Briton Roger Penrose received half of this year's prize "for the discovery that black hole formation is a robust prediction of the general theory of relativity," the Nobel Committee said.
German Reinhard Genzel and American Andrea Ghez received the second half of the prize "for the discovery of a supermassive compact object at the center of our galaxy."
The prize celebrates "one of the most exotic objects in the universe," black holes, which have become a staple of science fact and science fiction and where time seems to stand still, according to the committee.
Black holes are perhaps the most mysterious and powerful objects in astronomy. They are at the center of every galaxy, and smaller ones are dotted around the universe. Nothing, not even light, can escape their incredible gravity. They are the ultimate cosmic dead end.
"Black holes, because they are so hard to understand, is what makes them so appealing,'' Ghez told The Associated Press Tuesday morning. "I really think of science as a big, giant puzzle."
Penrose proved with mathematics that the formation of black holes was possible, based heavily on Albert Einstein's general theory of relativity.
"Einstein did not himself believe that black holes really exist, these super-heavyweight monsters that capture everything that enters them," the committee said. "Nothing can escape, not even light."
Penrose's detailed his studies in 1965, but it wasn't until the 1990s that Reinhard Genzel and Andrea Ghez, each leading a group of astronomers, trained their sights on the dust-covered center of our Milky Way galaxy, a region called Sagittarius A(asterisk), where something strange was going on.
They both found that there was "an extremely heavy, invisible object that pulls on the jumble of stars, causing them to rush around at dizzying speeds."
It was a black hole. Not just an ordinary black hole, but a supermassive black hole, 4 million times the mass of our sun.
Now scientists know that all galaxies have supermassive black holes.
In 2019, scientists got the first optical image of a black hole, and Ghez, who was not involved, praised the discovery.
"Today we accept these objects are critical to the building blocks of the universe," Ghez told an audience at the Royal Swedish Academy of Sciences by phone shortly after the announcement.
Ghez is the fourth woman to be awarded the Nobel Prize for physics, after Marie Curie in 1903, Maria Goeppert-Mayer in 1963, and Donna Strickland in 2018.
"I hope I can inspire other young women into the field. It's a field that has so many pleasures. And if you're passionate about the science, there's so much that can be done," Ghez said.
The Nobel Committee said black holes "still pose many questions that beg for answers and motivate future research."
"Not only questions about their inner structure, but also questions about how to test our theory of gravity under the extreme conditions in the immediate vicinity of a black hole," it said.
It is common for several scientists who worked in related fields to share the prize. Last year's prize went to Canadian-born cosmologist James Peebles for theoretical work about the early moments after the Big Bang, and Swiss astronomers Michel Mayor and Didier Queloz for discovering a planet outside our solar system.
The prestigious award comes with a gold medal and prize money of 10 million Swedish kronor (more than $1.1 million), courtesy of a bequest left 124 years ago by the prize's creator, Swedish inventor Alfred Nobel. The amount was increased recently to adjust for inflation.
On Monday, the Nobel Committee awarded the prize for physiology and medicine to Americans Harvey J. Alter and Charles M. Rice and British-born scientist Michael Houghton for discovering the liver-ravaging hepatitis C virus.
The other prizes, to be announced in the coming days, are for outstanding work in the fields of chemistry, literature, peace and economics.
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