The 2020 Nobel Prize in Physics has been awarded to three researchers—Roger Penrose, Reinhard Genzel, and Andrea Ghez—for work leading to the discovery of black holes, regions in space imbued with such intense gravity that even light cannot escape from them. The discovery profoundly changed scientists’ understanding of the physical structure of galaxies such as the Milky Way.
In work dating back to the 1960s, Penrose, based at the University of Oxford, developed mathematical tools that proved that black holes are directly predicted by Albert Einstein’s general theory of relativity. Until then, they were considered mathematical curiosities, and even Einstein didn’t believe they really existed.
Genzel, who holds positions at the Max Planck Institute for Extraterrestrial Physics and at the University of California, Berkeley, and Ghez of the University of California, Los Angeles, each headed research groups in the 1990s that trained their telescopes on stars at the center of our galaxy, the Milky Way. By painstakingly analyzing the movements of these distant stars, the teams determined that the stars were orbiting an extremely massive invisible object, thereby providing experimental evidence—albeit indirect evidence—of the existence of black holes.
Since then, several other research advances, including the detection of gravitational waves in 2015, have added further experimental evidence for the existence of these supermassive celestial objects.
“Black holes are gravity at its most powerful, so they test our knowledge of gravity to its limits,” says Andrew Liddle, an astrophysicist at the University of Lisbon. Originally, black holes were mainly considered theoretical phenomena, Liddle explains. “It was Roger Penrose’s pioneering work that showed that they should also exist in reality, all around us in the universe. Indeed, his work made their reality seem almost inevitable.” Liddle adds that “the stunning results” of Genzel, Ghez, and their teams “showed that they really are there, our own Milky Way hosting a splendid supermassive black hole with a mass of over one million suns.”
Speaking by phone at the Nobel press conference, Ghez remarked that “we have no idea what’s inside a black hole. That’s what makes these things such exotic objects. It’s part of the intrigue.” Noting that she was just the fourth woman to become a Physics Nobel Laureate, Ghez said “I hope I can inspire other young women [to go] into the field. If you are passionate about science, there is so much that can be done.”
Half of the roughly $1.1 million prize money will go to Penrose. The other half will be shared by Genzel and Ghez. As a result of the COVID-19 pandemic, the usual Nobel Prize ceremony, typically scheduled for December in Stockholm, will be replaced with a virtual event.
UPDATE: This story was updated on Oct. 6, 2020, to include additional comments and art.