic field.
Sullivan
Did you contact optical astronomers and try to set up some sort of joint program? It would seem like...
Burke
Yes, at a very early stage, we were in contact with Richardson at...
Sullivan
Caltech.
Burke
Caltech. The joint observations never showed much. Of course, in retrospective it’s clear that they didn’t have much chance of doing so. Obviously the first thing that we wanted to do was to see if there were some connections with visible features in the cloud deck. This was in the very early stages and Richardson did do some simultaneous observations that coincided with ours. And before the system 3 rotation came up, we tried very hard to see what feature on the planet could be responsible. For awhile it looked like it was the red spot then of course the Australians had seen some white spots or seen that it had corresponded to some white spots but of course in retrospect it didn’t mean much...
Sullivan
Well, you continued this kind of work for a year or two with this specialty built interferometer.
Burke
Yeah, as I remember it was about two years.
Sullivan
And I wanted to ask about the role of Ken Franklin. He was not an electronics man per se?
Burke
No, he came from Berkeley with a background in astronomy and joined in on the work.
Sullivan
Was it a Ph.D. in astronomy?
Burke
Yeah, he had a Ph.D. in astronomy. He did his thesis on Capella.
Sullivan
I see, so just stellar astronomy, and how would you characterize your different contributions to the Jupiter work?
Burke
Oh well the designing and building the equipment clearly was a thing I did. We both worked together on the analysis of the data and Ken was still, although he wasn’t technically an expert, he was quite happy to work very hard in the field on the repetitive, hard work of getting antennas built. We worked just generally together.
Sullivan
Right. Because he was a traditional astronomer, was there any advantage to that since it was a classical astronomical object?
Burke
No, I don’t think so. It was somebody who knew the ways of science, enjoyed it, and knew how to work with people. He was a very easy person to work with.
Sullivan
Well what was the basic reason you stopped this? I mean, the work continued at Florida and at many other places for several years thereafter.
Burke
I suppose that the event that had the most effect was the fact of Howard Tatel death.
Sullivan
Which happened, it seemed, in late ’57?
Burke
That’s right. The 60 foot telescope just about to be erected at Deerwood. The multichannel hydrogen receiver which I had occasionally used just joining in with Tatel on his work but not very deeply, that was completed and clearly was in working order and so when Tatel died, I took a much more active line in the hydrogen...
Sullivan
In that project, I see.
Burke
So that’s why I would say, rather than to say that I lost interest in the Jupiter radiation, I’d say that my interest in 21 cm work picked up. The Mills Cross was not very useful. We’d pretty well established that the lack of a nice uniform ground plane gave it enough uncertainty in its pattern so that you really couldn’t look for weak sources. You could see strong sources just fine but to go after very weak sources, it was very hard to tell the difference between what was real and what was just an artifact of the side lobe pattern. And so, solar activity was picking up so the 22 MHz band was becoming much more filled with interference so the motion went, we moved away from that particular kind of work.
Sullivan
In fact I think it’s correct, isn’t it, that there was nothing published from the Mills Cross except for this Jupiter discovery and a couple odd things like a symposium but no real survey?
Burke
Yeah, there was no proper survey. We looked at a few well known sources and we established that phase around well known sources. We were looking for weak sources down in the noise wasn’t really accurate.
Sullivan
Now you said that there wasn’t a sufficiently accurate ground plane. Was this because of not a flat enough field or?
Burke
Oh the field was plenty flat but we didn’t put down a metallic screen. We just relied on the conductivity of the ground and it changes seasonally and there was a variable amount of water.
Sullivan
So you just felt that it wasn’t worth the effort?
Burke
Yeah, and it was a lot of work maintaining the thing because it was built on a very minimum budget. Maintenance was getting to be a pretty big load because dipoles would fall down and cows would come in and chew on the twin lead so it was a combination of many things. We built another antenna at about that same time, roughly 1957. That was when Bill Erickson came to the Carnegie Institution and Bill and I built a long V type antenna where the aim of our project was to measure some accurate positions of radio sources at 400 MHz. That was, we built it rapidly so that we didn’t have to worry much about cows and broken wires.
Sullivan
Is that the corner reflector?
Burke
The corner reflector, yeah, and I think that what happened is that time went by, it looked as though the scientific pay dirt was at 21 cm at that period so that increasingly became something that I was more active in.
Sullivan
So you more or less just left the low frequency?
Burke
Yeah, that’s right.
Sullivan
Well you brought up the name of Howard Tatel. I just ask was this the first radio astronomy he’d gotten involved in, the dish and channel receiver and so forth?
Burke
Yeah, I think that he became involved in radio astronomy roughly in 1952.
Sullivan
When [Merle A.] Tuve got into...
Burke
Did Tuve describe to you how he got the receiver?
Sullivan
Well he probably did. It’s been many years now. To be honest...
Burke
This is all secondhand. That is Tuve was visiting Harvard and was an old friend of [Edward Mill] Purcell. I think he probably [Talking over each other]. Any way I think he got Purcell’s old receiver.
Sullivan
In fact, Doc [Harold "Doc" Irving] Ewen has told me.
Burke
Yeah, and at the same time he got a giant Würzburg antenna, I suppose. I’m not sure and they built a homebrewed interferometer and when I arrived the system was just barely working and they were in the process of replacing various elements of Ewen’s receiver with more reliable, more modern...
Sullivan
Right. Let me just ask that Würzburg, there is a standard picture of it that shows it right in the back of the extended American houses. Where was that actually located?
Burke
It was located on the back lawn of the Department of Terrestrial Magnetism.
Sullivan
Right in Broad Ranch Road?
Burke
Right in Broad Ranch Road. Right in downtown Washington.
Sullivan
I see. I didn’t know if that was Tuve’s house or?
Burke
Nope, those were neighbors; no actually the houses you probably saw were not neighbors’ houses at all. There is one building that is a low frame building that was built as an anti-magnetic, non-magnetic building, and that’s probably what made you think it was a neighbor.
Sullivan
Perhaps, anyway it was right at the site. So [Howard] Tatel never did get involved in observations because of his death?
Burke
Well, he became involved in observations with the Würzburg. There were a couple publications, Larry Helfer was one of the authors, in which they published profiles through the galaxy at a particular longitude plus or minus five degrees or so. And actually that was some of the data that I used to, when I looked at their maps and saw that the outermost arms did not lie on the plane, I took a look at all of their data plus whatever data has been published by the Australians and the Dutch and realized that it was in the same sense as a tidal deformation of the galaxy.
Sullivan
I’m trying to find that, here it is. It was an AAS [American Astronomical Society] talk in late ’57. So that did use some of that Würzburg HI data as well as the?
Burke
Yeah, there was HI data from the Würzburg by that time.
Sullivan
But I guess it was felt that something bigger was needed than the Würzburg, something that would steer better and so forth?
Burke
Yeah, well it steered well enough but something with a better angular resolution. Originally they hoped to build an 84 foot dish but they didn’t have enough money for it, so a 60 foot was the compromise. And that was designed largely by Tatel with Tuve taking a very active role. Construction didn’t start till after Tatel died.
Sullivan
What was Tatel’s background? Was he a physicist?
Burke
He was a physicist who worked with Tuve at the Johns Hopkins Applied Physics Lab and then eventually joined Tuve as sort of his right hand man. He was Tuve’s foil, his principle foil.
Sullivan
And let me just ask about Helfer, what was his background in?
Burke
Ok, Larry Helfer and I arrived at the Carnegie Institution at the same time in fall of ’53 and he came as a theorist from doing his thesis under [Subrahmanyan] Chandrasekar so the two of us were put together in the same room with the hope that we would stimulate one another.
Sullivan
So his forte was in theoretical matters?
Burke
Yeah, but he became interested in observing at that time. He became very active in the observing program.
Sullivan
Ok, that ends talking with Bernie Burke on 22 September 1981.
End of Tape 156A
Sullivan Tape 156B
Sullivan
Ok, after an interruption of a couple hours, this is continuing with Bernie Burke on 22 September 1981. So when Tatel died you moved, more or less, in his place on the 21 cm work, is that correct?
Burke
It was an adiabatic transition because we were building the long 400 MHz Vee’s at the same time. At first it was an occasional interaction and then it became more intense when the 60 footer was completed. That was the critical point at which the focus really changed.
Sullivan
Was that built in house, more or less?
Burke
No, well it was contracted out to antenna constructors and Blaw Knox and all we did was to act in an oversight role to see that it was done right.
Sullivan
What were the corner reflectors used for primarily? Let’s finish that one off.
Burke
Ok, we measured the positions of some radio sources. It turned out...
Sullivan
Who’s we when you say that? That’s Firor, I guess.
Burke
John Firor. He left before the project really went very far. And we looked at the galactic center and we measured the flux of the galactic center. Then it was becoming increasingly clear that more antenna area was needed because they were a small set of antennas. It began in my mind to be clear that paraboloids would be better than that type.
Sullivan
The only two publications that I see that I think are on that are two AAS abstracts of you and Firor.
Burke
That’s right. We measured a small number of sources but I would say that by 1960, my main focus had certainly shifted to the 60 foot.
Sullivan
So what did you see as a good thing to do with the 60 foot?
Burke
Well the first thing we did was to try to improve our knowledge of baselines, I think hydrogen line profiles.
Sullivan
You had 64 channels? It was a very large number.
Burke
It was approximately 64 channels. I don’t remember the exact number.
Sullivan
I have it written somewhere but anyway.
Burke
It was roughly 64 channels.
Sullivan
And I don’t think you had computer reduction?
Burke
No, it was a chart output but we worked out an analog way of reducing the data which turned out not to be too cumbersome. There was a light table and if one had a sequence of integrations, you just took a piece of proper sized graph paper, overlaid it, quickly traced one record, and then went on to the next record tracing in a different color and so you could stack together records pretty conveniently.
Sullivan
But if you had n channels, and that can be checked how many it was, did you have that many traces?
Burke
No, it was a step switch arrangement where the step switch went through sampling the integrated signal on each one of the capacitors and it did it...
Sullivan
At a faster rate than the integration time so you..?
Burke
Yeah, that’s right. It took about roughly one minute to read out the channels.
Sullivan
And were you tracking a given position in the sky typically or were you..?
Burke
Yeah, we’d typically be tracking a position in the sky. Then the 30 foot came along, when was it 1961, and wanted to look at the Andromeda Nebula.
Sullivan
Well, before we get to the 300 foot, I’d like to finish off what got accomplished on the 60 foot. You said you had to understand baseline problems. These were what, just LC filters?
Burke
Well, baseline problems had not to do with the filter bank but with the RF problems that everybody dealt with at 21 cm spectroscopy. There is experience finding out that there are standing waves in the local oscillator line, all sorts of things tracking those down.
Sullivan
What was your front end?
Burke
The front end was a crystal mixer and then eventually we replaced it with a parametric amplifier.
Sullivan
Which would be roughly when?
Burke
I guess about ’63 or ’64. We copied an AIL pattern and then learned how to tune the thing.
Sullivan
But what did you see as a good project to do and what did you accomplish with the 60 foot?
Burke
Ok. With the 60 foot, I became interested in the area of the galactic epicenter and surveyed a big area about the galactic epicenter. I was looking for correspondence of hydrogen with the dark clouds of Taurus. And also, I never published the work but I did notice that you could see evidence for a general progression in the large scale map which was a way of measuring the distance to the next [?] amount.
Sullivan
A progression in velocity versus direction?
Burke
Yeah, that’s right. Also we had a very nice measurement of the hydrogen surrounding an OB association, Perseus 2 association I think it was, where you could quite clearly see a hole surrounded by a ring of gas. We didn’t publish much of the work though.
Sullivan
That is a fair statement for a lot of the work that got done at DTM?
Burke
Well it was generally published, one of things that we did do was to write a very clear annual report and in general, I think that the main line of the research was summarized in there. I think that probably in those days you didn’t have to worry about publish or perish. If you had a really important result you published it but if it was a good continuing line of research that was adequately described in the annual report then my general feeling was that that takes care of getting the knowledge across to whoever wants to find out about it because in those days the annual report was pretty well available to all the observatories of the world.
Sullivan
It was like an observatory survey almost.
Burke
Yeah, that’s alright. It was much more like the annals of the observatories that used to be published in the old days.
Sullivan
But was not this attitude something to do with the special character of the Carnegie Institution or do you think that you didn’t have to worry about publishing as much as if you were at a university also at that time?
Burke
I really can’t say. I can’t address that because I don’t know what the general spirit of the time was at universities. There was so few in the late ‘50s that you just have to ask the few people who were there. Generally, people were starting up new things and I think that under those circumstances in those days, there was great pressure to publish.
Sullivan
Because obviously you needed a lot of time to get things established and try things out.
Burke
Yeah, that’s right.
Sullivan
Well, let me ask about the Carnegie Institution as a whole, it strikes me as sort of an oddball institution in some respects, certainly very different from where radio astronomy originated otherwise around the world. How would you characterize it?
Burke
Well the origin can be described fairly succinctly as I know the history, I’ll give you my version of the history. After the war, Lloyd Berkner and Merle Tuve both were very strong personalities. Berkner wanted to start doing radio astronomy. His approach was always let’s do the biggest thing we can do and he wanted to build an enormous array of dipoles at the field station at Deerwood or so I’m told. Tuve was the director and Tuve was skeptical about the ability of radio astronomy to make definitive measurements. And his reasoning, I think, that with was such long wavelengths will never get any angular resolution. Without any resolution, you will never be able to find out what you are studying. You want to know what the state of the matter is and you may hear these very words from him because I heard from him that he felt that the radio waves were very interesting but until you knew what the state of matter was that you could get from optical observations, you really didn’t know what you were dealing with. In 1951, two things happened that changed his attitude completely. The first was the discovery of the 21 cm hydrogen line where he appreciated immediately that it was a new tool for studying the Galaxy and that you could get plenty of angular resolution at 21 cm for the job at hand. The other thing that happened was the interferometry done by Mills [Bernard Y. Mills] in Australia and by [Francis] Graham Smith of [Martin] Ryle’s group at Cambridge and of course, the outcome of that positional work was the identification of Cygnus A, [?] and Cas A. And the realization that you could actually measure the positions well enough and that the objects turned out to be extraordinary objects completely changed his mind. Tuve was a person of very strong opinions. If he thought something was no good he usually would advance good reasons for why he thought so. It wasn’t an arbitrary choice but faced with good evidence, he was also always willing to change his mind. And so he changed his mind in the period ’51, ’52. He invited both Mills and Smith to go to the Carnegie Institution. Graham Smith spent the longest time. Mills made only a very brief visit.
Sullivan
Yeah, Smith was there for a year.
Burke
Yeah, that’s right. It was a year and a half actually but some of that time was spent with Palmer. The other person who was brought there was Leif Owren from the Cornell group.
Sullivan
Was that O-V-R-E-N?
Burke
O-W-R-E-N.
Sullivan
Owren. I’ve come across his thesis. He did his thesis is solar?
Burke
His thesis was solar astronomy and Tuve also was interested in the Sun. I think he had a philosophical feeling that the Department of Terrestrial Magnetism should be concerned with the Sun because its effects on the Earth’s ionosphere and magnetic field. So Owren was working on the solar properties and John Firor pretty much gravitated to Owren’s projects and picked them up when Owren left.
Sullivan
I see so I hadn’t realized that Owren was there. He must be in the annual reports.
Burke
Yeah, that’s a new piece of information.
Sullivan
Was that the connection with the array of helixes?
Burke
Yes, that’s right.
Sullivan
They were doing some solar work. I see.
Burke
And I tended not to work on the Sun and John Firor tended to concentrate on the Sun. The boundary lines weren’t very sharply drawn. We helped each other.
Sullivan
Where is Owren now, do you know?
Burke
I don’t know.
Sullivan
Ok, continuing with Bernie Burke after a couple hour break. You told me how Tuve’s attitude changed in the early ‘50s and why, but could you speak a bit little more generally about the nature of the group at Carnegie in the ten year period that you were there?
Burke
Ok, I think that basically it was a marvelous place to be to work at fundamental physics because you weren’t under pressure to produce instantly. In fact, if you make a mistake, in fact I did make, I think, one mistake. The 400 megacycle array of Vee’s turned out not to be the right thing but well, it took some of my time and a small amount of money so it was no big loss but the thing is it was a place where you really thought you couldn’t try wild things all the time, you had to do some things that had definite results, but still it was a good place where you could try sort of a slightly long chance that is hard to get supported in an ordinary academic environment.
Sullivan
And I gather there of course there were no teaching responsibilities and there was little committee stuff and writing up proposals and that sort of thing. Now was this Tuve’s specific policy or was this just the...?
Burke
Yes, it was really, I think, his philosophy that everybody should spend 10% of their time doing something that was almost outrageous, something that had relatively low priority pay off. 90% of your time ought to be spent on something that is a reasonable bet.
Sullivan
Was this why you were working on SETI 10% of the time?
Burke
Well, not 10% of my time. I think that’s more like 2% of my time.
Sullivan
Ok, let’s go back to the 21 cm work. With the 60 foot, you worked in the anti-center. I was going to make the comment that it seemed very similar to a couple projects you described as to what was going on at Agassiz at that time.
Burke
Well actually it was motivated by the fact that I wasn’t very happy with what Agassiz had done and I felt...
Sullivan
In what sense were you not happy?
Burke
Well, I didn’t think that their signal to noise ratio was all that great and they were trying to look for things without being critical of data. So I was able to survey a larger amount of sky because it wasn’t a sequence of theses. I was able to do a rather large block of the sky and, of course, Tuve wanted to survey the whole sky, do the whole thing. If fact, he eventually did in through the ‘60s, that was after I left.
Sullivan
You think it’s a fair statement that really out of all that 21 cm work not very much science came out of it.
Burke
No major breakthrough. That is we did look at M31 and M33 and we got good rotation curves and showed something...
Sullivan
That’s on the 300 foot though. I’m talking about...
Burke
The 60 foot. No, I think that’s right. As far as my work at DTM is concerned, it was marvelous preparation but the 60 foot itself didn’t produce much for me.
Sullivan
Well, I’m saying even more generally.
Burke
Well the only thing it did really was that survey of Tuve’s and whether that’s been valuable or not, I don’t know. I suspect not.
Sullivan
Ok, let’s move on to the 300 foot. What was your motivation to go to that telescope and what did you do there?
Burke
Well we knew we had the world’s best one channel spectrometer and so the 300 foot was being just finished so we proposed that we would, in fact we proposed to take our equipment there and to examine M31 and M33. We ended looking at NGC 6822 also. And there we came into a very primitive situation. We knew we had to track and focus to get a long enough integration and there was no moving feed. So we our own moving feed and put it up there and made it work. In fact, the whole system did work.
Sullivan
And you still had to add together many days, I presume?
Burke
Yes, our observing run was fairly limited.
Sullivan
But you are saying that you had to track to get [talking over each other] a prohibitive number of days?
Burke
We could get a good profile in one four minute scan and you typically would look at one point for two or three days and that allowed us, principally we looked with one beam pointed along the major axis and one along the minor axis to establish that it was rotating the way it should. There was a clearly defined rotation curve. There was hydrogen very far out and very little hydrogen in the [middle?].
Sullivan
This was a follow up to the work that had been done at Dwingeloo, right?
Burke
That’s right. The Dwingeloo work didn’t have a good enough resolution to say anything about it except that there was hydrogen there.
Sullivan
Well they had a rough rotation curve, did they not?
Burke
They did but it turned out that the steepness of the rotation curve and the flattening out was something that wasn’t present in their data at all.
Sullivan
Well it was resolved out. Did you have the same type of output now? A strip chart recorder?
Burke
That’s right. A strip chart recorder.
Sullivan
But there was a computer at NRAO in the early days, was there not?
Burke
There was a computer but we were not interfaced to it. We used our complete system. We put our spectrometer, well Tuve had insisted in the beginning we put the spectrometer in the trailer because he knew that there would be bigger radio telescopes elsewhere. And it was something of a tour de force that we were able to get down there in a very short length of time. My recollection is that it was less than a week, we went from arriving at the dish to getting our first hydrogen profiles. I’d have to look at the numbers to be sure but it was a very short length of time. And it was a great deal of fun because at that time we couldn’t be sure that the dish was pointing properly so we rigged up our own pointing device. We made index marks on the wheel and we observed it with a TV set.
Sullivan
I see. It was even at that stage... Were you the very first users that were assigned...?
Burke
We were among the very first users. I don’t know whether we were. We were certainly among the first few users.
Sullivan
Well at DTM [Department of Terrestrial Magnetism] I think you left in ’64 or ’65?
Burke
‘65.
Sullivan
And I think it is also fair to say that is where the end of the radio astronomy output from DTM in any useful sense. What really lead to the decline do you say?
Burke
Hmm?
Sullivan
What lead to that decline?
Burke
Not enough people. That is we were spread fairly thin and Tuve had started up a cooperative program with the Argentines.
Sullivan
Oh, that’s right.
Burke
And Ken Turner was a new addition to the staff for the last couple of years and actually, Ken did the major amount of work with the Argentines in getting everything going.
Sullivan
Yes, that’s right.
Burke
Along with Everett Eckland who was the engineer who worried about mechanical details. Excellent mechanical engineer, self taught. And so Eckland worried about the actual construction of the telescope and Ken took the major responsibility for the construction of the electronics.
Sullivan
Do you think that was really a mistake for such a small group?
Burke
Yeah, I think. Well it was a mistake for our scientific careers in the short run. That is, it certainly meant that our time was divided up. It would have been better I think personally if we hadn’t bothered. Now there were some side effects. I know that a lot of my time at the DTM was spent struggling to make things work. Well any good place, with the exception of the Dutch who had a very structured approach, you had to struggle to make things work no matter where you were and it was relatively inefficient in time but I don’t think it was wasted time because you got to understand a great deal about how systems work and even to this day even though I was dealing with digital electronics, I find that it’s a lot easier to understand the system, what might be right and wrong with the system. The training wasn’t so bad and we did a number of useful observations along the way.
Sullivan
Now you are talking about your entire time at DTM?
Burke
That’s right but at the very end there, it was when it was just Ken Turner and me and we were trying to build a thing in South America and do things both at Green Bank and at the DTM. It was probably spread a little bit too thinly for the size of the number of people we had.
Sullivan
OK, let me just close by asking you, you are a physicist primarily. I mean you got your Ph.D. in physics and you’ve been at MIT in physics and yet you are a radio astronomer also. I’d be interested in your comments on how you think radio astronomy has influenced physics or is it just a sub branch of physics or it is something that is in astronomy that doesn’t really impact on physics. What is the relationship between the two?
Burke
Oh, I think that the physicists have a much keener appreciation of the role of astrophysics as a branch of physics. That is the notion that there are other kinds of fundamental science and radio astronomy has focused on the sort of thing I think physicists are most comfortable with. That is you are dealing with a relatively small class of objects: supernova remnants, radio galaxies, quasars, jets of relativistic gas, magnetic fields. You can relate what you are trying to do to physicists’ knowledge of basic physics in a fairly direct way if you work at it. A lot of people don’t work enough at it because they get tied up in the zoology. Whereas optical astronomy really has an enormous mass of details and there are huge sectors of optical astronomy where the details are the thing and I think that doesn’t make a physicist feel that it is a very fundamental science.
Sullivan
You mean he can relate better to results that come from the radio kind of observations, I think of stellar astrophysics and solar physics as being very well defined problems that the physicist...?
Burke
But they don’t address the favor problems of the physicist.
Sullivan
They had been solved in the ‘30s and ‘40s.
Burke
Yeah, but [Victor Frederick] Weisskopf has two types of frontiers. He calls them external and internal frontiers and the external frontiers are where you really don’t know even the basic principles. You might say that the large scale structure of the universe has some of that quality where you’re really not sure that you have the correct law of gravity. On the other hand, if you are worried about neutron stars or relativistic plasmas, you’re not worried about the basic physical principles. You may have to make some discoveries on internal frontiers, properties of organization and order, collective motion, things of that sort of thing.
Sullivan
Ok, that tells me what you think about the scientific ideas. Has there been any impact in terms of techniques or is that not a proper question?
Burke
I don’t think very directly, no. The concerns of radio astronomy concentrate, I think, on low noise technology and signal processing. For the most part, we deal in much more massive signal processing problems than most of the particle physicists with a very small set of exceptions. There are some who also have enormous computational problems but it’s a rather different kind. They’re not handling as much data but they’re dealing with computations in multiple dimensions essentially.
Sullivan
What about a comparison of the problems of radiometry to the radio astronomers’ microwave spectroscopy in the lab?
Burke
I think that that the microwave spectroscopist in the lab is doing absorption spectroscopy so he doesn’t have any problem with the receivers. Now a days he has reliable microwave sources that are tunable over a wide range.
Sullivan
I was thinking more during the ‘50s and early ‘60s. Was there any interaction there or did they really sort of just go along in parallel?
Burke
The nature of the interaction was that I came from microwave spectroscopy as with Charlie [Charles H.] Townes and his students. It was a very easy transition to make because you did in fact have much the same kind of technology except for not worrying about vacuum.
Sullivan
So it was more people coming from that field rather than that radio astronomy was influencing how microwaves...
Burke
Yeah, not much going the other way.
Sullivan
Ok, well thank you very much.
Burke
Ok.
Sullivan
That ends the interview with Bernie Burke on 22 September 1981.