At the speed of light, it would take 16,000 years to reach the nearest black hole; nevertheless, those on Earth can feel the massive gravity vacuums tugging at their imaginations. How can the same laws that keep the cosmos in order allow infinite light-sucking voids the size of suns to dot the expanses of the universe? It turns out, the answers do more than just assuage curiosity; they define the very nature of the universe. On October 6, the 2020 Nobel Prize in physics was split among three of today’s top astrophysicists: Roger Penrose, Reinhard Genzel, and Andrea Ghez for uncovering some of the mysteries of black holes and paving the way to a deeper understanding of the universe.
When a massive star runs out of hydrogen, it can no longer support its own gravity and collapses into an infinitesimally dense point with an inescapable gravitational pull, known as a black hole. No force has enough power to counteract their collapse, causing the massive ball of burning gas to contract eternally, growing denser and denser without bounds even as it continues to shrink. In milliseconds all the star’s immense mass gets crammed into a sphere with a minute radius that has no mass and becomes a singularity, or a single point in space-time with infinite gravity. “Wait!” Newton cries from his grave. “That’s impossible! Physical phenomena can’t have infinities!” Einstein, on the other hand, made room for infinities in the staunch laws of physics through his theory of general relativity, which models the universe in four dimensions with gravity and motion making up the curvature of the space-time continuum. But he never believed such infinities – which would be manifested in the form of black holes – actually existed. Then, in January 1965, Roger Penrose proved that black holes not only exist but also confirm Einstein’s theory of general relativity.
Quasars, massive starlike bodies that emit exceptionally large amounts of energy, just had been discovered in the late 1950s. A few years later, Penrose began wondering if such imploding stars could form actual singularities. In the autumn of 1964, Penrose was mulling these ideas over as he walked along the London streets with his physicist friend, Ivor Robinson. Back at his office, he suddenly recalled “having an odd feeling of elation which [he] could not account for” as he crossed a bridge (Thorne). Then he realized, while walking across that bridge, he had subconsciously solved the mystery of black holes. When stars implode, they leave nothing but gravitational attraction behind, which has “settled, like a soap bubble, into the simplest configuration consistent with the external constraints:” a single point (Fletcher 27). As Penrose made clear in a famous 1965 paper, if Einstein’s equations are correct, the matter distribution of an imploded star across space-time must undergo gravitational collapse. Furthermore, if it reaches a certain critical condition (Schwarzschild’s radius, or RS = 2GM/C2), it must result in a singularity no matter how imperfect the transition may seem. Because “Einstein introduced a new way to think of gravity – not as a force but instead as an inherent response to curvatures in space-time,” the infinities associated with black holes confirm rather than contradict Einsteinian relativity (Bartusiak 28).
Black holes affect the galaxy more directly than people might think. In 2008, Reinhard Genzel and Andrea Ghez independently discovered a massive black hole at the center of the Milky Way, which defines the galaxy’s structure and the orbits of the planets and stars. Beginning in the 1990s, Genzel’s and Ghez’s teams began carefully mapping the paths of approximately forty stars near the galactic center. After years of research, both found that, instead of the typical elliptic orbits displayed by most stars, these stars were slowly tracing rosettes across the sky, “precisely what general relativity predicts for very close orbits around a black hole” (King). Furthermore, they found that the body exerting such strong gravity had to have a mass of about four million times that of the sun. Radio waves emitted near the object indicated that it was minuscule, providing even more evidence for the presence of a black hole. The Milky Way isn’t the only galaxy with a black hole at its center. In fact, Genzel and Ghez’s discovery has led scientists to believe that most galaxies form around black holes, with some being thousands of times heavier than the one determining the course of the Milky Way.
This year’s Nobel Physics Prize winners have pulled black holes from the dark, allowing human understanding to reach out and gingerly draw the most basic conclusions regarding their nature. Now their existence has been proven, with one at the center of the Milky Way pushing the planets and stars into their proper orbits. Each discovery, from relativity to the origin of black holes, makes up only a tiny drop in the vast ocean of undiscovered knowledge. Black holes reflect the complexity and power of the rest of the universe. Because the all-knowing, all-powerful God perfectly pieced the universe together, grasping even a rudimentary knowledge of a minute portion of its construction boggles the mind.
Bartusiak, Marcia. Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled on by Hawking Became Loved. Yale University Press, 2015.
Fletcher, Seth. Einstein’s Shadow: A Black Hole, a Band of Astronomers, and the Quest to See the Unseeable. HarperCollins Publishers, 2018.
King, Andrew. “Nobel Prize: How Penrose, Genzel and Ghez Helped Put Black Holes at the Centre of Modern Astrophysics .” The Conversation, The Conversation, 7 Oct. 2020, 10:10 EDT, theconversation.com/nobel-prize-how-penrose-genzel-and-ghez-helped-put-black-holes-at-the-centre-of-modern-astrophysics-147613. Accessed 18 October 2020.
Penrose, Roger. “Gravitational Collapse and Space-Time Singularities.” Birkbeck College, 18 Jan. 1965.
Thorne, Kip S. Black Holes and Time Warps: Einstein’s Outrageous Legacy. Macmillan Publishers, 1995.
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