Maarten Schmidt, Caltech astronomer who changed our understanding of the cosmos, dies

Maarten Schmidt, Caltech astronomer who changed our understanding of the cosmos, dies

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 might of beasts that roam deep space, died at home in Fresno.

Professor emeritus at Caltech, Schmidt died Saturday at age 92.

Schmidt had only recently arrived at Caltech when he climbed into the observation cage of the Palomar Mountain Large Telescope to try to figure out the measurements radio astronomers were getting from a bizarre object that should have been a star but isn’t. couldn’t be.

The object, known as 3C273 in bland astronomy slang, was 3 billion light-years away, a good chunk of the way 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 was unlike anything he had seen before.

After weeks of futile puzzles, Schmidt told his wife, Corrie, “Something terrible happened in the office.”

It turned out that it wasn’t so terrible after all. Maarten Schmidt had discovered the quasar (quasi-stellar radio source), an engine of incredible power. It’s so incredible that it took another six years before Donald Lynden-Bell, one of Schmidt’s students, found the explanation: a hungry black hole consuming a meal. Nothing can escape the fearsome gravitational power of a black hole, but the matter at the edge of its whirling vortex is so superheated that bursts of energy shoot out at near-lightspeed.

This burst of energy was what radio telescopes on Earth were picking up. It wasn’t a galaxy, and it wasn’t exactly a star, or even a black hole. It was the radiation produced by the greatest spectacle in the universe.

The discovery made Schmidt famous. Her angular, bespectacled face appeared on the cover of Time magazine. The rewards poured in. And unlike some oddity discoveries in space, the importance of Schmidt’s work only grew over time as cosmologists came to realize the role quasars played in building the modern universe.

“The discovery of quasars is one of the fundamental discoveries of astrophysics, and it completely changed astronomy,” said George Djorgovski, professor of astronomy and director of the Center for Data Driven Discovery at Caltech. Black holes had been a theoretical concept for some time, but quasars have proven their existence in real life. They would play a role in everything from proving the existence of dark matter to forming 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 which “greatly expanded the scale of the observable universe and led to our current view of the violent universe in which black holes play a key role.

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

Oort put Schmidt to work at Leiden University’s observatory, the oldest in the world, measuring 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 kid’s cap gun.

Schmidt’s reputation for demanding stubbornness eventually brought him to the attention of astronomers at the Mount Wilson and Palomar Observatories in Southern California. At the time, these observatories housed the largest assemblage of star surveyors in the world, 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 was revolutionizing astronomy, the radio telescope. For millennia, visible light was the only means people used to understand what was happening beyond Earth. But electromagnetic waves come in all sizes, from the shortest wavelengths and 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, which is why radio telescopes must be very large. That can be a problem, but a radio telescope has key advantages, including the ability to see through interstellar dust that would block radiation with shorter wavelengths. This meant that radio telescopes could probe extremely remote regions of the universe.

In 1961, Schmidt finally got the chance to operate Palomar’s Large 200-inch Telescope, an instrument so awe-inspiring that top astronomers waited months and years before they could use it. Schmidt’s job was to track down strange objects discovered by radio telescopes. It was a long and tedious job, but one for which the patient young astronomer was perfectly suited.

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

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

The mysterious 3C273 turned out to be two sources, a star and an attached jet of gaseous matter. The spectra he was getting on his photographic plates made no sense. The emission lines on the spectrogram didn’t match anything he knew.

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

Yet it was brighter than most nearby galaxies. If it was so far away, how could we even see it? It shone with light from 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 happening?

Schmidt still wasn’t sure if he was looking at something much closer, in our own galaxy, and therefore much less interesting, when he went to see a colleague who was thinking about 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 instant scientific celebrity when he and his colleagues published four now classic papers describing what Schmidt called quasi-stellar radio sources. It took some time before the scientific community accepted the term quasars.

In a 2014 interview, Schmidt recalled the excitement around his discovery. It was all very flattering and, not insignificantly, good for his career. He became chairman of the physics, mathematics, and astronomy division at Caltech in 1975, then director of Hale Observatories, which operated the Palomar and Mt. Wilson instruments.

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

The most satisfying work came later, when he was able to show where the quasars were in the timeline of the universe. As some of the most distant objects that can be studied, which also makes them the oldest, “they show a snapshot of what the universe looked like at that time,” he said. “I was able to gather evidence about the early evolution of the universe.”

According to Djorgovski, they provided the first indications of what is known as the epoch of reionization of the early universe, when stars and galaxies began to form. “It was one of the major milestones in the evolution of the universe,” added Djorgovski.

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

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

Supermassive black holes are now thought to exist at the center of most large galaxies, such as the Milky Way. But relatively few these days have active quasars, or what are now called galactic nuclei. They are active because they eat. Over time, the vast majority of black holes consume all the dust, 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 part of. In the future, however, his appetite will arouse. The nearest large galaxy, Andromeda, is steadily approaching the outskirts of the Milky Way. The two giants will collide in about 4 billion years.

This event will send tides of gas and dust against the deadly shoreline of black holes in both galaxies. It should be a fantastic sight, but no one on Earth will see it. By then the sun will have swelled and reddened and rendered our planet uninhabitable.

After coming close to fame, Schmidt served for two years as president of the prestigious American Astronomical Society. Besides the Kavli Prize, he won the Royal Astronomical Society Gold Medal 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 is survived by his three daughters, Anne, Marijke and Elizabeth.

Johnson is a former Times writer.

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