Black Hole Son

One morning in April 2019, the world awoke to an orange and black mass splashed across news sites around the globe. The Event Horizon Telescope (EHT), an international network of radio telescopes, had captured the first-ever image of a black hole from within the colossal Messier-87 (M87) galaxy, forever changing our understanding of physics, the cosmos, and our place in it. What had once been intriguing fodder for sci-fi movies became visible evidence for scientists to start dissecting.

Dominic Chang ’18 recalls feeling both disconcerted and thrilled by the fuzzy image of M87’s black hole. “I’ve been working with black holes mathematically for a long time, so I thought I understood them very well. But then, when I saw the actual image, I realized, ‘I don’t even know what I’m looking at,’” he says. Like many theoretical physicists, he had long used black holes as material for speculative thought experiments—but there was nothing theoretical about where his black hole research would take him next.

The son of an English teacher, Chang was raised to appreciate literature of all stripes; however, his preferences at a young age were predictably niche. “I liked world-building fiction like the Harry Potter and the Percy Jackson series—anything where [the author] built a universe where people could do some things but not others and the rules were given to you in pieces,” he explains. “I guess that’s similar to what you do in science, finding clues and seeing if they’re consistent with what you knew before.” He also spent countless hours with his family’s encyclopedia set, lingering in the sections on space and astronomy.

When it came time to choose a dedicated area of study, a decision typically made during high school in his native country of Jamaica, he allowed himself to be swayed by his peers’ cultural values. “It’s really common for Jamaican kids to want to be lawyers, engineers, or doctors,” he says. “Or, at least, for their parents to want them to be those things.”

Esoteric and almost impossibly complex? He enrolled in (now emeritus) Professor George Phillies’s notoriously difficult Introduction to Physics course. Despite “barely scraping by” with a C, he was hooked and switched his major shortly thereafter.

“[Phillies] was very much interested in teaching you how to do physics more so than just how to use equations. I think most people would feel defeated from doing so poorly in an introductory class, but I really felt a great sense of personal improvement after completing his class and thought that there was nothing stopping that improvement from continuing in the future,” says Chang. “I think that experience made me want to do physics more, if anything.”

In preparation for an independent study project, he asked his would-be mentor for a recommendation on a research topic. Phillies confided he was considering retiring so Chang asked if there were any topics Phillies would have liked to research. “I’ve always wanted to work on quantum gravity,” he replied.

Chang dove headlong into the field, which seeks to reconcile gravity according to the principles of quantum mechanics. This led him to the black hole information paradox, a research topic first described by renowned theoretical physicist Stephen Hawking.

The paradox contrasts two seemingly irreconcilable principles: On one hand, Hawking proved that black holes evaporate over time. Conversely, physics has long asserted that information (in this case, the contents of a black hole) cannot be destroyed. This conundrum captured Chang’s imagination, pitting the rules of one physics discipline against those of another. “That’s what makes the black hole information paradox so special,” he says. “It creates a link between general relativity, thermodynamics, and quantum mechanics.”

Chang continued his research on black holes with his Major Qualifying Project, supervised by then-WPI professors Shanshan and Leo Rodriguez. “The basic problem was to calculate the number of states that could exist for a given black hole,” he says. In his final presentation, he explained the traditional (and highly complex) means of calculating the emission of Hawking radiation from black holes. He went on to demonstrate that by using the holographic principle, a theory that the information trapped in a black hole is also encoded on its two-dimensional surface, one could much more easily calculate the emission of radiation for both spinning and non-spinning black holes. “Technically, it was a solved problem, but I was using a different technique than how it’s traditionally done.”

He knew that pursuing a theoretical topic for his MQP, rather than one he could tangibly demonstrate, could diminish the “wow factor” of his presentation. However, the significance of his work and the rigor with which he approached it was not lost on those in the audience.
One professor remarked that it was the best MQP presentation he’d seen to date. And his theoretical research began opening doors in the real world.

Following graduation, Chang stood at a crossroads. “I was thinking about applying to grad school, but I was pretty broke and couldn’t afford to take the GRE,” he recalls. With the help of a generous friend, he took the exam and applied to five schools—the maximum number his budget would allow. Harvard University was among them. Word of his impressive MQP project preceded him, and Harvard invited him to pursue his doctorate at one of the world’s most prestigious academic institutions. “That MQP definitely helped me get where I am now,”
he says.

Despite his theoretical research background, his work at the LHC was decidedly hands-on. Nearly 17 miles in circumference, the collider’s tunnel includes eight distinct experiment centers, including the ATLAS experiment, which provides a research platform for more than 257 institutions worldwide. Detectors include endcaps embedded with large silicone chips that track particles when accelerated protons collide. “[Accelerated] particles deposit radiation on the detectors, so the silicone chips have to be replaced at the end of their shelf life,” he explains. “I worked on the upgrades.”

Chang enjoyed the transition to practical research, a far cry from the abstract, paper-and-pen calculations he had performed as an undergrad. “At CERN, you’re getting petabytes of data and you’ve got to process it,” he says. “That got me much more comfortable with coding for research and processing large amounts of data.”

Though his position was highly skilled and exposed him to a world-class network of scientists, over time he found the work’s precision and predictability lacking in adventure. “CERN is such a well-oiled machine, but that also means that the analysis pipelines are set in stone,” he says. “That’s appealing to some because you have a sense of security. But for me, it took a bit of the fun out of a PhD.” He began acknowledging his restlessness during a trip back to the States, when forces larger than himself made the decision that it was time to move on.

In the fall of 2019, he came home to find his roommate furiously washing his hands. He warned Chang that a new virus had been discovered in China and threatened to spread globally; COVID-19 had begun its reign. “I couldn’t go back to Switzerland, which meant that I had a lot of time to meditate,” he recalls. “I enjoyed the experiments we were doing, and I loved the country—best chocolate I’ve ever had—but it wasn’t the science I wanted to explore.”

Back in Cambridge, he went on a professional walkabout, taking inventory of his passions, his aspirations, and where the science would lead him next. His personal exploration also took place against the backdrop of a historical breakthrough. Several months prior, the Event Horizon Telescope team had released the world’s first image of a black hole, turning his attention back to his first love. “That was when I decided that I wanted to come back and work on black holes, but not in the way I was doing before,” he says. “This time, I wanted to work on theoretical physics that was closer to observation.” His advisors at Harvard knew exactly where his skills would be best put to use.

In describing his reaction to seeing the first-ever image of a black hole, he recalls a story from the life of Vladimir Nabokov. Famously trilingual, the novelist could read and write English long before he emigrated from his native Russia to England. However, when it came to casual conversation with an English speaker, Nabokov found himself speechless. Chang knows the feeling. “If you asked me a question about a black hole, I could easily find the answer through [scientific] formalism. But when I actually saw the image, I had no idea what I was looking at,” he recalled. “Theory and experiment are just two different realms; they should meet more.”

For Chang, theory and experiment met in a superlative way at the Black Hole Initiative (BHI), a research center at Harvard University focused exclusively on space’s darkest corners. In need of more general relativism specialists, the BHI team welcomed him in 2020—and he was certainly in good company. The first center of its kind, BHI hosted Stephen Hawking at its inaugural celebration in 2016 and now boasts a team of graduate students and fellows that include astrophysicists, philosophers, mathematicians, and historians—all dedicated to a deeper understanding of the universe’s least understood and most consequential celestial bodies.

 “That’s one reason that BHI exists; the concept of a black hole links so many ideas together,” he says. “For example, historians might study how scientific pictures bleed into the general populace over time, and how that transforms our collective understanding.”

Here, Chang is not speaking in the abstract. In 2019, when the Event Horizon Telescope team released a fuzzy image of a supermassive black hole in the heart of the Messier 87 galaxy, it was the first of its kind. Five years later, the team released a sharper image of the M87 black hole, augmented by greater data. Both images closely followed what astrophysicists expected to see in terms of M87’s constitution and behavior.

Herein lies the mystery of black holes: Just because the theory of relativity (or Newtonian physics, or quantum mechanics, or cosmic inflation) may suggest that a black hole will behave in a certain way, this may not accurately predict what is revealed in observation. And it is precisely this level of complexity that makes Chang love his work at BHI. “A lot of theorists tend to think they know more than they really do, because when you do theory, you’re biased by yourself. But when we take an image [of a black hole], we’re moving that bias; you’re only going to get what nature gives you,” he says.

Since coming to BHI, he has also taken on the project of converting existing 2D images of black holes into reliable 3D images, allowing the viewer to “walk around” a void in space. “We have apps that can do this in normal space. You can take a picture of a room, and it’ll give you a 3D rendering of that room,” he says. “The question is, can we do the same thing with a black hole?” His paper on this topic is currently in peer review and he expects it to be published soon. In addition to this project, Chang and his colleagues are processing new banks of data that they hope will lead to even sharper images of both M87 and Sagittarius A*, the black hole at the center of our very own Milky Way galaxy.

As he completes his doctoral work at Harvard, he faces another crossroads regarding his time at BHI. But wherever his research brings him next, he is determined to bring the theoretical nature of physics to real-world application, illustrating the point with a joke common in scientific circles: A farmer discovers that his cows have stopped producing milk and asks a physicist to explore the problem. After several months of computation, the physicist comes back with a solution, though it comes with a catch: It will only work for spherical cows in a vacuum. “Physics is full of theoretical situations, simple models that we can work with,” he said. “But the thing is, these models are actually quite good at solving real-world problems. They make physics applicable.”

In the years ahead, Chang and his colleagues will unveil more images of black holes, reaching deeper in a realm where physical laws are stretched to their limits. And when they do, our imaginations will travel with them, floating and dreaming to the event horizon and beyond.