Nicolaas Bloembergen


Interview, June 2004

Interview with Professor Nicolaas Bloembergen by freelance journalist Marika Griehsel at the 54th meeting of Nobel Laureates in Lindau, Germany, June 2004.

Professor Bloembergen talks about his childhood and the challenge of studying physics, the hardships for the family during the war years (1:48), the move to America and Harvard University (4:22), the most important applications of laser (7:07), his thoughts about the use of laser in military industry (13:41), the joy of creating an international community in the lab (18:40), and the importance of communicating with young students and involving the public in science (21:00).

Interview transcript

Professor Bloembergen, welcome to this interview. Thank you for being here with us.

Nicolaas Bloembergen: It’s a pleasure to be here.

I have read in your autobiography that you must have been a child with a great desire to learn new things. Your siblings had to drag you away from the books. Was it so? Were you …?

Nicolaas Bloembergen: That’s correct, but I liked to read and I always liked challenges. So in fact I chose to study physics because I found it the most difficult topic in my gymnasium, the Latin school I went to in Utrecht.

In Holland where you were born.

Nicolaas Bloembergen: … in Holland, yeah, where I was born and raised.

And did that give you what you wanted, obviously, but how was it during your student’s year, did you feel it was a challenge?

Nicolaas Bloembergen: It’s still a challenge. I mean, it’s still a difficult topic, but I’m fascinated by the very curious correspondence between mathematics and physical phenomena, and that mathematics can describe so many phenomena with such accuracy. A professor Wigner, Eugene Wigner, a famous theoretician, he called that connection between mathematics and the real world uncanny.


Nicolaas Bloembergen: Uncanny. And I think that’s a very good description.

I would like to come back a little bit to your youth years. You lived in Holland and grew up in Holland during the years of the Nazi occupation, and it was obviously a very difficult time. But you continued to study, yet it was very difficult to read, there was hardly any light at home and so on.

Nicolaas Bloembergen: What happened is that I passed my final qualifying exam. After that, the only thing to get a doctor’s degree you have to hand in a thesis and do independent research, but I passed all the formal examinations in early -43, two weeks before the German occupation forces closed down all Dutch universities. But I was at an enormous advantage at that time, because the older students had to decide whether to sign a declaration of loyalty to the occupation forces or else they would be transported as forced labourers to Germany, not in concentration camps but nevertheless forced labourers. And I didn’t have to make that choice, because legally, after having passed all the exams, I was not legally a student any more. So I could still live, and in fact I got on my identity papers a little stamp that I belonged to the fire brigade of the university. I had to protect the buildings. Purely a formal advantage.

You talk very nicely about your parents in your autobiography as well, the way they were trying to keep you children in good health and so on. Would you describe a little bit about that?

Nicolaas Bloembergen: My father went by bicycle and a little cart to get potatoes to feed his family, and he travelled for 50 kilometres or more. And then he exchanged objects for food, and so they did a wonderful job keeping the family alive.

After the war …

Nicolaas Bloembergen: Because young men couldn’t be in the streets. They would be picked up.

So you had to hide.

Nicolaas Bloembergen: I hid the last … we call it the hunger winter of 1944-45, when the offensive of the Allied near Arnhem, they didn’t succeed to cross the Rhine there, so we had to wait until the next spring.

After the war you eventually moved on and you came to America.

Nicolaas Bloembergen: Yes, my [INAUDIBLE] was in ruins, and it would be very hard to do significant research at a Dutch university immediately after the war, so at the suggestion of an older brother who was a lawyer, he said why don’t you write to some American universities, and that’s what I did.

You regretted that.

Nicolaas Bloembergen: Did you read that …

I saw a bit of that, yes, what happened after that?

Nicolaas Bloembergen: I chose three universities where I knew significant research was going on, but I decided those, on the basis of the Journal of Physical Review of 1939 because those were the last issues available in the Nederlands, until 45. And I picked three of them, and in retrospect they were all very good choices. I picked the University of Chicago, the University of California in Berkeley, and Harvard University. The University of Chicago never answered my letter, the University of California wrote back, it took about two weeks by airmail right after the war, to get across, and then two weeks to get an answer back, so after about a month I received a letter from the University of California in Berkeley which caught me by complete surprise.

They said they would like to admit me, but as long as the war was going on they couldn’t take non-American, people who were not American citizens. And in Europe, in Holland, the war was over, you know, had been VE Day, and we didn’t think about any further war. But actually, of course, there was this great fight in the Pacific between the United States and Japan still going on, and that just opened my eyes that the world was bigger than Europe. And then two weeks later the bomb on Hiroshima exploded, so then everybody realised that there was still a war going on. And so Harvard said just send some more letters of recommendation and copies of documents, and that’s what I did, and they admitted me, and it turns out I’ve stayed there almost ever since.

Yes. When you look at what you have achieved with your work and the way the laser, and its various application, the way it’s used today, what makes you most proud?

Nicolaas Bloembergen: I’ve been lucky that the two topics that have interested me have both lead to very important applications. In the case of nuclear magnetic resonance, the thesis data, in my thesis, concerned what is called nuclear magnetic relaxation in liquids and also some solid materials, but most importantly we measured the relaxation time of protons in water and aqueous solutions, the influence of viscosity and temperature, and those data are now the basis in which MRI pictures can be taken, because the nuclear magnetic moments of protons which are water molecules, it’s about 70% of the body, water, they measure small differences in relaxation time between healthy cells and tumorous cells and whatnot. And in blood vessels. So we are, my data was really very basic, to an application I didn’t foresee, nor did my thesis supervisor, Purcell, in fact nobody had an idea that MRI would come even as late as 1960.

And last year you received a Nobel Prize. Was it …?

Nicolaas Bloembergen: My teacher, Purcell. Yes, he shared the Nobel Prize with Felix Bloch in 1952 for the work on nuclear magnetic resonance in condensed matter, already in -52. And I feel that it was fully deserved, but I did a lot of the hard work and the data taking. And then later, when I got a Nobel Prize, I know that my students and graduate assistants did a lot of the work, to help me get the prize.

Is it often like that? It’s teamwork, when you …

Nicolaas Bloembergen: These were not big teams in the sense of high machines. They were small groups but of course there are lot of rather tedious laboratory procedures that have to be carried out, and that is often left for the graduate students, professors being too busy to spend the time on those details.

On one of your lectures that I listened in to you also told us about other uses of the laser that I was not totally aware of. Would you just mention a few that might not be so known to the public in general?

Nicolaas Bloembergen: As I said, the second item was going into optics and especially non-linear optics, which is the behaviour of light and propagation of light in media at very high light intensities. Those high intensities are only available from laser sources. So I was really interested in what one can do with lasers and I mentioned in my lecture that lasers are heavily used in surgery and in optical communications systems. Those are the two large scale applications that affect many people, everywhere in the world, because the optical fibre communications systems which, incidentally, use little lasers of … produced by [INAUDIBLE] inside the fibre, make the world very small, and we can now e-mail to anybody, anywhere in the world, we can dial up the worldwide web and all this information flows over large distances under the Pacific and Atlantic ocean, if necessary, to other points on the earth.

So those are the two big ones, and there are smaller and a little more trivial ones, like read out at supermarket checkout counters. You know, you have a code on each article, it’s read by a little laser and so even with the ambient light it doesn’t matter, the reflection on the code gives the information of what article and how much it cost. And the other, which seems rather trivial, but is very important, is to use laser beams which propagate straight lines over long distances. They are used to lay pipelines, including trivial things like sewer lines. I lived in a suburban neighbourhood and there were no sewers yet, and then in 1972 they laid out the sewer line with laser beams. That saves a lot of manpower, you need only one person with a mirror somewhere to do it. But of course, all the major oil pipelines and gas pipelines, they are all laid out by laser beams, and any big building that goes up, the verticals and horizontals are all checked with laser beams. So in the constructing industry it is a very widespread use, too.

Did you think it would have such an impact?

Nicolaas Bloembergen: No. For several years, in the early 1960s, my colleague, Art Schawlow, with whom I shared the prize in 1981, he said the laser is a solution looking for a problem. He had a sense of humour. And that was really true, and all the applications really came gradually in the next decade.

The laser technique is also used in the military industry, of course.

Nicolaas Bloembergen: That was an application that was recognised very early by people concerned with defence.

Have you had any thoughts about whether scientists have any responsibility …?

Nicolaas Bloembergen: Certainly, but what do you do? You know, science itself is basically neutral, and then you get the problem, should I refuse to help to defend my country? So I was advising government committees on the use of laser beams in trying to shoot down intercontinental missiles. And soon thereafter we realised that it would be very difficult, and then 20 years later in 1981 President Reagan instituted the strategic defence initiative and the idea was to put lasers in the upper atmosphere and just beyond in space, and try to shoot down incoming missiles, supposedly, which might be fired by the Soviet Union. And then we wrote a report because everybody felt that that would not be feasible. Neither scientifically nor technologically.

But many people were afraid to express, well, they expressed their opinion, they weren’t afraid to express their opinion, but then they got the answer you haven’t studied the problem. So the American Physics Society said we’ll go and make a scientific study of the issues involved and then we’ll come out with a public report. But they selected 14 or 15 people and I and Kumar Patel were co-chairmen of that committee and the reason these people were chosen is because they had never gone very open in public of what their political opinions were. And we were not supposed to give any political opinion, just as scientific, purely scientific evaluation.

And your opinion was that it wasn’t feasible.

Nicolaas Bloembergen: And then we studied the problem for a year and a half or two years. We all had access to top secret data, because if we didn’t critics would say well, you’ve written this report, but you don’t know the secrets. And so if you knew what I know your conclusions would be the opposite. And so, in order to avoid that, we had access to all the government installations and government workers who worked on the problem. So we could judge … You know, initially, I really thought there are certain things I don’t know because they have been kept secret, and maybe there is something that might make the strategic defence initiative possible. But we found that that was not the case.

It wasn’t.

Nicolaas Bloembergen: And we wrote a report, and the report had to be public, and of course it had to be cleared that we didn’t spill any secrets, and it was refused twice. First by the security agent of the SDI itself, but then they considered it so important that after he cleared it also the security agent of the Ministry of Defence had to evaluate it again. And that caused a delay of eight months, but it did come out, and we wrote the conclusions and even in the 20 years that have since past, almost 20 years, 15 years, everything is still valid, all we said.

So you don’t see that there will be in the near future …

Nicolaas Bloembergen: No, no strategic defence, well, we don’t need it any more because there is not a large nation that would fire a hundred missiles at a time. What we are worried about now is trying to shoot down a single intercontinental missile from a terrorist group or from a rogue nation, or whatever, and even that isn’t still very hard to do. The method they pursue now doesn’t involve lasers. They involve … So our laser report has stood the test of time. It’s still valid.

You have travelled wide and far and have had lots of contacts with universities all over the world and with other scientists all over the world. What has it given you, and why has it been important to you to be so global, so international?

Nicolaas Bloembergen: Well, a university like Harvard University attracts many foreign students and the brightest of them, and I find it interesting to see people from … you know, I myself was an immigrant, into the United States, and so I had many students from all parts of the world, and it’s nice to visit them later and see how they are doing in their respective careers. So we always enjoyed having an international community in the laboratory, involving Frenchmen, German, Norwegian, Italy, and people from the East, Japan, and especially China, different parts of China, some Taiwan, some Hong Kong, some mainland China, very interesting.

And that was done at a time when it wasn’t so much working together, I would say, as it might be today. What kind of creativity does it create when you …?

Nicolaas Bloembergen: I even had some Russian post docs.

I believe so, yes.

Nicolaas Bloembergen: Even during the time of the Cold War I was allowed to entertain Russian visitors.

That must have been fascinating.

Nicolaas Bloembergen: Yes.

What kind of creativity did it create? Is it a special community this scientific …?

Nicolaas Bloembergen: It’s an intellectual community, and these people usually got on, very interesting conversations. In fact, one was between a French student and a lady from Bulgaria, and they communicated in broken English. The Frenchman’s conversation in English was very hard to follow, for me. And the Bulgarian lady the same. But the two worked together on a science project and I don’t know, they communicated in very broken English.

They understood each other.

Nicolaas Bloembergen: Yes, that’s right.

Is it important to work with young people, I mean, to keep one’s spirit, one’s creativity, do you enjoy that?

Nicolaas Bloembergen: Yes, I mean that is the only way not to go to sleep. During old age. No, that is very important to have this. That I think is the most important aspect of this meeting here in Lindau, that there are all these young people to interact with, too.

Do you still have lectures, do you still do …

Nicolaas Bloembergen: No, I’m 84, I get … I give an occasional lecture like I did yesterday here, mostly on the history of a scientific topic.

Next year it will be the year of Einstein. What relationship do you have to him, and why is it important to highlight him, if you look in a broader sense to the public in general?

Nicolaas Bloembergen: It’s very important to take opportunities to involve the public with science and the centenary of Einstein papers is certainly a worthy excuse to focus attention on scientific efforts. But Einstein wrote a popular book, Einstein and Infeld, I forgot the title, I read it in German and it was originally written in German, and I was in high school, gymnasium and that fascinated me very much, and he explained in simple terms the ideas behind the relativity theory.

Is it difficult in general do you think for the public at large to understand the need for scientific research?

Nicolaas Bloembergen: Weill it is, but you have to ask them what would you do without computers, without worldwide web, without, you know, cell phones, and so on. Or even without electricity, yeah? Let’s go back further. And it was all started by physicists.

Professor, is there anything you would like to add at the end, in general, something you would like to say to young students who might be looking into the idea of becoming scientists and going into research? What do they need, what kind of spirit …?

Nicolaas Bloembergen: The first thing they need is curiosity. If they are not interested in trying to get an answer to a question they have posed for themselves, or somebody else has posed to them, if they are not interested then, and are not curious to find an answer, don’t go into science. And also don’t go into science unless you have a strong perseverance, because science is really usually only a few per cent inspiration and the rest is perspiration. Hard work.

Hard work. Thank you so much.

Nicolaas Bloembergen: You’re welcome.

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