Dr Guy White, physicist

Dr Guy White

Physicist

Guy Kendall White was born in Sydney in 1925 but spent his early years in country New South Wales. In 1935 he moved to Rose Bay, Sydney where he attended Scots College. After high school, White completed a BSc (Hons 1) (1942-45) and an MSc (1946-47), both from the University of Sydney. During his university holidays, White worked at CSIRO’s National Standards Laboratory on wartime projects. In 1947 he took up a CSIR Overseas Studentship to attend Oxford, graduating with a PhD in 1950.

White returned to Australia as a research officer at the CSIRO Division of Physics (1950-53). White moved continents again in 1953, this time to the National Research Council, Ottawa. Here he worked as a post-doctoral fellow (1953-54) and then associate research officer (1955-58). The warm weather lured White back to the CSIRO Division of Physics where he worked as a principal research scientist (1958-62), senior principal research scientist (1962-69) and chief research scientist (1969-90). While at CSIRO, White visited the prestigious Bell Laboratories in New Jersey as invited visiting scientist (1965-66) and the Universities of Oxford and Leeds as a senior visiting scientist (1976). The latter enabled him to update a new edition of his widely used text on Experimental Techniques in Low-Temperature Physics. Upon retirement, White was made an honorary fellow of the CSIRO Division of Materials Science and Engineering (formally the Division of Telecommunications and Industrial Physics) (1990 – 2008).

Teachers' notes to accompany this transcript.
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Interviewed by Professor Neville Fletcher in 2010.

Contents


I am Neville Fletcher and I am interviewing Guy White for the Australian Academy of Science. Good morning, Guy. It is nice to be talking to you. We have known each other for a very long time, haven’t we?

I hate to think how long.

It goes back to 1950, I think.

In your case, you have been well preserved over all these years.

Landless Country Boy

You started as a country boy in New South Wales, didn’t you?

More or less, yes. My family were all country farmers on Dad’s side. James White arrived with sheep for the Australian Agricultural Company back in 1824­1825 and he stayed with them for a few years. Then he got friendly with Dr Bowman, who was the head of the Australian Agricultural Company. He got some very good land grants for his six sons along the Upper Hunter, in Muswellbrook, Denman and Murrurundi. The trouble is that one son, my grandfather, decided to go into the church. So I had no land. His brothers sent him to Oxford as that was before Sydney University opened. My grandfather did his BA at Oxford and came back to be a rector and then Archdeacon of Muswellbrook for 40 years.

So Dad and his brothers had no land and they had to make their own way. A couple of them went to university and one did medicine. Another did engineering and one did law. But, there must have been a depression in the eighties, and dad got a job as an overseer for one of his relations, the Bettingtons. They had properties out at Merriwa. He was looking after sheep until the First World War and he then went to a Light Horse Regiment in Gallipoli and Sinai. By the time he came back, he was 48. After a while, in 1924, he got married and I was born a year or so later. But I spent all of my holidays up in the bush.

My Dad tried orcharding after the First World War in Terrigal, which was a lovely little village in those days. It had a few fishermen but nobody else there. But the orchard failed when the depression arrived. He said that you couldn’t give away oranges then. He lost the orchard in 1930, when I was about five or six. He then got a job with his brother out on the Barcoo on a property called Albilbah. It is out beyond Blackall about 100 or 150 km. He had a job there and he stayed there for the rest of his working life. But there were no quarters there for married people and no school. So Mum and I moved down to Sydney when I was about nine or ten.

So you became a city boy rather than a country boy.

My mother had had one or two jobs, looking after houses of old friends of hers up in the Dungog area and up at Goondiwindi. That’s where I learnt to ride when I was about six. I became a fair horseman by the time that I was about ten. My relations and friends were always glad to have me on the place. Particularly when the war arrived and their sons were all away at the war and they wanted somebody who knew how to handle a reasonably young horse and a mob of cattle or sheep. I rather liked it. Incidentally, it gave me an interest in geology, although I never became a geologist.

Eventually you decided on a career in science. Did that start at high school or somewhere else?

Scots City Boy

When I was about ten, in 1935, we came down to Sydney and rented an inexpensive little flat in Rose Bay. With the help of friends of Mum’s or aunts, they managed to afford for me to go to Scots College. It was a school nearby. I wasn’t a boarder. I was a day boy. I think people of my mother’s generation would have thought about careers in medicine, engineering, dentistry or law. I wasn’t very keen on any of those, but at Scots I had a very good teacher in science. You might have met him once before he died, Michael Simmons, he was very well known. He was a PhD from London University and he used to come to all the AIP physics lectures. In those days, health restrictions weren’t so great and you could do interesting experiments. You could drop bits of sodium into water and see it go ‘whoof’. I think he excited me in physics, and particularly in chemistry, although I lost that a little bit after first year at the university.

There was also a geology teacher at Scots who was very good. He used to take us on excursions. In those days, boys’ schools unfortunately didn’t do any botany or zoology, only the girls’ schools did. I mistakenly dropped French after the intermediate exams and did geology for two years and I loved it. I did a year in geology at university, but there were no jobs for geologists. That was before the days of the nickel boom and Poseidon, so there were no jobs for geologists. I stuttered then, and I still do a little bit, so I decided that I didn’t want to be a teacher. I wasn’t the teacher type, I think.

Summertime physics job

So physics grabbed you while you were at university, did it?

Yes. I found first­year organic chemistry a bit dull, but physics gradually grabbed my interest. That was largely influenced when, by the end of second or third year, I got a vacation job at the National Standards Lab. It was only 300 or 400 yards away in Sydney University. Of course, it was moved later. At that time there were some very good people there. When they first started the Standards Facility in CSIRO there were graduates in physics in Australia but there were very few jobs. You had to wait for a professor to die. As a result, when the National Standards Lab (NSL) started to recruit in 1939 they got some very good people. They got university medallists from various universities around Australia, people like Beattie Steele and various others. They were fun to work with. I worked one summer in photometry and one summer in heat, measuring and controlling the temperatures of oil baths for wartime. These were wartime jobs, essentially. The photometry was measuring the filters that were used by aircraft pilots. The pilots needed to have particular types of filters in plane spotting. They needed to pick out Zeros or Japanese aircraft that were approaching against a sunny background. Anyway, photometry was fun. Ron Giovanelli was the head of that group. But the next summer I worked in the heat section under Alan Harper, who was later ‘Mr Metrication’. I learnt quite a bit there about how to make little thermocouples and temperature

He was the one who led Australia into the metric system.

Yes, he was the chief executive officer. I won’t say that he was the brains behind it, but he was the driving force.

So you had this summer job at CSIRO. Then, you wanted to go on to a PhD. There were no PhDs being offered in Australia, so what led you to Oxford?

Two or three things. I had done my masters degree in Sydney in an aspect of nuclear physics. It was using a plasma source to produce deuterons which you fired at other deuterons and produced neutrons. John Carver was with me there. He was a year behind me, but he helped me with measuring counters for detecting deuterons. But I wasn’t grabbed by nuclear physics in particular. It was fun and I learned quite a lot about high­vacuum techniques, but that was that. The powers that be in the NSL realised that, with wartime work being over, they had to find some long­term strategic jobs, which ultimately would also be helpful to industry. One area they picked was solar physics. This was because Ron Giovanelli was a theorist in flares on the sun – why you get sun spots and all this sort of thing.

That was one field. The other was largely influenced by George Briggs who was the chief at the time. Although he had been a nuclear man at Cambridge with Rutherford, George thought that there was nobody in Australia who knew much about low­temperature physics. Except that liquid oxygen was used in welding plants and that it was made by CIG at Alexandria. But there was no feeling for anything below liquid air temperatures. With the space age coming and rocketry for various things being developed, it was thought that this was an area in Australia where there ought to be a laboratory that knew something about it. So they set out to make a helium liquefier, which they did. It is the only homemade one. The rest were those invented by Sam Collins at MIT during the war and then made commercially by Arthur D Little. By the late 1950s they had sold hundreds of them. But Australia had no dollars in those days, so our lab, with a very good workshop, made it by the same design. Dear old Sam Collins, who designed this, was a great guy, an ex-farmer but a very good engineer. He and Howard McMahon, who was the head of Arthur D Little, gave the drawings to NSL. They knew that we had no dollars for buying a liquefier. When I got back from Oxford in 1950 it was just in working order.

Super-cool at Oxford

Getting back to Oxford, the fact was that CSIR were offering studentships in various areas. Some of the guys in CSIR went to work with Oliphant in Birmingham on nuclear physics, but I decided that nuclear physics wasn’t for me. I did get short­listed for an 1851 scholarship, but I decided that a bird in the hand was worth two in the bush. I knew that with the help of Harper and Briggs, I was assured of a CSIR studentship in learning about cryogenics and low temperatures. That is, how you liquefied helium, how you liquefied hydrogen, how you poured liquid oxygen, etc. So I gladly accepted it. My theoretical colleague, who was a year behind me, Paul Klemens, also got a studentship to do theoretical work at Oxford.

Oxford at that time was the key low-temperature lab. Cambridge had a good one, but it was much smaller. There was also the Kamerlingh Onnes’ laboratory at the University of Leiden in Holland, where helium was first liquefied. The war years had chopped it to pieces. They had almost stopped a lot of their work. Mind you, they became a very good lab afterwards. But Oxford was the key place. Partly because they had got three guys I admired very much who had all left Berlin. They had all trained under Walter Nernst, a famous thermo-dynamicist. He developed the third law of thermodynamics and various other things. Nernst was a kingpin in Berlin and a friend of Bismarck’s. Lindemann trained under him – he was an Englishman. But Nernst had three other very good students who all had Jewish backgrounds, Simon, Mendelssohn and Kurti. They all wisely decided to leave Germany, although Simon had gone first to a chair at Breslau. They all accepted the financial support and jobs that were offered at Oxford, partly through Lindemann. Lindemann – or Lord Cherwell, as he was later – had a friend who was the head of ICI in Britain and they had funds. So a lot of other people with Jewish backgrounds came from Germany – Peierls was one and there were various others. Some stayed in England and some went on to America. But it was during that period of 1932­33 up to 1936­37 that migration certainly helped physics in England and in the States.

Was your time at Oxford a really great one?

Oh yes, it was fun. Food was a bit scarce and rationing survived for years after I left there – but it was fun. There were so many other things to do, apart from working with your liquid helium until two or three in the morning and then cycling home in the dark. There were a lot of very good people there. A lot of them had been servicemen who had been held up by the war but some were younger ones. There were people who afterwards were Fellows of the Royal Society and had chairs in various places around the world. It was a very stimulating atmosphere.

What sort of low­temperature work was being done at Oxford that you were a part of?

The nominal head of the lab was Lord Cherwell, but he spent half of his time in London helping Churchill or something. Simon – later, Sir Francis Simon – was my supervisor. He said, ‘We don’t know very much about properties of materials. We’ve done a bit of work in the liquid helium range’, which is between one and four degrees absolute and where you use a little bath of liquid helium that you dip things into. ‘But there’s a whole range from there up to 100 degrees absolute liquid oxygen temperatures that we don’t know very much about. We don’t really know how the electrical conductivity and the thermal conductivity at these temperatures behave.’ He said, ‘I’ve got somebody working on phased transitions in solid hydrogen and there’s another man working on the effect of pressure on the melting point of helium. Kurti is in charge of the high magnetic field studies looking at what happens to magnetic impurities and various things. Why don’t you do this?’ But first he said, ‘I’d like you to try building a slightly larger helium liquefier. We have a hydrogen liquefier here and everyone has their own individual little helium liquefiers made by what’s called a Simon technique.’ In this technique you compress helium in a little bomb at very high pressures and then expand it quickly and you are left with a bit of liquid. Simon said ‘But we also have another type of liquefier in which you use the Joule-Kelvin effect’. In this one you again compress helium but then you let it dribble through a little valve very slowly. Some will cool and some will liquefy and you will have liquid helium.

When you do it in a glass vessel you can actually observe the liquid helium and the funny things it does when it becomes a super fluid. It becomes a super fluid when you cool it down below 2.2 degrees absolute, or -271oC. This was most exciting. The thing that you first see is that it bubbles away like water in a kettle – it bubbles everywhere. But then you pump on it and reduce the pressure and it cools down. Then suddenly ‘wham’, it is absolutely still and quiet. You could hardly see it because there are no bubbles in it any longer. By that time it has become what is called ‘superfluid helium’ or ‘helium-2’ and it has perfect thermal conductivity. This means that any evaporation takes place at the surface. It is of a uniform temperature all the way through. Whereas in a kettle, and in ordinary helium, you get spots where little bubbles appear and the bubbles come up through that spot. But, once you cool helium below this so-called ‘lambda transition’ it becomes a superfluid. The word ‘lambda’ is a Greek letter (Λ) and its use signifies that one of the properties goes to this lambda shaped curve, thus they called it a ‘lambda transition’. You see it first after you have spent hours waiting for your liquid hydrogen and then waiting for the helium to cool down. You suddenly see it there and the helium becomes absolutely transparent and you can hardly see it any longer. I still get an excitement out of seeing it change. Actually, as I said, to see it you have to have a glass-tailed Dewar. You have another glass thermos around the Dewar, which nowadays contains liquid nitrogen but in those days we used to use liquid oxygen. Nowadays, people wouldn’t allow liquid oxygen around Dewar with liquid hydrogen so close.

Was that a long job?

With about 20 or 30 guys all doing some aspects of low temperature research, you had to wait your turn in the day to get your big Dewar of liquid hydrogen, which is the pre-coolant for the helium. You might get some at 10 o’clock in the morning or you might not get it until three or four in the afternoon. If you got it in the afternoon, you would probably work through until two or three o’clock in the morning. Once you got the liquid hydrogen, you then used that to cool the compressed helium and, when that liquefied in half an hour or so, you finally got enough liquid helium to do the experiment.

My experiments were measuring the rate at which the superfluid helium flowed through very fine channels. We were measuring the viscosity of the liquid helium, either the superfluid or the ordinary fluid, as it went through the channels. Actually, if it were an ordinary fluid, it wouldn’t flow through at all. But, once it was super fluid, it would go through. Also it has a funny habit. Imagine a little glass cylinder or glass test tube full of liquid helium – once it becomes superfluid helium, it forms a film up over the glass and comes over the edge and drips off the bottom. You can’t actually see it, because it is only about 100 atoms thick – but you can measure the drips as they come off the bottom. One of the interests in those days was to find out how the liquid helium did this, why it did it, what the forces were that drove it up and down again and did it matter whether it was a glass surface, a platinum surface or polished or etched glass. My first job was to make a helium liquefier and then pursue the flow rates. So the first papers I wrote were on that area.

Friends and fun at Oxford

I guess there were other distinguished researchers there working on similar things.

Yes, on similar things. In my room there was a guy named Keith McDonald, whom I worked with later in Canada. He was a Fellow of the Royal Society by the time he was 38, but sadly he died of central motor neurone disease when he was 42. He had been away in the war for a little while and he had worked as a scientist at Shrivenham, the defence laboratory in the south of England. I worked in the same room with Keith. The only problem was that his music was Gilbert and Sullivan. He would sing Gilbert and Sullivan all day. You might quite like it, but I am an early jazz man. Anyway, Keith and I got on very well. There was another Canadian guy, Jim Brown, who was there on a scholarship. Also young Graham Hercus came over two or three years afterwards – his father was a professor in Melbourne. And there was Jorgen Olsen from Zurich who did a lot of very fine work on superconductors and who is a very old friend still – or was, until he died recently. There was a group of about five or six. We shared one rather big laboratory, where we had room for our ‘cryostats’ or ‘liquefiers’. We used to wander off and have lunch together at the nearest pub.

Actually, for the first year or two I used to lunch in Magdalen college. I was rather fortunate. At Sydney University, the lecturer who tried to teach me thermodynamics, without much success, was Malcolm Fraser (JM Fraser) – he was no relation to the ex-PM. He had been to Oxford and he was an old friend of one of the senior men in Magdalen College. He said, ‘I’ll get you into Magdalen. It really is one of the nicest places’ – and now I would agree. It is one of the most beautiful buildings in England. He got me into there. He said, ‘Via that, you’ll easily get into the Clarendon Laboratory’, which is the research laboratory where I worked under Sir Francis Simon.

Did you enjoy all that extra social life while you were there?

Yes. I joined the swimming club – I was captain of it for a while. An old friend of mine, Lloyd Williams, who was in CSIRO ceramics, he was very good. He was a Rhodes Scholar. He was a very good swimmer and also a very good oarsman. He worked in CSIRO at Fishermen’s Bend for years. I was captain of swimming one year and he was president the next year. We both swam together. Peter Treacy, ex-Sydney Uni and later ANU, swam for the opposition – Cambridge. Every year you would have the main competition in the year in each sport. If you competed in that, you would get a Blue. So Lloyd and I used to swim against Peter Treacy down in the big pool into London. Afterwards they had us dress up in ‘black tie’ and have a very good dinner. That was always fun.

That’s very Oxford like.

During the year you went swimming against other schools and London clubs. And, except for the cold exercise of cycling up to the pool, which was where the Oxford Temple Cowley car-works were, there was lots of fun. Also, there were various clubs that you could join. You could try the socialist club, the labour club or the something-else club. There were functions that you could go to or a ‘law moot’ and hear discussions.

It sounds like an interesting time. I guess that the stuff you did really shaped the rest of what you were going to do for the rest of your life, didn’t it?

A few thousand miles from the grapevine

In 1950, you came back to CSIRO.

Yes. I think you were asking about whether I had to think about where I was going. But actually I was at Oxford on a CSIRO studentship, so there was a guaranteed position back there. At the same time Paul Klemens, who was a year behind me, came back to the same CSIRO lab. Another man named John Rayne, also went on a CSIRO studentship to the Chicago Institute of Metals, where he also did low­temperature work. He was looking at elastic constants, bulk moduli. That is, how the moduli of elasticity vary at very low temperatures. He also measured their heat capacity. He came back to the CSIRO lab, so we were a nice little group working on related problems. Not measuring the same things but things which all joined together: conductivity, heat capacity, and measuring metallic strength by sound waves. At the time I arrived back in Australia in 1950, the National Standards Laboratory liquefier was just beginning to function. It had a couple of teething problems which we solved, so I was able to get on.

I had some good advice before I left Oxford from my supervisor, dear old Simon. He was always wandering the world, speaking somewhere else, so I didn’t see him very often, except at Sunday afternoon tea. I would go around and Lady Simon would provide afternoon tea. But, before I left, Simon said, ‘White, I would not try to do work on the properties of liquid helium or super conductivity. You are too far away. The main work on that is here. And in Leiden, Harvard, MIT and Cambridge. But there is all this other work on the transport properties. That is, the thermal properties of materials over the whole temperature range, that we don’t know very much about. We know a little bit about the transport properties right down the bottom of the temperature range and a little bit up high, but we don’t know very much in between. There you have a wide open field and it doesn’t matter if you’re a few thousand miles from the grapevine.’

That was good advice, wasn’t it, and it shaped what you were then going to do?

Yes, it did. He sort of shaped this. I got a real technical interest in measuring things, especially in terms of the aerospace age. People didn’t realise, that if you pick about five bits of copper off the shelf – one very high, one very pure and one ‘free machining’ copper, etc – at low temperatures the thermal conductivity can differ by a factor of a thousand. And these low temperatures are what you have up in space. This diagram here shows the thermal conductivity up this axis against temperature. The temperature is in what is called a ‘logarithmic scale’. It goes from one degree absolute, or -272oC, running up to 100 degrees absolute (-173oC) and up to higher temperatures. All these curves here represent the thermal conductivity of various types of copper. They show the enormous difference in their conductivities. At high temperatures they tend to come together but at low temperatures, where the conductivity is dominated by impurities, they are all vastly different. As I say, there is a factor of about a thousand between here and here (indicates). This is an ultra-pure copper – copper which probably has only impurities of one part in a million. Whereas down here we have other coppers, some of which contain up to half a per cent of tellurium. There is one here called ‘free machining’ copper.

Firstly, I looked at copper, silver, gold, magnesium and aluminium to get a feeling for those. I looked at their electrical resistance and tried to tie it in with what Klemens was doing in the theoretical area. Before the war, John Bardeen and Rudolph Peierls had done some work on this, as well as Dick Makinson at Cambridge. Incidentally, John Barbeen was the only man who ever won two Nobel Prizes in the one subject. Anyway, they had a simple theory using the scattering of waves that would determine the thermal conductivity and electrical conductivity in these metals. That is, scattering similar to sound waves or lattice waves. They worked out a theory of what it would be like at low and high temperatures. It turned out, when you went to measure them, that the theory was quite right. But the ratio of high temperatures and low temperatures was different by a factor of four or five. Klemens eventually explained this in terms of what are called ‘Umklapp processes’, as when the electron collides with a phonon. ‘Umklapp processes’ is German for ‘flip-over processes’.

It is a bit like Bragg reflection in X-rays. When you see an ocean wave coming against a wall, it reflects backwards. But if it hits a post, it just gets broken up into little bits. That’s really what Bragg reflection for X-rays is like, and these conductivities in metals are the same sorts of processes. This had been neglected in the early theories.

Your main interest was in the experimental part, finding out what happened, but there were other people around you who did the theory and worked that out.

Yes. John Rayne was interested in the heat capacity, which is related to these things as the heat in a metal also controls how much heat it carries around. We worked quite separately with our own things, but we interacted. Ron Kemp was involved in it, to a certain extent. In that he had done a lot of hard work on making the helium liquefier. Later on, Bogle came back from overseas and we interacted too.

Given that you were doing this practical stuff, if I were to ask you a modern question, I’d say, "Did you invent anything that made a lot of money for somebody?"

Not directly. As far as I was concerned, that was the justification for doing curiosity work using cryogenics. The message was already getting back to me from the States that they wanted to know how the physical properties of brasses, stainless steels and various things behaved when you were up at four degrees Kelvin or so in space.

But one hoped also that Australian industry would get interested, but there wasn’t much interest. Lou Davies, who was making very nice silicon crystals, was persuaded by Taffy Bowen to leave CSIRO and go and join AWA. Lou had learnt at Oxford how to grow silicon crystals. He had built up a nice little group in CSIRO and NSL for doing it, but then he disappeared and was wafted away to AWA. That work lasted for a while in AWA but, as you’ve pointed out, they thought they weren’t going to make money out of it and eventually they forgot it.

Canada eh?

Despite the fact that America was the leader in the space race in those days, you didn’t go to America; you went to Canada instead.

I had had three years in the National Standards Lab, from 1950 to 1953, but I was a bit tired. Thermal conductivity and electrical resistance were being tied together very nicely and I had a very good theorist to work with and there were interesting people to talk to. But I had itchy feet and I wanted to travel. I had been up to an ANZAAS conference and met Hertzberg’s offsider in the National Research Council in Ottawa, Dr Howlett. He said, ‘We’re just setting up a low-temperature group in Ottawa in the National Research Council of Canada. I’ve got some very good people. I’ve got MacDonald and we’re already a going concern there. You ought to think about it. We have these postdoctoral fellowships.’ They had a much more regular scheme than CSIRO had. Every year they advertised at least 100 to 200 postdoctoral fellowships. In my case, I was later invited to join the staff there.

But you didn’t take the job. You decided to come back?

Well, I did join the staff. But I said, ‘I’ve got to go back to Sydney. I’ve got a Colombo Plan student, a very good one.’ His name was Sreedhar and he later was the head of the NPL in New Delhi. Before I left, I said, ‘We have done copper. Why don’t you have a look at iron, titanium and one or two other things that we can get nice pure and ordinary crystals of?’ He was actually doing some of these measurements. We also had quite a good technical assistant, Ron Tainsh. I said ‘He could help you with this. The helium is all there. Go ahead. You know how to do it now.’ So I disappeared to Ottawa in August.

But, before the year ended Dr Herzberg, who was the head of the division, said to me, ‘Guy, why don’t you think about taking up a staff post here as a research associate.’ It is like our old research scientist or research officer in CSIRO. He said, ‘There’s a permanent position here.’ I explained that I had a duty back in Sydney where Sreedhar and Ron were doing jobs. I said, ‘Give me six months. I’ve got to go back and tidy up these loose ends. I’ve got some other people coming in there who will continue on with some of this work and there are sabbatical physicists who will want to come.’ So I went back to Sydney and we tidied up some of the papers that we were doing.

Looking back over your long research career in low­temperature science, what do you think was the most productive or the most interesting thing that you did during that time?

I think my most productive time was when I returned to Canada. I went back to Canada and spent three years there. I had two small children there. The Canadian climate is not conducive to babies in nappies. You spend five minutes wrapping them up for 20 degrees below zero and then they come back inside again. This was a bit hard on my wife at that time. We didn’t have money there then. We couldn’t get money out to buy a house, so we decided we would come back to Australia and buy something in Sydney. Whoever was on the executive at the time said, ‘Guy, any time that you want to come back, you’re always most welcome.’ So having filled three years as a Research Associate at the National Research Council in Ottawa, and having had a previous one-year doctorate, I thought, ‘Let’s get back to the warmer climate again.’

Low temperature expansion in a warmer climate

So I came back at the end of 1958 to the National Standards Lab. Paul Klemens was still there and so was John Rayne. They left within the next three or four years, seduced away by Westinghouse. Dr Carl Zener of the Westinghouse Laboratories in Pittsburgh had the idea that they could make money out of super conductors. That turned out to be a dead loss and they closed it up. But, before I came back, actually before I left Ottawa, I was a bit sick of just measuring thermal conductivities and electrical resistance, although there are all sorts of little oddities you get. Some things have a particular thermal mode or optical mode, which makes them behave differently, or they have a magnetic transition. All these guys are measuring heat capacities and they are measuring them very, very accurately down to low temperatures. But what we needed to do is to also look at the thermal expansion at the same time. You not only have the heat in there, but you also have magnetic effects, depending on the material. Nobody had ever managed to measure the expansion at low temperatures or, at least, at the scale that you can measure the heat capacity. They can measure the heat capacity to parts in a billion, but nobody could do the same for thermal expansion.

I talked to Clayton Swenson, an old mate at Ames Lab in Iowa, and he was trying one method using an inductance that had problems because it is affected by magnetic properties. My other friend Olsen in the E.T.H Lab in Zurich was using an optical lever device. But that had mechanical junctions which automatically affect the measurements. We wanted to measure expansion down to the angstrom unit level, down to the thickness at an atom level. Then, I started talking to Mel Thompson and I read one or two of his papers which had a completely different objective. He produced a theorem with Doug Lampard, a Fellow of the Academy, who was at CSIRO. Anyway, they produced this theorem which would connect very accurate electrical capacity measurements with length, and this was very important in standards. He said, ‘I’ve developed a thing called a three-terminal capacitor, with which you get rid of the stray capacitances. All you are doing is getting two surfaces and you are only looking at those surfaces. You are not worried about all the other leads. You get those two surfaces and you can actually measure the capacitance between those two little metal plates to parts in ten to 100 million. If you make that space nice and small, I can actually measure movements of a picometre.’ A picometre is ten to the minus twelve of a metre or 10 to the minus 10 of a centimetre (10-10), which is about a tenth or a 100th the thickness of an atom.

This is a material here (indicates) and we want to know how much it expands and contracts at very low temperatures. We do it by measuring the gap in between this material (indicates) and the surface above it which is a very tiny gap of very small fractions of a millimetre. We either heat it or cool it and, as this gets hotter or colder, this gap will change. And we can measure changes in that gap to a few parts in a billion. This material here may be a bar of copper, it may be a bar of silicon or it could be a glass, it could be any one of a number of things. Some are of technical interest and some are just of fundamental interest. All the rest of this apparatus would be surrounded by liquid helium. This is a vacuum, like a thermos flask, that surrounds the material. There are also platinum and germanium thermometers, for measuring the temperature of the copper cell. The cell contains the material that we want to know more about. We have another little chamber on top, which will be filled up with liquid helium or liquid oxygen, and we can reduce the pressure to control the temperature. We can control the temperature of the whole system, anywhere to a thousandth of a degree over quite a wide range of temperature.

This developed what is called the ‘capacitance expansion gauge’, which was then reproduced by lots of people in the next ten to 15 years. But that first one depended upon an electrical bridge in which you compare two fixed capacitors. Imagine four arms here (indicates). You have your unknown capacitance in the middle, which is the thing that you want to measure. You have a fixed capacitance here (indicates) made out of invar or some material that you keep at a fixed temperature. Then all that you had to do was get rods. I had a very good technician who could polish those rods with absolutely flat ends. With those rods, when they were put into the capacitance cell, I could measure changes in that at low temperatures right down to one degree absolute, where the expansion is very small. At that temperature the heat capacity is very small, but the capacitance, the thermal expansion coefficient, will only change by a fraction of an atomic diameter. At room temperature, if you change the temperature of a bar of copper or steel by ten degrees it changes length by a part in 10,000. Whereas at low temperatures, a change of one degree will mean that the material will only change length by a fraction of an atomic diameter, which is the actual spacing between the rods. The fact that the surface of the rod is slightly rough doesn’t matter. It is not really atomically flat, but it averages out.

So, for the first time we were able to detect how much the magnetic impurities and electrons contribute, not just the vibrations of the sound waves, which die away. When you get to low temperatures the impurities contribute almost nothing. But there is still a gas of electrons, if it is a metal, or in some materials there are magnetic impurities. I could pursue those right down to one degree. Later on, we found that there were some peculiar materials which have an impurity in them where they have a little bump that goes right down to a hundredth or a thousandth of a degree. We made a dilution refrigerator which takes you down below normal helium temperatures. It still uses helium, but it depends upon mixing the helium-3 isotope and the helium-4 isotope and getting them to flow. We won’t go into the details of it. But the main thing anyway, to cut a long story short, is that you can measure expansions right down to that sort of a subatomic level and we could then compare them with the heat capacities. In some materials, like the rare earths, where you get the little magnets lining up in some way, the bump in expansion would be at two degrees absolute and sometimes it was at 30 degrees absolute. You get sharp little kinks there. All these have some significance in understanding how they behave.

John Rayne and I collaborated. He was first in Pittsburgh and then at Carnegie Mellon University. He was making crystals which have a spiral structure like a chain. There are magnetic nickel atoms distributed along the chain and they start to order and interact with each other at 40 or 50 degrees absolute. You get a broad peak in some of these properties. But, down at very low temperatures, you get an even weaker reaction between the chains themselves and you observe a sharp little kink, and this was fundamentally interesting. But, in the case of the rare earths, it is also probably technically interesting.

I was surprised to hear the other day that the Chinese have monopolised the rare earth industry with the resources in the Gobi Desert. I thought our Western Australian sands and Roxby Downs still had a fairly large proportion of the rare earths. Rare earths such as yttrium, terbium and neodymium are the metals that go into television screens and other electronics. They have these very peculiar magnetic interactions controlling them.

Negative expansion

Some of the materials that you measured actually had negative thermal expansions over the temperature range that you studied. What was the importance of those?

A famous lattice dynamist and theorist who was Professor of Applied Mathematics in Imperial College, named Maurice Blackman, suggested a theory years ago. He said, ‘Where you have atoms in a very open structure, such as only having four nearest neighbours, there ought to be room for it to expand in some directions and contract in others. Unlike a copper atom which might have twelve neighbours, or eight nearest neighbours in something else.’ My model of this is a guitar string. After all, you have got a guitar string held between two points. If I pluck the guitar string, it pulls these points in.’ It expands in this direction (indicates), but it actually pulls things in, in the other direction. This is what is called a ‘transverse mode of vibration’ and it is important in silicon and the semi-conducting materials: gallium arsenide and

gallium phosphide. With these, each atom is what’s called ‘tetrahedrally bonded’. It has just four neighbours and it has a very open structure. Actually, silica – glass – has a somewhat similar structure and thus pure silica also has a negative expansion. At low temperatures, that wavy mode that’s transverse – not the one that pushes in and out here (indicates) but the one that goes sideways this way – it has a pulling-in effect here (indicates). It pulls in and produces a contraction in one particular direction. This contraction dominates at low temperatures in those semi-conducting materials, as well as in vitreous silica and in a number of minerals.

This diagram illustrates that silicon itself at low temperatures contracts initially and then begins to expand. Vitreous silica is much the same. There are combinations of materials which were produced some years ago where you can get a zero expansion over a certain range. These are of technical interest and were made by Corning and Schott-Mainz and are

used, for example, in modern stove tops. With the one that Corning produced, they have added a little bit of titanium dioxide to the silicon dioxide. It has a big negative expansion at low temperatures but they have tailored it and heat-treated it so that it has zero expansion around room temperature, which is what they want for a stove top. You can tailor materials to get a very low expansion so that it doesn’t crack. So the materials are carefully doped and heated in the right way. But they are basically silica or a silicate with certain additives that produce this behaviour.

It is interesting to see such a common practical application of research which goes right back to fundamentals.

Unpopular changes

Essentially, nearly all your career has been spent in CSIRO. Over that time there have been quite a lot of changes, particularly the move out of the Sydney University site up to West Lindfield. What can you say about the effect of some of those changes?

Sydney University had a registrar at one stage who wanted to get rid of the workshops that we had at the back of the National Standards Laboratory (NSL) in the Sydney University grounds. At the same time the government had this ground at Lindfield, which was used during the war for an elementary flying training school. After the war, all those huts were used for a migrant hostel in West Lindfield or Bradfield Park, as it’s sometimes called. The Commonwealth government were anxious to get rid of it. There were one or two people in CSIRO – and I won’t blame Fred Lehany for it – who said, ‘What we want is more space for a big high­voltage test laboratory. It’s got to be about 100 feet high and be a great big thing so that you can test sparks that are 100,000 volts.’ Mel Thompson and I and various others were a part of the architectural planning committee. Mel and I both said, ‘Why the hell do we want this thing there?’ We only had one customer and that was the State Electricity Authority. We said ‘If they want one of these, why don’t they build it? Why should we move up there? We’ll lose some of our nearby industrial contacts in Waterloo and Alexandria. We’ll also lose the contacts we have had with the university engineering department, the physics department and the maths department.’ A lot of our people at NSL were giving part-time lectures. John Collins was giving lectures in Prof Bullen’s Department and I was giving some in cryogenics. But it was that general interaction in the university grounds that we didn’t want to lose in moving up to Woop Woop at Lindfield. There were little technical advantages to moving. A new building would have better, more sophisticated air-conditioning.

Also we became far more visible to the politicians. Before they moved CSIRO HQ to what some of us liked to call ‘Tombstone Territory’, head office was in 314 Albert Street in Melbourne. The politicians started to say, ‘You’ve got this big building up there, this building here, another there and that there – what are you producing for all this?’ People were starting to breathe down our necks. The move certainly didn’t help our relationships with industry. We had contacts with the firms out in Alexandria, particularly for thermal insulation – a dirty subject at the moment – and temperature measurement. In that Waterloo-Alexandria area there were a lot of people. One guy used to go out there and test the vibrations on their equipment and advise them on this. At Lindfield, we lost that contact. I think we lost a lot. That lab got so expensive that they had to split off part of it which became the National Measurement Institute.

It has all changed, hasn’t it?

Yes. I don’t think it was a positive move.

Busy retirement

You have been retired from CSIRO now for quite a number of years. What have you found to occupy your time and fill in your interests over that time?

When I officially retired in 1990, I was made an Honorary Fellow. I think this happened because the work of the people in the SQUID unit – that is super-conductivity – applied to mining operations. SQUIDS are very delicate instruments for detecting very small changes in magnetism. You can fly a suitably designed super-conducting SQUID across a potential mineral bearing deposit and detector ores. For quite a while, they liked to have my cryogenic experience in the background, although I am not a SQUID person really. Cathy Foley was running the group. Actually, preceding her was Graham Sloggett, who sadly died. Graham was going to use those SQUIDS for magneto-cardiography and magneto-encephalography. In other words, he was going to use these magnetic detectors for studying the brain and also the heart etc. But I think when he died some of the impetus in that direction was lost. On the other hand, they did continue on FOR mineral exploration. That has been a long slow job. I was able to help them in some areas. Mind you, some of them were fairly difficult. Consider a SQUID flying in a drogue behind a plane, where it is away from all the metal of the plane. But you want to control it. We are using these high­temperature super conductors and we need to control them at say 61 degrees absolute with a liquid nitrogen bath. How do we keep that under control? If we want to put it down 1,000 fathoms into the ocean to do it, how on earth do we manage to control it, because the nitrogen will evaporate all the time? There were those sorts of technical questions, some of which I don’t think they have solved yet. But I was able to help them occasionally in this sort of area.

At the same time I was on the board of a journal called Cryogenics and also the International Journal of Thermophysics, in which I had quite an interest. Also, one of my major international interests was in CODATA. I became a great believer, from the fairly careful work we were doing on these physical properties, that what you really want is somebody to do an evaluation of the different materials. It’s no good as an engineer being shown a book in which there are 100 different graphs of the thermal-conductivity of steel. They are all quite different because they are different steels. The engineer wants to know which graphs are the useful ones. When I went through this, I found that the reliable ones nearly all came from laboratories where you had very good temperature measurement facilities. NSL was one, the Canadian National Research Council and the National Bureau of Standards (or NIST) in Washington were others. There are also one or two university labs where they do very good temperature measurements. Including the one that Swenson runs in Ames Iowa, and the National Physical Laboratory in Teddington. Most of the errors that you find in the DATA are usually due to the fact that temperatures haven’t been measured or controlled properly but particularly measured accurately.

I did quite a bit of work on producing and evaluating DATA. One of the jobs I was persuaded to do by my friend Olsen from the E.T.H Lab in Zurich. He had done enough of this and said, ‘Would you act as editor for Landolt-Bornstein?’ Springer had been producing for 100 years volumes of evaluated things on every possible aspect of physics and chemistry etc. Olsen said, ‘Would you edit and co-author a major part of a volume on thermal conductivity?’ The chief editor was a professor named Madelung. I went and talked to him, but he didn’t know anything about solid state physics. So I produced – with the help of Klemens – a theoretical chapter. A German guy I know produced another chapter on alloys. Anyway, that was quite a lot of work for a while. So there are those sorts of things to fill a retirement.

I was also asked to give talks in various parts of the world. For quite a while I liked going to Europe. They have a European Conference on Thermophysical Properties, which is held every two years. I got quite interested in high-temperature properties as well as low-temperature properties. There are oddities that you get up near the melting point, for example ‘superionic conductivity’ in things like strontium fluoride. There are various things like that that I became concerned with. In fact, I have only just resigned my editorship of Cryogenics. I was one of the first editors and one of the only

surviving editors I gather. I retired from it last year. They still send me free copies, but I find that now much more of the journal is concerned with cryocoolers. Cryocoolers are individual little refrigerators. You don’t have to bother to produce liquid helium. They use compressors and expanders of various types. There can be thermoacoustic vibrations. They are particularly very handy in space and you don’t have to produce large thermoses full of liquid helium. Some of the next generation – in fact, probably the present generation – of MRI machines are being cooled already by cryocoolers. In other words, mechanical refrigerator compressors. You don’t have to pour in liquid helium once every six months, as you do with the present magnetic resonance imaging.

Life beyond science

We have concentrated on the scientific aspects of your life – which, after all, are the main purpose of this set of interviews. What else have you done? I know you have moved to Tasmania. What other things have interested you and occupied you in your life?

Golf, tennis and swimming. The trouble is that about five or six years ago I tore a shoulder rotator. One is so badly torn that the ‘orthopods’ are not terribly keen to try to fix it. I think I can still go back to golf again when this knee is right. But tennis is out, and I used to love it. I used to belong to – it sounds like an anomaly – the Rose Bay Surf Club. It has a little private surf club over in Bondi. A lot of its members are fellow golfers from the Royal Sydney Golf Club. They built it back in 1926 so that members could go over there and have breakfast and then go off to work. I used it for years and years. But, since I buggered up the shoulder, I can’t catch a wave any more. It is important that you keep your shoulders up high. I wasn’t a board rider, I was a body surfer.

The reason we moved to Hobart was that I met Belinda. I met her at an Academy function over lunch one day about 12 years ago. We had met at Sydney University before that. She used to be deputy director (Programmes) for International House, which was for foreign students. She worked there for a year or two and eventually became a student adviser at Monash and she got married. But at any rate, to cut a long story short, we had both separated in our own ways. She had four children and I had three, they are all grown up. We met here one day over an Academy lunch at the AGM. She was looking for Robyn Williams, I think, to buttonhole him in the queue. And Belinda said, ‘Good heavens, I recognised the character over there, but he used to have a beard.’ That was me.

So we got together again and we lived in Canberra for a year, when you kindly organised that I was a visiting scientist and had an office here in ANU. She continued on with some work for the Science Summer School. She was really there – not fund raising so much as building partnerships with companies. After Rio Tinto pulled the plug on them financially, she had the job over the next five years of building up partnerships with other companies to finance the summer school. She is a good organiser and she rapidly managed to raise a quarter of a million or so a year from major companies. She has now retired from this. But she was still doing it when we went down to Hobart.

The reason we moved to Hobart was that we had children in Melbourne, Sydney, Canberra and London, and they were grown up and had got on with their own lives. They can come down to see us, if they want to. Actually, Belinda has just had her first grandchild about three days ago here in Canberra. Her son is in Defence. She had found a house down in Hobart years ago by chance, when she was visiting there, which was just near the Bellerive Oval. She is a sportaholic, even more than I am, and we could walk to the cricket. She, unfortunately, is an AFL supporter, whereas I’m rugby. But I can still go to watch her games and we can enjoy these things together. We are both going up to the test cricket. She is a member of the Melbourne Cricket Ground and I’m a member of the Sydney Cricket Ground, and we’ll spend Christmas and New Year up there. Then she’s driving for the Tennis Open in Melbourne all through January. I was going to a Wagga conference. Wagga is a conference that was started in 1977 for solid state physicists in Australia to get together. In those days, quite a lot of solid state physics research went on at Monash, particularly, and the University of New South Wales. Monash didn’t start until 1961, when Bob Street came out from the UK. Solid state physics then spread to the University of New South Wales, the ANU et cetera. So we decided that we would have this annual conference in February at Sturt University, which was equidistant from CSIRO, Monash, the University of NSW, Lucas Heights etc. Anyway, I think I probably went to my last one last year.

It sounds like an interesting life and it sounds like Hobart is a great place to live.

We are at Bellerive and it suits us. It is very dry and has the lowest rainfall of any city in Australia, except for Adelaide. We are right beside the water and yet it’s dry because all the moisture drops on the mountains in the south­west. Transport is very easy. Instead of taking an hour and a half from Rose Bay to get to Lindfield, I can go to the University of Tasmania in 15 minutes. The trouble is that at the University of Tasmania people talk mainly astronomy, but anyway. We like it there.

Advice to broaden the mind

Finally, do you have any wise advice for young people who want to enter careers in science?

Funnily enough, Belinda and I were discussing this over dinner last night. I said, ‘My idea is that you tell them, “The main thing is to keep your options open, but those options ought to include the basic things, which are some maths – you don’t have to be a high­class mathematician – and some physics, enough to understand”.’ You don’t have to understand the Big Bang particularly, but you do want to understand how the electric light works, how your stove works, how you insulate the floor or the ceiling, etc. Even simple thermodynamics in the way that sustainability comes into this. ‘You want to keep those options open. Even if you decide to be a medico, you will still need them, particularly in modern medicine. If you’re going to be a geologist or something, you’ll still need these sorts of things. Even lawyers need to understand how the world works and how we live.’ I suppose that was part of the advice: to keep the options open, try new things every now and again and have a sideline. Do a little bit of Chinese or French, whatever it happens to be. That was one of the other small things from my Oxford stage. Gib Bogle, another Rhodes scholar from New Zealand and three or four others including myself went to a ‘heute abend’ class for about six months, where you learn elementary German. I have forgotten most of it now. But those sorts of things were fun – if one had time to do those one night a week. We weren’t in the lab every night of the week.

Thanks very much, Guy. This has been a most interesting interview, and I’m sure that those people who watch it will enjoy it and learn from your experiences. Thank you.

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