Einstein of the sea

He predicted the height of the waves in the invasion of Normandy, drilled a hole in the belly of the earth and measured the warming of the oceans with giant loudspeakers. Last month, the pioneering oceanographer Walter Munk, one of the most important marine scientists in the world, died at the age of 101.

Yishai Danieli, Angle - news agency for science and the environment

If you had to name a great physicist of Jewish origin, who explored space and time and dared to think in areas that no other scientist had explored before him, who emigrated from Europe to the United States before the Nazis came to power and whose invention was used by the Allies to win World War II, you would probably name one without hesitation : Albert Einstein.

But not only Einstein fits this profile. The American oceanographer Walter Munk, who recently died at the extreme age of 101, shared biographical lines with Einstein (and was even called the "Einstein of the sea") and belonged to a generation of scientific pioneers, whose contributions went far beyond the confines of the laboratory. Israeli Science Day, which falls on March 14 (Einstein's birthday), is an opportunity to recognize and cherish those who changed the way we know the sea in many countries.

The student who helped the Americans land in Europe
Manek was born in 1917 in Vienna, which at the time was still the capital of the Austro-Hungarian Empire, to a well-established and well-connected Jewish banking family. His parents, who divorced when he was ten years old, destined him for a career as a banker, but this was not the future that young Walter imagined. "I was a bad student," he recalled in an interview on the occasion of his 100th birthday, "and I preferred to spend most of my time skiing in the mountains." After being expelled from school, he was sent by his mother when he was 15 years old to New York, to attend high school and college and continue on the path that was planned for him.

In the United States, far from being committed to his family, Manek decided to abandon the banking profession and work in sunny California, where he studied applied physics. The connection to the sea, which changed his life, came about entirely by chance: in the summer of 1939 he moved to live near his girlfriend in San Diego, and found a temporary job at the Scripps Institute of Oceanography - one of the oldest and largest research institutions for earth and ocean sciences. Scripps became Munk's home, where he spent his entire academic career.

Munk. He relied less on technology and more on conceptual development, which allowed him to look at problems much more broadly. Photo: Prolineserver, Wikipedia

After the annexation of Austria by the Nazis (the Anschluss) in 1938, Munk enlisted in the American army. Unlike his classmates at Scripps, who enlisted in the Naval Research Unit, Munk joined the US Army Alpinist Unit utilizing his talent in skiing. But very quickly he was asked to return to the Naval Institute at Scripps and assist in the war effort - the US was about to join the campaign, and a challenge of hundreds of kilometers of open sea separated it from the battlefields in Europe and the Pacific Ocean.

Ahead of the naval invasion of the North African coast, Munk discovered that the waves in the landing zone were too high for most of the time for the American boats. The landing could have ended in disaster. Manek alerted the army about this, and at the same time approached a scientific task that had not been done until then: to produce an accurate forecast regarding the height of the waves in a certain area, in order to determine the window of opportunity for an invasion. The model, which Manek created with his supervisor at Scripps, turned out to be accurate, and was used by the American forces to determine the landing dates in North Africa, the Pacific Ocean and Normandy. The work of Munk, who was a 27-year-old graduate student, saved many lives and changed the course of history.

Heavy rain is about to fall
After the war, Munk continued his studies and became a permanent researcher at Scripps. He studied sea waves in collaboration with the American military and took part in the famous nuclear tests conducted by the United States in the Pacific Ocean, where he and other scientists studied the spread of radioactive substances in seawater. In 1952, he was a participant in the hydrogen bomb experiment at Anutak Atoll, where he tested the formation of tsunami waves following the explosion. During the experiment he and his team were caught in a shower of radioactive rain and had to throw their clothes into the sea.

"Munk was a physical oceanographer who specialized in waves," explains Steve Brenner, professor of atmospheric and marine sciences in the Department of Geography and Environment at Bar-Ilan University. "You have to understand that waves in the sea are not only the wind waves, which we know and see on the surface, but a whole world of phenomena that occur in time and space. There are waves in the sea of ​​all kinds of sizes, such as tides or tsunamis, and also internal waves - which occur in the intermediate layer between the upper water and the deep water. These internal waves are very slow, but they have an impact on the internal dynamics of the entire ocean."

In the XNUMXs Manek was involved in pioneering research on sea currents, and especially the Gulf Stream. He also studied the rotation of the Earth and the effect of tidal currents on the rate of rotation. He is considered to have formulated the basic concepts in these fields. At the same time, the indefatigable Manek began to set his sights on bigger and more ambitious projects. He was the originator of the idea behind "Project Mohol" - the American attempt to drill into the earth's crust below sea level, to sample the sphere's shell. The project was launched off the coast of Mexico, but after several years it was stopped due to financial and technological difficulties.

In the XNUMXs, Manek initiated one of the most ambitious and expensive experiments conducted up to that time in ocean research: he and his team deployed sensors in the sea from New Zealand to Alaska, to locate evidence of waves originating from storms in the southern Indian Ocean, thousands of kilometers away. Munk himself moved with his wife and young children to an isolated measuring station in Samoa, depending on the electricity produced by a generator alone. "It was a great time", he recalls. "But most of the time we were busy repairing the generator and not the scientific experiment," he commented with characteristic humor. Munk was able to document the arrival of the waves as far as Alaska, a distance of thousands of kilometers from the place where they were created.

The voice heard around the world

But all this was just a prelude to the high point of Manek's professional life. Starting at the end of the seventies, the topic that has occupied many scientists ever since disturbed Manek's rest - global warming. He was particularly troubled by the lack of observational evidence for sea warming. And Manek like Manek, decided to produce a scientific method that would answer his question.

"Manck hypothesized that if low sound waves are transmitted, even lower than the range of human hearing, they can move in the sea over distances of tens of thousands of kilometers," explains Brenner. "And since the speed of the wave is affected by the temperature, measuring the arrival time of the sound waves can teach about the average temperature of the sea in the path of the sound wave, which can over time give an indication of the warming of the earth."

Munk liked to think big, and the method he devised reflects that well. "This is a good method because it represents the heating of the entire system: the sound wave travels over enormous distances and passes warmer and less warm areas, but its arrival time reflects the average temperature of the entire system. If you follow it over years, it can show trends in the average sea temperature of the entire system."

But how do you test the method in reality? In 1993, after two years of hard work, Munk's huge experiment was launched: huge speakers provided by the US Navy were placed in the depths of the sea near Heard Island in the southern Indian Ocean. The research was conducted in international cooperation with ten countries in which acoustic sensors were placed, designed to pick up the sounds. The experiment was nicknamed "the sound heard around the world". In scientific language, the method is called acoustic tomography.

Five days after the start of the experiment, a fierce storm hit the isolated island, shaking the research vessel and causing irreparable damage to the equipment. The experiment was stopped, but enough information was collected to confirm the assumption: the passage of sound waves in the water medium over such enormous distances is possible and measurable.

Manek was not satisfied with one experiment, and during the nineties and early XNUMXs, when he was in his eighth decade, he continued with a series of experiments that would prove that the method is effective over a long period of time. But these experiments brought him into a head-on collision, which he did not foresee - with the environmental organizations.

The reason for the conflict is a possible harm to marine mammals, and especially whales, who navigate their way using sound waves. Environmental activists feared that Munk's experiments, which were supposed to be conducted, among other things, in the Monterey Marine Reserve off the coast of California, would harm the whales that live in the area. Munk and the US military, which funded much of the research, did not anticipate the magnitude of the opposition. The wave of protest caused Munk to fold and move the test site away from the coast.

At its peak, the fight over Munk's sea experiment became a real clash between oceanographers and marine biologists, which ultimately led to the termination of the series of experiments in 2006. But Munk himself was convinced until the end of his days that the royal road could be found. "I am convinced that underwater acoustic research can be done without harming the whales, by taking appropriate precautions," he said in an interview. "The parties need to learn to work together."

The man who knew how to ask the right questions
Manek was ahead of his time in many ways. In the early seventies, for example, he proposed an ambitious plan for the city of Venice, with the aim of preventing its repeated flooding by sea water. His plan included three "sea gates" between the city's lagoon and the Adriatic Sea, which would be opened and closed alternately, blocking the tide water when necessary but also being used to create a circulation that would carry pollutants out of the lagoon. The plan encountered bureaucratic difficulties and has not been implemented to this day, but similar sea gates have since been installed in other parts of the world, with the aim of protecting cities from rising sea levels.

Munk is described as a noble man with boundless curiosity and an old-world flavor, who knew how to ask the right questions at the right time. "It's at least as important as finding the answers," he said, "and I think I would have been better at asking the questions."

He was also an outdoorsman, who liked to jump into the water and install the measuring devices himself. In most of the photos he appears shirtless. He liked to dive and liked the long trips at sea. "I'm not a great theoretician," he testified himself, "and I don't say this out of arrogance. I knew what questions to ask, and I had the good fortune to choose topics that at the time were unpopular, which after a few years became so. Then, as soon as too many words were written on a certain topic, I moved on to the next question."

Munk received many military and civilian honors during his lifetime, including the United States National Medal of Science in 1985. Part of his work, concerning the use of sound waves to locate and hide submarines, remains confidential to this day.

What makes Manek a scientist of Einstein's stature, one who left his mark on human history? "Manck was characterized by great curiosity and intellectual depth on the one hand, but at the same time he had a tendency, reserved for few scientists, to look at the big picture and fearlessly touch on a wide variety of subjects," says Brenner. "Manck relied less on technology and more on conceptual development, which allowed him to look at problems much more broadly. Unfortunately, today there is a tendency to over-specialize and rely heavily on technology, which causes researchers to lose this broad point of view."