Black Holes

Into the Heart of Darkness

Black holes, some of the most enigmatic and fascinating phenomena in the universe, are far from being mere voids in space. Imagine a star ten times the mass of the Sun, compressed into an area as small as New York City—this is the essence of a black hole. Such an extreme concentration of matter produces a gravitational pull so powerful that nothing, not even light, can escape its grasp.

Near a black hole, any object, whether a star, planet, or spacecraft, undergoes spaghettification, a process where it’s stretched and compressed. Astrophysicist Neil Degrasse Tyson vividly describes this process: “While you’re getting stretched, you’re getting squeezed—extruded through the fabric of space like toothpaste through a tube.”

NASA animation sizes up the biggest black holes

NASA animation sizes up the biggest black holes

The concept of a space object so dense that even light cannot escape dates back centuries. Albert Einstein’s theory of general relativity famously predicted the existence of black holes. It suggested that the death of a massive star leaves behind a small, dense core. If this core has a mass more than about three times the mass of the Sun, its gravitational force becomes overwhelming, creating a black hole. In contrast, smaller stars transform into dense neutron stars or white dwarfs, insufficiently massive to trap light.

Once a black hole forms, no known force can halt its collapse. The material compresses endlessly into a singularity, a point of infinite density. This singularity is surrounded by the event horizon, an invisible boundary beyond which escape is impossible. Crossing the event horizon means there’s no return, as escaping requires exceeding the speed of light, which is impossible.

Supermassive black holes, as massive as billions of suns, are believed to dwell at the center of most galaxies, including our Milky Way. Our galaxy’s center is home to Sagittarius A*  (pronounced “ay star”), a supermassive black hole over four million times the mass of our Sun, located some 26,000 light-years from Earth. In 2017, the first-ever image of Sagittarius A* was captured, marking a significant milestone in astrophysics. It was publicly released in May 2022.

The image of Sagittarius A*, captured by the Event Horizon Telescope in 2017

The image of Sagittarius A*, captured by the Event Horizon Telescope in 2017

Meet Sagittarius A*: Zooming into the black hole at the center of our galaxy

Meet Sagittarius A*: Zooming into the black hole at the center of our galaxy

Detecting black holes directly through telescopes that pick up X-rays, light, or other electromagnetic radiation is impossible. However, their presence can be inferred by observing their effects on surrounding matter. For instance, a black hole passing through a cloud of interstellar matter or drawing in a nearby star causes the captured material to accelerate and heat up, emitting X-rays detectable from Earth.

Despite their elusive nature, scientists believe the Milky Way alone could contain between ten million to a billion stellar black holes, based on the number of stars capable of producing them.

The first black hole ever identified, Cygnus X-1, was discovered within our galaxy in the constellation Cygnus, the Swan. Initially detected in 1964 through X-ray emissions, its black hole status was confirmed in 1971 when astronomers recognized that these rays were from a bright blue star and a mysterious dark object, consuming material from the star.

This image, taken by the Event Horizon Telescope, shows the M87* supermassive black hole in polarized light

This image, taken by the Event Horizon Telescope, shows the M87* supermassive black hole in polarized light

In 2019, the Event Horizon Telescope collaboration captured the first-ever image of a black hole at the center of the M87 galaxy, 55 million light-years from Earth. This historic photo, unveiled on March 24, 2021, offered a visual testament to the reality of these cosmic enigmas.

Editors’ finds

Words of wisdom

“I mean, you could claim that anything’s real if the only basis for believing in it is that nobody’s proved it doesn’t exist!” —J.K. Rowling

“Beware of the man who works hard to learn something, learns it, and finds himself no wiser than before.” —Kurt Vonnegut, Cat’s Cradle

“Never stay up on the barren heights of cleverness, but come down into the green valleys of silliness.” —Ludwig Wittgenstein

“Wasn’t friendship its own miracle, the finding of another person who made the entire lonely world seem somehow less lonely?” —Hanya Yanagihara, A Little Life

Bibliography

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