Interview with Lee A. DuBridge

DuBridge: 00:00

. . . NDRC was a wartime laboratory and would be disbanded at the end of the war. I think he felt that the National Research Council, which had been set up in World War I as a war research organization, had probably made a mistake by perpetuating itself and there were years when the National Research Council, I think, was sort of hunting around for things to do and it was still associated with the National Academy of Sciences, of course. And I think there was a period in there when it was doing rather routine work and he felt rightly or wrongly that the NDRC was trying to self-perpetuate itself and it really should have been set up as a wartime enterprise and then resolved. And then if another occasion came up either war or peace to reorganize again. He didn’t like organizations as a rule, so he made it very clear that the NDRC would end immediately at the end of the war. And so as soon as the Japanese surrender took place, it began just dismantling the whole operation.

Sullivan: 01:23

And the Radiation Lab would be just part of that.

DuBridge: 01:26

Just part of it, yes. So, we began demobilizing the Radiation Lab immediately after the Japanese surrender as far as continued active research was concerned, except for two or three partially finished projects that the Air Force and Navy wanted completed. We completed them at least carried them on to the point where they could then be handed over to a military laboratory and all that happened after VE, VJ Day really, was winding up the affairs, getting rid of the equipment, writing the report, and demobilizing and findings jobs for everybody.

Sullivan: 02:08

Was there any wish amongst the civilian staff that they liked to stay together in any respect?

DuBridge: 02:12

No, I don't think so. Quite the opposite. The key members of the staff had all been borrowed from the universities and they were all anxious to get back home. And they fled back home as fast as they could. Now there were a number of younger people who didn’t have pre-war jobs, and they probably would have liked to have stayed on, but we made a special effort to find jobs for them and I think for the most part that it happened. So, I left and went about to Rochester on 1st of January.

Sullivan: 02:52

What was the recruitment policy? What fields were these people mainly in before they got into radar research?

DuBridge: 03:00

All physics. The original group was all nuclear physicists. You see it was Ernest Lawrence really that got me into the Radiation Lab. He was on the microwave committee headed by Loomis and they had been talking with the British representative, Tissard, and others who came over and had learned about the British TRE and how they recruited from physicists of the universities who weren't doing anything then except physics, not doing anything for the war, and Ernest and Alfred Loomis [inaudible] we got a large number of good physicists from around the country and they felt that the microwave work was in line with the experiments especially of the cyclotron physicists with their high frequency experience and so on. So, he got me and a number of others who were in the nuclear physics business. Several from Berkeley like McMillan and later Luis Alvarez and then we got Milton White and we just went around the country to the cyclotron labs, and so on, so that the initial group of 30 or so were almost entirely from the physics labs of the universities. And it was mostly from the cyclotrons.

Sullivan: 04:42

Right. It sounds like it was a very narrow part of physics, actually.

DuBridge: 04:44

It was, yes. Initially.

Sullivan: 04:45

Is that only because of the people who [crosstalk].

DuBridge: 04:47

Well, they were our friends. The “Cyclotron Club” was a kind of a closely knit and very active and friendly group of people. And we were all excited in the early days of nuclear experimentation and theory. So, it was natural for us. And we saw at that time, wartime application under nuclear physics. And so, getting into something useful for the war effort appealed to many people.

Sullivan: 05:18

Did this continue throughout the war or did it branch out a bit more?

DuBridge: 05:20

Well, as time went on, of course there weren't enough cyclotrons.

Sullivan: 05:24

We they still mainly physicists and?

DuBridge: 05:26

To a large extent, yes. To a very large extent. When we started some work on radar countermeasures, we set up a separate little segment of the lab to do the countermeasure work.

Sullivan: 05:48

Was this the Harvard?

DuBridge: 05:49

It became the Harvard thing, but first of us, we brought in Fred Turman from Stanford. Who was an electrical engineer, of course, to start the countermeasure work. Well, he recruited electrical engineers, his friends, and so there was quite a little group of electric engineering people that were working on countermeasures. And some of us decided that we ought to separate the countermeasure work from radar work for the two were in competition, so to speak. And also, the countermeasure work was slightly more highly classified than the--

Sullivan: 06:18

Yeah, I've read that some. Why is that?

DuBridge: 06:20

Well, this was pretty critical to not let the enemy, the Germans especially, know what we were doing to counteract their radar. They had radar too.

Sullivan: 06:34

Sure.

DuBridge: 06:36

And it was kept quite secret as to what methods we would be--

Sullivan: 06:40

But why more critical than the fancy new things being developed for the American radar?

DuBridge: 06:47

Well, I think it was--

Sullivan: 06:52

Was it the idea that if you split it up, then one person only knows one aspect of it? Or is that ?

DuBridge: 06:56

Well, that was part of it. Yeah, there were a few people, like myself, who were supposed to be fully familiar with both sides. So, Fred Turman and I worked closely together and there were no barriers between us and a few other key people in both labs. But you see, they wanted a seamless countermeasure, countermeasures one by one on the Germans out there having any previous inkling of it. So, they had no time to prepare. It wasn't so important that the radar became known because the Germans had some of it anyway. I don't know it, I can't recall exactly all the arguments.

Sullivan: 07:43

Okay.

DuBridge: 07:44

But anyway, that was the way it was. So, Turman recruited engineers and so the Harvard lab was largely the electrical engineering group and electronic engineers. And so, it continued that the Radiation Lab we recruited by personal contacts and then spread out, but of course we eventually got in solid state physicists and physicists in other branches and some quite a number of engineers too came into it. But the wish [inaudible] as it was in England.

Sullivan: 08:22

Right. Now, you mentioned, of course, that you did this somewhat because of the British experience and their recommendation, but now it's interesting. Now you have these two labs, one of which is primarily engineers and the other physicists, did you find that it produced a different style, or?

DuBridge: 08:39

I think so. Yes. Yeah. It's a little harder to put your finger on how different it was but somehow the subtle differences were perfectly evident to many of us. It's not that one was better the other. And indeed, for many purposes, the engineering group was quite suitable to do the countermeasures work.

Sullivan: 09:09

It wasn't as fundamental a research effort. Is that what you're implying? It's more just [crosstalk]

DuBridge: 09:16

Yes. It was somewhat more-- yeah. Yeah. It was somewhat more practically oriented, I might say. It is hard to put your finger on specific differences but because it was an engineering group that started it and ran it and ours was a physics group.  Actually I developed that style. If it would've been the other way round it might have been equally successful but just a little different flavor.

Sullivan: 09:48

Yeah. Okay. Now, let's come to the end of the war again. You say the older people anyway had jobs waiting for them at the universities, the younger people you helped to get university jobs also usually.

DuBridge: 10:02

Yes. Yes. Many of the older people, as they went back, wanted to take some of their younger colleagues with them and did. So, it was evident at the end of the war that the universities just had to rebuild for physics departments which had been pretty badly gutted. So, they not only brought back the old timers, but had a number of new younger people because they hadn't been doing any recruiting during the war. So, there was a big market for them.

Sullivan: 10:34

Right. And I suspect they brought back some equipment also.

DuBridge: 10:37

Oh, yes. Yes. That was one of the jobs that we had at the end of the war was to find a way of getting our equipment out into the civilian life. And there were problems on that because, you know, the military still wanted to keep the equipment highly classified. But it was finally agreed that what was classified would only be the final military hardware and not the components, the receivers, the pulsers, and the magnetrons and so on. So those were declassified and great deal of that equipment was made available to various universities and other places. A lot of it went to the Naval Research Laboratory and other places too. So, we set up a scheme for getting that equipment distributed right at the end of the war.

Sullivan: 11:36

And what fields do this equipment now and the people really influenced the most in, say, the five years after the war in terms of scientific research?

DuBridge: 11:50

Well, mostly in fields connected with higher frequency work because the magnetron was the first penetration into really microwave technology in this country except for some very low energy, low power experimental work that had been done at MIT, Stanford, and other places. So here was a new tool for generating and detecting and using microwave frequencies. I remember one of the first things I did when I went back to Rochester was to set up a little 10 cm transmitter receiver system and use it to demonstrate interference or waves.  We used to so it with sound waves. But it was much nicer to do it with [crosstalk] demonstration. You get big interference patterns instead of little tiny ones that you had to look at optically with a microscope.

Sullivan: 12:55

It's still a standard physics lab.

DuBridge: 12:58

Yeah. Yeah. Made a striking demonstration to see real interference and diffraction on a large scale that you can demonstrate the lecture. I'd just move a little receiver back across through the interference pattern. Well, that was just one example although I think a great deal was done toward developing the lecture and laboratory equipment using microwave frequencies. And they were much easier to use in longwave radio and also the very shortwave optical frequencies for lots of demonstrations of physical…

Sullivan: 13:35

But what about for frontline research? Which areas?

DuBridge: 13:39

Well, I think it also reflected back the new high frequency technology reflected back onto greatly improved oscillators for cyclotrons and other later nuclear physics equipment, because people just developed a whole new concept on how to do high frequency radio and electromagnetic circuits. As you say, apparently, I didn't get into radio astronomy right away except for Chris Ellsworth. I thought he'd done that earlier than '51 but--

Sullivan: 14:17

Well, the discovery was at ‘51 and it began around '49.

DuBridge: 14:20

Yes. I see. Yeah. Well, it was early '46 that Purcell went back to Harvard, but apparently he didn't start this work right away. I think he did some other high frequency work.

Sullivan: 14:34

Oh, yeah. He did a lot of nuclear magnetic resonance in the laboratory.

DuBridge: 14:37

Okay. All right. Yeah. Yes. Now that was another almost immediate application, I think, of microwave technology was in magnetic resonance. And then I think Rabi and his students right there and their molecular beam work, that wholly new technology for having a high frequency radiation and circuits.

Sullivan: 15:01

But--   (telephone rings)

DuBridge: 15:03

I'm sorry.

Sullivan: 15:07

Well, a related subject, what was the division of labor, so to speak, between-- we talked about the radio radiation lab was called at Harvard.

DuBridge: 15:19

What do they call it? The Radio Research Lab

Sullivan: 15:22

and the Rad Lab? But what was the division of labor between those and NRL and Fort Monmouth and so forth? Can you just give me some idea because there were radio astronomy efforts, for instance, the first lunar radar came out of Fort Monmouth right after the war.

DuBridge: 15:41

Yes. Well, we were in touch with them.

Sullivan: 15:45

And Bell Labs.

DuBridge: 15:46

Yes. We were in touch with Bell Labs, more with the Bell Labs than the others because the Bell Labs owner took the manufacturer of our first radar equipment for aircraft, and so we worked very closely with them. We worked, but not intimately, with the Naval Research Laboratory. They didn't get into the microwave work right away, and nor did Monmouth. They had been with the longer wave radar equipment, and they were still at work on that developing it. And we were starting out on a whole new area of radar technology. So there probably was some-- there was back and forth between the two groups. I would say that the relations were not intimate. Although certain individuals who happened to have close connections or overlapping interests would frequently just visit from both of those places, and they would research. And we welcomed visitors from both of those places who'd come to the lab to see what was going on and keep in touch.

Sullivan: 16:54

There was some microwave research at Bell Labs [crosstalk]--

DuBridge: 16:57

At Bell Labs, yes.

Sullivan: 16:58

Yes, and what was the difference in nature between [inaudible] them, or was it just [inaudible]?

DuBridge: 17:05

Well, the first association I had with the Bell Labs was after the British had come with the magnetron. And the Bell Labs, I think, were asked right away to start making magnetrons. They wanted to get the technology for development and manufacture of magnetrons underway quickly. And so, they went to GE and to Bell Labs, I think, to Western Electric.

Sullivan: 17:35

Western Electric, perhaps they're on the manufacturing arm, or?

DuBridge: 17:39

Well, I think mostly the Bell Labs, initially, at least. They probably got Western Electric to do some manufacturing, yes. So, our contacts with Bell Labs were in the microwave region using the magnetron as their source. That's my wife just [inaudible]. I'm sorry. [inaudible] closer together. And almost at the beginning, NDRC arranged that the Rad Lab would develop the first models of the so-called AI equipment, Airborne Interceptor, equipment for aircraft. And we would develop the first models and then turn them over to Bell Labs for manufacturing the kind of things to be installed. So, we worked closely together. In fact, we had people down there quite a good deal of the time, especially after we did have a successful laboratory model of the AI and took it down and [monitored ?] where people went along to see the transition [crosstalk]--

Sullivan: 18:48

So, it sounds like you remember them as being more of the development side of it.

DuBridge: 18:51

Yes. Yeah.

Sullivan: 18:53

But what about people like the [inaudible] that were doing more fundamental research, were they [crosstalk]--?

DuBridge: 18:57

Yes. Well, I think Rabi and others at the Rad Lab were more in touch with them too. I think the relation with Bell Labs was pretty close. There were no barricades between the two. I had respect for what they were doing and vice versa, and by [inaudible] back and forth [inaudible].

Sullivan: 19:20

Okay, let's move to Phase 2 of your contact with radio astronomy. And that is the mid-50s when Caltech began to get an interest in radio astronomy. First of all, who initiated that, in your view?

DuBridge: 19:38

I can't remember. I was thinking about that after I got your letter, and I can't quite put together the real initiation of it. I know we got Bolton involved quite early It may have been Taffy Bowen had been through Pasadena and we talked to him about it. It's quite possible. But I just can't put my finger on who in the Caltech astronomy area-- I first said we ought to have radio astronomy.

Sullivan: 20:22

Okay. [I'll?] start it off. I don't want you to manufacture something if you--

DuBridge: 20:25

No. Yeah, but I do know that once the idea was suggested by whoever it was people said, well, of course. We've got the greatest optical observatory in the world. We ought to get into the radio astronomy end too and so it was greeted with enthusiasm once the idea--

Sullivan: 20:49

You're backed this from the beginning?

DuBridge: 20:50

Pardon?

Sullivan: 20:50

You backed this from the beginning?

DuBridge: 20:52

Oh, yes. Yeah. Yeah. Yes. Yeah. Already there was enough in the air-- to realize that this was an important field of astronomy. So yeah, we were anxious to get into it and I guess it was probably through Taffy Bowen or we got Bolton to come here, and he kind of--

Sullivan: 21:10

Yeah, [inaudible] doubt about that. I know I just mentioned it to Jessie Greenstein. He says that it was he, Baade, and Minkowski who were the ones that pushed--

DuBridge: 21:21

Okay, that sounds perfectly reasonable.

Sullivan: 21:25

Yeah, it does to me too. But now what was going to be your approach? How does one get Caltech into radio astronomy?

DuBridge: 21:33

Well, you draw up some ideas of to what kind of things you want to do and I was clear that the next steps just off the beat to build some sizeable antenna receiver systems and it was also obvious that to build them in Pasadena or Los Angeles would be no good because of the large volume of radio interference and pretty early begin to explore for a site which was free from—relatively free from radio interference. Came up with the Owens Valley site. That was one of the very first things that was done. And then, of course, we had to see where to get the money, and fortunately, the National Science Foundation was getting interested in radio astronomy and this was one of the first I guess that they financed large scale.

Sullivan: 22:38

But wasn't ONR an important funding source also?

DuBridge: 22:44

Well, you have the records on that I suppose. ONR

Sullivan: 22:46

I think they were.

DuBridge: 22:48

It may be. It may be. We were working closely with ONR at the time on the nuclear physics work and--

Sullivan: 22:57

Well, they started several radio astronomy places like University of Michigan and others. They were very interested in setting up antennas around.

DuBridge: 23:06

Yeah. Yeah. Okay. Then later went over to the Science Foundation I guess.

Sullivan: 23:10

I think that's right but there could've been-- NSF might have been in from the beginning too.

DuBridge: 23:14

When did you find the first trace of discussions of the Owens Valley?

Sullivan: 23:19

Oh, '54,[that sort of thing.

DuBridge: 23:23

Yeah. Well, at that time, a science foundation was hardly underway. It wasn't--

Sullivan: 23:27

Yeah, that's right.

DuBridge: 23:28

--so, it's logical that ONR would have been the source.

Sullivan: 23:32

John Bolton came here in '55 I believe it was, maybe '56 and the first antennas were in '59 [inaudible]. I guess it was simply your wartime contact with Taffy Bowen that-- as far as staffing this thing [crosstalk].

DuBridge: 23:58

Well, yes, I think so. I guess I put us in touch with the Australians and the group all right. And he was anxious to see the work go ahead here. And it was quite a contribution to have Bolton come.

Sullivan: 24:21

Did you play any role-- serve on the side in the development or in the securing of the grants for the Australian large telescope, the Parkes Telescope? They got a Rockefeller grant. And they later got a Ford Foundation grant, large fraction of that big dish.

DuBridge: 24:41

No. I wasn't involved in that as far as I know. I was on the Rockefeller Board, but I think that was later. I never had any connection with the board.

Sullivan: 24:52

Yeah. Okay. Now, once again, up through the early '60s only Owens Valley, of course, began to be a very successful thing in terms of the bright, young graduate students, the support from them, late '50s, early '60s. What do you see as the main contribution that Caltech made? I main, I realized you're not a radio astronomer yourself. But from your point of view, how did it affect the Caltech's prestige? Or how would you like to comment on what radio astronomy did for Caltech?

DuBridge: 25:34

Yeah. Well, I think it was a great source of pride on the campus. And I also heard that it was regarded as a very logical extension of the Palomar and Mt. Wilson work. And a number of the Palomar and Mt. Wilson people also became interested in all kinds of things that the radio astronomers were doing. I think one of the first-- one of the great achievements of Owens Valley was the beginning of, well, the early stages at least of the multiple antenna arrays.

Sullivan: 26:16

Right.

DuBridge: 26:17

And how by having at least a double antenna, and very early, we made two antennas to be movable apart, interference better, and therefore extend the accuracy. And I think the technology for doing a multiple array business got a big boost from them, from the work with Bolton, the others did here on learning how to do it electronically. And they had hoped to have a considerably larger array. But the VLA,

Sullivan: 26:54

Yeah, that's somewhat later now. Yeah.

DuBridge: 26:58

Not later, but the idea of more than two and a larger array was--

Sullivan: 27:04

Well, from the beginning two was only considered starters.

DuBridge: 27:06

Yeah, yeah. Well, of course, I think it was after the two were successful, but Bolton and the others, we just had some more look at the additional things that could be done. And so, they found the ways of correlating the signals from two or more at distant points. And we had hoped, but I'd forgotten when that hope was made clear to have several, at least, in the array out there. And there was room for it up in the Owens Valley. But by that time, the National Radio Astronomy Observatory, they had the funding backing of the NSF. And so, their VLA was the one that won out.

Sullivan: 27:56

Do you happen to remember-- and when John Bolton, of course, went back to Australia in '61 or two when the big Parkes dish was completed and became the director of that observatory. But do you happen to remember if from the beginning there was an understanding that Bolton was going to go back? Or was this quite a surprise when he left Caltech?

DuBridge: 28:16

I think initially it was understood that he'd come and help us get started for a year or two. But as things went on, I think we sort of secretly hoped that he'd forget about that and would stay. And I really suspected at the time, but I can't prove it, that if we had got larger grants to expand the Owens Valley, he might have stayed. But I think he saw a better thing coming in Australia. So, though it was not exactly a surprise, I was [inaudible] to see him go.

Sullivan: 29:00

Yeah. Okay. One final question is, you look at the development of scientific research and in particular astronomy and radio techniques and microwave research in this era up to the early '60s, do you have any general comments on where you see radio astronomy, how it has changed our view of things or how it has influenced techniques? Or when you think of radio astronomy from that era now, where does it fit in?

DuBridge: 29:33

That's a big question. Try to put myself back in 1960.

Sullivan: 29:40

Well, yes, that's the first prerequisite. And I'm asking you as a person who obviously has to have a wide grasp of many different physical sciences and so forth. I mean, should it be considered different in any respect or is it just one of the many new exciting techniques that developed after the World War II?

DuBridge: 30:03

Well, it's true that there were many exciting things developed after the war. The whole nuclear technology. The high frequency work in many areas, microwave transmission, and the civilian radar. And on the purely scientific side, things like the [inaudible] and radio astronomy.

Sullivan: 30:53

Well, it sounds like you're saying that doesn't stand out, particularly in your mind is being of more importance or, you want to [inaudible] either.

DuBridge: 31:01

Yeah. I can't put, yeah, number one importance, but to me it's always been one of the exciting things that's happened in the last 30 years is the development of radio astronomy and what has come out of it. I guess from a point of view up here at basic science, the site of technology, it is one of the most exciting new developments in the physical sciences. Certainly was to me.

Sullivan: 31:38

Okay. Well, thank you very much.

DuBridge: 31:40

All right. Okay.

Sullivan: 31:43

That ends the interview with Lee A. DuBridge at his home in Pasadena on 29 March, 1983.