[Cover of Sullivan's book 2009, Cosmic Noise]
Sullivan's Cosmic Noise, Cambridge University Press, 2009


NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with Thomas Gold
At the AAS Meeting, Haverford, Pennsylvania
June 24, 1976
Interview Time: 1 hour, 28 minutes
Transcribed for Sullivan by Bonnie Jacobs

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 2

Sullivan

This is talking with Tom Gold at the AAS [American Astronomical Society] Meeting in Haverford on 24 June í76. Can you tell me when you first became aware of this new field of radio astronomy and so forth?

Gold

[Fred] Hoyle and [Hermann] Bondi and I had discussed possibilities in various areas of radio astronomy during the war when we were working together on radar. Of course, all three of us in the Theory Division at the Admiralty [Sullivan: Signal Establishment, Witley] were interested in astronomy and very much concerned with what would come of radio methods.

Sullivan

I didn't know that you were all in the same group in the radar lab.

Gold

Yes, that's right.

Sullivan

What sort of theory did you work on there?

Gold

Hoyle- radio propagation, ion reflection properties of various things, like airplanes and the rough sea, things like that.

Sullivan

Amazing.

Gold

That's where we got to know each other.

Sullivan

And you knew about [Karl] Jansky's and [Grote] Reber's work?

Gold

A little but it was only sort of - in those days it had not yet come to be regarded as a ground-breaking new field. It was just some strange effects that had been observed. I remember very clearly observing on a radar set that I was running, observing the interference caused by the Sun and thinking and discussing with my colleagues then how interesting it would be if I was only allowed to use that same instrument just for the solar studies.

Sullivan

This is after [James] Hey's discovery?

Gold

Yes. It was very obvious. This was a 10 cm radar set, I had no trouble at all observing, at disturbed times, the Sun.

[Interruption]

Sullivan

Now what was the nature of the discussions that you had?

Gold

We discussed what kind of instruments one would build and what one would do. And also we were very much concerned with what one could do in the solar system with radar. I remember then discussing that one would want to build a very large vertical, essentially vertical-looking dish.

Sullivan

A hole in the ground?

Gold

The hole in the ground idea was already then very much discussed. I discussed it for various purposes including radar to the Moon and the planets and we worked out approximately what it would take and it was clear you needed very large instruments. Receivers were not as good then as they are now so the calculations came somewhat bigger than they now turned out to be. But that was all discussed then.

Sullivan

Were there any British attempts right after the War to bounce off the Moon like the American...?

Gold

Unfortunately not. In fact, I pressed very much for that and I had written a paper, secret, of course, in those days, but now after that many years I'm sure I can safely say, I'd written a paper advising the Admiralty that they could make a secret communication channel to their distant ships at sea by bouncing off via the Moon.

Sullivan

The Moon surface, yes.

Gold

And so that if at high frequency they merely looked from a ship at the Moon it would not give away their position even if they transmitted and it was received back home. It was much harder to position-find on a beam directed upwards.

Sullivan

This would have required an incredibly higher gain though than...

Gold

Well, the dish they could have built back home at the Admiralty could have been a pretty big one. And then the satellite object does not have to be all that big.

Sullivan

Yes, that's true.

Gold

I had, however, not solved- when I wrote that paper I said that it would of course, it will mangle the speech by the different delay times because the big size of the Moon. And I had not appreciated, or couldn't, of course then, appreciate just how smooth the Moon's surface at longer wavelengths would be. And as it turns out now at 10 cm you can, in fact, communicate speech. And it doesn't mangle it too badly, it mangles it a bit but not too badly. So in fact it was better than I had claimed it would be.

Sullivan

Very interesting. You said you discussed, besides the radar, you discussed what one would do and what sort of instruments one would build for radio astronomy but can you tell me in a little more detail of what directions you were thinking at this time?

Gold

Essentially just thinking about the types of antennas that we built for radar purposes and how we would use larger versions of them for radio astronomy.

Sullivan

And what about from the astronomy side? What did it seem like would be most promising to investigate?

Gold

That we really didn't know. We knew the Sun would be interesting and we knew the [Sullivan: lunar] radar would be interesting. And then we had heard that there was some radiation from the Galaxy but I suppose that we then thought, most people then did, that there would be just some diffuse gas component in the Galaxy that would radiate a little and that would be the end of it. Because then we didn't really realize what a wealth of new information that was to come I don't remember that we really appreciated that.

Sullivan

Then what happened when the War ended?

Gold

Well, then the three of us all returned to Cambridge and we started to interest ourselves in cosmology. Although we were all three cognizant of radio methods we somehow did not manage to get anything organized. I was very keen to become a radio, whatever it was then, radio astronomer. But I had no real opportunity. I was too junior still to make my own arrangements and so I didn't succeed.

Sullivan

Why not get involved with [Martin] Ryle's fledgling group?

Gold

Because that was a little bit too much of an in-group already then. [John] Ratcliffe was running it in those days, and I had, to say the least, a rather poor relationship with Ratcliffe. Ratcliffe is a very stern man and a big organizer he was and from the beginning I didn't get on with him. Chiefly because I had firstly had a plan to leave the Admiralty and get to Cambridge on the basis that I was an expert in ultrasound devices having developed them for Doppler radar where I'd built mercury delay lines. And so I'd become quite knowledgeable in that. And I thought that would like to build an instrument which is now, now after 30 years or whatever it is, has now become, only just now, a most interesting thing, namely, a medical instrument to give a pictorial display of an ultrasonic reflection pattern. And I argued that we immediately look into somebody's inside and use it like X-rays, you see. And I also had argued that one could use it for looking through metal components for cracks and indeed it is very good for that, much better than X-rays, of course, because to find cracks with X-rays is difficult because they don't introduce any extra opacity, you see. Well, unless you look along the crack you don't find it with X-rays. With ultrasound, of course, they are completely opaque, the crack is just absolutely- so I wanted to build such a thing and had already raised the money and had agreement of the Cavendish that they would give me space and let me work there with my money that I had raised for the job from a government agency. And just before I was to take up this job there, Ratcliffe informed me that he had a recent look over the space problems at the Cavendish and he found there was no possible accommodation for me and so he had to turn me down, me and the money and this job. Had he not turned me down, I would claim that I would have produced exactly this instrument that we now have after this long time because that was exactly what was the program then.

Sullivan

Well, anyway, this sort of thing drove you to theory, I take it?

Gold

It didn't put me in the Ratcliffe camp, anyway.

Sullivan

That was the only game in town, really.

Gold

Yes, that's right. Well then we worked on various theoretical matters and then we had these sorts of colloquia meetings where the radio astronomers presented their story and frequently, as I think [David O.] Edge reports, there were minor sort of tussles between Hoyle and myself on the one side, and Ryle and some of his group on the other side.

Sullivan

Starting when?

Gold

Starting in '49.

Sullivan

When the first few radio sources were beginning to be found and identified?

Gold

Yes, that's right.

Sullivan

And how would you sort of summarize the nature of these tussles?

Gold

Well, the one outstanding one that I remember clearly is that Hoyle and I made at one evening meeting, I think in perfectly good taste, a suggestion of how one could sort out some particular puzzle that was left from a discussion that Ryle had given us. Ryle had told us he'd observed this, that and the other and we said what I thought was perfectly normal etiquette, we said, "Well, couldn't you observe so and so, then you would settle that question." And instead of saying, "Yes, that's a good suggestion," or, "Yes, we thought of that before and we will do it, or yes, we can't do it for one reason or another." Instead of saying that, he was absolutely annoyed and he said, "Well, you can go out and drag the cables all over the ground to do this work." It wasn't our business to drag the cables over the ground, but he was just annoyed that we should at all interfere to the extent even of making some suggestions which evidently were not erroneous suggestions, otherwise he would have tackled that, you see. He would have been able to say, "Well, no, that's no damn good." "No," he says, "You can go out and drag the cables over the ground to set it up." So there was a sort of air of annoyance anytime we opened our mouths. And it was always clear as every other observer of the scene was, of course described. It was always clear that the Ratcliffe organization was very closely organized system; they didn't like to talk to anybody outside about anything. A few of them did but did so very sort of sheepishly. Some of them would be quite friendly with me and talk to me but, I came fairly soon to be recognized as somebody who had a role to play, you see. And so whether somebody knew me or didn't was of some concern.

Sullivan

And so I guess you would say that - or would you - that the present reputation which the Cambridge group has in radio astronomy of secrecy and so forth grew directly out of the ionosphere group, Ratcliffe?

Gold

Yes. I mean, I suppose that Ryle went along with that in the first place and then augmented it later.

Sullivan

What was the scientific nature of these tussles primarily? Did you have basic agreements there, or was it only a matter of philosophy in any sort of suggestion you made?

Gold

I think the first major matters of disagreement were the two items that you know. One was the discussion in Ď51 or '52- when was the IAU [International Astronomical Union] in Rome?

Sullivan

'52.

Gold

Well, it was previous to that.

[Interruption]

Sullivan

So the í52 Rome Meeting.

Gold

Well before that, you see, was the meeting in London, [?] organized meeting at University College at which radio astronomy, what was then known, was discussed pretty thoroughly. And it was there that Ryle presented what he thought was the evidence of the sources observed, 50 about by then...

Sullivan

1C

Gold

That they were on a scale of stars and at distances like stars from us.

[Interruption]

Gold

That they were on stellar scale and that his evidence showed that very clearly. And then I got up and I said, "Well, I can't believe that that's what the evidence is because all that you can really say is their angular distribution around us and if that's reasonably isotropic, as it was then, then I can either believe that they're very close like you say, or that they're very far so theyíre outside the Galaxy."

Sullivan

But Ryle must have considered that they might be very far, too and not liked it because of too much power required...?

Gold

That's right. And he said, "Oh, but the power requirements are absolutely outrageous," and my reply to that was, "Well, we know of some galaxies that are very different from our own that had greatly broadened emission lines," that was stated then.

Sullivan

The Seyferts?

Gold

Well, what were they were...

Sullivan

Seyfertís paper was during the War in '42.

Gold

Well, that could be but I...

Sullivan

They weren't called that, anyway.

Gold

No, no. But in any case, I said, there existed galaxies with greatly broadened emission lines suggesting that enormously violent activity went on in them and I was not one to say that they could not be producing that much more power than ordinary galaxies. And in any case, I said, "You'd have to have more power for the star story, you would have to have a certain factor in power up on a star, for the Galaxy story you have to have a certain power up in the Galaxy and I canít tell which one of those two is more likely than the other." And then Ryle replied to that, he said, "The theoreticians have misunderstood the nature of the evidence," and so on. He was absolutely adamant that he had proved that they were not extragalactic. I merely insisted that both were possibilities and that really there is some evidence for thinking that very different galaxies occur. You'd better look at that because that I think was the sort of best discussion.

Sullivan

Is there a proceedings of this meeting somewhere? I've never seen that.

Gold

Yes.

Sullivan

Do you know where?

Gold

As I say Edge reports substantial parts of it.

Sullivan

So it's a separate volume?

Gold

If you have Edge's book you'll find a lot of it reported there.

Sullivan

Ok.

Gold

But it was not printed, it was duplicated. And I have one of the duplicated copies of it.

Sullivan

How many pages is it?

Gold

Oh, it's quite thick.

Sullivan

Well, I might like to get a Xerox copy myself. It sounds like it could be pretty valuable because it summarizes the state of the field at that time.

Gold

If you want just the radio astronomy parts Xeroxed, that's not so much. There was also a lot of geophysics and so on in the same meeting.

Sullivan

Oh, I see.

Gold

If you didn't want that, then the radio astronomy would maybe be a matter of say 60 pages or so.

Sullivan

That's quite reasonable, yes.

Gold

Well, then I'll tell you the story which is a sort of pretty personal matter. Because we had this so very definite fight at that meeting, that the sources could be extragalactic, it seems that because of that Ryle was particularly upset. When in Rome, [Walter] Baade waved me over as soon as he saw me in the antechamber to the meeting when I'd just arrived. He waved me over and said, "Look, Tommy, you'll be delighted, we have here the picture of the Cygnus colliding galaxies," as they were called then. Then he showed me the picture. "Thereís no question," he said, "That we've identified that that is what the radio source is, and there's no question that they're extragalactic, you will be delighted to know." Because he'd known that I'd favored that point of view. So I looked at the pictures and I was delighted. A moment later Ryle appears in the distance and Baade shouts over, "Hey, Martin, come over here, have a look at this." So Ryle comes over and is shown the picture, is given the same story, of course, from Baade, and I stand right by the side still and I didn't make any very biting comment but I said something like, "Well, it seems that they could be extragalactic," you know, just some slight reminder of what was said a few months before. So I said, "Well, it seems they could be extragalactic," or something like that. Would you believe it, Ryle collapsed on the bench, on the settee in the room, buried his head in his hands and sobbed.

Sullivan

Incredible. Was this the first time he'd found out about this? Wasn't there correspondence between Baade and [Francis Graham] Smith?

Gold

This was the first time that he was forced to believe the evidence. Up till then he'd believed that it was a misidentification.

Sullivan

I see.

Gold

This was the first time he really had to believe the evidence.

Sullivan

So he apparently had gotten so wound up with this interpretation you're saying?

Gold

That it was such a matter - I mean, he's a terribly emotional person. It was such a deep concern to him that they really were extragalactic and that he was wrong and that I was right. Because he had remembered the conversation and the fact that he'd been so biting before, saying that, "You've misunderstood the nature of the evidence."

Sullivan

But then it's rather interesting in things like the Bakerian Lecture in '58 that Ryle becomes the chief proponent to show that they must be extragalactic.

Gold

Not only extragalactic but much further than...

Sullivan

Cosmological essentially.

Gold

Absolutely, yes. He was always on the side of passionately wanting his objects to be most dramatic. And in the first place he thought if they were star-like things he would have discovered that there was a whole new world as dense as stars of new things. And nothing interested him more than that the occasional galaxy should be of a funny kind. But then having to have it that it was galaxies, then he preferred to think they were extremely far and therefore were the most valuable cosmological tool. And then, of course, his only case that they were far was that the gradient was not three-halfs. With a gradient of three-halfs, well then you wouldn't know what distance they were. Incidentally, at that same meeting I also said that as an argument in that I thought argued against it being star-like objects, I said that if they were star-like objects then I would imagine it most probable that they would be collapsed stars, just because the high density allows strong magnetic fields to exist and allows the fields to extend into gasses of lower density. And that I said was a particularly favorable circumstance for radio emission. I said all that, it's all in the book.

Sullivan

This was before the synchrotron mechanism.

Gold

Yes, yes. And I said that was a particularly favorable mechanism for radio emission, I would imagine that it's those stars that you will be seeing if they were stars. But in that case, I said, I will be very surprised to find them steady and not fluctuating with time constants appropriate to such small objects. So this really is absolutely a prescription for the pulsars except that I did not see the regularity of them.

Sullivan

Incredible. But now what were you thinking of for the emission mechanism? Something like solar flares? No, they were steady though.

Gold

No, no, flares were bursts. But what I had in mind was that you needed big gradients of electron density and you needed big accelerations of electrons to make radiation. And without understanding in detail how you jiggle the electrons, I knew that a vacuum tube will produce radiation in radio bands if you have a lot of electrons that suffer a high acceleration and if there is a large gradient of electron density because if there's a tenuous electron gas extending out from there, then the radiation doesn't get out. So that much I understood and that was my picture, well, the nearest tube to the vacuum tube that makes radio waves that I could think of was from a very strong field that has electrons in it and then I would have imagined the...

Sullivan

It's a shame you didn't really publish in this game at this time, I mean, in terms of interpretation, because these sort of thoughts were not being thought very much at this time, in print, anyway.

Gold

Yes, yes. That's right. Well, as I say it is at least in those documents, so it's all there. And then I also commented at the same meeting on the galactic radiation that Ryle wanted to attribute to the same stellar sources unresolved, the summation of them in the Galaxy unresolved. And I argued against that point by saying I could perfectly well imagine that as a small by-product, and energetically I said it would be only a small by-product of the cosmic rays that there would be, if there was any mechanism for converting a tiny fraction of the cosmic energy into radio waves, that that would account for it.

Sullivan

Yes, I remember that comment, that's in one of the Observatory things, I think.

Gold

And that, of course, is also correct.

Sullivan

You didn't explicitly say if there was an electron component?

Gold

No. Because I did not really know. I was not really clear about the mechanism. Before synchrotron one didn't really understand how one was going to make it anyway. But I just thought that if the cosmic rays in going through a plasma will make it a little noisier in some way.

Sullivan

There's a lot of energy there, yes.

Gold

A tiny fraction of the energy converted in that plasma in some way into radio waves so they could be sufficient I said, "So therefore with that discrepancy in the energy I didn't really think it was necessary to invent another."

Sullivan

Going back even before logN- logS, there had always been the galaxy count business and controversies with how well you could do that. But when the radio sources came along they turned out to be isotropic and at least you were thinking they might well be extragalactic. Did you think that this might be a good test?

Gold

Oh, yes. Of course, we'd thought a great deal about the galaxy counts and it was quite clear that there would be some. We perhaps were not as clear about the fact that even if one had no idea of the individual nature of the objects that those statistics- many could still be used. I think that I have to say that I did not think of that first myself. It was immediately clear to me when it was pointed out, but I don't think that I thought of that. And that that would be the way around, we would go for the radio sources, I don't think - I don't know, but in any case, it was certainly immediately clear but it was also immediately clear as I think I mentioned to you earlier that if a moment I thought about it then, that if any errors were made that they would tend to steepen the curve.

Sullivan

Could you just say that again?

Gold

Yes. That it was clear that if a uniform background in uniform in depth gives you the three-halfs law that if you make no error for the strong sources but make progressively more and more error for the weak sources then even if each error that you make is an equal probability of going to the weaker, going to the stronger when you measure the intensity of a source it will mean that you will always transport more sources from a weak category to a strong one because there are more in a weak category than vice versa. And so it means automatically that you will shift the upper part of the curve where you make errors, you will shift that over to the right, the lower part you have not shifted and so therefore when you draw a line through you're going to have a steeper line. That we were clear about and in fact, I remember visiting on one of the sort of slightly charged visits that I paid to Ryle's group in the Cavendish. I remember sitting in the Cavendish with Ryle and some of his people around to discuss this and I said something like, "Well, how accurately can you measure the radio sources? Can you give me some estimate of the amount of error that you are likely to make depending on the intensity," with this very point in mind, which I'd understood but I'd not discussed with them yet, you see. And so Ryle's first reply to that was an absolutely ridiculous one of saying, "Oh, well, the errors donít matter. Don't you understand that the statistics don't depend on the errors?" So I said, "You mean to say the errors don't matter? Why bother to have a radio telescope at all? You can just suck them out of your thumb those figures of yours. What are you doing if not measuring the intensities?" So then he had to think again, and only then did it become clear that what in the statistics did not matter to him was the identification of the distance to any particular source.

Sullivan

Right. The intrinsic luminosity distribution didn't...

Gold

The intrinsic luminosity distribution didn't affect the matter. But the measurements of it, of course, did. If you make an error in the measurement then it does affect it otherwise obviously you wouldn't need to measure.

Sullivan

And you say your recollection is that this was published.

Gold

My recollection is that this was published.

Sullivan

But I don't remember it and you can't remember where. Who were the authors again?

Gold

[Dennis W.] Sciami, Bondi and myself, I think.

Sullivan

Ok, I'll have to check that.

Gold

I'm absolutely certain that we worked on this and I have a recollection of a brief note being published but Iíll check on it once more. This is an item that previously I would keep but only in recent years Iíve completed a bibliography and every now and again I find some item of earlier years thatís been forgotten and this was one of them that I sort of penciled in and said, "Well, we must identify that one."

Sullivan

Now while the 2C survey was going on, were both Ryle and you and Hoyle thinking all the time this was going to be a nice test or was it sort of an afterthought that you can do some powerful cosmology with this? In other words was it a driving thing for the 2C or was it only what was more or less beginning to be completed?

Gold

Well, I think that what we said then was we didn't believe the error situation of the Ryle story. We'd considered that it would be a valuable test specifically and in some writings that he's in, specifically because of the steady-state Universe giving you a precise prescription. While in other cosmological theories you would not have a prescription what you ought to be seeing. You always wiggle out on grounds of evolution of how a galaxy evolves to make radio noise, we haven't a clue. And so we said specifically the steady state is an important cosmological model for tests of that nature. And I still think to this day that that's the right attitude to take.

Sullivan

Very well defined as to its prediction in this case.

Gold

Yes.

Sullivan

And so was it a matter then that you were eagerly awaiting to see what the result of this was going to be?

Gold

Except after the very first announcement from Ryleís group [Sullivan: 1955], where the gradient of over three, which was immediately coupled to this being a final disproof of the steady-state theory, we were very suspicious of the veracity of this and evidently correctly so. As I say, having after that a meeting with him and finding out he didn't even know...

Sullivan

This meeting was after this big brouhaha?

Gold

Yes. Oh, yes, that was absolutely in the usual fashion of the Cambridge group that that press announcement was the first thing we heard.

Sullivan

You knew there was a large survey going on? You didn't even know that...

Gold

Not much, no. And that was the first thing. So after that, as I say, when I then met with him and I found that he didn't even understand that you really had to measure to a good accuracy- that put me on the side of then saying well, I don't trust the data at all. If somebody produces this big noise without even having realized what the accuracy has to be before the thing works, I wasn't too impressed. And so I told Hoyle that, and I said, "You needn't believe any of that stuff, you see." But Hoyle is always much more cautious than I in that way and always said, "Oh, no, you..." He didn't like Ryle but he always felt, "Oh, but you must listen to the observers. If you don't listen to the observers you're lost." And I said, "Well, I listen to them but they have to be right." But Hoyle was much more concerned that these data were correct and that he had to invent new cosmologies to fit those data. And I just brushed them off and said, "Well, I don't believe they're right."

Sullivan

So you didn't worry about finding other things, problems?

Gold

No. And whatever the state of affairs is now it is quite clear that the gradient of three was absolute bunk, wasn't it? Because the gradient, as it now turns out, is 1.8; well, it's significant, maybe but that's another story.

Sullivan

Yeah, it's not three.

Gold

It's not three and the difference between 3 and 1.5 is nearly the same as difference between three and 1.8. So there's no use saying now, "Oh well, you see, it was indeed a steeper gradient." If it is, I'm still not sure but there's no use saying now....

Sullivan

But are you saying then there were no other major objections that you brought to the 2C survey results other than this one of the errors you mentioned? Before [Bernard Y.] Mills' results, of course, that changed the scene. But before then?

Gold

Before then we just discussed that the errors would be making it steeper and that you didn't know about that correctly. And then that [Peter A. G.] Scheuer discussion which we didn't really understand, that you didn't need to- I don't know, didn't need anything- and that must have been wrong too, because obviously that seemed to agree with the count and then the count is now known to have been wrong. So I don't know what was wrong.

Sullivan

This is very confusing. I haven't been through it all in detail. I think the p of d is basically correct but its application to...

Gold

Well, I tell you there must have been something wrong because at the time we were told, "Oh, well, if you do it the Scheuer way you get the same answer." And now we know that that answer, if it was a gradient of three, was wrong. So there must have been something wrong with that too. That's all I know.

Sullivan

So, was the next major development when indeed the results from Australia came in and what happened then? How did you get wind of those results, first of all?

Gold

Yes. That goes a little deeper in my memory than I can remember. I don't really know.

Sullivan

I'm wondering was there something before a preprint? Some meeting or something?

Gold

No, I don't think I had any particularly close contact in those days with the Australians. I suppose I remember the '58 Paris meeting where there was a straight head-on clash between Mills and Ryle.

Sullivan

Right, but that was a year or two after the [?].

Gold

Yes, but I don't really remember the earlier phases.

Sullivan

But what happened when the word did get to England about this Mills survey, the first part of it anyway?

Gold

Well, the obvious thing is that we just thought, well that's going in the right direction and it shows we can't trust the Ryle survey.

Sullivan

And were you willing to trust the Millsí simply because it gave the result you wanted to see?

Gold

No, but I still insisted that the errors would always tend to steepen the curve and so therefore anybody getting a flatter curve was more likely to be free of errors, that's all.

Sullivan

Well, maybe you could tell me about this Paris Symposium. There's a couple of papers and some discussion that are recorded.

Gold

My main recollection of my own position at the Paris Symposium was not in relation to the Mills/Ryle story, because I was perfectly willing to let these characters fight that without my intervening in any way. Although I listened carefully to it, but that's all. But I remember then standing up to the viewpoint that the 21 cm observations did not reflect the gaseous mass from the Galaxy because it was more likely to be in molecular form.

Sullivan

I see.

Gold

And the only other person who was supporting this point of view at this Symposium was Bart Bok. He remembers the story very well, he says it to me every time. And now it has taken these many years until last year, from '58, almost 20 years, before that has now been shown to be by true, because by now I think we're pretty clear about the fact that the bulk of the hydrogen is in molecular form. And that the 21 cm maps therefore refer to just those regions presumably where the densities are not high enough to make molecules.

Sullivan

And the people, it was [Jan Hendrik] Oort, I suppose, the Dutch were saying that this was the gaseous component?

Gold

Yes. In those years, it was every time that the 21 cm people discussed the gas in the Galaxy I would always say, the gas that happens to be left in atomic form and I'd sit down again. Every time I would do that.

Sullivan

Were you thinking that this other gas might or might not show these features which were called spiral arms?

Gold

Well, I thought it would be in some patterns of this kind too, but I wasn't sure that they would be the same patterns.

Sullivan

Right, it was just really a caveat that you were getting out everything.

Gold

Yes. That's right. I didn't want to have it said that we've demonstrated where the spiral arms are in the Galaxy from the 21 cm data. It was not true.

Sullivan

When did you actually leave England and go to Harvard, I guess?

Gold

In '56 or '57. '57.

Sullivan

And what was your job?

Gold

And then I was at Harvard at the Harvard College Observatory as a Professor. And one of my duties was to run the radio astronomy there, which in those days just had that 60 foot dish.

Sullivan

That was taking over from Bok? When he was going to Australia?

Gold

Yes. And [T. Kochu] Menon was the sort of young man there. And there I organized that it was equipped with a maser and I got Cooper from Australia, Brian Cooper, and John Jelley from England. I got an NSF grant and within a year we had a brilliantly working maser at the focus on the telescope.

Sullivan

You were mainly running this show, not really directly involved yourself, in terms of dirty work, anyway?

Gold

Not in terms of dirty work but, you know, we had our weekly meetings and program and so on organized.

Sullivan

Were you enthusiastic about this hydrogen line as a way to...?

Gold

Oh, yes.

Sullivan

What did you think were its main...?

Gold

In fact, when I left Harvard in '59 to go to Cornell the then Director of the Observatory, Donald Menzel, wrote me a very complimentary letter about the direction of the radio astronomy project and the construction of the maser and what a marvelous thing it was and how they were all pleased and proud of it and so on.

Sullivan

What did you see as the main things that could be done with the hydrogen line? Apparently at Harvard there was not great surveys done like in Australia and Holland. There were more areas of star formation and so forth. Was this under your influence somewhat?

Gold

Well, it certainly was a little under my influence in that I didn't feel that we were well set up for contributing with any organized survey work. We had, you know, just the odd graduate student who could spend a few hours out there and very little staff, no great organization. Not like CSIRO or somebody. And so I didn't want to steer into anything other than an individual studentís program that he could do in a year and write a paper on it, that's all.

Sullivan

I should ask you why you came to the United States? You're an Englishman?

Gold

Yes. I came to the United States from a job as Chief Assistant at the Royal Observatory. I'd left Cambridge in '53 to become Chief Assistant at the Royal Observatory when Spencer Jones was the Astronomer Royal and so I was the next one in charge, the next person down. And that suited me quite well and I liked it. And then in '56 Spencer Jones had to retire and they appointed [Richard] Woolley, and as soon as he appeared on the scene he was so opposed to every area of work that was other than classical optical astronomy that you wouldn't believe it. I had just built what was called a neutron monitor, a solar cosmic ray measuring gadget and there was the great flare in February of '56 for which we had one of the best records. And I regarded it very appropriate for the Royal Observatory to have long term cosmic ray records. Because like other things there ought to be long term records in existence and this was the place to keep long term records. This was exactly what the Royal Observatory was doing.

Sullivan

If you didn't do it, then no one would.

Gold

Yes. So exactly the thing. So we set up very excellent equipment, the best in the world, built a little building for it and everything. And Woolley appeared on the scene, "Cosmic rays," he said, "That's not astronomy! Get rid of it," in those words. In those words, not in any softer way. They had built this stuff for two years and in that case, yes, indeed, with my own hands, built it and absolutely marvelous equipment it was...

Part 2

Modified on Wednesday, 17-Dec-2014 16:28:16 EST by Ellen Bouton, Archivist (Questions or feedback)