Astrophysicist Feryal Özel lectures on her work with the Event Horizon Telescope Collaboration to capture the first-ever photo of a black hole on Thursday in the Amphitheater.
Feryal Özel’s research has focused on three questions: What form does the densest matter take? What is the boundary between matter and singularity? And are black holes singularities with event horizons?
That third question was the focus of her lecture on Thursday morning in the Amphitheater, part of this week’s Chautauqua Lecture Series theme, “Wonder and Awe.” Özel, currently the department chair and a professor at the Georgia Institute of Technology School of Physics, has spent over two decades contributing critical research to answering the question. Those decades of research culminated in pictures that have changed the way humanity understands the universe: the first-ever photograph of the black hole at the center of the galaxy Messier 87, and the first photo of the black hole at the center of the Milky Way.
Astrophysicist Feryal Özel lectures on her work with the Event Horizon Telescope Collaboration to capture the first-ever photo of a black hole on Thursday in the Amphitheater.
But Özel’s journey to improving the world’s understanding of black holes didn’t happen overnight.
“Let me tell you: It did not start with black holes,” she said. “It started with something much, much, much smaller than that, when I was much, much, much smaller than I am right now.”
Ozel was a “math whiz” in elementary school, a fact that her parents caught onto pretty early on, she said. Then, when she was in third grade, her parents bought her a science encyclopedia. Inside was a picture of an atom, its nucleus surrounded by orbiting electrons — “the building blocks of matter,” the encyclopedia said.
Already curious about how everything in the world worked, how all the different shapes came to be, Özel was captivated.
“From that point on,” she recounted, “when people asked me, ‘What are you going to be when you grow up?’ I said, ‘atomic physicist.’ There was no hesitation.”
Özel went on to study particle physics at Columbia University, eager to learn more about atoms, the building blocks of the universe — and what the building blocks of atoms were. Even smaller than the atom is the quark, she explained, which make up the protons and neutrons in the nucleus of every atom. After she received her bachelor’s degree from Columbia, Özel began working at the European Organization for Nuclear Research, more widely known as CERN, in Switzerland.
At the time, CERN was home to one of the world’s largest particle colliders. Particle colliders, she explained, are central to the scientific study of atoms. Using magnets, particle colliders speed atoms up along a circular track, then smash the atoms together. When they collide, the atoms rearrange themselves depending on what was colliding, she said, and researchers are able to examine the results of a collision to better understand how certain particles work.
But the Large Electron-Positron Collider at CERN was about to shut down, and there wouldn’t be another collider of its magnitude ready to use for 15 more years.
“It just wasn’t the right time to be using this tool to get at the question that was burning me: What is the smallest constituent of matter and how does matter behave in those extreme conditions?” she said. “I realized that the universe actually provides a laboratory by which we can study these questions — only if we formulate them a little bit differently. Why, necessarily, (do we) have to speed up particles and smash them against one another when there are places in the universe where gravity does that for us?”
Gravity is the force that makes planets move, that holds us firm to the ground, and that, in some circumstances, can smash so many particles together that it creates the most dense object in the known universe: the neutron star. Sometimes, she explained, when a star runs out of fuel and dies, gravity will leap into action, pulling the star further and further in on top of itself until all that’s left behind is a sphere no more than 13 miles across. That sphere, smaller than the length of Chautauqua Lake, carries the potential to collapse into a black hole.
“There’s this invisible line in the universe, where if particles can withstand gravity, you get these amazing neutron stars,” Özel said. “If gravity wins over, even past that point, beyond that invisible line, we get what we call a singularity.”
A singularity is an almost unfathomable concept, where the gravity and density of a celestial body become so intense that it is no longer measurable by any human capabilities, with the capacity to bend light rays and to completely alter time. The notion of singularities was first posited by Albert Einstein in his theory of general relativity, which predicted their existence with a mathematical equation, Özel explained.
Einstein, however, did not believe that singularities could actually exist — in fact, he spent his entire life trying to find an alternate explanation to his theory of general relativity. Özel decided that she wanted to figure out whether Einstein’s theory was correct, returning to the question at the core of her lecture: Are black holes singularities with event horizons?
To answer that question, Özel turned to one specific star cluster that many scientists believed was capable of harboring a black hole: Sgr A*, located at the center of the Milky Way galaxy. The reason scientists believed a black hole may be at the center of the Milky Way, she said, was because of the interesting behavior of the stars around it; all of the stars near the center were orbiting around a completely dark area in space — not a larger star.
“There’s a cloud of stars at the very center (of the galaxy) that are orbiting around an object that is 4 million times the mass of our sun,” she said. “But it’s basically black. … If it was something like a star, it would be many, many trillions of the brightness of the sun. It would be the brightest object in our galaxy.”
Özel and her team at the Event Horizon Telescope Collaboration were determined to figure out whether or not that object at the center of the galaxy was a black hole. The issue, she said, was how indescribably tiny the potential black hole was from the perspective of Earth; it would be like placing a donut on the moon and asking someone to photograph it with their phone camera.
They would need a massive telescope — larger than any that had ever existed up to that point in time. To do that, they turned to a method called very long baseline interferometry; essentially, they would place huge telescopes at various places all around the world, and then use a massive supercomputer to process the incredible amount of data those telescopes would produce into one cohesive “image.”
In 2017, after over 15 years of work to set up the expansive network of telescopes around the world, Özel and her team were ready to use them for the first time. In the years before, they had been building a massive library of simulations, all trying to predict what the telescopes would reveal to them.
And in 2022, for the first time ever, the black hole at the center of the Milky Way had been photographed, displayed to the world in Washington D.C. All of their simulations had accurately predicted exactly what they would find at the center of our galaxy. Özel and her team had proven Einstein’s theory correct. The answer to her question — “Are black holes singularities with event horizons?” — was yes.
“We were both very relieved, but also disappointed,” she said. “That’s how science goes. All of that effort to try and answer a question, secretly hoping that we’re going to find something different from what we thought because that’s the way we get the next idea, … but we move forward.”
For Özel, moving forward means looking toward the next frontier. She said that researchers are now working to move the vast network of telescopes they used to photograph the black hole up off the Earth’s surface and into space, where they will be able to take even more photographs and bring in even larger amounts of data, all contributing further to human understanding of the universe.
The main reason that she continues to find more questions to answer and more mysteries to solve, Özel said, is because she never lost the same sense of wonder she felt looking at a picture of an atom in the science encyclopedia her parents bought for her when she was 8 — and she implored Chautauquans to keep wondering with her.
“I’ve never lost that sense of wonder — I am a little kid,” she said. “My hope for all of you is that neither do you ever lose that sense of wonder when you look at the world around you; the nature, the space. Whether or not you have the mathematical tools … it doesn’t matter. I hope that you all look at the world with a sense of wonder going forward.”
