Yale astrophysicist maps the cosmos: unlocking black holes and dark matter

In 2019, humanity got its first photograph of a black hole—a direct image of something that had existed only in mathematics and theory for more than four decades. Yet the moment we saw one, we realized how little we actually understand about them. Their properties remain bizarre and counterintuitive. Their role in the universe is still largely mysterious. Priya Natarajan, a theoretical astrophysicist at Yale, has spent her career chasing these enigmas, and she brings to the work a perspective that stretches from ancient stargazers to modern physics.

Natarajan delivered the fifth annual Dan MacLennan Memorial Lecture in Astronomy at St. Mary's University in Halifax, Nova Scotia, drawing on her book Mapping the Heavens: The Radical Scientific Ideas That Revealed the Cosmos, published by Yale University Press. "One of the reasons I love black holes and I'm drawn to them is because they represent the limit of human knowledge," she said. That framing—black holes as a frontier of what we don't know—sits at the heart of her work and her thinking about how science progresses.

Our cosmic map has transformed radically in just over a century. In 1914, the Milky Way was thought to be the entire universe: isolated, unchanging, small. Cosmology still operated within gravity as Newton had described it in the seventeenth century. Today we understand the universe as dynamic and expanding at an accelerating rate. We have detected planets orbiting distant stars. We debate whether other universes exist. And yet the ordinary matter that makes up stars, planets, and us—all the elements in the periodic table—accounts for only 4 percent of the universe's total inventory. The remaining 96 percent consists of dark matter and dark energy, both invisible, both still poorly understood.

Natarajan traces this scientific journey back to its roots in human mythology and observation. Ancient peoples looked at the sky and saw the actions of gods—Enki, the Sumerian water deity whose anger brought floods; Indra, the Hindu storm god whose bow was the rainbow. These were not mere stories. They were humanity's first attempt to explain the invisible forces that governed natural phenomena, to locate ourselves within a cosmos that seemed to operate by rules we could not see. The ancients made maps of the heavens, and though their explanations were supernatural, their method was sound: they watched, they recorded, they predicted. That tradition of observation—of taking data from the night sky—became the foundation for astronomy itself.

Natarajan's own path to astrophysics began in Delhi, where she was captivated by the Encyclopedia Britannica on her parents' shelf. She became transfixed by maps—ancient maps, maps of exploration, maps of the sky. As a teenager, she programmed a Commodore 64 to generate monthly sky maps for a Delhi newspaper. That early work was her first taste of scientific research, and it kindled a love of discovery that has never left her. She studied physics and mathematics at MIT, then moved to Cambridge for her Ph.D. in astrophysics. Her training in the history and philosophy of science runs parallel to her work as a practicing researcher, informing how she thinks about the process of discovery itself.

Today, Natarajan's research focuses on two interconnected mysteries: mapping dark matter and understanding how black holes form and grow. She uses gravitational lensing—the bending of light from distant galaxies caused by the presence of massive objects—to trace the invisible scaffolding of dark matter that structures the universe. Black holes, those bizarre and enigmatic objects, remain central to her inquiry. She is looking for gaps in our current models, hints of physics yet to be detected. In doing so, she is engaged in the same fundamental human project that moved the ancients: the search to explain the universe and to understand our place within it. The invisible, she notes, has always held her attention. It still does.