By Naser Al Wasmi, NYU Abu Dhabi Public Affairs
Dark matter’s absenteeism has vexed the scientific community, and mocked the widespread consensus that the existence of the universe’s dark constituents is all but a forgone conclusion. Its elusiveness is made more puzzling considering that, according to the most fundamental laws of physics that define gravity and energy, it not only exists but accounts for 85 percent of all matter in the universe.
As an associate professor and program head of physics at NYU Abu Dhabi, Macciò lives in a high-risk, high-reward world. Dark matter has the biggest target on its back in the world of science. The reward for its discovery: an almost guaranteed Nobel Prize. But its existence has never been directly detected by scientists. Despite that, Macciò remains committed to the scientific process, never letting the allure of glory nor the fear of failure deter him from his research.
His work revolves around the cold dark matter theory, with cold being a measure of velocity and not temperature. Among his peers, he’s known as the lawyer of Cold Dark Matter, responsible for defending the theory’s impenetrable adherence to scientific logic. Time and time again, discoveries made in his field believed to undermine the entire theory have been disproven and brought closer to work within its system. It’s a gravity that both reassures those working in the field of astrophysics but also irks them. Macciò’s adherence to truth is just a stalwart as the theory has proved itself to be, and his approach is clinical if not a bit unorthodox for what society perceives as astronomers looking ever upward.
“I’ve never owned a telescope in my life,” he says. Instead, Macciò recreates the universe on his desk, studying the laws that define its existence in a supercomputer simulation of the universe. He then probes in the dark to find some evidence of this enigma that has kept astrophysicists in a frantic hunt for its existence. Despite the lack of results in the last ten years, scientists working in this field point to the fundamental laws of physics and how they all strongly suggest dark matters existence.
It’s like magic, he says.
“A magician takes a card, they make you sign it, they rip it apart, they set it on fire, and the exact same card comes out of the pocket of the person sitting next to you. Now you have two options: to say he’s a true magician or you say it’s a trick. Of course, we know it’s a trick, but if I asked you what is the trick, you wouldn’t know, you can’t tell me. But why do you know there’s a trick? Because you know that there are certain laws of physics that cannot be violated. The same applies to dark matter.”
The evidence of our universe’s darker side, he says, are in the stars; it’s the movement of galaxies that makes scientists so dead-set on the existence of dark matter. Stars on the outer layer of a galaxy should, in theory, travel slower than those closer to the center of the galaxy. It was it observed with planets in our solar system. But astronomists observed both speeds as constant regardless of their proximity, indicating that the larger distance from the center of external stars is compensated by the presence of unseen mass."
Astrophysics remains one of the most nascent fields in science. As it stands today, 96 percent of the universe is still unknown, leaving much for astrophysicists to discover. It’s somewhat of a rockstar lifestyle in the world of science, and early in his career, Macciò experienced firsthand the blazing pace of his field.
As a young post-graduate student, Macciò had just finished his mandatory military service in Italy and was eager to return to his research in astrophysics when he found out that his world had changed. He had been away for less than a year but the theory of the accelerating expansion of the universe had been further validated, pushing it to the forefront of the field and outdating the thesis he submitted right before enrolling. The new theory was elegant, universe-defining, and apt for a field that was changing at the speed of light.
It was 1999 and astrophysics was in its nascency — perfect for a young academic in an exciting field. He began his PhD with an insatiable appetite for knowledge. His work progressed rapidly as physicists made one academic breakthrough after another, until he found himself at the very vanguard of discovery. He was a scientist standing at the edge of the known deep space literally looking into the darkness for answers. The last 20 years Macciò has continued that search to answer one of humanity’s most fundamental questions: How did the universe form?
Despite the initial excitement and the endless possibilities in the field, astrophysics, and in particular the pursuit for evidence of dark matter, is not for the faint of heart. Progress has slowed, and working in a field that has fallen short on finding the Holy Grail of astrophysics leaves even those in the top of their field with some uncomfortable questions.
“I really hope the next thing is going to be dark matter, because I’ve spent 20 years working on dark matter and sometimes in the back of my mind, I have some kind of terror that says ‘What if, what if we have completely misunderstood reality.’ Maybe that’s my biggest fear, that maybe in 10 years I’ll be told there’s no dark matter, it’s something completely different, and I’ll realize I spent all my efforts trying to find something that isn’t there.”
Failure to detect dark matter isn’t for lack of trying. At the Max Planck institute, a German-funded research institute home to 33 Nobel prize laureates, Macciò headed a lab named “Galaxy Formation in a Dark Universe” comprised of a group of world-leading scientists standing at the edge of the known universe looking for clues.
What if we have completely misunderstood reality?
At NYUAD he heads the physics program and leads a research center that is taking interdisciplinary stabs at these questions. He, along with some of his peers around the world, have been relentless in their pursuit of understanding dark matter.
It’s Macciò’s curiosity that keeps him searching — an attribute he says has driven him his entire life. As a child growing up in Italy, he was fascinated by questioning certain natural phenomenon. When the seasons turned he wondered why winter or summer occur, on a bike he questioned how he remained upright, and while playing football he pondered on why each subsequent bounce was less energetic than the first: it’s this natural curiosity that drove him to learn the mysteries of the universe. And now, it’s that attribute that has made him such a staunch researcher in the field.
“Of all the things I want to know how they work; the universe is the biggest thing. If you understand how the universe works, there’s a good chance that knowledge would cascade on us from above,” he says.