May 2020

The Man Who Delayed D-Day

The eminent oceanographer Walter Munk reflects on science and war.

By John Steele

When Dwight D. Eisenhower was planning the invasion of Normandy, he made sure to check with Walter Munk and his colleagues first. Munk had come to the United States from Austria-Hungary to work as a banker before switching to oceanography, eventually making major advances in the science of tidal and wave forecasting. He was a defense researcher at the Scripps Institution of Oceanography in 1944 when his team calculated that the seas on June 5 of that year would be so rough that a delay was in order. The invasion would happen on the following day.

It was just one highlight among many in Munk’s career. From explaining why we always see the same side of the moon to sending a sound signal halfway around the world, Munk, who passed away in February 2019, was the very definition of the enterprising scientist. When I spoke to him at a workshop of the Pontifical Academy of Sciences at the Vatican, he spoke with an energy and enthusiasm that belied his 96 years.

Interview Transcript

Why do current models of how climates will change vary so much in their conclusions?

Because people do not understand the fundamental processes. And I think there is a bit of exaggerated dependence on computer modeling because it’s so neat, and in a way so cheap, and in a way more comfortable than going out on a ship—and too little emphasis on basic observations.

You have to do both. But I think we’re a bit out of balance at the moment—the amount of support available, the number of people, our graduate students working on their Ph.D. theses—they’re tempted to chose computer modeling intensive work. I think a little bit out of balance with making the basic observations.

How did scientists and generals get along during WWII?

Well, there were some scientists who didn’t and some who did. I don’t think there’s a generalization. As a whole, in the United States, the university community and the Navy community worked very well together, and I think that was not as much the case in Germany or in Japan. There the military depended less on working with the university community.

How has the working relationship between scientists and the military changed since WWII?

Well, it was wonderfully positive after the war ended. The Navy community, the leading [inaudible], the university community decided we’d just have to continue working together. If you recall, we started the Office of Naval Research, ONR, which was at the time the only government support of science. Later on NSF came in. I think quite a few years later. And the Navy, particularly, was very adventurous and willing to support far off ideas that may even have seemed a little ridiculous. But I think it was a very wonderful age for being an oceanographer, and I happen to have the date lock of coming into my career just at that time and having wonderful support from the Navy. And they helped us when we made our mistakes, which is so important. We’d take [inaudible] out to sea with us, we lost an instrument. They said, well, we’ll find a way to get you another one! So that day has now ended. The money is sparse, and willingness to take chances, which I think are very important, have diminished. I’m particularly sorry that there is less opportunity for people to take chances that things may fail. It should be a basic part of the research effort.

You learn a lot from failure, but I’ve been unable to persuade our graduate students and our faculty. Our faculty should be willing to give the Ph.D. for an experiment that failed, provided it’s been done responsibly.

Tell us about sending a sound signal halfway around the world through the oceans.

It was a low frequency acoustic signal, 100 hertz. We went to a place in the Southern Indian Ocean, Heard Island, 52 south, because it has a direct route. It’s called a great circle on the globe. It’s a straight line on a sphere into all of the ocean basins of the world, to the west past the Cape of Good Hope into the South and North Atlantic, to the east past New Zealand, into the South and North Pacific. So we could see whether we would be heard at long distances, distances equivalent to halfway around the world.

It was a good experiment because we really did not know whether it would work. And estimates made before the experiment differed by orders of magnitude all the way between impossible and relatively easy. We had no idea how it would come out.

What was the reaction to the sound signal experiment?

Somebody used the word “the shot that was heard around the world” and the German magazine Der Spiegel thought that was a great expression, so they quoted it and had an article called, “Radau in der Tiefe.” Radau is another favorite expression for noise! It’s a bad noise. And we fell into the tentacles of the environmental groups, if you wish, I think a bit undeservedly so, and we never recovered from that phase. It really has meant ever since then a continuing effort to try and continue our work.

We started about the same time as the people who started the Argo floats, having floats in the ocean which go down and up again, report to satellites. We thought that between the Argo float and our attempts, we would learn lots about climate changes in the ocean. And they’ve done lots better than we do, in part because we’ve been very seriously limited by the whaling community.

What is your proudest scientific accomplishment?

Probably that Dave Cartwright, the British oceanographer, and I, wrote a paper on tidal prediction, which I thought was pretty good. It was a new way of predicting tides since the days of Newton and others. But tidal prediction worked pretty well already, so we improved something that does work pretty well! But it was a better way of doing it and it has made a difference. The most exciting was when we found that our signal at Heard Island was in fact recorded halfway round the world.

What would you say is the most misunderstood aspect of the oceans today?

I’m trying to give this some thought. I think that people think of the ocean in a negative way. At this meeting yesterday, questions about having energy sources—they think that shallow water is better than offshore deep water. I think it’s the other way around. The oceans can be a friend and a foe and it’s probably more friendly in deep water at great depths. And people are afraid of great depths, the deep water, and I think have made a mistake in that way. I would think that the disaster in Japan was due to the fact that people thought that a nuclear power plant just on the coast very close to the ocean would be safer than in the ocean. It’s certainly safer than in the ocean at very shallow depth. But I think there’s a case to be made that these things would be a lot safer if you go to some other depths seaward, where the waves are not broken. When you are aboard a ship you can’t even know that there’s a tsunami passing, the dimensions are such, and I think that a better assessment of the dangers and the advantages of the ocean environment could be a useful thing to do.

Can you give an example of an important problem that ocean scientists are working on today?

I have been working without success on understanding wind drag. The wind drags the ocean, causes currents, like the Gulf Stream upwelling, aeration of the oceans, and it depends significantly on the fact that the ocean surface is not glassy smooth, usually, but rough. But the word rough doesn’t tell you what is meant. It’s apparently very short waves that really make the ocean difference between the smooth and the rough situation. And although we have good empirical rules for understanding and allowing for that roughness, we have no further mental understanding of what that really means.

Do you think that attitudes toward science have changed during your career?

Yes. It was more adventurous, more observation-oriented, certainly less computer-oriented, less modeling-oriented. And my chief hope is to persuade some people to be willing to take more chances and to do experiments which have a significant chance for failure, because I think so much can be learned by our mistakes, by things that do not work, and we’re too afraid to do that kind of thing.

Tell us how you found your way to Caltech as a student.

I was sent to America because I was supposed to work in a bank affiliated with Grandfather’s bank in Vienna, and I hated every moment of it and made a lot of mistakes!

Well, I had a terrible time working in that little bank in New York! And I did it for two years and I didn’t like living there, and I fell in love with street names in California: Pasadena, San Marino, these beautiful Spanish street names. So, my mother finally gave up on me, gave me some money and said, “you do what you want.” And I bought a car, drove out to California, presented myself at the dean at Caltech because I’d fallen in love with their street names, and said I’m going to be a student here. And he said, “let me pull your files.” I said, “I don’t have any files here!” And he was so amazed at my naivete. He said, well, you can sit down and study for a month and take our entrance exam, you probably won’t make it, but if you wish I will give you that chance. And I worked for the first time in my life, studied, and the greatest wonder of the world is that I passed that exam, I think!

Who are your scientific heroes or mentors?

A man in England named Sir Geoffrey Taylor, who studied turbulence, your question, was a fantastic person. My teacher, Harold Sverdrup, North Pole explorer, to whom I owe so much of my career. And finally my associate, Roger Revelle, who did so much for the Scripps Institute, and who would be very, very good at the meeting we’re having today because he had such a broad view of science and interaction of science with social problems.

You’ve often been called the “adventurous emotionographer.” Do you like that title?

Yes! I’m not really a very good problem solver. There’s people very much better than I am. And my mathematics was alright for its day, but it’s now behind that of my students. But I have been successful in asking questions that weren’t being asked and became later on worked on by very many people. For instance, you asked a question about tides. When I tried to get into tides, nobody was working on tides and it was generally considered a dead subject. I went to the National Science Foundation and they said, “Don’t you know that the subject went to bed with Victorian mathematicians?” And I said, “No, I think it’s time to take it up again!” We have just built an instrument that makes it possible to measure tides in the deep sea, which nobody had been able to do. The computers were coming in, which meant you could calculate tides of a real ocean basin, not some highly idealized thing. And we’d learned something about the analysis of stochastic processes, and 10 years later it’s a thriving subject. We now believe that the mixing of the oceans is partly dependent on tidal dissipation, and it was a good question to ask.

This article was originally published in Nautilus magazine on July 31, 2014.