Professor Chris Christiansen (1913-2007), physicist and engineer

Professor Chris Christiansen

Professor Chris Christiansen was born in 1913 in Melbourne. From the University of Melbourne he received a BSc in 1934, an MSc in 1935 and a DSc in 1953. In 1980 he was awarded a DScEng from the University of Sydney. After graduating with his MSc he was a physicist at the Commonwealth X-ray and Radium Laboratory in Sydney for two years. In 1937 he became a research engineer at Amalgamated Wireless (Australasia) Ltd (AWA). In 1948 he moved to the CSIRO Division of Radiophysics where he worked until 1960. He began his work in radioastronomy by investigating the quiet sun. To study solar radiation, he developed a new type of aerial array known as a grating interferometer. In 1953, by adding a second array of aerials at right angles to the original array, he was able to scan the sun in two dimensions. He developed the innovative cross-type radio telescope, known as the Chris Cross, which was completed at CSIRO's Fleurs field station near Sydney in 1957. Christiansen became Professor and Head of the Department of Electrical Engineering at the University of Sydney in 1960, a position he held until 1978. In 1963 the CSIRO handed over the Fleurs field station and its radio telescopes to his department. He retired in 1979 and moved to Canberra where he was a Visiting Fellow at the Mt Stromlo Observatory of the Australian National University until 1983.



Professor Christiansen, or Chris as he is more widely known, was born in Melbourne on 9 August 1913. The hallmarks of his long and distinguished career in science and engineering, spanning almost five decades, were his inventiveness and his commitment to, and success with, large-scale projects, mostly in radioastronomy. These projects were the outcome of his innovative skill as physicist and engineer. Paralleling this was his equal commitment to forging strong international links and friendships, leading to his election as Vice-President of the International Astronomical Union for the years 1964 to 1970, as President of the International Union of Radioastronomy from 1978 to 1981, and subsequently as Honorary Life President in 1984 and as Foreign Secretary of the Academy from 1981 to 1985.

Starting life as a goldfields mixture

To start at the very beginning, Chris, what brought your family to Australia?

I was a real goldfields mixture. My grandfather, Jens Christiansen, came from Denmark as a teenager, jumping ship in Melbourne and walking up to the goldfields. My father was one of about eight children. He went to the Three Mile one-teacher school and later to Beechworth College, in the north-east Victorian goldfields. He earned his keep and secondary education there by tutoring, which was a substitute in those days for the schools giving people scholarships. Later he went down to Melbourne with most of his brothers and sisters. They rented a house and all did different things. For example, one did metal work as an apprentice in a factory and one went to the Academy of Music; she became a professional singer. My father had a job at the National Library, and while working there he did his university course. Later he did theology and became a clergyman.

When and where were you born?

I was born in 1913, in Elsternwick, where my father was the minister of the local Congregational Church. When I was five or six, my father was shifted to a church in Perth, so we went across on the newly formed east-west railway, with our luggage following us by boat. Until my mother arrived with my sister and my brother, I batched with my father for several weeks. The manse wasn't furnished and our furniture was coming by boat so I ate with my father while sitting on a wooden box and with a jam tin on the table and so on: marvellous after normal home life.

My father died of peritonitis when he was 37 – he had appendicitis which was wrongly diagnosed – leaving my mother with four kids, I being the eldest, at seven, and my baby brother being three weeks old. The Congregational Church had no pension scheme in those days so my mother, who fortunately was a good musician, returned to Melbourne and brought us up there by teaching music at a local private school and also to pupils at our home. Strangely enough, having spent all her time looking after her brats and teaching music, she seemed to have nothing to do in the evening but to play the piano, and being the last to go to sleep (because I was the eldest) I always went to sleep listening to Beethoven, Brahms and so on.

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School, improved with hobbies and inventions

Where did you start school?

At the local State primary school in Perth. I was shifted twice during the short time I was there, I don't know why. Each time I was moved I was terrified at going into a new class.

What about the schools in Melbourne?

I went to the local State primary school, until the headmaster of a local grammar school who had known my father offered to have us three boys taught at his school at no charge. I don't know whether my mother would have accepted this, except that while I was at the primary school my aunt had spotted me hopping on the back of a tram during the lunch hour and hanging on from one stop to another. Apparently she relayed this information to my mother, who said, 'We must get him away from that school.' The result was that I went to Caulfield Grammar.

Was it in the later school years that you began your inventions – perhaps as a result of getting into trouble?

Oh yes, I did a few inventions at school and one was very popular with my cobbers. As a punishment – an ancient sort of thing the English used to go for – we would have to write out 100 lines, so I devised a way to do five lines at a time, cutting down our work to 20 per cent of what it was meant to be.

I became very keen on hobbies at school: that was much more interesting than my work, I found. I had an old Box Brownie and I became secretary of the camera club, and also of the radio club. I built several models of a crystal receiver, which was quite interesting work. The crystal receiver consisted only of a capacitor, an inductance, a galena crystal rectifier, a pair of headphones and a cat's whisker to make the connection. To buy a crystal rectifier cost me threepence, which would now be equivalent to a dollar and was an awful amount, but I had learnt about galena in my first-year chemistry at school and I thought, 'It's only lead sulphide. I've got some sulphur' – it had been used for something else – 'and there are some bits of lead around. If I cooked this up I might make some lead sulphide and it might do as a rectifier.' And to my surprise and joy it did, so I didn't have to buy any more rectifiers. In fact, I had enough to give to all my friends. In addition, I attempted to get some amplification (on analogy with the triode valve) by using a second contact on the crystal, with a different voltage. This was an unsuccessful attempt to invent the transistor.

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University: science studies and a special girl

Was it the hobbies that gave you an interest in physics and took you to a science degree at the University of Melbourne?

Yes. Actually, when I was applying for a scholarship at the university I had no idea what I should do. My favourite subjects were mainly physics, English and drawing. I thought, 'Well, physics and drawing go together in architecture, and I like building things, so I should apply for architecture.' Then at the last minute before I posted it, for some unknown reason I just crossed out 'Architecture' and wrote 'Science'. That's how I went to Melbourne University to do a course in science.

It was about now that you met Elspeth, wasn't it?

That's right. About a year before I left the university, in the Labor Club we used to have occasional weekend camps, with speakers. The club contained a pretty bright bunch, several of whom were in the honours English course. They said to me, 'There's a very bright girl, she always gets the Medal and she's very nice. We ought to try and get her to come along to one of our camps,' and apparently they persuaded her to come. We used to hire one of those old open trucks with a canvas over the top, and as she couldn't climb up I gave her a hoist into the truck. I must say I got quite a kick out of it. Anyway, we became very friendly. She got her MA at the same time as I got my MSc. Then I shot off to Sydney. She had thought of going to Oxford to do some further work, but she decided to stay and teach senior English at the Melbourne Girls High School. Her father was headmaster of the boys high school, and she came from a long line of headmasters. She stayed on for about a year.

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AWA: the radio research interest

Why did you go to Sydney, and how old were you then?

I was about 21 or 22. After graduation in Melbourne I spent two years at the Commonwealth X-ray and Radium Laboratory, but then Geoffrey Builder asked me to join AWA [Australian Wireless (Australasia) Ltd] in Sydney. He and John Green, the other head there, had previously been working for the Radio Research Board. There were some very interesting people at AWA, a very good lot to work with – John Downes, Fred Lehany, Alan Richardson and others.

How were the research activities of AWA divided up?

They were in groups. Healey and Reid, for example, were in a research lab connected with the factory itself. The biggest group, however, was the laboratory of Builder and Green.

What was it focused on, mainly?

At that time AWA had bought up all the patents of Marconi, Bell Telephone and so on in America and all manufacturers here had to pay AWA for the use of their patents. Everything produced in Australia had to have a sticker on it to say all the dues had been paid, and they all went through AWA, so that the real purpose of the research labs at AWA was to produce patents. Later on, when I was more senior, as a sideline I had the job of vetting patents that came in, from Germany and England and America, which AWA wanted to put on the list.

Was your first job there connected with patents?

No, the first job I was given was to produce a direct-reading field intensity meter. Then, because AWA was angling for the job of building the long-wave naval transmitter at Harman, near Canberra, I was sent to investigate the ground conductivity there – that is, to find out how rapidly long waves would be attenuated. The Navy didn't want to find that there was nothing of its signal left by the time it reached the sea. I did that first job with John Downes, who later became a CSIRO division chief.

I got married very shortly after that job, when Else was the senior English and Latin mistress at Ravenswood College, in Sydney. As my pay at AWA was pretty low, she was then earning more money than I was.

Aerials at war

By now World War II must have been beginning, was it?

Yes, as the 'Phoney War', when it looked as though the whole thing was going to be a completely phoney effort. At that stage AWA was saying, 'Business as usual.' But shortly afterwards the government began to realise that it was going to be a bit serious. The only communications between England and Australia were by a cable, which could very easily be cut, and the AWA Beam wireless in Victoria. That was a short-wave wireless link which used a single wavelength and was rather out of date, having been built by the Marconi Company in about 1926.

AWA then was half owned by the Commonwealth government, and doubtless had been told that the Beam wireless would have to be improved rapidly. I was sent down there to investigate the problems, to send up reports to the factory at AWA so that new receivers could be made, and particularly to see what I could do about the directional aerials. Although they were fine antennas, they could only be used at one wavelength, whereas because the ionosphere changed during the day, different wavelengths should be used at different times of the day.

A directional antenna which Bell Telephone had invented had the big advantage that it could be used over a very wide range of frequencies, but it directed energy in many directions as well. So it was quite bad for wartime use, because the enemy would be getting some of the signals.

People were worried about Japan by this time. To eliminate the nasty effects of signals going out in all directions, I decided to use a group of rhombics. This produced a very good design which, during the period when short-wave was used everywhere for long-distance communication, was the best antenna in use anywhere. It was used in quite a few countries, and brought me in five bob for my invention!

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An ecumenical antenna

Later you took part in an ecumenical venture for AWA. Tell us about that.

In a peculiar arrangement, AWA owned several of the broadcasting stations in Sydney but leased them to other organisations: for example, 2CH to the Council of Churches and 2SM – named for Santa Maria, I presume – to the Catholic Church. The difficulty was that AWA's stations were transmitting from very different locations, and various church congregations would complain bitterly that the rival signals were coming in much stronger than their own. Recalling an old question in mediaeval religion as to how many angels could sit on the point of a pin, I decided to try sitting both of these 'on the point of a pin' – putting both transmissions on the one aerial and using filters to separate them. This worked like a charm – the broadcasts for the Protestants and the Catholics came out from the same point and at the same strength all over Sydney.

Later on I used that when AWA was applying for the entire job of doing the New Zealand broadcasting system, putting in two transmitters at about a dozen stations . I said, 'At each station we'll put the two on one aerial'. Since AWA could produce one antenna more cheaply than a rival could build two, it got the job. (I think those aerials of mine are still all over New Zealand.) AWA in those days could compete with RCA and Marconi and Telefunken in other countries who were wanting to improve their radio broadcasting, so being the AWA expert in antennae I was always dragged in to design the directional aerials.

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CSIRO: joining radio to astronomy

How did you come to move to CSIRO?

CSIRO were starting to investigate mysterious radio signals from space, so I wrote and said I was very interested, telling them what I had been doing. I was offered a job in their radio research labs.

Who was there, Chris, at that time?

Bowen was the Chief, doing cloud physics and other things, and Pawsey was second in command, doing the radioastronomy.

Give us a thumbnail sketch of Pawsey, a very famous figure in Australian science.

He was a wonderful fellow – absolutely pure in heart, I think you could say. I remember a very advanced lecture being given at the university on a radio topic, going over practically everyone's head. When it came to questions, old Joe said, in his innocent fashion, 'I can't quite reconcile this with the conservation of energy.' This floored the lecturer completely, but Joe was absolutely right: the thing was phoney. But he would do this in such a nice way.

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Studying the sun by Earth rotational synthesis

What was your first job in CSIRO?

Joe Pawsey's group was at that stage studying the sun, although I think he stayed on it too long. That was one of the few things I could criticise him for. Thanks largely to Joe, it had been discovered by this time that most radio waves from the sun came as radiation from a pretty uniform hot body. Secondly, there was a thing called the slowly varying component, which changed slowly from day to day. It was known that when there were a lot of sunspots, it was highest, and when there weren't, it was lowest.

Still not identified to any location but just generally coming from the sun?

Yes, but known to be associated with sunspots. Thirdly, an occasional blow-up of the sun would always be associated with a big sunspot and with sudden enormous increases in energy that would vary like mad. Of those three main factors I was told to investigate this slowly varying component. The first thing I did was to record the radiation during an eclipse of the sun. I tried using three stations, but well separated – one in Tasmania, one in Sydney and so on – so that the eclipse shadow of any part of the sun would occur at different times at each station and we should be able to locate the emitting regions. That worked out very well and it also gave me an idea of the size of these regions, roughly three minutes of arc.

Was that very much larger than the dimension of a sunspot?

Yes. Then I thought, 'We can't wait for these damned eclipses. We ought to be able to look at the sun every day,' and I started to wonder how we could get such a high resolving power from a radio aerial that we could get down to three minutes of arc. You would need an enormous aerial if you made it in one piece but I thought, 'Well, if you have a series of aerials, not together but spaced out, you get a number of very narrow responses from that. If I can so space those that there is only one response on the sun at a time, we should get a series of scans across the sun as long as we like, provided we point the aerials in the right direction.' I worked out that we could collect the energy we would need with a lot of six-foot diameter dishes as aerials.

And they had to be steerable. Were they steered automatically?

No, we took it in turns to change them and the running kept us thin and healthy!

Where was the array, Chris?

I discovered that we could get the use of the side of the Potts Hill Reservoir, which contained the drinking water of Sydney. Only one of our people ever fell in.

You've got a picture there showing a close-up of one of the dishes. I think you have told me that they were made from 6 x 3 aluminium sheets welded together and then spun. Who are the three people in this picture?

I'm the one demonstrating part of the telescope to Professor van der Pol, the famous Dutch engineer and scientist. And there, with his black hat on, is Sir Edward Appleton, looking as though he were going to a morning party. This was at the 1952 General Assembly of the International Union of Radio Science (URSI).

That just gave, in effect, a knife-like beam across the sun, and so I built another one on another side of the Potts Hill Reservoir – this time we used mechanical help to turn the aerials. With this one we did something that hadn't been done before. By looking at the sun during about a 12-hour period, we were scanning it in every direction during the day as it went round the sky. By doing a bit of mathematical jugglery called Fourier synthesis we could get a real picture of the sun, with its hot spots and so on. This method of using the Earth's rotation to produce a picture is called an Earth rotational synthesis and now all the really big aerials in the world use it. But that was the first time.

Approximately how many individual sources on the sun were you looking at?

Usually not more than 10 or so. They were always associated with either the sunspots or where sunspots had been, the previous time the sun turned round.

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The first radio evidence of our spiral galaxy

About this time came some very interesting news from Harvard.

Yes, that's right. About the time of the URSI meeting, while we were still building the second linear array, we got news from Professor Purcell in America that one of his students, after working for a couple of years, had found a particular radio spectral line from space which would enable us to look, not at the hot or active parts of space, but at the hydrogen in the cold regions of space. This important discovery had been predicted by van de Hulst in Holland, but the Americans made it first. Purcell asked us to try to confirm the discovery, and he asked the Dutch to get a move on and have a go at it.

Was there any particular direction to look, Chris?

All we knew was that this had been seen with a fixed aerial when the Milky Way went through. With Jim Hindman as my assistant I got stuck into this very rapidly, using all sorts of old junk that we could collect. We did have to make up one special bit of instrumentation. Within six weeks we confirmed that the radiation was coming from the Milky Way, but we went further and mapped it all over the Milky Way, showing that in fact it had exactly the same shape as the Milky Way. Moreover, because we were doing it in a special way, we were able to show there were spiral arms in our galaxy – the first radio evidence that we were living in a spiral galaxy. Later, other people in CSIRO and also the Dutch started mapping these things in detail, and after a lot of time they produced between them very reliable maps of the source of radiation.

Our research was done crudely but it was good fun and the results were exciting. When Purcell's research student Ewen came over and saw the gear I had, with cables lying all over the floor and ancient oscillators, he said, 'My God, I can understand why you could do it in six weeks and it took me two years!'

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Avoiding starvation in France

You then went back to further work on the sun. But round about that time you went off to France, didn't you? Was there a particular motivation for that?

The French were very interested indeed in our work, and at the URSI General Assembly in Sydney one of them suggested that I go and work in France with them. I hadn't been overseas and I thought this would be great, so the family packed up and we went over to France. Unfortunately, I discovered there that the group I was with was not the best French group, so I didn't do as well over there as I thought I would. But I made up for it by learning a lot about France and optical astronomy.

Where were you based mainly?

I worked at the Meudon Observatory, near Paris, inside the stables of Louis XIV. I spent a lot of time there, learning about the optics of the sun. There were a couple of dear old souls who had been taking H-alpha pictures of the sun – for 50 years, I think, because inside the stables there were long planks of wood bent down with the weight of all their glass plates on them. I used to sit down and have my sandwich with that delightful old couple at lunchtime.

We were living in a beautiful 17th century house that had been divided up by le Baron for use by foreigners – the rents were so high that no decent Frenchman could afford it. In fact, it took the whole of my CSIRO salary to pay the rent, but he said, 'M'sieu, I am not a wealthy man and I cannot afford to pay income tax, so you will send me every month a little note thanking me for the use of the house and saying, "This is a small donation towards the expenses."' We nearly starved, as I wasn't getting anything from the French, but CSIRO made special arrangements so that I could get a bit of a hand-out from the Australian Embassy to pay for our food for each coming month. Oh, it was fun, though. We didn't starve.

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The Chris Cross

So after that you came back to Sydney. What then?

Both we and American astronomers were very keen on getting daily maps of the sun, but the Earth rotational synthesis method was useless for that purpose, being slow and getting only one picture a day. So I thought that if I combined my arrays in the form of a cross, as Bernard Mills had in his Mills Cross, this would enable us to produce a very narrow pencil beam to scan the sun, in television fashion, every few minutes.

Tell us about the early Mills Cross.

Oh, that was the first telescope at Potts Hill. It was invented by Bernard Mills and consisted of two lines of dipoles, one east-west and the other north-south, which gave a narrow angular response, very economically. I built a larger Mills cross with two lines of multiple paraboloids, rather than dipoles. This gave an angular response narrower than any existing radio telescope.

What was the principle behind doing a scan – your rastering, as it were?

We let the sun go through and then I would shift the response by an elaborate method of shifting the beam, running 30-odd little devices that went over the transmission lines to change the phase. We were producing daily pictures of the sun for a long time, and sending them overseas too.

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The way to go: one dish or more?

At this stage I think there were discussions within the CSIRO Radiophysics Labs.

Oh yes, quite bitter discussions, actually, because there were two lines of thought. For a long time Bowen had been keen on getting a great big parabolic aerial to follow Jodrell Bank, Manchester, and he was very strongly supported by Bolton. This would be very expensive and there were great discussions about whether it was worthwhile. Those of us who had done the work to produce economical telescopes with very high resolving power thought this was a lot of nonsense. Rather nastily I referred to what would be the future Parkes Telescope as the 'Last of the Windjammers', which I think those who were supporting it considered a bit of treachery.

What was the alternative that you favoured?

I wanted another multiple dish telescope, such as the one that was later built for the Australia Telescope. Bernard Mills and Joe Pawsey did too. Joe was so fed up that he accepted a job as more or less the number one person in radioastronomy in the United States. Unfortunately it was then found he had a malignant tumour in the brain, so he couldn't go. Although Bernard Mills was trained in engineering, not in physics, he got a Chair of Physics in Sydney and built a big aerial of the sort he wanted, a big Mills Cross, near Canberra. Several other people were thinking of leaving, and after a real bust-up with Bowen I said, 'I'm off.' I think he was only too pleased that I was going. Fortunately, I was able to take up a job offer as Professor of Electrical Engineering in Sydney.

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A detour to Holland

Prior to joining Sydney University you had an invitation from Holland, didn't you?

Yes. This was a complication. I went to the university and said that I had promised to go to Holland for a year. They treated me very generously, giving me special leave to go to Holland provided I went to the university first, for six months. So that suited everyone.

What was your mission in Holland?

I had been asked by Professor Oort in Holland to build a 400 MHz cross-type radio telescope. My family and I set off by ship again to Europe and during that time I worked out two good designs, as I thought, one consisting of a pair of crossed cylindrical paraboloids and the other, a lot of ordinary paraboloids.

Again two crossed linear arrays?

Yes, both crossed. When we got to Holland I produced this almost straight away and it was received very enthusiastically. I was given the task of organising the group that was going to build it. They had a very good scientist there but he said that he was used to working in small things and refused to have anything to do with these big shows. With the help of a very good Dutch civil and mechanical engineer we organised a gang of scientists, but what happened happened very slowly. We were all prepared to make a start, but Jan Oort had second thoughts. He decided that we'd do better at a much higher frequency than 400 MHz and told me to work out a design for 10 cm rather than 75. That would be 3000 MHz. So I got to work again on that.

Meanwhile, people were doing the electronics required for the lab, but suddenly, when it was pretty well going, the Belgians decided they were no longer interested. The telescope had to be very close to the border, and I had found what I thought was an ideal situation with the southern border going into Belgium: it was a suitable place to do it, and it ended right at a monastery that produced about the best beer in Belgium – a wonderful, wonderful situation! But the telescope was never built. When I left Holland, I left behind my offsider, Högbom, who got his PhD degree working with Martin Ryle at Cambridge. They decided to build a smaller compromise between what we had worked out and the Cambridge antenna.

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Earning an oilcan in Sydney

So back to Sydney and the beginning of about 18 years as Professor of Electrical Engineering. Madson was a very influential figure in Australian science. Did you succeed him?

I was worried. I'm not an engineer but trained in physics. I hadn't really wanted to change my profession. For some time previously this department had not had any consistent line of research – although the first professor, Madson, had been interested in radio work his interest in it had waned very much. The university knew I wanted to turn the department back to research (eg, radioastronomy) and very generously they gave me all the support in this that they could.

I came to the Chair under a bit of a cloud, I suppose, in that I was not a qualified engineer (although I had worked as one), I was a physicist and even worse I might be an astronomer. This didn't go down too well with some students. Later on, though, I got a couple of honorary doctorates in engineering, one from Melbourne and one from Sydney, the students presented me with a beautiful engraved oilcan, congratulating me on my 'first degree in engineering'!

Taking over the CSIRO field station

How did you set about increasing the level of research in your department?

First thing, I was looking for something cheap. I could see there were no radio telescopes useful at millimetre wavelengths in the country, so I worked out quite an interesting design for one, including a hole in the ground, spherical, with a correcting mirror which had actually been designed by Head in CSIRO. It looked quite a good scheme and I applied for money for it, but it was knocked back by someone who said that there was no interest in astronomy in millimetre wavelengths. That turned out to be ridiculous, because there were molecular lines which are terribly important. But then Paul Wild rang me up and said, 'Taffy [Bowen] is going to bulldoze all your aerials. Why don't you ask CSIRO to give them to the university?' That was an excellent thing of Paul to do, and CSIRO was very generous. We took over the whole field station.

Did you modify it?

Oh yes, by turning it into a really sophisticated instrument, putting in several large antennas, well spaced from the existing arrays. We got the resolving power down to about a third of a minute of arc and produced some beautiful pictures of various sources in the sky, with more detail than before of any source in the southern hemisphere, but I don't think anything startling in astronomy came out of it.

A very good training ground for electrical engineers, though.

Yes, and it turned out that our engineers – for example, Bob Frater was really my offsider on this – played a major part in the building of the Australia Telescope.

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The Chinese connection

You were gradually increasing your international connections, including training students who would return to their own countries. Was it the 1963 International Astronomical Union assembly which led to your intense interaction with China?

My interest started in about 1920 through an aunt who was matron of a missionary hospital in China. I later read a book called Red Star over China, by Edgar Snow, and became still more interested in China. When I had to go to the IAU meeting in Japan I thought, 'Why don't I try to get into China?' So I wrote to the Chinese Academy, saying that I was representing our Academy, more or less, at the meeting and asking if they could help me to get a visa to China. Nothing happened for quite a while, and then suddenly they said they would be glad for me to go as their guest, and give lectures and so on. They'd read everything I had ever written, I think. After that the connection just increased, because while I was there I met the President of their Academy and I suggested that he ask our Academy to send a delegation to China. A delegation did go, probably in 1964, and in return a Chinese one came to Australia.

When I made my first visit, they told me they were having soon the first big scientific conference in China for very many years, maybe even the first general one, and they asked me, 'How about getting a delegation from Australia to this one?' So I collected a few people who wanted to go, and we went the next year to the Peking Symposium, which was for all branches of science. That enabled me to visit their '10 cm' telescope at Purple Mountains Observatory, near Nanking. They were quite interested in radioastronomy there.

I asked one of their astronomers, who spoke excellent English – an extremely bright and interesting person – to come to work with us in Australia for six months. He and another, much younger, fellow came and lived with us for a while and then in a college at the university. As he left us he said, 'You've got a sabbatical year coming up, Chris. Why don't you spend it in China?' I thought, 'That's an idea,' so we went to China.

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A much longer wavelength in China

Where did you go in China in 1966, on your sabbatical?

I went to Peking, but way out from the city, where they were building a version of my first radio telescope at a much longer wavelength. They had made a small model of it and had started on a larger one.

And so you had to set to and actually create it, did you?

Yes, but they were getting pretty clued up by this time, anyway. Also, I had to give a lecture every morning – an hour and a half, but it went for three hours because it had to be translated. The students were a bright bunch but I was a bit worried about the way they started talking about my 'teaching', as though this was coming from heaven or something. So I said, 'Look, I'm waiting for someone to say this is a lot of rubbish.' That rather shocked them, I think, but after that they did have a go at me if they thought what I said was wrong.

You found yourself right in the middle of the Cultural Revolution, didn't you?

Oh yes. No sooner had we got there when they said, 'The Great Proletarian Cultural Revolution has just commenced. We're against bad authority.' As soon as my colleagues back at the university heard this, they said, 'Chris up to his old tricks!' Anyway, the young people were really in revolt, egged on very strongly by Mao. They were all shouting out, 'To rebel is right,' and large demonstrations were taking place.

It was a terribly interesting time to be there but it was a bit difficult for me to do my work. The construction was being held up because the young people were spending all their time at meetings. I got fed up one day because I wanted to get the transmission line in, which meant putting in a lot of posts, and nothing was being done at all. So I said, 'Look, we can't do anything until they're done. For God's sake, get me a pick and a shovel and a crowbar.' The ground was frozen stiff – it was minus 20 degrees – but I started digging post-holes. After I had done a few, I had to give up to go back to where we were living. When I arrived at work next morning, the whole lot was done. The boys had worked all night, at minus 30 degrees. They were good lads!

Tell us about your son going to live in a commune.

Steve went with us for all our time in China, just after he had started at the ANU doing Oriental Studies. He was a bit of a linguist, having had primary school in France and secondary school in Holland, and within six months he became fluent in Chinese. This was wonderful because a lot of things were not released to foreigners in the Cultural Revolution – the Chinese always play their cards pretty close to their chest anyway – but Steve could give us all the lowdown on what was happening. He was working at the Language Institute, and he and his fellows all went out to work on different communes. He enjoyed it so much, he didn't want to come back to Australia. The local peasants reckoned he was a beaut worker.

Did you get the telescope array erected?

Yes. It wasn't in a real working order when I left, but they have since been producing some very beautiful maps with it. In real Chinese fashion, they've got their maize growing right around the edge of the array. They're not going to waste anything.

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Recognition in China

When was it that you had the pleasure of meeting Chou En-lai?

It was while I was working over there. He was terribly busy – in fact, that was for him a sad and historic day. He'd had the first visit from an American, Nixon, and had just been down seeing Nixon off; and also that very day (although I didn't know it when I met him) he'd got the report from his doctor that he had terminal cancer. I was introduced to him just as, 'This is Christiansen from Australia,' and he said, 'How's that telescope going?' So he was really on the ball. He always used to go to meetings of the Academy, apparently. If he had not died, I don't think the Tiananmen trouble would have happened, because he was always right on the spot where any trouble was brewing, and was a real diplomat. He knew absolutely how to hose anything down.

Your work in China, both in the scientific and in the cultural sphere, was acknowledged, wasn't it, by the Chairman of the Chinese Academy.

That's right, yes. He gave a nice speech in which Bohr and a lot of other famous scientists were mentioned – it was wonderful being put in the company of such people.

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Ripples from a fortuitous life

You retired from Sydney in 1978 and you were Foreign Secretary of the Academy for four years from 1981. To make the job a bit easier, I think, you moved up to Canberra in your retirement.

Yes, and the ANU very generously gave me part use of a room at Mt Stromlo. That enabled me to do the two things I had in mind. I wanted to produce a second edition of my book with Högbom, Radio Telescopes. The first edition had been written in China in 1966, throughout the Cultural Revolution. It had done very well, being translated into Russian and Chinese, and the Cambridge University Press wanted a second edition and also a paperback. And also I was working in the International Union and for our Academy.

You were elected as Vice-President of the International Astronomical Union from 1964 to 1970, and as President of the International Union of Radioastronomy from 1978 to 1981 – very fitting tributes to your work and the fame you had achieved in radioastronomy. Just briefly, what reminiscences of life would you give us?

Well, it does look a bit as though I'd had a nicely planned existence, that I'd been interested in astronomy and then went into radio, and then that just fitted perfectly into radioastronomy. But everything happened purely by accident in my life. I didn't plan any damn thing.

Having had roughly a third of my working life in the research lab of an industrial factory, a third of it in CSIRO, a research organisation, and a third as a university professor, I would have to say that my most interesting time undoubtedly was in CSIRO. Most of the worthwhile things I did were there, although being at the University of Melbourne as a postgraduate and working in AWA were very interesting too. One's ideas probably diminish in number as one gets older, because I had dozens of them in that early period. Then the University of Sydney treated me very generously, allowing me time without any demur to do work for the international unions and the Academy, and also encouraging me to build up an engineering department into a sort of research organisation.

Do you think that the ripples from your work went out more from your university years, simply because you were training students?

I think so. That is the good thing about the university work. One takes quite a bit of pride in what one's offsiders have done, and even now, getting on for 20 years in retirement, I get a lot of kick out of seeing what my former students are doing and their contributions to science and engineering. You get a long-lasting pleasure out of that, which compensates for the slight irritations you get at university from never being able to do anything without being interrupted.

On that note we'll finish, Chris. Thank you very much for giving us your time for an entirely fascinating interview.

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