The 2020 Nobel Prize in Physics was awarded to three scientists for their discoveries on black holes. One half of the prize was awarded to Roger Penrose for his discovery that black holes are a direct result of Einstein’s theory of general relativity. The other half was awarded jointly to Andrea Ghez and Reinhard Genzel for their discovery of a supermassive object at the centre of our galaxy.
“Black hole formation is a robust prediction of the general theory of relativity”
Roger Penrose gained notoriety with Stephen Hawking in 1965 for the Penrose-Hawking singularity theorems. Together they proved that black holes are able to form and that they are to be expected if the universe is spatially closed or if there is an object undergoing a gravitational collapse. This theorem is regarded as the most important contribution to the general theory of relativity since Einstein formulated it in 1915.
Decades later, Penrose has been awarded half the Nobel Prize in Physics for more of his theoretical work on black holes. He mathematically proved that “black hole formation is a robust prediction of the general theory of relativity”.
General relativity is considered the modern theory of gravitation is physics, superseding Newton’s theory. The main idea of general relativity is that spacetime is curved when there is matter, energy, and momentum, resulting in what we perceive to be gravity. When Einstein developed his theory of general relativity, he did not believe black holes could exist, but now we have very strong evidence for their existence.
The second half of the prize was awarded to Andrea Ghez and Reinhard Genzel.
Their independent measurements both revealed a supermassive invisible object at the centre of the Milky Way
Andrea Ghez is only the fourth woman to ever win a Nobel prize in physics along with Marie Curie, Donna Strickland, and Maria Goeppert Mayer. Currently, Ghez is an astronomer and professor of physics and astronomy at the University of California at Los Angeles.
She is known for using high spatial-resolution imaging techniques to study star-forming regions and a region at the centre of the milky way known as Sagittarius A*. Since the 1990s her and her team have been observing and mapping the stars that orbit Sagittarius A* in order to characterize this extremely dynamic region of the galaxy.
Similarly, Reinhard Genzel, a German astrophysicist and professor emeritus of physics and of astronomy at the University of California Berkeley, led a team which carried out a program of observing the centre of the galaxy and its surrounding stars.
Genzel and his team developed a technique to accurately measure and precisely determine the mass and behaviour of stars orbiting the centre of the galaxy. Using some of the world’s largest telescopes they discovered an invisible object in the Sagittarius A* region with a mass of around 4 million solar masses.
Their independent measurements both revealed a supermassive invisible object at the centre of the Milky Way that pulls on stars causing them to be flung around the galactic centre. Their research has provided some of the most convincing evidence to date that there is a super massive black hole at the centre of our galaxy as predicted by Einstein’s theory of general relativity.
Featured image © Nobel Media. III. Niklas Elmehed. For strictly editorial use. No changes made to this image.
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