Maarten Schmidt dies; Caltech astronomer has changed our understanding of the cosmos


Maarten Schmidt, the Dutch-born American astronomer whose discovery of quasars dramatically changed our understanding of the evolution of the cosmos and revealed the power and potential of the beasts that roam space, has died at his home in Fresno.

Emeritus professor at Caltech, Schmidt, died Saturday at the age of 92.

Schmidt had only recently arrived at Caltech when he ascended into the observation cage of the large Palomar Mountain telescope to try to understand the measurements radio astronomers were getting from a bizarre object that should have been a star, but could have been impossible.

The object, known as 3C273 in tasteless astronomy, was 3 billion light-years away, well back to the Big Bang. Yet it was hundreds of times brighter than our own galaxy of 100 billion stars. Even more curiously, when Schmidt finally got a spectrum of his light signature, it looked like nothing he’d seen before.

After weeks of pointless puzzling, Schmidt told his wife Corrie, “Something terrible has happened in the office.”

It turned out not to be that bad after all. Maarten Schmidt had discovered the quasar (quasi-stellar radio source), an engine of incredible power. So incredible that it took another six years for Donald Lynden-Bell, one of Schmidt’s students, to come up with the explanation: a hungry black hole eating a meal. Nothing can escape the terrifying gravitational pull of a black hole, but material at the edge of its swirling vortex is so overheated that bursts of energy are blasted out at nearly the speed of light.

This energy explosion was what radio telescopes on Earth picked up. It wasn’t a galaxy, and it wasn’t a star, or even a black hole, exactly. It was the radiation caused by the greatest show in the universe.

The discovery made Schmidt famous. His angular, bespectacled face appeared on the cover of Time magazine. Prices were flowing his way. And unlike some discoveries of quirks in space, the importance of Schmidt’s work only grew over time, as cosmologists realized the role quasars played in building the modern universe.

“The discovery of quasars is one of the fundamental discoveries of astrophysics and has completely changed astronomy,” said George Djorgovski, an astronomy professor and director of the Center for Data Driven Discovery at Caltech. Black holes had been a theoretical concept for some time, but quasars proved their existence in a concrete way. They are said to play a role in everything from proving the existence of dark matter to the formation of galaxies.

In 2008, more than four decades after its discovery, Schmidt and Lynden-Bell were awarded the $1 million Kavli Astrophysics Prize for their work that “dramatically expanded the scale of the observable universe and led to our current view of the violent universe in which massive black holes play a key role.”

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The son of a government accountant, Schmidt was born in Groninge, Netherlands, on December 28, 1929. At age 12, he built his first telescope using a lens he found on his grandfather’s farm. He was still a student at the University of Groningen when he caught the attention of the country’s foremost astronomer, Jan Oort, who gave his name to the Oort cloud of comets around the solar system.

Oort put Schmidt to work at the Leiden University observatory, the world’s oldest, to measure the brightness of comets. But it was his other early work studying the spectroscopic fingerprint of hydrogen that would prove crucial a decade later, when he discovered an object that made a supernova look like a child gun.

Schmidt’s reputation for exacting tenacity eventually brought him to the attention of the astronomers at the Mount Wilson and Palomar observatories in Southern California. At the time, those observatories boasted the world’s largest collection of astronomers, from Walter Baade, who doubled the known size of the universe, to Fritz Zwicky, who predicted the existence of dark matter.

By the time Schmidt joined them in 1959, an important instrument revolutionizing astronomy, the radio telescope. For thousands of years, visible light was the only medium humans used to understand what was happening beyond Earth. But electromagnetic waves come in all shapes and sizes, from the shortest wavelengths and the highest frequencies—powerful gamma rays and X-rays—through ultraviolet, visible, infrared, microwaves, and finally low-frequency radio waves.

Radio waves are much longer than light waves, ranging from centimeters to kilometers, so radio telescopes must be very large. That can be a problem, but a radio telescope has important advantages, including the ability to see through interstellar dust that would block radiation of shorter wavelengths. This meant that radio telescopes could examine extremely distant regions of the universe.

In 1961, Schmidt finally got the chance to operate the large 200-inch telescope at Palomar, an instrument so grand that the greatest astronomers waited months and years for a chance to use it. Schmidt’s job was to track down some strange objects discovered by radio telescopes. It was time-consuming, tedious work, but one that the patient young astronomer was ideally suited for.

“It was romantic!” he later told an interviewer. “Occasionally you just had to stop and look around.”

Most of the radio sources turned out to be ordinary elliptical galaxies. But a few were puzzling. They didn’t look like galaxies at all. Instead, they looked very much like stars. Very powerful stars. He was particularly interested in 3C273, which radio astronomers in Australia had narrowed down enough to a sky region that Schmidt thought he had a chance to capture near Palomar. In late December 1962, just weeks after the Cuban Missile Crisis brought the world to the brink of nuclear destruction, Schmidt finally succeeded. But that didn’t solve the mystery. In fact, it had only just begun.

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The mysterious 3C273 turned out to be two sources, a star and an attached jet of gaseous material. The spectra he got on his photographic plates made no sense. The emission lines on the spectrogram matched nothing he knew.

A few weeks later, Schmidt was sitting in his office on the second floor of the Robinson Building in Caltech when something clicked. The image, he suddenly realized, looked a lot like the fingerprint of hydrogen, the primary fuel of stars. Only it was massively red-shifted, meaning the object was traveling away from Earth at a fantastic speed, nearly 30,000 miles per second, and was fantastically far away.

Still, it was brighter than most nearby galaxies. If it was so far away, how could it be seen? It shone with the light of 2 trillion stars, but it was only about the size of our solar system, less than a light-year, while the Milky Way is 100,000 light-years in diameter. What was going on?

Schmidt wasn’t sure if he was looking at something much closer, in our own galaxy, and thus much less interesting, when he went to see a colleague who was puzzling over a similar object. It had the same telltale signature and was even more red-shifted, meaning it was even further away. That was the aha moment.

In March 1964, Schmidt became an instant scientific celebrity when he and his colleagues published four now classic papers describing what Schmidt called quasi-stellar radio sources. It took a while for the scientific community to accept the term quasars.

In a 2014 interview, Schmidt recalled the excitement surrounding his discovery. It was all very flattering and, most importantly, good for his career. In 1975 he became chairman of Caltech’s Department of Physics, Mathematics and Astronomy and then director of the Hale Observatories, which operated the instruments of Palomar and Mount Wilson.

“It was a fantastic event,” said Schmidt. “But once it’s done, it’s done.”

The more satisfying work came later, when he was able to show where quasars fit on the universe’s timeline. As some of the most distant objects that can be studied, making them the oldest, “they show a snapshot of what the universe looked like back then,” he said. “I was able to collect evidence about the early evolution of the universe.”

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According to Djorgovski, they provided the first clues to what is known as the reionization era of the early universe, when stars and galaxies first began to form. “That was one of the most important steps in the evolution of the universe,” Djorgovski added.

Quasars turned out to be cosmic dinosaurs, ancient beasts that roamed the landscape of space, preying on weaker creatures to feed their huge appetites. This, along with the discovery of the cosmic microwave background, proved to be the final nail in the coffin for the so-called steady-state theory of the universe, which claimed that the universe had always been and always would be.

These remnants of an ancient cosmos, so fantastically distant and so different from anything created in space today, were proof that the young universe was a very different place.

It is now believed that there are supermassive black holes at the center of most large galaxies, such as the Milky Way. But relatively few today have quasars, or what are now called active galactic nuclei. They are active because they eat. Over time, the vast majority of black holes consume all the dust and gas and other things in their region and go into hibernation.

The black hole at the center of the Milky Way, known as Sagittarius A*, is one of them. In the future, however, his appetite will awaken. The nearest large galaxy, Andromeda, is steadily approaching the outskirts of the Milky Way. The two giants will collide in about 4 billion years.

That event will cause tides of gas and dust to wash up against the deadly shoreline of the black holes in both galaxies. It should be a fantastic show, but no one on earth will see it. By then, the sun will have swollen and turned red, rendering our planet uninhabitable.

After his brush with fame, Schmidt was president of the prestigious American Astronomical Society for two years. Along with the Kavli Prize, he won the Gold Medal of the Royal Astronomical Society in 1980 and the James Craig Watson Medal in 1991.

Schmidt was married to Cornelia “Corrie” Schmidt-Tom for 64 years, until her death in 2020. He leaves behind his three daughters, Anne, Marijke and Elizabeth.

Johnson is a former Times staff writer.


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