[Bolton, 1976]
Bolton, 1976 (Photo courtesy of NRAO/AUI/NSF)




NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with John G. Bolton
At Parkes Observatory
March 15, 1978
Interview time: 3 hours, 40 minutes
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.

Part 1 | Part 2 | Part 3 | Part 4

Sullivan

Continuing with John Bolton on 15 March ’78. The reason that so few identifications were made on the original 3C survey, for instance, [David W.] Dewhirst was at Caltech at that time, as I'm sure you remember...

Bolton

Oh, yes.

Sullivan

Was simply because of these very large effective error boxes despite the low formal errors in positions.

Bolton

That's right. And of course, Dewhirst did get a few identifications.

Sullivan

He got a few, yes, but a very low percentage of the overall catalogue. So then, what was made of this 16th magnitude star? This is 1960, I believe?

Bolton

Yes. Well, it was initially very hard to talk anybody into doing anything about it.

Sullivan

Even to look at a spectrum?

Bolton

Yes. And Rudolph Minkowski had retired, of course, by then. It was his last run on which he got the redshift of [3C] 295 and actually Jesse Greenstein was the person that we said, "Jesse, you've got to do something about this, or else." And Jesse did, or he attempted to, it was actually the first time he’d ever been in the prime focus cage.

Sullivan

I see.

Bolton

And unfortunately, he was clouded out. And so it was Allan Sandage- Allan was a lot more junior then than now- who was told by Jesse to get a spectrum of the thing. And, of course, nobody could recognize the spectrum, and everybody- well, we had the idea when it was found that here was start of something optically. The general idea when we got it was that here was something very, very distant. That it's the bright flash in a galaxy which ultimately leads to the standard wide double radius source. But, of course, at that time, nobody had any knowledge of what the ultraviolet spectrum of anything looked like- rockets hadn't flown.

Sullivan

Did this flash business, of course, is just a bit of speculation, in those days?

Bolton

Yes, pure speculation. But this was a flash, we were seeing the optical phenomenon.

Sullivan

A few million years later maybe the radial lobes will be there.

Bolton

That's right. And well, a large number of people attempted to solve the spectrum. I, indeed, did get the right answer for the redshift of 3C48, and I had forgotten till quite some years later when Fred Hoyle reminded me- he came into my office one lunchtime and- Fred used to spend three months each year at Caltech- and I said to him, "Well, either the redshift of this object is .36 or I don’t know what it is." And indeed, I had the line identification right, but the wavelength fit was not very good. Of course, nowadays, one just doesn't worry because you know that the emission lines in quasars are chopped up on one side if it’s a permitted line, they're chopped up by absorption lines.

Sullivan

But you had to be very conservative on this thing.

Bolton

Yes, we had to be very conservative, but, in fact, well certainly Matthews and I were convinced that it was something of super luminosity. But, of course, until the later stage of 3C273 at Parkes, people were starting to, well, Jesse Greenstein and Maarten Schmidt had written a paper to explain how a star could produce these lines at these wavelengths. The idea had been dropped, of course. I think about 4 or 5 founded with peculiar emission line spectra or no emission lines at all in the Caltech search. The reason we never got 3C273, I mean it would have so much easier if we'd identified 3C273 at that time because its spectrum is very obvious- here's the hydrogen line staring you in the face. But, of course, 3C273 has the same right ascension as M87 and M87 was observed every day with the interferometer, it was one of the fundamental calibrators, and so 3C273 was...

Sullivan

I hadn't heard that story, that's interesting.

Bolton

That's true, and later when we come to the Parkes dish, the position I set on the telescope for the lunar occultation of 3C273 was the position that came from the occultation.

Sullivan

But why couldn't you observe off the meridian?

Bolton

We tried to catch one observation on the meridian always, and I suppose we could have done it, but M87 was the fundamental thing- what's happening to the drift in our cables and that kind of thing.

Sullivan

So you always caught it at transit.

Bolton

We always caught M87.

Sullivan

And 3C273 was just another 3C source- or is that true? That there was no particular need...

Bolton

No. Just another 3C source.

Sullivan

I'm confused now, was it not one of the Jodrell Bank very small sources?

Bolton

No.

Sullivan

It was not. Okay.

Bolton

In any case, its declination was rather low. And it would have been a challenge to get its declination with the Caltech interferometer at that stage.

Sullivan

You were concentrating on the ones you could do better?

Bolton

Yes.

Sullivan

But was there any published record of this toying around with such horrendous redshifts in that day and age?

Bolton

No, I don't think so.

Sullivan

I'd never heard that anyone had really ever come up with a possible number before Maarten Schmidt’s.

Bolton

The lines one could see in 3C48 were Mg II, Ne IV and oxygen 3727.

Sullivan

No hydrogen lines?

Bolton

No. In fact, I think it was only 3727 and Mg II, those two lines. 3727, of course, is forbidden and Mg II is not.

Sullivan

Yes. Just looking at the other papers to 1960, in which you’re a co-author, let me see if there's anything we haven't discussed. You actually published a paper with Radhakrishnan on H I absorption on the Owens Valley interferometer in 1960.

Bolton

That's right.

Sullivan

Where did the idea of doing interferometric H I absorption come from? Were you thinking these must be small clouds or...

Bolton

No. The interferometer was always envisaged to do H I absorption measurements. Simply because one isolates the source and then you avoid the difficulty of having to subtract. An average emission profile of the surrounding region from the absorption profile, in fact, our first observation which Radhakrishnan and I ever did get totally different profiles from the single dish profile. We'd said the structure between, the emission structure in between fringe size and our single dish size, in fact, Rad later stages where he successfully using the interferometer here.

Sullivan

At Parkes, yes. So you're saying as soon as NRL showed that there were these narrow absorption lines that it was clear to you that this would be a good thing to do with an interferometer.

Bolton

Well, the point was that one could only observe sources which gave you antenna temperatures which were in the at least in the tens of degrees, because you faced the emission break down of 100 degrees. If you were ever going to work large numbers of sources and determine what the sort of interstellar background looks like in many directions, and wanted to work on sources which have antenna temperatures of 2° or 3°, then you had to go to interferometry.

Sullivan

Were you thinking in these early, you know, 1957, 1958 were you thinking that, indeed, you might come up with a different kind of gas? Sort of thing that eventually happens- that you might be finding a different component of the interstellar medium?

Bolton

Yes. I was convinced of that in 1955.

Sullivan

That these clouds were...

Bolton

That there must be hot and cold clouds. In fact, Rad and I, Rad published in the PASP- did find self-absorption at one stage, which coincided with the dark lane, we found this near IC443. Actually found self-absorption in the emission background. But that was before we had the interferometer going. This is now very familiar - cool clouds of molecules...

Sullivan

Then, of course, it was not a standard concept at all. Well, this is all the publications I have to 1960 before we come down to the Parkes antenna. Are there any other aspects of Caltech that should be covered?

Bolton

Well, Caltech never sort of continued in the very successful run we had in 1959 and 1960 era.

Sullivan

You mean after you left?

Bolton

Yes. And Caltech is principally to blame for that. They had a very keen crew of graduate students, people like Ken Kellermann and Barry Clark and Bob Wilson and so on. But unfortunately, of course, Caltech would not appoint another director.

Sullivan

Was this basically a financial reason?

Bolton

No, I don't know why. I really don't know why. Minkowski and Baade had gone. So the pressure from optical side was lacking, Caltech wanted somebody with a big name. I made two suggestions as to who should be the next director, one of whom was finally appointed, Marshall Cohen. If Marshall had been appointed when I left, I think it would have gone on from strength to strength. The other was Bill Erickson who had worked with us to quite some degree, but you see, it left Caltech with nobody who could say, argue with people like [?] and [?] and Mike Bowen and so on. Gordon Stanley very reluctantly- he never wanted, I mean, his interest was purely from the technical side. And it unfortunately died to a certain extent. It still continues but...

Sullivan

The thing that sort of interests me is that with these two movable antennas, you had the possibility to do what is now called Earth rotation synthesis or super synthesis. Did this ever occur to you people in those days or were you just so fixed on just getting sizes and positions that this was outside of your realm?

Bolton

We used two antennas as very flexible single experiments. In a way, we did synthesis. I mean, Moffet's work on angular sizes is synthesis.

Sullivan

Right.

Bolton

But at that stage, we had 100 or 200 sources on which we could get detailed information. And...

Sullivan

You wanted to do that first before you spent a lot of time...

Bolton

Time...

Sullivan

One single map.

Bolton

That's right, yes. And the other problem, of course, is the tremendous effort one has to put in on the computing side.

Sullivan

Although at Caltech I would think if anywhere there must have been some good computers coming along by the late 1950's.

Bolton

Yes, this is true, but you've got to get computer data recording and...

Sullivan

Right, and you've got to develop all the software...

Bolton

Everything like that. We were, by no means, we were doing the easy experiments.

Sullivan

Okay, so then Taffy Bowen offered you, what was the official title of that position? Directorship of the Parkes Observatory?

Bolton

Yes.

Sullivan

And you came down here in what year?

Bolton

At the end of 1960.

Sullivan

’60, so the year before the dish went on the air?

Bolton

It was before it was built.

Sullivan

Before it was built? Was it late in 1962 before it went on the air?

Bolton

No, late 1961.

Sullivan

Oh, it was built that fast?

Bolton

Yes. Just the tower was here when I came back.

Sullivan

Okay. And what was the program you were envisaging for the dish?

Bolton

Well, one of the things we could not do very successfully at Caltech was to employ the whole of the radio spectrum. And this is one thing, I mean, we didn't have the collecting power at very short wavelengths. We didn't have the resolving power at long wavelengths. I mean, Caltech was ideally suited to, say, around 21 cm region, where one could see the collecting area being useful as short a wave length as 10 cm and the resolving power useful at wavelengths as long as, say, 70 cm.

Sullivan

Did you have enough staff to maintain such a wide stable of receivers? Also, at Caltech if you’d had...

Bolton

No, Caltech's primary resolving power and collecting area, the collecting area, you see, sensitive receivers change very radically so one almost has to look at the epoch. We were struggling past 21 cm even though we sort of got experimental traveling wave tubes at 10 cm and towards the end, the maser possible, but we really had to go to 1 gigahertz to get adequate resolving power in our single dish, so what I principally saw in Parkes was the possibility of using a very much bigger bite of the radio spectrum.

Sullivan

I see.

Bolton

And, of course, in my, well John Shimmins and I found that one could, in fact, distinguish what one was looking at through the spectra. There was a 99% chance of flat spectra object in the quasar and [?] so one can do some sort of blind astronomy.

Sullivan

But that wasn't clear when you came down here in 1960? Or were you thinking that maybe...

Bolton

Well, we didn't have at that time, we didn't know what we could do if we used the whole spectrum. And Parkes offered me the addition.

Sullivan

It just hadn't been investigated.

Bolton

In any case, I was committed to come back here quite some time before I did come back. Taffy was over for the dedication of the 90 footers and was very impressed with them and everything like that and he said, "I suppose you're here for life." And I said, "No. I'd like to come back when things are running properly." And he said, "Well, [?] the job is yours when you want it." Of course, the pressure came on me a little early, we were really having a very successful time at Caltech when Taffy began to make noises that I should be here when the dish starts to go up. So I really...

Sullivan

So you would have preferred a little bit better timing.

Bolton

I would have preferred another year at Caltech as it happened, but there were other things which, you know, our kids were getting to the stage where, were leaving school and that kind of thing, so from a family point of view, it definitely changed things.

Sullivan

So the Parkes dish itself, I talked to people like Harry Minute and so forth and it seems that the construction went very smoothly and very fast - even finished before you expected, it's almost unheard of once it started being built. And your program then was, from what you said, to look at spectra of...

Bolton

Well, no, I don't think the Directorship of Parkes was very different from the Directorship at Owens Valley. The Directorship of Owens Valley was, in fact, building the equipment and directing its research program. In the case of Parkes telescope, it was principally getting the antenna going and finding people to use it. And I certainly had no expectations of doing anything, personally, with it. My main job was to get it built and then to get it operating. And of course, when I came back, we still had the many small groups and really, there were very few people who even conceived of using the Parkes dish, you see, because it was something quite unreal to most of the lab. But, of course, many people from Radiophysics had gone overseas. Roberts was with me at Caltech and he came back with me. Radahkrishnan and Morris came to Australia from Caltech. Mathewson came back from Jodrell Bank, Ryan Robertson came back from Leiden and so on, but I mean, the people who were really wanting to use the dish- well, Frank Kerr, Tom Mathewson, who just arrived back, you see. Frank Gardner was the only sort of local radio physics person who, in addition to Frank Kerr, who had ambitions on the 210.

Sullivan

Because people were not oriented towards large...

Bolton

No, they were not oriented. They didn't think of it. And they all had their own little field stations. And actually no provision made for even operating for the 210, and I went around first or second year after it had been built, visiting closing field stations to get some...

Sullivan

Get some operating funds.

Bolton

You had to employ the man who cut the grass and that kind of thing. We were very short of funds.

Sullivan

So really, it was a very big change in style, the whole way the lab operated.

Bolton

Yes, it was a very big change in style.

Sullivan

And which, obviously, makes for various sort of adjustments.

Bolton

Of course, we had a number of almost immediate successes. And that sort of gradually changed the whole pattern. People who didn't want anything to do with it either had a bad time, or drifted away, you see, even Pawsey quit. Unfortunately, of course, he died shortly afterwards.

Sullivan

That was before the dish went on the air, was it not?

Bolton

It was round about that time. I think Pawsey made up his mind, well, he went to investigate Green Bank about six months through construction.

Sullivan

Yes, right.

Bolton

And then he fell ill and was out of action for oh, perhaps, another nine months. But he was in on the Faraday rotation work.

Sullivan

The planning for it?

Bolton

No, no, I mean he saw the results of that.

Sullivan

Oh, I see.

Bolton

I forget whether he, yes he saw the 3C273 occultation results, but I mean he was an invalid by then, and I would go to his home and tell him what was going on.

Sullivan

You seemed to be showing more enthusiasm for these sort of things?

Bolton

Oh, yes. One of the things that I very greatly regret, actually, was I had built the polarization equipment for this dish, it was modeled on Caltech, and Joe wanted to use it on a much smaller dish to see if he could find polarization in a general background. And I refused to let him have the equipment. And, of course, the Dutch got that first. He could have found it if I had only let him have the polarization equipment.

Sullivan

What sort of frequency was this?

Bolton

This was a 400. The reason I refused to let him have it was that I had a lot of effort in designing it, making it work and everything like that. It would have had to be chopped up and mounted on something and by that time we were well into this construction and it was one of the things I had...

Sullivan

Was it a small dish he was thinking of?

Bolton

Yes. A small dish, 15 foot dish or something.

Sullivan

Interesting. Well, I think, the 3C273 story would be a fitting end to the scientific side of things anyway. Could you tell me about how that came about? As you saw it from the director's point of view. I don't believe you yourself were involved.

Bolton

Yes, I was very involved. I directed the experiment.

Sullivan

Oh, I'm sorry.

Bolton

Well, Cyril Hazard came out to Australia to work with the Sidney University group about the same time I came back from 210 and I'd known Cyril for a long time. Cyril came into Radiophysics one day with the results of a lunar occultation; the only really successful lunar occultation he'd done with the Jodrell Bank telescope. Many people, of course, had had the idea of doing lunar occultations. We tried one at Caltech with the interferometer actually prior to Cyril. And Cyril showed me the results of those and even though he didn't get an identification still of one unidentified 3C sources, the potential of the technique was very, very obvious, and I invited Cyril to make use of the 210 for it.

Sullivan

What was the technical difficulty, for instance, of Caltech? You say you tried one.

Bolton

Well, we tried it on a 3C source which was in the wrong position.

Sullivan

Okay. You didn't try it on ones you had good positions for.

Bolton

Well, I mean, this is one which we hadn't positioned; it was a prediction from [?] office, we had to cut out the Moon with the interferometer and we did that successfully. But when we came to make the actual observation, we got no results and we later found in hunting around the 3C source was [?].

Sullivan

I see.

Bolton

But we got this prediction list, oh that's [?] yes. Only a week to plan and get the dishes in the right place to cut the Moon out.

Sullivan

It was just sort of a quickly done thing.

Bolton

Yes. It was done on a level of sensitivity which we couldn't easily see the source directly, but could easily see it in lunar occultation. And, of course, 3C272 was one of the sources which occultation was predicted for, I think, '62. Yes, 1962. John Shimmins was assigned to help Cyril because it required some tricky dish driving and John was responsible for the telescope drive system and Brian [?] was assigned because Brian and I had built the two receivers which were going to be used.

Sullivan

You were tracking the limb of the Moon.

Bolton

Yes. Well, no, the signal was made to track the source.

Sullivan

So why was there tricky dish driving?

Bolton

Why was there tricky dish driving? There was tricky dish driving because all these occultations occur outside the limits of the telescope.

Sullivan

Oh. Below the minimum [?] elevation.

Bolton

Yes, and I think the first one, we actually had to use offset feed for it. And the first occultation, it was the first occultation was bungled. They didn't get anything.

Sullivan

On [3C] 273?

Bolton

Yes. And so I decided the second one which was the most promising one because we looked as though we should get both the inertion and emersion. I took charge of the dish and well, it was rather I took the precautions which we later took for the Apollo missions and so on, of doubling everything, practice runs and two clocks, two recorders. I forget what happened, I think, you know, a silly thing like the ink running out on the recorder had blown the first one. And so it was a military operation.

Sullivan

Yes. More like an eclipse.

Bolton

Interference, the site was closed the roads were blocked.

Sullivan

Oh, really? Then what?

Bolton

Oh yes, the telescope and everything was closed for three days beforehand so that nothing went wrong. We were prepared to...

Sullivan

Why did you attach so much importance to it?

Bolton

I don't know. Well, I suppose it irritated me that it had been missed, it wasn't going to be missed again.

Sullivan

Okay.

Bolton

Of course, it was very successful and I suppose the extreme length to which I went was that Cyril and I flew back to Sidney on different aeroplanes with the records.

Sullivan

But only one person had the record...

Bolton

No, everything was duplicated.

Sullivan

Oh, I see. You had two strip charts and everything.

Bolton

I think we had four strip charts. Clocks were duplicated, everything was duplicated, timing, everything, was duplicated.

Sullivan

I think you meant you just had back-up in case the one failed. You ran them all, too. You must have had some unconscious premonition about this is going to be important.

Bolton

Well, you see, Rudolph was here. Rudolph Minkowski. And Rudolph had sent to Caltech for his plates of the region of 3C273.

Sullivan

To date there was only one quasi-stellar or had...

Bolton

No, there'd be half a dozen. We didn't know what 3C273 was, but the position which we determined with this dish prior to the occultation said on Rudolph's plates it's either that star or it's that jet. We couldn't determine...

Sullivan

Either way it was very interesting.

Bolton

Yes. And of course, it turned out to be both.

Sullivan

Yes. What sort of accuracy did that result in? In the position of the source?

Bolton

About 1 second of arc. But you see, the position we sat on the dials for the occultation was the position which the occultation said it was.

Sullivan

Was that how it turned out actually?

Bolton

Yes.

Sullivan

I see.

Bolton

But we said mid-way between the jets.

Sullivan

You didn't change the position, you just changed the error bars.

Bolton

That's right. The occultation gave us a structure which said it's a star and a jet.

Sullivan

Well, let me just go back and ask a couple more general questions. First of all, you mentioned this trip in 1950 where you visited Leiden and other places. I was wondering if you could just give me some idea of your impressions about the efforts that were going on at other places and the reception you got as one of these?

Bolton

Well, as I said prior to that I had written, I had corresponded with Oort and Linblad and with Minkowski and Baade. I went to England to start with and Westfold, actually went to Oxford at that time. I made Oxford my base and from there Westfold and I made forays and to various astronomical centers in Europe. At Leiden we spent quite a long time, we lectured at Leiden in the summer. We went to Keel, we went to Paris, and became great friends with the French early group [Jean-François] Denisse, [Emile-Jacques] Blum, and [Jean-Louis] Steinberg and so on. We went to Sweden and saw Linblad and [Olof E. H.] Rydbeck. We went to Denmark and saw [Bengt] Strömgren. He's been a close friend for many years, also.

Sullivan

That seems rather odd to me. Strömgren was a very classical stellar astronomer, why would you go to see him?

Bolton

I think I was interested in knowing these people. I had read their papers and so on. Where else did I go? We went for the URSI meeting in Zurich. In Cambridge, of course, all those problems with Ryle but I got to know Fred Hoyle and Hermann Bondi and Ray Littleton very well.

Sullivan

You say 'all these problems', what were they?

Bolton

Well, of course, we get back to where we talked about scintillation.

Sullivan

Oh, that right.

Bolton

I had corresponded with Ryle and so forth.

Sullivan

He hadn't told you about...

Bolton

Didn't tell me about it at all. And I wrote...

Interruption

Sullivan

You were saying you were talking with Ryle about what?

Bolton

Yes, and when I got to England I went around various places and finally I wrote to Ryle and said that I was hoping to come over for the May week or couple of weeks around the May week, which is sort of end of the term and boating activities and lots of celebration at Cambridge. And I got a reply back from Bragg, who was then director of Cavendish, saying that Ryle had told him of my visit and I should understand that Ryle's group were doing research which was in the forefront of world work and the group was pestered by hundreds of visitors and...

Sullivan

Incredible.

Bolton

And he was sorry I couldn't come.

Sullivan

Really? From Bragg. So you didn't?

Bolton

Oh, yes. I went for a month.

Sullivan

At Cambridge?

Bolton

Yes, there was a very big stink over it and, of course, it got all around the university and everything like that I was made very welcome by anybody who didn’t like Ryle.

Sullivan

So you just showed up in the hallways and started talking to people?

Bolton

Yes, well, I hadn't actually met Fred Hoyle except for one occasion during the war, but I'd had quite a bit of correspondence with Fred on various things. The attitude of the Cambridge mathematical group and so on was totally different from that of Ryle.

Sullivan

But what I'm getting at is did you visit the radio astronomy group?

Bolton

Oh, yes, I did. As Ryle realized afterwards, he'd made a terrible mistake and went and saw George Bexler, who was the sort of Dean of Australians in Cambridge, to back him up that he'd done the right thing and George told him he certainly hadn't.

Sullivan

I see, so in this way contact was made although it was undoubtedly strained.

Bolton

Oh, yes. And, of course, I met Graham Smith and John Shakeshaft and we've been friends for years out of that group- Ryle's a very unfortunate person. I remember one incident, I think I was having dinner with Fred Hoyle in John’s [Sullivan: College], and there was discussion at the table about it and a professor of anatomy whose name when I was a student was Sex Harris because he always began his first year lectures by writing SEX in 6 foot high letters across the board. He pricked up his ears at this conversation and looked across the table and said, "You know what's wrong with Ryle?" And I said, "No." He said, "His mother was an Anglophobe Dutch and his father was a medical failure who accused everybody else of plagiarism."

Sullivan

At Leiden I was thinking you must have discussed at great length models of the galactic radiation because Westerhout and Oort were working on this. I guess they had just finished publishing their paper at this time.

Bolton

Yes. We'd done, Westfold and I had done similar things to Oort.

Sullivan

Were there any points of disagreement?

Bolton

No. You were asking earlier why I went to see Strömgren. I mean one of the things that Westfold and I realized was the importance of free-free absorption in modeling at the wave lengths we were interested in and nowhere in the literature could we get a really good handle on the interstellar electron density. And we corresponded with Strömgren and we corresponded with Lyman Spitzer. It was both density and temperature we wanted. And Lyman had written two papers, one was a thing with all the phenomena which heat up the interstellar material and the other one was all the phenomena which cool interstellar material, and paper three was promised and actually it was never written. Paper three was how you put it all together and you get temperature and density of interstellar material. So that was one of the reasons for talking to Strömgren.

Sullivan

And what was the conclusion- you were at 100 megahertz then?

Bolton

We were at 100 megahertz.

Sullivan

What did you conclude?

Bolton

Well, I think our conclusions were probably that it didn't matter that much except at very, very low latitudes.

Sullivan

It was such a broad beam that would dilute the effect.

Bolton

Yes, but unfortunately it is an important effect. But we were looking to develop our work by modeling widths of the radial and z distribution of absorption. We never got around to that, we just playing with the idea. Where else did I go in Europe?

Sullivan

But let me just go back, were there ever any major differences in outlook as to the source of the galactic radiation between your model and Oort's ideas at that time?

Bolton

No, I mean, we both attributed it to essentially an unknown origin. Kevin and I called it radio stars, but that was just a volume emissivity element except one couldn't be quite certain. As I said, we later came to the conclusion that the density was that of the electrons. It wasn’t stars. To a certain extent, the teaching at Leiden was based on a lot of work that Kevin and I had done, spherical integration methods, concept of antenna temperature and so on. These were really devoured at Leiden and what we put into a paper was expanded out to three lectures by the Leiden people. I think we were there something like a month and two or three days a week Oort would call us in and we'd just sit down and have a two or three hour discussion, maybe Oort and van de Hulst, and Westerhout and I. I mean Oort was a great seeker after the truth.

Sullivan

Well, so long as he liked the idea of your truth. You visited Jodrell Bank, I guess?

Bolton

Yes, I spent quite a lot of time at Jodrell Bank. In fact, one of the things I was given was the Hanbury Brown- [Richard Quentin] Twiss notebook on the amplitude correlation interferometer, to look through it and see if I could find mistakes in the mathematics. In those days it was terribly complex and you just got lost in the mathematics and you had no physical insight, and all I could do was just plod through it and say, "Well, I can't find any mistakes, but I don't understand how it works." Later that year I went back to Jodrell Bank and of course, they'd done the solar angular diameter by using two overlapping antennas. And I saw Hey at that stage, who was still in Surrey.

Sullivan

Was the 218 foot hole-in-the-ground [Sullivan: actually, 218 foot dish is entirely above ground] built when you were there?

Bolton

Yes. It was there.

Sullivan

This must have made some impression, obviously...

Bolton

Yes.

Sullivan

In terms of later building one yourself?

Bolton

And then I went to Canada where I saw [Arthur E.] Covington’s work, and then to Toronto and Cornell and Harvard and Yerkes Observatory, which was solely optical.

Sullivan

At Harvard you saw for yourself Ewen and Purcell working on [Sullivan: 21 cm line]- this was 1950 now. So this was the year before it was detected.

Bolton

Yes. Well, of course, I'd seen the Dutch work going on with the receiver and it, of course, destroyed in the fire, they should have won, but the fire destroyed the initial receiver. And then I traveled across the country and spent quite a lot of time in Pasadena and finally Berkeley.

Sullivan

Where...

Bolton

And, of course, I lectured in all these places. Many people said afterwards, "You know, the thing that really changed history with your visit to Copenhagen and Götenberg."

Sullivan

And in what sense?

Bolton

In the sense that radio astronomy became a reality to them.

Sullivan

I see. Places that hadn't had the contact.

Bolton

Places that hadn't had the contact- actually met people with slides and records and ideas and that kind of thing. You see, radio astronomers didn't get around.

Sullivan

They didn't go to optical observatories.

Bolton

I was the first person.

Sullivan

Which is perhaps having to do with your reading twenty years of ApJ and so forth. You obviously had more of an orientation this way.

Bolton

Yes.

Sullivan

In fact, a question I want to ask you: in the late ‘40s if someone asked you, "What do you do?" at a cocktail party or something, what did you say?

Bolton

By 1949 I was saying, "I'm a radio astronomer." I think I was the first person to use those words. In fact, I gave a lecture at the Royal Society of New South Wales and the title was "Radio Astronomy" and this was the first time I'd used it myself.

Sullivan

And before that you'd have said what?

Bolton

Before that, nobody asked me. I mean, I worked out on Dover Heights and it was very difficult to say what I was doing and I had some contact with Mt. Stromlo, particularly Clair Allen.

Sullivan

I talked to him a couple of days ago. But indeed, that's very early for someone to be calling himself a radio astronomer. I don't think I've had anyone else say...

Bolton

Well, I made radio astronomy the title of this lecture, you see.

Sullivan

But it seems to me there was a discipline called radio astronomy starting in 1948 or '49 and everyone sort of understood this, but people did not call themselves radio astronomers until really, the late 50's in general. They were always thinking of themselves as radio physicists or engineers or physicists.

Bolton

Oh, no, I was appointed Professor of Radio Astronomy at Caltech. It was the Radio Astronomy Department right from the beginning.

Sullivan

That's '55.

Bolton

You said the late ‘50s.

Sullivan

Okay, mid- ‘50s. And Ryle also got a chair in Radio Astronomy in 1958 or so, and I guess Lovell a little bit earlier.

Bolton

I think the Manchester people always considered themselves radio astronomers.

Sullivan

I may not have asked that question of Lovell.

Bolton

They called those things "telescopes".

Sullivan

Yes, that's true. And I know Lovell does have an article in 1948 or so where he talks about radio astronomy. Another general question - over the years and especially up to the Parkes dish, what, in your opinion, are the key ingredients to the success that Radiophysics has had in terms of being one of the three or four leading places?

End of Tape 101B

Sullivan Tape 102A

Sullivan

To what do you attribute the success Radiophysics over the years?

Bolton

Well, we did get in on the beginning, which is an important step. There was very little point in coming in second, which meant that we could do things with pretty simple equipment in the early days. We had the advantage of weather, winter or summer one could work outside here. If you're in the Soviet Union, you can only lay concrete during three months of the year and that kind of thing. And there are the same difficulties in North America, even in Britain. So the weather was on our side. And I think Taffy Bowen was on our side.

Sullivan

In terms of constantly supporting the effort?

Bolton

In terms of letting people have their head, I think. Giving you a pat on the back when you did well and commiserating with you when something failed. I think he had an attitude which helped things along. And the other thing, of course, was the complete openness at Radiophysics; people talked to each other about what they were doing and so on, which didn't happen in a place like Cambridge.

Sullivan

Even amongst the sub-groups at Cambridge, you're saying?

Bolton

Yes.

Sullivan

I’ve gotten the impression that, while there may have been openness, there was a lot of isolation because of all these field sites and so forth.

Bolton

Well, you asked for the very early days.

Sullivan

Well, no, I'm asking over the whole period.

Bolton

Over the whole period. Well, I think one of the things is that there was enough of us, and so generally somebody was on top. This was important, say, in the middle phase, around 1950-55. Where you can have three or four groups who are building equipment for a couple of years, but one of them had got stuff coming out and so on. And so from the outside it looked as though Radiophysics was...

Sullivan

A lot of depth in other words.

Bolton

Yes. There was a lot of depth.

Sullivan

You did not work here during the war. Most other people have commented on the outgrowth of the laboratory during the war, and how this set the style for rapid innovation and these sorts of things. But that's not part of your background.

Bolton

No.

Sullivan

You didn't observe this to be an important influence though?

Bolton

Radiophysics has not always been successful. I mean, I think, at all stages someone must have been very irritated with the lack of progress that, when you compare...

Sullivan

Well, yes.

Bolton

I mean, that's why the Germans lost the war, we were bloody inefficient, but they were even less efficient, you see. There are only really a couple of places in the world that I've visited which have something of the same spirit as Radiophysics. One is Bell Telephone Labs and the other is Lick Observatory. Lick Observatory over the years, as you know, has been much more successful than its massive counterpart a few hundred miles south. Bell Telephone Lab was always a very good organization; well, it's not such a good organization now, it used to be in a lot of little huts with duckboards between for bad weather and that kind of thing, the director took his turn each week in cutting up on day a week, and so on. But there, individuals were allowed to operate as individuals.

Sullivan

So you think that's a key element in any...

Bolton

Yes, I think that's a key element. Of course, how one integrates it into a large machine like we've got now... there were stages when this was pretty difficult, but we now very much are back to operating on an individual basis. Parkes is set up so that the observatory is virtually autonomous.

Sullivan

What do you mean by that?

Bolton

Well, it runs itself. Radiophysics doesn't run it.

Sullivan

I still don't see what you mean. What would be the alternative to that? You've got to have somebody who selects who gets what time and what the overall...

Bolton

Well, this is done by a committee, who gets what time.

Sullivan

By autonomous, do you mean democratically run rather than in an authoritarian fashion?

Bolton

Yes, I mean, the local staff here operate the telescope without interference from, there's not a great deal of interaction between...

Sullivan

From Sydney, yes.

Bolton

From Sydney, I mean, Radiophysics is just one of the organizations which uses this telescope.

Sullivan

In fact, that's true now, yes.

Bolton

Yes, it wasn't so true in the early days, but in the early days we didn't have the support facilities here. There was me and John Shimmins, one mechanic, and one electrician and that was it. So people had to do the things that a telescope was capable of doing; nowadays, of course, it's equipped with receivers which span the entire spectrum, off- and on-line processing equipment and everything like that, so if a program's feasible at all, you can get it on the Parkes telescope whether you know anything about radio astronomy or not... About one quarter of our observers now come from optical observatories. You know, the U. K. Schmidt people, the Anglo-Australian people, the British visitors that come out to the A.T. and so on, they all get on the Parkes telescope. So there are really lots of individuals using the telescope once more. This wasn't true in the early days, when the scientists very largely- you couldn't use the 21 cm parametric amplifier unless you worked with the man who built the 21 cm amplifier.

Sullivan

And you knew how to tune it and where the liquid nitrogen was?

Bolton

That was Frank Gardner, and what's more you couldn't operate unless you worked for somebody who knew how to drive the telescope.

Sullivan

I think this has been a fundamental change in the science which took place in the mid ‘60s somewhere.

Bolton

We have evolved to this state, although people still can't get their observations done for them as they do at Green Bank.

Sullivan

Or Westerbork, of course, is the ultimate in this.

Bolton

Westerbork is the ultimate in this.

Sullivan

But don't you think this was inevitable? There are very few places where this is not the style of operation now, because of the extreme complexity of the instruments.

Bolton

You have to have the support. But still, the people who are capable of building their own equipment and their own telescope do a lot better.

Sullivan

It certainly is a plus for them, but it's not a necessary thing.

Bolton

No, it's not a necessary thing.

Sullivan

Well, is there anything else that you would like to comment on the overall history of radio astronomy up through the early ‘60s?

Bolton

I don't think so, really.

Sullivan

We really haven't commented specifically on the whole log N - log S business and what radio sources are telling us about cosmology. Let's just end with that. Starting with your attitude in the '50s, it seems like it was clear to you that these Cambridge sources were not real- what about the Mills survey? Did you feel like that was giving you more reliable...

Bolton

Yes, certainly more reliable because it was a synthesized pencil beam, which is one stage better than the confused interferometer stage.

Sullivan

But you're implying still not as good as a filled aperture?

Bolton

Oh, no. Nothing can beat the filled aperture. But I mean the whole log N - log S business is pretty well sorted out now, everybody is in agreement as to what the log N - log S does, it goes up very slightly steeper than -1.5 and comes down and eventually turns over, and depending on what frequency you're using, those effects are magnified or diminished to some extent.

Sullivan

But, of course, what has changed greatly is the general attitude toward its applicability to telling us something about the nature of the universe.

Bolton

Well, as far as the nature of the universe is concerned, it all depends on what you want to believe in. If you are looking for something that parallels the birth and death of a human being, then you're going to find the birth and death of the universe. But that's not necessarily so- it's very difficult to get away from this attitude.

Sullivan

In our western culture anyway.

Bolton

It’s the circumstances of one's environment. One lives in a bio-chemical, irreversible-process world, and so on the large-scale physics of the universe, it's hard not to inflict your personal life history on that of the universe but I don’t think that is necessarily the way. Fritz Zwicky used to say, "You must look at the universe for what it has to tell you, not for what you want to find, because you'll always find what you want."

Sullivan

Right, but of course, that's extremely difficult to do.

Bolton

Yes, it is difficult to do.

Sullivan

Sounds like you're a bit of an agnostic as far as cosmology goes.

Bolton

Yes, because one is constantly, forcibly struck by... When I grew up in astronomy, the universe was a quiescent universe in which all the energy in the universe was represented in the thermonuclear processes which took place in the inside of stars. Apart from certain cataclysmic events, 1010 years was the sort of time scale on which things changed. Now the universe has taken an awful beating since those days. Things change in milliseconds. And the energy in the universe is by no means confined to the thermonuclear processes in stars. I mean, physics is a reversible thing, not an irreversible thing. sure, in most cases radiation is down-graded, but then there are things like masers in which radiation is not being down-graded and I don't think that we're, by any means, at the end of these things. So I think it's very naive to look for births and deaths in the counts of radio sources. One of the curious things is that one doesn’t find as much "birth and death effect" in the objects which are very much more distant, the flat-spectrum quasars and so on show nothing like the steep log N - log S that the radio galaxies do. Now this is very peculiar, you see, because you’re looking back a lot further.

Sullivan

Yes.

Bolton

And I have a sort of vague integral theory, that all one has to do is just expand the universe and these things all happen naturally. I think the key to this is perhaps the relationship between interstellar and intergalactic densities, perhaps in the very early universe. I mean just taking something which is expanding, intergalactic densities were at one time on of the order of interstellar densities, and so the confinement of the radio source is almost assured.

Sullivan

Yes.

Bolton

Then as the universe expands, the galaxies don’t scale, but the intergalactic material does scale, so you're left with a changing ratio of interstellar to intergalactic densities. What this means is that you now come upon two classes of objects, one in which the interstellar densities are high enough to confine a radio source, and one in which the interstellar densities are not high enough to confine a radio source and once it is out in intergalactic space there is nothing to confine it. And out of this one can put quite a nice scenario that, say looking back to redshift of 3 or something like that, everything is in the form where the interstellar density and the intergalactic densities are of the same order, and one has confinement and only small-diameter sources. As we get down to redshift of .5 or something like that, one gets to the stage where elliptical and spiral galaxies are very different, and in the case of the spiral galaxy arm still has the interstellar density to confine the source. But in the elliptical galaxy, it’s gone down, and one produces the epoch of large-diameter, high-luminosity sources. The last three graduate students I’ve had, for example, even though I have the attitude it doesn’t necessarily say anything about the birth and death of the universe, they all ended up with the same thing. [Jet Merkelijn’s?] thesis, which was on the luminosity of high-redshift radio galaxies, simply says that if one interprets the redshift as cosmological, then some rather drastic evolution is required for radio galaxies. Jasper Wall on quasars came with the same thing. Now Ann Savage has come up with the same thing- even more so- on optical QSOs.

Sullivan

But there seems to be a little bit of a contradiction, because you at first made the philosophical point that the answer you get depends on the question you ask. And yet you were saying that in the past thirty years you were saying the universe has taken a real beating because of what's been observed - fast time changes, very energetic processes, and so forth. Are you then saying that these things have been observed because these are only the things that we've looked for? You see what I'm getting at?

Bolton

Well, theorizing is always based on the belief that we know everything.

Sullivan

I don’t follow that. You mean you know everything that's of importance for the problem at hand?

Bolton

Yes.

Sullivan

Something could be discovered tomorrow which...

Bolton

Yes. If one had some down-conversion process which affects the transmission of radiation, this would get rid of the strange paradox of the flat-spectrum sources not having a steep log N - log S. The only real relation to anything I can find is the spectral index of the object, the steeper the log N - log S curve. And that’s something which really nobody has explained. It may be just that spectral index is an indicator of angular size, brightness temperature, or this idea of the non-scaling intergalactic medium- that kind of explanation, but there may be some other explanation.

Sullivan

So in terms of pre-1960, I would think that you would say that this was not premature to be making cosmological implications based on source counts if you had some reasonably reliable source counts and this process is still going on today.

Bolton

Yes, it's perhaps unfortunate that the issue was clouded for so many years by inadequate experimental data which gave you very much exaggerated slopes.

Sullivan

But the principles were okay if the right data had been put in? Or some more adequate data?

Bolton

Not necessarily, no. No, as I said, a down-conversion process would operate just as well.

Sullivan

Okay.

Bolton

I mean we're going back to the assumption that we know everything... Why I brought up the changes in what we know about the universe is that it's quite clear, even with the progress we’ve made in the last thirty years, that we don't know everything, and there may be other factors. One is still up against quite a lot of difficulties I think, in the energy-generation processes for some of these objects on the assumption of any reasonable lifetime. You can say we can invent some new physics to explain the generation or invent some new physics to explain the energy generation or invent some new physics to explain the redshift. Nobody can think of the other ways of getting the redshift- that appears to be the most difficult, so we leave the energy generation to the unknown...

Sullivan

Okay, well, thank you very much. That ends the long interview with John Bolton on 15 March ’78 at Parkes.

Part 1 | Part 2 | Part 3 | Part 4


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