Interview with Fred Hoyle on 23 April 1981

Sullivan: 00:00

Okay, okay. Because of that problem [ed. 2024 note: very poor audio quality of original recording, tapes 135B, 136A&B], I'm now going to listen to the entire interview and transcribe it orally with both my questions and Hoyle's answers best I can do while it's still fresh in my mind. This is now 27 April 1981, four days later. Okay.

The interview is on 23rd April 1981, from Cambridge, over the telephone, to his home in Cumbria.

Me: what was your training before the war, and when did you first come into contact with radio astronomy? Him: my training was in the mathematical tripos at Cambridge. Graduate training was in quantum physics under Paul Dirac before the war. During the war, I worked on radar. And the simplest way to put what I worked on was that I, with several others, including Thomas Gold and Hermann Bondi, was responsible for the software for airborne radar. Software is the modern term. But what we were involved in is, what could you do to improve the performance of the airborne radar sets? Amongst other things, we improved the reliability of the radar sets. Especially, we were working for the Admiralty and ships that are away for many months. This is a much more important factor than an aircraft, which come back very quickly, so to speak, and things can be fixed. This was at the Admiralty Research Establishment. Now, as it happened, I was involved with a bit of research with a fellow called Pryce, P-R-Y-C-E. I believe I got that right. In this research, we explained, I believe, for the first time, the anomalous propagation of radio waves at high frequencies. The propagation due to effects of water vapor, what is now called tropospheric scatter and waveguide problems, and so forth, they worked on in 1942 and '43, or we worked on. We also worked on the problem of the window effect of tin foil strips to give false radar echoes. And Tommy Gold was the head of that. Now, because I was involved in these kinds of problems to do with propagation and design of radar equipment, I was one of two Admiralty members on an interservice committee called-- the committee was called the Radio Propagation Committee and was chaired by Appleton. One of the army members of this committee was J.S. Hey. And therefore, you can say that, following on the work of Jansky and Reber, that I was one of the very first ones to hear about the discoveries of Hey during the war. He would tell us what he had been finding at our meetings. Now, Hoyle doesn't particularly remember the solar discovery. But he does remember the discovery of what came to be known as Cygnus A. And he thought it was during the war. But it must have been right at the end of the war. In any case, he heard about it. This committee existed in the immediate post-war period also.

So I asked him what was his reaction to this. His answer was that he couldn't believe in the hot gas theory for either the general galactic background or for the question of discrete sources as they became known. But on the other hand, he didn't know what to do with it, know what to think. But the hot gas, the bremsstrahlung just didn't seem right. So that's the answer to your first question about how I first came into contact with radio astronomy. I have often wondered what would have happened if Gold and I had gone into collaboration with Hey. It never occurred to us really to do anything like this. The strange thing which must have contributed to the personality troubles which came up in later years was that the army people got a shot at radio astronomy through Lovell. Air Force people got a shot at it through Ryle, but those who were the corresponding people in the Admiralty didn't have the corresponding support either at the Cavendish, Cambridge University, or at Manchester. There's no powerful patron that we could appeal to.

So I asked him, "Are you saying then that this was a source of the later difficulties?" And he says, "Yes, I'm sure it was." And here I'm assuming that he's referring to the Gold versus Ryle business. So I asked him, "But there weren't any people that are oriented towards observing in the Admiralty group, were there?"

Sullivan: 05:14

He said, "Oh, yes, there were several people. There was a fellow called Moxon."

Sullivan: 05:18

To which I replied that, "Oh, yes, I know about the short paper that he published in Nature in, just after the war." And then he says, "But the strange thing is that we already had the design for a spherical dish dug out of the ground and that's what we really wanted to get." So I asked him, "Was there a design study done for that kind of thing?" And he said, "Oh, yes, in those days we did that, a lot of things like that. And there was a fellow called Otto Böhm, B-Ö-H-M. Böhm was of the older generation but was perhaps the finest antenna engineer that we had in the group. We worked under him and so we knew what we wanted to do. But of course, my trouble was that I was not single-minded about it. I had scores of other interests as well. And possibly if I complain, my complaint is false because if I had been single-minded then we might well have done something. I think it's fair to say that in 1945 I did not see how far radio astronomy was going to go. On the other hand, I don't think that anybody really did at that time. Ryle and Lovell went that way because that was the one avenue that was open to them." So I asked, "Was this spherical dish being specifically thought about for radio astronomy?"

Sullivan: 06:44

And he says, "Oh, yes, it was being thought about for radio astronomy. It was just a question of digging out the ground and building the mast and so forth." So I asked him, "Was it possibly from this study that Hanbury Brown got the idea for the hole in the ground fixed dish which he built at Jodrell Bank around 1950 or so?" And Hoyle answered, no, not that he noticed of. Although possibly Gold said something to Lovell at some time. Perhaps tangentially I should say this is something that I should probably ask Hanbury Brown and/or Lovell about. I asked him if there was possibly any documentary evidence about this idea of a spherical dish towards the end of the war, and Hoyle answered, "No, I don't think so." He said, "We just didn't write up things as much as we should have in those days. We never published our whole study of the window problem, for instance, either. When I look back at the whole war time dissemination of information problem, it really was not anywhere near as good as it should have been. We used to work on things in the office and they would get kicked around and they would never get outside. In general often things just didn't get to other labs and other services. There were attempts made by the government to set up inner service channels and so forth. And Appleton [inaudible] key person in coordinating and clearing this kind of information. And then I asked him if he could confirm the date of this study that they did at the Admiralty Establishment. And he said to the best of his memory it was 1945.

So now coming to the-- I asked him, "Coming to the end of the war and the immediate post-war period when radio astronomy was beginning to have many interesting results on the galactic background and in particular solar radio astronomy you were not actually part of astronomy at Cambridge, were you?" And he answered, "No, I was in the Applied Mathematics Department." He said, "You have to realize that the Cambridge tradition was that all theoretical astronomy was done in the Applied Mathematics Department and not in the observatory at all." So then I reminded him that his first publications relative to radio astronomy were in observatory minutes of RAS meetings in which he was talking about the causes of solar bursts and so forth. And this led up to his 1949 books on recent researches in solar physics in which the last short chapter was on radio emission mechanisms from the sun. And then I asked, "Now, what is your view of radio astronomy during these post-war years? Did it fundamentally change our knowledge of the sun, our outlook of the sun? Or was it just a matter of a new technique which could find things out and be useful but was not really a fundamental change?" And Hoyle's answer, which really didn't answer my question, was that I would say looking back at those years that it was very heavily weighted towards the sun. In retrospect, it's absurd that we spent so much time at that time trying to understand what has turned out to be extremely difficult problems. We should have paid more attention to following on the discoveries of Jansky to do with a galactic background and so forth. I was thinking about these kind of things quite a bit. But then I made the terrible mistake in 1948 of following upon the publication by Schwinger-- the publication by Schwinger on synchrotron radiation. We had a fellow in the Cavendish Lab who I believe may now be at Southampton University named Hutchinson. [Well?], Hutchinson really got on people's nerves about this whole idea of applying Schwinger's theory to the galactic background. And he had a theory about all this but to some extent was one of those situations where a chap has come upon an idea and has developed it to some extent and one doesn't feel like one can really work on that same idea, that it is sort of his domain. See, I was senior to him which made it even more difficult. And the fact that he went around talking with everyone about this idea. And in those days things were not as brutal as they are today where there'd be no problem at all in jumping on someone else's idea and publishing it. And so I did not feel that I should work on this problem even though I undoubtedly could have developed it a good bit further than what he was doing. So I made the terrible mistake of not appreciating this, developing it or thinking about it as carefully as I should have done. Then I pointed out that I thought that Hutchinson's publication on synchrotron radiation was in 1952, and Hoyle countered by saying, "But he was already talking about it in 1948." He was a research student at the time of the Cavendish and-- then Hoyle says that he thought that what Hutchinson had done was quite interesting. He felt that it was his territory and that I shouldn't work in it. By 1949 or 50, I wasn't thinking about it at all. And he says, "You know the way it is that once something has gotten out of your mind for whatever reason, then there's sort of a psychological barrier and it's very hard to get back in the groove working on it, so to speak." So I asked, "Do you happen to remember why in the late '40s that Hutchinson didn't publish a short note in Nature or something like that?" And Hoyle said, "Oh, everybody was on his back." They were trying to get him to publish, but he never did. Parenthetically I might add here that I guess I really still don't understand why he didn't publish. I'm not sure even if he got his PhD at the Cavendish. That would be worth checking. But I mean, he says, "Also you have to realize that there was a huge bandwagon at that time that everyone was getting on, that the mechanism of the emissions was plasma oscillations. Oscillations not just for the sun, but for everything." And then Hoyle says that the international bandwagon for plasma oscillations was really strong.

Sullivan: 13:44

And to illustrate this, he was at the January 1954 conference on radio astronomy in Washington DC. And he was the only person there that was not in favor of plasma oscillations for the cause of the radio emission. Of course, I might add here that this is getting a little bit later than the era that he was originally talking about, which was the same error as Hutchinson in the late '40s. But he was the only one that said that plasma oscillations were wrong and the correct explanation was synchrotron radiation. So then Hoyle says that he remembers that the paper by Alfvén and Herlofson was pointed out to him. He didn't give the date, the 1950 paper, and he went back and looked at it. But when he looked up that paper, he found that it really wasn't a cosmic thing at all, it was to do with the radio stars. But then I reminded Hoyle that there was the paper in Phys. Rev. 1950 by Kiepenheuer in which he was the first to apply in print the synchrotron radiation theory to the galactic background, and Hoyle apparently did not remember that and said, "Oh yeah, so Kiepenheuer got everything right."

Sullivan: 14:56

When you look back at it now, you can pick out those things. But when you lived through it, that was just a drop in the ocean. People paid no attention whatsoever to those papers. It was all plasma. Then Hoyle says that the conference in Washington in 1954, he thinks was the first time that somebody stood up in the West in front of all the astronomers and said, "This is the correct answer, not that this might be correct." I asked him, "When was the first time that you remember becoming knowledgeable about the Soviet publications?" And he said, "About six months after, my letter to Nature." He's referring to the Nature paper in 1954, my reference number seven. And he says that he was preparing for a Verdun stand against the astronomers because he was convinced that synchrotron was correct. So I asked him, "What was what made you so convinced?" He's said, "Well, the thing was that I've been stumbling around from 1949 to 1953." He was stumbling around over the technical problem which almost seems a bit ridiculous now to spend so much time on it, but the problem of the conductivity of a plasma, and he spent a lot of time on working on how to mathematically work with that problem. And then it was in the late autumn of 1953 that he finally convinced himself that he had that problem solved. He says it sounds ridiculous but it was sort of a mental block. And once I'd gotten that problem solved then I was able to think with a proper mental perspective. You can distinctly remember that the time when all of this sort of clicked in his mind was at the end of 1953 at the Robinson building at Caltech where he was spending a short time. I asked him [inaudible] on the basis of the observations of that time what was it that convinced you that this was a much more satisfying explanation. Well, basically it was that one could avoid all the plasma trapping problems. And also, he says, "I think you'll find a letter to Nature sometime after the one in 1954 in which I argued." He argued that you could apply the [Fermi?] ideas of acceleration cosmic rays also to electrons and thereby get the synchrotron radiation. He said that when you work with plasma oscillations one always has the problem that the very modes that generate the radio waves also tend to trap them. That was where everybody was stumbling. How you ever got the radio waves out.

Sullivan: 17:39

So I asked them what about the similar problem with synchrotron where the very short lifetimes meant that you'd have to keep on generating these electrons? No problem. Because I had the notion that these things were being continually accelerated by the violent motions of the filaments and so forth. Those filaments would be the kind of things in discrete sources, and I asked them what about the galactic background. He said well, that was just the integrative effect of a great number of discrete sources. He said I was convinced at that time that things like the Cygnus loop were connected to supernovae and so forth. So I said, "Well, this brings us now to the point of the relationship between the galactic background and the discrete sources," which of course was quite a point of argument. And I also said I do know about the conference at University College London in 1951 in which there's this famous exchange and Hoyle then said, "If you were there you would have laughed." I'm referring to reference 4.5 on my card. So I said, "Why do you say that?" And he said, "Well, you would be amazed at the absolute blank wall," I believe it is. He said of the whole audience who just wouldn't believe it, the whole audience reacting to the, saying that this is just a crazy idea.

Sullivan: 19:15

He said, "You just wouldn't believe the attitudes." Alfvén actually stood up at the end of the conference and said that if one had taken everything that gold and I, meaning Hoyle, had said, and if you changed all the minus signs to plus signs and the plus signs to minus signs, then you might have something that would be close to correct. I recall setting out from London and we were driving in Gold's car and on the way out, back we were stopped at an all-night cafe near [Baldock?]. I can remember we discussed the conference and we were just absolutely appalled at the attitudes. So I asked, "This is on the issue of the distance of the radio stars that you're speaking?" and he answered, "Of course, the whole question of the extragalactic nature or not was a major part of what we were talking about." So I asked, "Were there other issues also on which there were great disagreements?" And he said, "Well, I'm sure that if you took a vote there were probably maybe something like 50 people there, and it would be 48 to 2 in any kind of vote." So I asked, "Was this the only issue that there was a great disagreement on, or were there several others?" And he said, "No, it was mainly that," and he said, "Well, my own contribution there was largely to do with the problem which we were just talking about, namely, the question of the connectivity in a plasma." And I said, "Well, in fact, it looks like from the record we have now that Gold was the one that gave the paper and your remarks were in support of him," and Hoyle agreed, saying that, yes, Gold gave the paper. And so then I asked him, "Would you say that it's fair to say that your attitude that time was not that they were definitely extra galactic, but that one just didn't know?" He said, "Yes, that's right, and I think that was Gold's attitude too.” And I asked, "Well, now, in your mind, from an observational point of view, what was it going to require to settle this issue? Some optical identifications?" He said, "Yes, that's right, and I think we made the point that what was required was that there was going to have to be something that would give a thousand times the power of our galaxy in the radio.”

Sullivan: 21:37

And then Hoyle said, "But then, of course, we got that source when Cygnus A was announced at the Rome IAU meeting in 1952. And then I explained about the plates being taken actually in the fall of '51 as a result of Smith's letter to Baade, and so forth and so it must have been known to some people before the Rome conference about the identification of Cygnus A. And then Hoyle is saying, "So are you telling me now that there were people that knew about this before the Rome conference?" And he said, "But of course, I didn't know Baade at that time and in fact, it wasn't until I got to know him at the Rome conference." And then Hoyle said, "Well, this is hard to believe that people knew about this identification before, because I remember Ryle being absolutely shattered at the Rome Conference." And then I said, "Well, you're right. I've heard that story before." And Hoyle then said, "Well, his emotional reaction would hardly have been that intense if he had known about this Cygnus A identification many months before." So then I said, "Well, it must have been that the actual identification of the nebula was made in the fall, but it was not until later that the red shift was determined and so forth," and indeed, Ryle didn't find out about it until the Rome conference.

Sullivan: 22:59

So at that 1952 Rome conference, what is your memory of the discussion on radio sources and so forth? And Hoyle said, "Well, my memory is--" well, of course, we had another thing at the Rome conference and that was the revision of the distance scale by Baade. And the distance scale thing tended to be the major point of discussion. And there was also, again, another thing, a confrontation with the Russians over stellar evolution. And so from Hoyle's point of view, the Cygnus A thing was really the third thing on the list. So I asked, "Did the resulting change in the Hubble time from Baade's new distance scale change at all the motivation in your mind for the necessity of the steady state theory?" And he said, "No, no. That never did. You know I've often been falsely quoted that the Hubble ages have affected me and the development of the theory, but I've never believed in those ages." He says ages can change quite a bit. So I said, "So you're also saying that in your mind that was, also, not even a strong motivation for the original development of the theory?" And he said, "No, it was not."

Sullivan: 24:21

So then I went back to the question I asked a long time ago, which he didn't answer, namely, did he feel that solar radio astronomy in the late '40s fundamentally changed our view of the sun to do with solar bursts and the hot corona and so forth, or was it just a new technique which was useful but not fundamentally changing the astrophysics? And I can't really hear his answer to that question, but my memory says that he didn't think that radio astronomy really fundamentally changed the view of things. Then I specifically asked him, "Do you think that the hot corona was much more firmly established by the radio evidence?" He said, "Oh, no. That was well known and accepted from the prewar evidence of Edlén on the ionization states and so forth." In fact he thinks he remembers that Edlén got the gold medal of the RAS around 1945 illustrating that this was a well-accepted result. The only place that radio astronomy came into this was that there was some debate and interest in whether the temperature indicated from the radio measurements agreed with the temperature indicated from the state of ionization.

Sullivan: 25:34

So now we switched the topic to cosmology. And I talked about the anecdote which he relates in his 1980 book, Steady-State Cosmology Re-visited, about Gold, Bondi, and Hoyle going to see a certain ghost movie which inspired them because in the movie it all ended up back where it started and things seem to be changing, but they weren't. And he said that was an important trigger to them to develop this cosmological idea. So I asked, "So are you saying that during the war when you three were working together that you didn't discuss cosmology at that time?" He said basically no, that they didn't. And I really couldn't get very much of the long answer. But my memory says that he said that Bondi had been working in quite a different field during the war, and it was only after the war when he began reading up on cosmology. And then he and Hoyle discussed it at times and began to have some kind of a collaboration, if you will.

So this is the end of side 135 B on the original tape and that, in fact, is the end of this side of this tape also. So go to 137 A for the continuation of this exciting oral transcription of the Fred Hoyle interview of 23 April '81.

Sullivan: 00:01

Continuing with the transcription of the Fred Hoyle interview of 23rd April, 1981. On 27 April 81, as I listen to the very faint telephone answers to my questions and try got to give you the scoop as best I can. So I reminded Hoyle that in his recent book, Steady State Cosmology Revisited, he says that he thought that one main source of the conflict between Gold and Ryle was that 1951 conference, where they argued about the distance of the radio stars, and Hoyle answered, "Well, I don't know that for certain, but it's always been my suspicion." And I asked him, "Was it about that time that you first thought that radio astronomy might have something to do with giving evidence for or against steady-state theory?" And he said, "No, I don't think so because Cygnus A was taken to be a colliding galaxy." He said, "If you think about galaxies as a cluster, it's not a very fundamental issue." He says, "They don't really do very much for cosmological problems." He said, "It was an interesting problem, certainly, but it was nothing to do with the structure of the whole universe." So he said, "I don't think that the announcement of Cygnus A had much impact, certainly, on me and I don't think on Bondi or Gold, relative to cosmology." He said, "Nor would I, at that time, have put much store in counting radio sources, if someone said to me at that time, 'do you think we should go out and count radio sources?'" If someone had asked him that, he would have said "No, that didn't look like a good idea at all because look at Hubble. They tried this with galaxies and hadn't gotten anywhere at all." So I asked him, "So therefore, you're saying that it wasn't with any pushing from your side that Ryle began counting radio sources?" And he says, "That's right, not at all." And then, Hoyle tried to remember when the first radio source counts were applied to cosmology. He had a memory of somebody, perhaps in the States, doing it even before Ryle. He said, "Perhaps Kraus." Parenthetically, I might add, I'm not sure what reference he's referring to here. He said that he doesn't think it was actually published, that it may have been a lecture or paper meeting or something like that. Well, then I asked him about the thing which I had seen in his recent book they referred to, namely a paper that Bondi gave at the RAS. I asked him where it was published, and it turns out that it's in Observatory for April 1952, where Bondi gives us talk about how theory can be every bit as good as observations, and observations are disproved every bit as much as theories are. And Hoyle gave the anecdote that Otto Struve at the Rome IAU meeting shortly thereafter, put his arm around Hoyle and said, "The lucky thing about that Bondi paper was that he didn't really know about the really bad observational booboos, so to speak." I asked Hoyle, "When was the first that he got wind of the usage of the 2C counts that the radio astronomers were doing?" And he said the first he heard about it was when it was published in Monthly Notices. But then I said, "Well, probably it was the Halley Lecture by Ryle," and he said, "Well, that may be right, but in any case, he was not involved at all as they worked on all this stuff." And then Hoyle pointed out that the animosity was really between Gold and Ryle, that he was not particularly pro- or anti-Ryle during this time of the-- before the 2C survey came out. And Hoyle said, "Well, perhaps the first thing that did make me not fond of Ryle, so to speak, was he knew that all of this was being done, and the first I heard of it was the first that anyone-- or the first that the rest of the world heard of it also." And he said, "But when it did come out, it didn't really make much impression on me as being very strong evidence because of the fact that Hubble had tried this and it led to so many difficulties. It seemed to me this was the same kind of situation here." So he said, "I just didn't take this very seriously."

Sullivan: 05:04

"So when was the first time that you sat down and really began to criticize it in a detailed technical fashion?" And he said, "Well, that was not until the 3C survey." "Yeah, I noticed that there were no papers by you through the mid-50s on this topic, and yet you must have been thinking about it.  " Hoyle says, "Well, you see, Gold and Bondi and I, because of our wartime experience, had the technical knowledge about radio receivers and aerials and so forth. And although we weren't up to the techniques of the mid-50s, we knew perfectly well that it was very difficult to get the absolute power measurements from a receiver." And then Hoyle says, "It was obvious that any random error that came in, no matter what its source, would steepen the log N-log S curve at the faint end. So even if you average for a long time and do that quite correctly, if there are any kind of random fluctuations, then it will steepen at the faint end of the log N-log S curve." So this was one thing that was pointed out to Ryle by people like John Bolton.

Sullivan: 06:21

And then Hoyle said the one thing he's never understood is that while many people were making comments about this in private, no one would come out and take Ryle on, so to speak, in public by criticizing and heavily in print. And then I pointed out, "Well, Mills had some pretty heavy statements in his 1957 or '58 first installment of his survey." So then Hoyle says that the combination of this random noise effect and the great difficulties that he knew that were making absolute intensity measurements in radio astronomy, measuring power flux densities, meant that he just didn't take it seriously, and he only took it seriously to the extent that the public took it seriously. He says, "It was only when there was a lot of propaganda about this that he had to take it seriously.” He never scientifically took it seriously. So then I asked him, "Well, what was your stance towards Mills' survey?" And he said well, he thought that Mills' measurements were more accurate. And then he asked me, he said, "Mills got a slope of 1.8, didn't he?" And I said, "Yes." Hoyle also pointed out that his errors were considerable, and that he wanted to be cautious about any results. And certainly, the 1.8 was not any different than the 1.5 in general. [inaudible] here that Hoyle was emphasizing Mills was much more cautious about possible errors and how much he read into his formal results. So then I asked him, "It has always struck me that both Mills and Ryle seem to be using 1.5 in the slope as their standard, flat Euclidian universe. But nobody thought that it was flat and Euclidean and that always seemed funny to me." And Hoyle pointed out that, although it was accepted by all at that time that they were extragalactic, they might not have been really far away, so they might not have told one about any cosmology. So still, the 1.5 was of some interest to see whether they were relatively nearby and yet still extragalactic. And although, Hoyle mentioned some much more modern results in late '60s, early '70s, with the Green Bank survey of Mike Davis and Kellermann, where they come up with a slope of 1.5. And Hoyle said that this result of 1.5 was sort of bothersome. One might wonder whether it was really an accident or not. So then I asked him, going back to the mid- or late '50s, "What did you make of the P(D) analysis of Scheuer and Ryle?" And his answer was, "Well, I suppose, I just didn't believe the power measurements. I was relying on our wartime experience where measuring absolute values was extremely difficult." And so I said, "So you mean that your basic attitude was no matter what kind of analysis they did on the data, the original measurements just weren't very good?" He said, "Yeah, that's right." So it was a judgment on technique. I mean, this, after all, was exactly where Hubble went wrong. Hubble had problems with his magnitude scale. And so we had all this history of-- we had this history of difficulties in the absolute intensity scale, and so for that reason, in my mind, technically, that the measurements were just too suspect. So then I asked him that, "So is it correct to say that even though you were a theorist, you did have a feel for the techniques, and you felt that Mills's technique was superior?" And so I asked, "Would there be any reason to suspect that Mills could make better absolute flux measurements than Ryle?" And Hoyle said, "Well, no, but Mills was much more cautious and realized the limitations much better." He said, "If you look at Mills' papers, you'll see that he says, 'Although, I've measured 1.8, it could well be 1.5.'" So I asked him, "What did you think? And which kind of observations were necessary to take care of this problem?" And Hoyle answered that he never felt and still does not feel that we were ever any better off in radio astronomy than Hubble was. Hoyle says, "To me, the thing that hit me in the eye was Penzias and Wilson. That was a different kettle of fish." And I said, "That led to your 1965 talk, which was published in Nature, in which the microwave background and also the quasars, if they were cosmological, made it begin to appear that an evolving universe was necessary." And Hoyle said, "That's right." Hoyle agreed with me that there was no resolution of the log N-log S controversy in his mind before the microwave background came along.

Sullivan: 11:55

So then I asked him about synchrotron theory again as to when, in his view, it became accepted in the West and what was it that led to that acceptance. And he answered that he thought it was the polarization that was the key thing. And then I said, "In the discrete sources?" And then he's talking about the polarization of the Crab, of course, in '54, or so. And then he said, there was no question that in those days work from Russia was marked up. And it was instantly accepted. He said there was a strong hangover from before the war, or actually from during the war, that the Russians had knocked the stuffing out of the German army. And he said that was still having its effect that if a Russian says something it was taken seriously. And he said that, for instance, "Shklovsky saying that it was synchrotron radiation would have a much bigger effect than my saying it." I asked, "Well, with that background, why was it that the work of Ginzburg and Shklovsky and their students in the early '50s was not accepted by, at least, a sizable number of people in the West?" And he said, "Simply because it was not translated. I just didn't know about these papers, for instance. And one couldn't interrupt his research to dig around in the literature of a language which one didn't understand." He said, "What we used to do was that we would pick up papers from the Russian journals that looked like they were interesting, and then we would contract privately with somebody to translate them for us." And he said, "But of course, that meant that you already had to know what was interesting." And he said, "It wasn't until the late '50s when in the US, the Russian journals began to be translated systematically that we really knew what was there." So I said, "So you think that by the time of the Paris Symposium that Synchrotron was pretty widely accepted?" And he didn't really answer that question. What he said was, well, the thing that it really did was the polarization of the Crab. Then I pointed out the galactic background polarization wasn't really detected until the early '60s reliably. And he said, "Well, that would not have affected it." It was the Crab polarization that was the thing. So then I asked, "Well, why would one be willing to accept synchrotron as a galactic background mechanism if you'd only accepted polarization of discrete sources?" And he said, "Well, that's a good question." He said that the astronomical community as a whole was pretty ignorant of theory in those days. And I couldn't really get the rest of his answer.

Sullivan: 14:52

So then I said, "Let me ask you about more details of mechanisms and radio sources," and said, "You have various ideas like matter and antimatter with verbiage in '56 and charge separation in '53. And then you became eventually convinced of synchrotron radiation." I said, "Given the double nature of Cygnus A in '54, and then the late '50s when you're getting these very compact, high rise temperature sources, what was the fundamental problem? Where was radio astronomy leading extragalactic astrophysics in the late '50s?" He said, "Well, I don't really know that there was any fundamental difficulty at all," he said, it didn't look like there was any new physics that was needed. And he said, "But what we were acutely aware of at that time was that they were lifetime problems. I, myself was aware of the difficulty of taking highly energetic electrons from a compact object and making them expand freely without losing their energy too fast, and so one had to think of some kind of collision processes or something to re-accelerate them. And then I asked him was it the double lobe structure of Cygnus which made one want to get things outside? He said he didn't remember that the double structure of Cygnus really caused any difficulty. It was looked more upon as an oddball case, not a basic model that needs to be explained. And then he pointed out to me - and I agreed - that it was really not till the early '60s that [inaudible] Maltby and Moffet, and so forth, that the general double nature of the radio sources became known and therefore it was something that one had to move more to the center of any explanations.

Sullivan: 16:59

Okay, this is continuing my oral transcription on 24 May 1981-- much later for the last part here. Anyway, so I asked Hoyle what about the idea of colliding galaxies?" Did he feel that that was just a red herring which, simply because the spectra and the morphology of a few cases, seemed to indicate colliding galaxies that people thought that was a good idea? What was the reason for its wide acceptance or was it really that widely accepted? And he answered, well, it's very difficult to understand his answer, but basically, he pointed out that Baade and Minkowski were the only ones that were doing any optical work on these things, and you must remember that there were only two or three telescopes in the world that could do any decent optical work at that time. You didn't have a situation now where you have loads of large optical telescopes. And so, it was pretty much listening to what they had to say about the whole thing and that put a very heavy bias into what one knew and thought about the nature of the radio sources. Hoyle also pointed out that when the Jodrell Bank group began producing the very small source sizes in the late '50s and early '60s, clearly one needed to look at that kind of a process rather than a very extended process as being the fundamental location of the radio emission in a case.

Sullivan: 18:51

Then I asked him about Ambartsumian's paper given at the 1958 Solvay Conference. Did he feel that that was a breakthrough paper? Did it have a large impact at the time in terms of drawing attention to the nuclei as the sources of the emission? Hoyle replied that when Ambartsumian gave the paper that it was not taken all that seriously. It was listened to, but not all that seriously. But then shortly after that conference was the IAU meeting in Moscow in 1958, and it was at that conference that people in general began to realize that Ambartsumian was not thought very well of by the Russian theoreticians-- that he was a bit of an outcast in the Soviet scientific hierarchy. Apparently, it was true that he was a good political operator, but his science was not given much weight at all and so Hoyle says that the combination of his peculiar views and this view of the Russians towards him meant that his ideas were given very little weight in the West also. But nevertheless, Hoyle thinks that whenever somebody comes off with a quote-unquote "wild idea" like that and turns out to be right later on, that you should give them the credit. So Hoyle has done that in subsequent years to some extent. So then I asked Hoyle if you could relate the incident at the ‘58 Solvay conference, in which he, according to a recent written version in one of his books, says that he told Oort that [Baade’s?] star at the center of the Crab Nebula might be showing few second variations, and it might actually be connected with the source of the relativistic electrons. Anyway, in retelling that incident to me, Hoyle says that it goes back to the [Vatican?] conference, which was 57 probably, and there Baade was discussing this peculiar star at the center of the Crab and its spectrum and trying to figure out what it was. And in discussion, Hoyle can't remember if he suggested someone else, they were thinking that, "Well, maybe this is a white dwarf star in the center." And so the question came up as to whether there might be time variations in such a compact object. And Baade said, "Well, how fast do I have to take photographs?" And the reply was by Hoyle, "Well, it has to be the order of a second or a few seconds and the characteristic trait of pulsation of a white dwarf." And Baade said, "Well, that'll be extremely difficult to do that kind of thing." And actually, let me add here that I'm not sure now if he switched to be talking about the ‘58 Solvay conference as opposed to the Vatican conference. But anyway, that's the way it went.

Sullivan: 22:05

Sullivan: 23:20

So then I brought up the point, "Well, what's amazing to me is that they didn't think of doing it photometrically rather than photographically, so you could actually do an experiment like this much better looking for fast time variations." In reply, Hoyle told me an anecdote from the time that he was at Caltech, sometime in the late 50s, I would suppose. Anyway, he was there at the same time, Martin Swartzschild, and he says that Martin Schwarzschild-- he distinctly remembers him complaining about the lack of electronics at Mount Wilson and Palomar Observatories and how there was only one electronics man for the whole Observatories and he wasn't all that good. And Schwarzschild was very frustrated because he felt that he had to have these large telescopes to do the things he wanted to do, and yet there was absolutely no vision as to the possibilities of what one could do electronics. And Hoyle says that he often thought that perhaps the reason that Schwarzschild went off to Princeton and got involved in balloon research and space technology, so to speak, was that he had much more of an interest in what that high technology could do than he could find in the ground-based traditional astronomical observatory.

So we're now moving on to tape 136B on the original tape. And so I asked Hoyle that-- one question I wanted to ask him about steady state theory was that from another one of his recent books. I realized that it was really the Bondi-Gold version of steady state theory that was much more in conflict with the radio source counts in his own version because in the sense that the Bondi-Gold version was much more invariant with time, much more disprovable, so to speak, than his own. I asked him, "Was this any source of confusion in the overall controversy or was it just really a side issue?" He said, Yes indeed, that was an important point that he always felt that the radio source counts had much more to do with the Bondi-Gold version than his own version and that this was an important point. And I said, "Well, that's something I think it's not even understood today and that there was this difference." And he said, "That's right, it wasn't even understood at that time. So it was a source of confusion." Well, he did have a couple of papers in which he tried to point out some of these differences. I think he's referring there to the papers with Narlikar, Monthly Notices ‘62 and Monthly Notices 1961. However, he said that really his theory was only expected to have time variations as he got to register three or so. And so we felt that he shouldn't really emphasize that because that would be very discouraging to the observers, that they needed to be encouraged to go out and get more data and so forth. So he felt like he shouldn't unduly emphasize this point.

Sullivan: 25:47

So I asked Hoyle if he was involved at all in the early discovery of the quasars and what he might like to comment about that. He recalled that about that same time at Caltech he was working with Willie Fowler on massive objects, the physics of massive objects. And then one day Fowler said to him they found our objects. And he's referring to Schmidt's discovery that the spectrum of 3C 273 was really a highly redshifted spectrum. But Hoyle says that he really had little input into the discovery of that redshifted spectrum or the discussions beforehand as to what the nature of the objects were. Then there was somewhat more discussion about the study with Fowler on these massive objects and could they be made stable and their physics and so forth. But I really can't understand most of it. In any case, it appears that, although Hoyle actually was in Australia and then came back to England via Pasadena about the same time, that he was not directly involved in these things, although there was interest even before the subject discovery, the quasars and these star-like objects and trying to understand what they might be. So I asked Hoyle, looking at the whole history of radio astronomy, what does he think have been the key impacts of radio astronomy on astronomy as a whole? And the first thing he answered was the introduction of electronics into astronomy and the whole different way of looking at how to do measurements and so forth. Second thing was the discovery of the microwave background, and then more recently the whole opening of the millimeter wavelength portion of the spectrum, especially for molecular spectroscopy.

Sullivan: 27:59

And then he mentioned that Jan Oort, of course, had said back during World War II, when there was only Jansky’s and Reber’s measurements, that we've got to find a spectral line. And now Hoyle says there are dozens and dozens of radio spectral lines, and this is really beginning to open things up much more so than you could do with just continuum. So then I confirmed with him that indeed he felt that it wasn't so much an actual discovery in radio astronomy as more an attitude and approach to how to do things was its big contribution to astronomy. And he agreed, saying also that, of course, radio astronomy had brought many physicists and radio engineers into astronomy, and that was a very healthy input. If you had to name one astronomical thing he said, it would probably be the bringing forth of the importance of compact objects in astronomy. But then there were other non-radio bits of evidence that were pointing out the importance of compact objects also, if you go through the 60s. Then Hoyle said he wanted to make sort of one closing remark, and that is that there's a great danger and when you look back over the development of things like trying to understand what the quasars are, that you see it as an orderly progression. And it's very difficult to put yourself in that place and see how confusing it was and understand the ebb and flow of how the evidence and the theories and the meetings and discussions were going back-and-forth.

Sullivan: 29:50

And then he said that since he's been away from universities for something like seven or eight years now, he's become very conscious of the effect that although there's the obvious advantage in the universities of being able to discuss things on a day-to-day basis and get ideas checked out, there's also a tremendous bandwagon effect. And when you stand back and just work by yourself, you're almost by definition not so subject to that. And of course, he's referring to [inaudible]. I had not [inaudible]many of the sort of strange ideas that he's been putting for us over the past few years about viruses and comets and steady state revisited and things like this. And then I told Hoyle that I would ask permission to quote anything and so forth. He said the only thing that he was sensitive about that he had said was that he would not like me to say anything about his statement that Ryle's data for the 2C survey was fundamentally not good, and that he didn't realize that. And apparently Ryle didn't want this quoted because Ryle is a sick man now. And so that was the end of the interview on 23rd April 1981 from Cambridge to Fred Hoyle's home in Cumbria. And I should say that's the end of my rough transcription of the interview, which I'm afraid is all that will ever be gotten out of that, because he comes through extremely faint, very difficult to understand him. But we'll just have to live with that.