Peter Scheuer

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ORAL HISTORIES
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Interviewed by
David Edge
Interview date
Location
Cambridge, England
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Interview of Peter Scheuer by David Edge on 1971 May 14,Niels Bohr Library & Archives, American Institute of Physics,College Park, MD USA,www.aip.org/history-programs/niels-bohr-library/oral-histories/4860

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Career in astronomy beginning with early work in the radio astronomy group at University of Cambridge in 1951. Scheuer's work in cosmology and radio source counts; the 2C survey controversy and the P(D) paper. Scheuer's work outside Cambridge. Change from experimental to theoretical work; the theoretical group at Cambridge and new discoveries; astronomers outside of Cambridge; comparison of astronomy at Cambridge and Jodrell Bank.

Transcript

Edge:

Peter, you joined the group in 1951.

Scheuer:

That’s right.

Edge:

Having done part II physics at Cambridge, having come straight from school to do physics at Cambridge.

Scheuer:

No quite, I had a year in between school and coming up here.

Edge:

Now, how did you come to join the radio astronomy group for research?

Scheuer:

Because in my third year, while I was doing Part II physics, one of the lectures given to Part II students was given by Martin Ryle, and he was talking about the radio sources they had just discovered with the aerial called the Long Michelson, and there were lots of these little sources popping up all over the sky and nobody seemed to know what any of them were, and it seemed to me that here was a something that one could… it was a problem that one could do something about by straight experimental physics of a kind which I could even at that stage grasp rather than subjects like nuclear physics in which it wasn't at all clear to me if even less clear to me now, where the frontiers of knowledge really are.

Edge:

Had you had any background in astronomy at all, amateur interest in astronomy?

Scheuer:

Slightly, yes, to the extent of putting two lenses in a piece of cardboard tube, and…

Edge:

But you hadn’t any interest in that sort of physics…

Scheuer:

Yes, but I hadn’t seriously considered doing research in astrophysics.

Edge:

So presumably the situation was, you were considering research at that stage in Part 2 course… the possibility of it.

Scheuer:

Yes.

Edge:

And you heard Martin Ryle talk and this seemed to suggest a possible area.

Scheuer:

Yes.

Edge:

Now, when you joined the group, most people who joined the group, or have joined the group in the earlier years get given a practical problem immediately, and have something else to sort of go away and think about it — what happened to you when you joined.

Scheuer:

I was given a practical problem to build a pre-amplifier, which was later described by John Thomson, I think, as something that one had to open with a tin opener. I don’t know whether it ever worked, and I was told to go away and think about the possibility of measuring the ionized hydrogen content of the galaxy, the point being that the… well, there were a variety of problems involved, one was that the… it was alleged at the time that the distribution of brightness across the Milky Way got broader as you went to lower frequencies, the question was, quite simply was this an effect due to broader beams being used at lower frequencies, or was this real, and the other thing was that a paper by Westerhout and Oort had come out not very long before, in which they made a model of the distribution of brightness over the Milky Way, described by a series of ellipsoids through the galaxy and superimposed on this there ought to be… whatever this stuff was, there ought to be a very much narrower distribution which really was the H II regions which were known to be within a 100 parsecs of the galactic plane. Martin suggested that one could use an interferometer to isolate this very narrow distribution from a wider one — and this in fact was the experimental problem I started with.

Edge:

Did Martin work with you on it?

Scheuer:

Yes, certainly for a while.

Edge:

In fact that was published fairly quickly.

Scheuer:

No, not till ‘53.

Edge:

That’s right. So it was a relatively short experiment?

Scheuer:

Well, two years, and it went on after that. There was a bit more done than was published in that paper.

Edge:

Now, at what time did you get into the cosmological and radio source count area.

Scheuer:

Well, during the time I was a research student the 4 element interferometer was put up at the Grange Road site and observations began, and — I can’t remember just when that was — but observations at 80 megacycles were pretty well complete, and strangely enough the worry so far as the source counts were concerned, which Graham Smith had already shown were a useful way of deciding what sort of distribution the sources had in space, and the first worry was that some of the fainter sources would get lost because they were in the glare of the brighter ones around and about, and the question was, was there some sort of way of allowing for this and so I set to work to find out what one could do about this, and that’s really how I got into the cosmological field.

Edge:

Did Graham think of the problem, in the group it was Graham who thought…

Scheuer:

Graham produced the first log N - log S plot in his thesis which was about 1951 — which was just before I joined the group — he had done this and of course it had been used in optical astronomy before.

Edge:

But the problem to which P of D was the answer… how did it come to you?

Scheuer:

Oh, as I said because Martin was worried that some of the faint sources might get lost, and of course, when I worked it out, it turned out the effect was predominantly in the opposite direction.

Edge:

Now, did Martin take you aside one time and say, ‘look, Peter, here is a problem’?

Scheuer:

Oh it is the usual way these things go, these problems emerge, and here was this problem and it seemed to me that if one asked not about individual sources, but asked about deflections on various places on the records and there was a mathematical problem that ought to have a definite answer, and in fact, had a definite answer.

Edge:

So you went away and thought about it?

Scheuer:

I went away and thought about it, in profound ignorance of statistics, of course, rediscovered various well-known theorems. It took me three months, as it happened.

Edge:

Three months work?

Scheuer:

Three months work, the guts of it, yes.

Edge:

And Martin knew you were doing this, the others knew you were doing this, there was nobody else actually doing this, did you go and talk to anybody in any detail about it.

Scheuer:

Oh well, when I had done it, it went in the usual manner to Mr. Ratcliffe who, I think was very skeptical of it, because it involved adding together a lot of sine waves, but didn’t seem to do Fouriers in any of the ways in which one was used to, so he sent me off to… now… who was it, somebody in the statistical laboratory, quite a well-known statistician…

Edge:

Not Wilkes?

Scheuer:

Not Wilkes, no… I will think of it later, and he said this is perfectly all right, but why don't you go and do it this way, which in fact was much simpler.

Edge:

So you re-wrote the paper?

Scheuer:

I re-wrote the paper. Well, I hadn’t written the paper…

Edge:

And that was the material that got into. Ryle and Scheuer…

Scheuer:

No, no, that was the material that got into Scheuer 1957. Now, that was a very tangled story, because Ryle and Scheuer 1955 just described the source counts and the straight source counts as they came out of the machine. This was a paper which in fact, of course, went off after I had left the group to do national service.

Edge:

The Scheuer ‘57?

Scheuer:

No, the Ryle and Scheuer, ‘55. I left the group in October ‘54 and came back in ‘56. And the P of D part didn’t get published until 1957 for a variety of reasons, but the chief one was that as soon as we got around to writing this down, by that time all the source count business was in such a polemical state and was regarded with such contempt by almost all the astronomical world that no Journal which respected itself would take a paper that had anything to do with it, unless it was on the right side, and so it was quite a long time before we were able to publish it, meantime of course, being attacked for not publishing it. There was another contributory cause which was, of course the P of D, the deductions that I made from the P of D didn’t agree with the straight source counts either. They were somewhere in between, a slope of 1.5 and what was claimed in the 1955 paper, and so it found favor with neither side.

Edge:

Now can we decouple a bit, because the team who were doing the 2c survey…

Scheuer:

No, no, I wasn’t part of the team, no.

Edge:

So you weren’t co-author of the actual paper?

Scheuer:

No, no. I had done no observation work at all on this.

Edge:

Now, the 2C paper did not include log N - log S curves, did it, the 2C was a straight catalog, or am I wrong about this?

Scheuer:

I think it is better to look it up — I think it did include a log N - log S, but I am not absolutely…

Edge:

But the major log N - log S curve was in Ryle and Scheuer, 1955.

Scheuer:

…I think that was the first actual publication of the log N - log S curve, I think that’s right, because catalogs take a long time to come out.

Edge:

Yes, you are absolutely right. It still is ‘55 actually when the catalog comes out, but it is not until later, that is correct. The 2C survey comes late in ‘55, Ryle and Scheuer is earlier in ‘55.

Scheuer:

Yes.

Edge:

So you were being used as a way — well used is the wrong word, you were in relation to Martin, you were operating as cosmological… you were working on cosmological problems, but not actually engaged on a survey.

Scheuer:

That’s right.

Edge:

Your thesis was the ionized hydrogen work was it?

Scheuer:

Yes, my thesis was the ionized hydrogen work.

Edge:

With no P of D.

Scheuer:

With no P of D. There is no P of D at all in my thesis. Things in the thesis were the ionized hydrogen work. There was a bit which I published in 1960 in fact on the absorption coefficient of ionized hydrogen and there was a bit about the theory of interferometers…

Edge:

…all in relation to that project…

Scheuer:

…which was saying much the same sort of things as Bracewell and Roberts.

Edge:

Now you went off on national service, before that, was your relationship to Martin a bit like, well I remember when he was writing the Bakerian lecture, he did the crude idea, and you filled in the gaps and put in all the proper calculus, and curves and so on, did you feel that Martin was actually using your facility with the mathematics and the thorough analysis of things, as if this is your role in the group, you have a problem here, a mathematical problem, chuck it to Peter first, he will work it out for you.

Scheuer:

Oh no, I don’t think so at all, I don’t think so at all, no… no, no, no.

Edge:

So you saw yourself just like anybody else in the group, there were practical projects going on.

Scheuer:

It just so happened I got into the cosmology field through doing a little bit of theory on it, but I certainly didn’t feel myself being used.

Edge:

No, no, I’m sorry… what I mean was, did you see your role in the group in this way, because it emerged, I would say, after a time when I was in the group, that people would tend to say, you know, Peter is the first stop if you want a mathematical work-out of a problem. You didn’t feel yourself as having that role in the group.

Scheuer:

At that time certainly not, no.

Edge:

You feel that this developed later.

Scheuer:

Well, that’s the… I really stopped doing experimental work when I came back from Australia, and not even quite then. That was when I consciously decided it was time to go and think about things.

Edge:

Now, you were away doing National Service when, as you pointed out, the controversy which the 2C survey gave rise to was blowing up…

Scheuer:

Yes, and went on long after that, as you know from a paper which you and John Shakeshaft and I wrote together, after many trials and tribulations.

Edge:

Yes, indeed. But presumably you were still in correspondence with Martin during this time, were you?

Scheuer:

Occasionally, yes, obviously it was not very practical, but…

Edge:

And when you came back there was the P of D which hadn’t been written up (that’s right) so the first thing you did was to be shut up and get that paper done.

Scheuer:

hmm… I doubt it…

Edge:

Was there some pressure on you to…

Scheuer:

It was fairly soon, certainly, and eventually it came out about 1957 or thereabouts… no, no, ‘58.

Edge:

I will check it up in the master list. Scheuer P.A. Historical Method was ‘57. Proc. Com. Phil. Soc. Was that in fact submitted anywhere else and rejected, do you know?

Scheuer:

We tried it in Phil. Mag., but they were unwilling to get involved.

Edge:

Well, it probably isn’t particularly important. But did you feel very much — Martin has talked to me in an interview we had yesterday about this feeling of generalized hostility after the publication of the 2C survey, every conference he went to, everyone seemed to be hostile to every cosmological remark, did you feel yourself that you were struggling against a received opinion everybody else held in this…

Scheuer:

Oh yes, I don’t think there is any doubt about that… I feel it was quite clear. I remember in particular… I remember particularly one comment at the Paris symposium in ‘58 made by somebody I could name to you which was a generalized comment claiming that this P of D of course, in particular what cut me… saying, of course, it’s rubbish that one could by black magic extract something from the data which wasn’t there. And I thought this was a little rich considering I had spent two pages of the paper, the P of D paper, explaining precisely why one couldn’t extract more information than what was there. Anyway, these things happen.

Edge:

You felt this is a personal thing in terms of conferences… were there any other, as it were, indicators, to you of unpopularity, out group hostility generally, or did it really not affect, I mean the group, that Cambridge carried on and it didn’t affect your work.

Scheuer:

Hmm… well obviously it affected work because… certainly Martin was very upset about this, and… it isn’t even easy to tell how much the rest of us were upset in the circumstances. Certainly it meant we had a lot of work to do on this kind of topic, going again and again into these questions to find out whether one could sharpen up any of the statements.

Edge:

So as it were, it wrote a large amount of your research programs for the coming year or two, having to think about this, and rethink about this.

Scheuer:

That… must be so. I think so, but you probably can remember as much as I do about this…

Edge:

That’s right. But there was a double difficulty, not only were you in conflict as it were with, shall we say, Australian based opinion, world opinion, but also in conflict in certain aspects with Martin himself over interpretation, were you not, and your P of D coming out with a somewhat different figure from the straight source counts; or was this immediately seen to be a defect of the source counts early on, and therefore a source of no great tension.

Scheuer:

Well, there was undoubtedly tension at times mainly I think… temperamental in character, and I tended to pull over to extreme caution and writing less in papers, which was very irritating at times to Martin, who saw a need to justify the group. And the main worry I had at the time was in fact the wrong one, what I thought was the most… the most difficult thing to do… the most difficult thing to rule out was that the source counts became steeper than the standard 1.5 because some of the nearer sources had large angular diameters where there seemed to be reduced fluxes in the interferometer surveys. Of course this turned out in the end to be not so.

Edge:

But Mills’ survey suggested large diameter sources.

Scheuer:

Oh yes, yes. Well, that’s another story and one which is a mess… which has vanished rather than… been sorted out.

Edge:

When you came back from military service you had this P of D to think about, you were also given, there were other project, experimental projects, is that not so. You actually got back into experimental work.

Scheuer:

Oh yes. I got into construction work, as it were, converting the four-element interferometer to 408 MHz. This was not a terribly fruitful exercise as it turned out, and was rather overtaken by big instruments elsewhere. It would have been a very useful thing if that had been the first… the first thing to be done with the four-element interferometer.

Edge:

And you had John Heseler as a research student, what happened to John, I knew John… I never actually… he went to Australia.

Scheuer:

He went to Australia, to Woomera.

Edge:

But did he get his doctorate, I never…

Scheuer:

He got an MSc. But I think he is now back in England.

Edge:

Yes he is, he works for Smiths at Cheltenham. Yes, I know him with another hat on. Now, you went to Australia…

Scheuer:

Yes.

Edge:

What year was that?

Scheuer:

That was December ‘59.

Edge:

For?

Scheuer:

For two years, I actually stayed a third year.

Edge:

How did this come about?

Scheuer:

Because… Bernie Mills wrote saying “why not come over for a while.”

Edge:

To think about…

Scheuer:

No, just to come. No, just come, yes.

Edge:

This was a straight choice… contacts, etc., etc.

Scheuer:

Yes.

Edge:

Did Martin have anything to do with arranging this, or setting it up?

Scheuer:

No, not to the best of my knowledge.

Edge:

He was detached about it all.

Scheuer:

No, no, he seemed to think it was quite a good idea. One of the… one of the… I don’t know what you want to use this interview for, how guarded I should or should not be — one of the things that strikes me is in a good many ways at least. Martin and Mills have rather similar attitudes, one of the strange things, at that time they were very much in conflict.

Edge:

Yes. Similar temperaments you would say as well.

Scheuer:

In some ways, not in all ways, in some ways, yes.

Edge:

What did you do in Australia?

Scheuer:

Well, in Australia I spent most of my time doing something which I never published unfortunately. I spent most of my time trying to measure angular diameters. This was a somewhat primitive and hectic exercise, obviously the main effort there was on the 210 foot Parkes dish and that means that other things had to… sneak in by at least claiming at first to be very small projects and this was a development of the fixed system they already had going between Fleurs and I wanted to do several spacings because it was becoming very clear, had become very clear already, that the sources were in general at least double, they were complicated things, this was both from the Jennison / Das Gupta work on Cygnus A and also from the measurements which we had in Cambridge at 408 MHz and Jodrell Bank had made at another spacing on Hercules A, that was also a double, and so obviously one needed more than one spacing to do any good. This produced great reams of information.

Edge:

But never a paper.

Scheuer:

Never a paper… calibrations were very tricky, and rather too much information to write up quickly.

Edge:

But you found it valuable, but it was not publishable.

Scheuer:

I think it would have been publishable, but there was too much of it. It’s somewhat on my conscience actually.

Edge:

Did you do anything else, work in Australia, apart from this?

Scheuer:

Well, the thing… the thing which is quoted probably more than anything else I’ve done is the paper on analyzing lunar occultations which cropped up when I was in Australia. I also did a little bit of work with thobes dish, it was great fun.

Edge:

On occultations.

Scheuer:

No, no, on looking at some of those Mills’ extended sources which you mentioned earlier. The occultation of 3C 273 which led to the identification of the source and then to the identification of the Balmer series happened while I was there, and Cyril Hazard appeared there just after the occultation started and so the problem was very much to the fore. There again it seemed there ought to be a best prescription for getting the results out. And that was in fact a fairly simple thing to do.

Edge:

And then you came back to Cambridge, to a Fellowship at Peter House, was that the way?

Scheuer:

Yes.

Edge:

And you have been here ever since?

Scheuer:

Yes.

Edge:

With no sabbaticals?

Scheuer:

I had, let’s see. I had three months in British Columbia in ‘66 — check on that — autumn of ‘66 I think it was… no, autumn ‘64 probably helping develop the 10 megacycle array there, and I had three months at the beginning of ‘66 — yes it must have been ‘64 — I had three months at the beginning of ‘66 at Cal Tech.

Edge:

On position work?

Scheuer:

Well, I took some 5C data and looked at some of the plates and found very very little that had not been seen here already and gave a course there.

Edge:

Now, going back to, you did your Part 2 and research was the obvious thing, presumably a career in research in physics in some branch was what you had in mind when starting research in the group.

Scheuer:

Oh I don’t think I thought as far ahead as that.

Edge:

You thought as far ahead as a doctorate.

Scheuer:

Yes, yes.

Edge:

At what point was it clear that you were going to stick with radio astronomy as such, because you have consistently done this apart from your National Service of course, stuck with radio astronomy as a career.

Scheuer:

Yes, well… this is a gradual process, isn’t it? It becomes clear… becomes more and more clear… I suppose, in time.

Edge:

Before you went to National Service, it was all fixed up you were coming back?

Scheuer:

Oh no, oh no, no, no, no, not at all.

Edge:

So how was it you came back? At what point was… deciding you were coming back?

Scheuer:

It became clear when I got a research fellowship at St. Johns.

Edge:

Which you applied for…

Scheuer:

Which I applied for… before disappearing.

Edge:

And that was for three years?

Scheuer:

That was for three years.

Edge:

And then —

Scheuer:

And then I had an 1851 studentship…

Edge:

And then you went to Australia.

Scheuer:

And then I went to Australia. Yes.

Edge:

And by this time it was clear you were going to continue…

Scheuer:

I think so, yes.

Edge:

And it still is, is it?

Scheuer:

For the moment, yes. Nothing is ever absolutely clear…

Edge:

But you would describe yourself as a radio astronomer, this means something to you as your identity as it were… or would you describe yourself as an astro-physicist, or physicist, or…

Scheuer:

Certainly not as a physicist, no, no, definitely not…

Edge:

This is what they all say. Astro-physicist?

Scheuer:

Possibly.

Edge:

Cosmologist?

Scheuer:

No.

Edge:

Astronomer?

Scheuer:

Astronomer possibly… I don’t think it matters.

Edge:

Radio astronomer, yes?

Scheuer:

I don’t know… I describe myself, I think… in my previous passport I described myself as an astronomer.

Edge:

You said since coming back from Australia you have done no experimental work.

Scheuer:

Except for helping with the 10 MHz array in Canada.

Edge:

Was this as it were a conscious decision?

Scheuer:

Yes, that was a conscious decision.

Edge:

That you got no satisfaction out of it.

Scheuer:

No, no, not at all. It just seemed to me there was a lot of information around about radio sources and one ought to start and think a bit about what the… what use one could make of this information.

Edge:

So you became essentially a theoretician.

Scheuer:

Yes.

Edge:

And have remained so.

Scheuer:

Have remained so, with this break in Canada.

Edge:

But not the first theoretician in the group, Harriet Tummer had been in the group before.

Scheuer:

Yes, and Harry van der Laan was a research student when I came back from Australia… and we overlapped one year…

Edge:

But you are now effectively coordinated with a small group of people who are all theoreticians in the group, are you, or —?

Scheuer:

Yes.

Edge:

How many does that group consist of?

Scheuer:

Well, there’s now… there are now two of us in university posts — there’s M. Longair who’s got a demonstratorship. On the whole I had been having one student at a time, there was M. Longair and then John Skilling who is away in the States at the moment and is coming back later this year, and I have got two students now, sorry… yes, I have got two theoretical students now.

Edge:

You have a university post as well as a fellowship here?

Scheuer:

Yes… that’s the same as the one I got when I came back from Australia.

Edge:

Now the theoretical problems you are dealing with now, are not confined to cosmological problems?

Scheuer:

Certainly not… in fact I haven’t… I’ve dropped the cosmology.

Edge:

So you are concerned with what, pulsars, quasars, structure of…

Scheuer:

Radio galaxies is what I have spent most time on and published best on. Those incidental problems that come up.

Edge:

Could I ask you a question that I asked some of the others, just to see what the response is — we have quasars and pulsars, the two obviously odd things that radio astronomers have discovered and focused a lot of attention on, do you see these as making a major contribution to physics, the discovery and analysis of these?

Scheuer:

I don’t know.

Edge:

You deploy the laws of physics in thinking about how they could work?

Scheuer:

Well, that’s certainly the first… the first attempt, otherwise the field is so wide open, but, well it depends on whether you regard cosmology as physics or not, obviously quasars will not obviously, not, absolutely obviously, it’s not obviously certain, but it is obviously possible that quasars have a lot to contribute towards finding something out about cosmology. But whether pulsars will directly affect what we know about physics, I don’t know, because it’s a very large stretch. Clearly the insides of neutron stars involve nuclear physics which one doesn’t know, and already again, the insides of pulsars, the question of the so-called glitches, have got people thinking about different kinds of a rather liquid state physics with which we are very unfamiliar indeed, but not necessarily involving new physics. Now, the nuclear physics in the middle is something quite different, because there one is likely to get hyperons in the cores of neutron stars and this involves really very unknown pieces of physics…

Edge:

But in doing this work you don’t really see yourself… what shall we say… as pioneering problems in physics in general, they are problems sui generis, of their own.

Scheuer:

They are problems of their own, now whether ultimately one can deduce by a roundabout way something that will help say, the nuclear physicist, and give him a data point somewhere or other, that I don’t know, because obviously this is a very long chain of deduction, one has to understand the rest of it rather well in order to be able to pin down something about interactions between hyperons from observations of pulsars, but it may happen.

Edge:

Can we go back a bit and talk about the build-up of the people whom you might say you see as the major actors in your professional work as an astronomer, your reference group — you start in the group and Martin is the major person you interact with –-

Scheuer:

Yes.

Edge:

— and who else in terms of professional interchange, who were the people who you were most closely related to in your work and problems and techniques within the Cambridge group?

Scheuer:

Now, let me see…

Edge:

Graham, Tony… ?

Scheuer:

Well, certainly, Graham, Tony, John Shakeshaft… never very much… professional interaction with John Baldwin and –-

Edge:

Robin Conway?

Scheuer:

Robin Conway again… not a tremendous amount of interaction. Jan Högbom, a certain amount because we were both interested in the principles of interferometry if you like. George Whitfield, of course, he was my research student.

Edge:

Johnny Blythe?

Scheuer:

John Blythe. Probably not so very much interaction.

Edge:

Bruce?

Scheuer:

Bruce, early on, yes. Bruce, of course, very much very early on when I first joined the group because he was a very kindly chap and… and… I knew absolutely nothing.

Edge:

Now up until the time you left for National Service, had you really become aware of other people outside the Cambridge group as important characters in the plot as it were?

Scheuer:

Oh heavens, yes.

Edge:

Who would, by this time…

Scheuer:

Well, in the Manchester group, obviously Sir Bernard as being the boss, and Hanbury Brown, Cyril Hazard and obviously people in Australia, Mills and Christiansen and Bolton.

Edge:

But these are the only two good groups effectively, who at that stage were playing the game?

Scheuer:

These were the groups that were playing the game, there were of course a few optical astronomers who took a serious interest, in particular, Minkowski.

Edge:

Had you actually met any of these characters, had you been to Jodrell Bank during your first few years.

Scheuer:

Yes, yes, indeed.

Edge:

So there was some professional contact?

Scheuer:

Oh yes.

Edge:

Cyril Hazard?

Scheuer:

Yes.

Edge:

Hanbury Brown?

Scheuer:

Well, with those two together, they were working together at the time.

Edge:

Had you met or corresponded with Minkowski?

Scheuer:

I met him because he had visited Cambridge and we were a very small group then. There was only half a dozen people.

Edge:

Had you any contact with David Dewhirst or done anything with him or any of the other people at the Observatory.

Scheuer:

Certainly I knew David Dewhirst, but hadn’t worked in collaboration with him.

Edge:

Now since then, presumably, that — what shall we say — invisible college of people you think of round the world as being related has grown, because you said you spent some time out at British Columbia, going to CalTech and so on, now who… well, let’s take the cosmological phase, the P of D phase, who do you see as the main characters you were either arguing with or exchanging with in this area outside Cambridge?

Scheuer:

In the cosmological…

Edge:

In the cosmological area.

Scheuer:

Outside Cambridge?

Edge:

Yes.

Scheuer:

Well, that was mostly Mills…

Edge:

And in later stages McCrea… McCrea and Davidson, were they people you actually…

Scheuer:

I never actually met Davidson and… I don’t think I ever discussed it with McCrea.

Edge:

So they didn’t actually join the debate in terms of the contributions you put forward, the contributions you put forward entirely on the P of D, the radio source distribution counts, the shape of the envelope curves, and what have you.

Scheuer:

My memory may be leading me totally astray, but I don’t think McCrea particularly took sides in this.

Edge:

So Mills is the main person, and…

Scheuer:

Obviously, lots, lots of people made odd comments at various times.

Edge:

I remember Bolton producing a log N - log S curve with some…

Scheuer:

That was recently.

Edge:

No, no, no, this was a small note in Nature in 1958 in which he said it is all error spread, as you get smaller sources you get bigger errors and that explains… I can remember –-

Scheuer:

Oh yes, this was the effect that… Bennett sorted out, here, and lots of people have rediscovered since then.

Edge:

I had a look at it in my thesis too…

Scheuer:

You did.

Edge:

I rather enjoyed having a look at that. But that was just the small letters, the usual, joining in the fun.

Scheuer:

Oh yes, there were lots joining in the fun obviously. I wasn’t thinking of naming all those.

Edge:

Do you see yourself now in the new phase of discussion over radio galaxies and all the oddities with the small group of people you perhaps correspond with, or swap… do you swap pre-prints?

Scheuer:

Well, Cambridge doesn’t produce pre-prints, you see, except on very rare occasions.

Edge:

But among the people you distribute off-prints to…

Scheuer:

Off-prints are distributed regularly to a fixed mailing list for the group as a whole; we don’t normally send them from one individual to another.

Edge:

But do you see yourself in terms of a small cluster of people who share the same problems in the world now…

Scheuer:

Oh, there are now lots of them, because it isn’t radio astronomy any more, ever since… ever since optical identifications have been made with many objects, a number of optical astronomers have taken profound interest in radio sources, clearly the group of people one is involved with has grown enormously.

Edge:

Apart from the small group of students you have here, Malcolm Longair and Martin, presumably you still have close contact within the group here, professional contact.

Scheuer:

Well, obviously the contacts within the group are not nearly as good or as close as they used to be simply because the group is bigger, much bigger and one simply cannot know what everyone is doing.

Edge:

But there are some people you have very close contacts within the group still?

Scheuer:

Yes.

Edge:

Do you have close contact with anybody in the theoretical astronomy institute?

Scheuer:

Occasional… rather than… obviously when people go to the various groups that are there, there are four groups in astronomy in Cambridge, we go to each other’s seminars, that kind of thing. And occasionally one goes and asks somebody about a particular problem.

Edge:

Can I ask you one or two quite general questions? Looking back over the history of the Cambridge group since it began, what do you think are the major contributions it has made, the scientific achievements?

Scheuer:

Well one of the… major scientific achievements, okay — well before I came obviously there were a number of things such as the discovery of Cassiopeia, and really the simultaneous discovery with the Australian group of large numbers of radio sources and the identification of Cygnus and Cassiopeia, obviously the actual identification wasn't made here, but Graham Smith’s positions led to those, and… that’s one stage. Then there was the development of aperture synthesis methods which I think is a very important contribution, and the two things that Tony Hewish has been particularly associated with, interplanetary scintillation which emerged actually from several people’s work before it obviously became Tony’s province, and… obviously pulsars, the discovery of pulsars.

Edge:

Cosmological deduction?

Scheuer:

The log N - log S, yes, I think the log N - log S, sorry I left that out, that should come somewhere in the middle there — obviously this is an important… I think those are the things that stand out.

Edge:

Could you make a similar catalogue for Jodrell Bank?

Scheuer:

…Right, I will try to do that. On the instrumental side I think it is to their credit that through all the various trials and tribulations they produced the first large diameter dish and in the process made a lot of mistakes which… and rectified a lot of mistakes, which obviously contributed greatly to the design of all future…

Edge:

The risks that pioneers take.

Scheuer:

Quite. Now… what are the major scientific achievements? The meteor work is a very big early contribution. I think one should mention the development of the long baseline interferometry, the early development of it, for a long time they were alone in that field, that and the Hanbury Brown-Twiss device.

Edge:

Radar work with the moon and planets?

Scheuer:

I am so ignorant about radar work on moon and planets…

Edge:

You wouldn’t assess it?

Scheuer:

I don’t care to assess it really, obviously it has now been refined beyond recognition in America, but I really wouldn’t care to assess their role in that.

Edge:

If you were to compare Cambridge and Jodrell Bank in their contributions and achievements, which would you make pre-eminent?

Scheuer:

I don’t think quite honestly that’s a fair question…

Edge:

Okay, then. What would you say was the reason why Cambridge is pre-eminent, if you start to sort of analyze why it was that the Cambridge group which started up with very similar numbers as Jodrell Bank and has had a similar time scale.

Scheuer:

Yes… well… I think it is simply that I produced a longer list of things that one could pick out as important individual discoveries or instrumental development.

Edge:

Where has been the major source of these in the group, how is it the group appears to have produced a longer list of these?

Scheuer:

Oh well, one thing is clearly, it is that Martin has been tremendously effective as a leader of the group, with tremendous energy and has produced all sorts of new ideas, and obviously there is an element of luck that, for example, it has been said repeatedly in the literature, various review articles, pulsars were discovered by a remarkable piece of good luck, then on the other hand, I think it was Pasteur or someone like that, who said, ‘fortune favors those who are prepared.’

Edge:

That’s right.

Scheuer:

I think the remark about pulsars is not justified really.

Edge:

Can I show you a graph here, and ask you whether you think there is any reasonable interpretation of it — this is a graph in which each cross is a Cambridge radio astronomer –

Scheuer:

Yes.

Edge:

— and this is the year in which he joins the group in Cambridge and this is the years of delay before he became a fellow of the Royal Astronomical Society. You see here Martin joining the Astronomical Society in ‘48, and Harold Staniner also in ‘48, and apart from Pat O’Brien who disappeared back to South Africa, taking membership out then, which is rather an odd thing, all the rest of these are Cambridge people who stayed around and you see there is a very large bump in the curve and then around 1955 it comes down again to a relatively consistent… there are lots of people after here who recall around two to four years. Now do you think there is any significant interpretation of that — you see people joining around ‘46, ’47, ‘48 up to ten years or so delay before taking a fellowship of the Royal Astronomical Society.

Scheuer:

I find it hard to put any particular interpretation on that Because… there’s… joining the Royal Astronomical Society is… although one is formally elected, hardly anyone is ever refused. It is not as if people became FRS’s…

Edge:

No, no. On the other hand it means that people weren’t very keen to try in the early stages. Once Martin was in, people immediately following, the next generation didn’t seem to appreciate the need, not till much later, that is around 1955, you find most of these people joining around 1955, or shortly after. It looks… this is a sort of autonomous… Now, I wonder… at what time did Graham Smith become one of the secretaries?

Edge:

Well, Graham Smith did not become a fellow of the Royal Astronomical Society until I think it is 1957 — that’s Graham Smith there, ten years after he joined the group. I am willing to be outvoted on this, but I think you will discover that is so. So you think you might be able to interpret it as his pushing. Here we are, 1955, I beg your pardon, he is the eight year one. It’s Tony who was 1957. In 1955… He became a secretary much later, didn’t he, it doesn’t mention it here. I see. But he joined in 1955.

Scheuer:

Well, let’s say when somebody in the group got on to the Council, and came to be a secretary, this might induce whoever it was — I think it must have been Graham, but I am only guessing, to push people, to say, why don’t you join the R.A.S.

Edge:

Now there is the same set with the Jodrell’s Banks points added, and you will note again Pat O’Brien’s point here is odd, but there is a large number of Jodrell Bank people within the Cambridge envelope…

Scheuer:

Yes.

Edge:

…so there seems to be much less of a reticence. How would you explain that? A similar thing?

Scheuer:

I have no idea. As a theoretician it is my duty to provide you with a number of interesting theories, people’s offices being further apart at Jodrell Bank therefore requiring various copies of Monthly Notices.

Edge:

Yes. You don’t see this as in any sense to indicate that the Cambridge group, sort of beginning to appreciate itself after 1955, as more as it were within the astronomical ambit, seeing themselves more as astronomers, previously having been perhaps autonomous, more technical…

Scheuer:

That could well be that one has more interest in more of the papers that are published. That could well be.

Edge:

From 1955 on by and large the radio astronomical community in Britain seeing itself as more main line of astronomy, more astronomical, than it was previously.

Scheuer:

Yes, previously, you are quite right, previously radio astronomy was isolated to a large extent from ordinary astronomy because there were so few objects which we had in common.

Edge:

Such as the universe?

Scheuer:

Such as the universe, a couple of supernova remnants Cygnus, M87 and the sun.